1.\" $NetBSD: options.4,v 1.479 2018/01/10 18:13:29 maxv Exp $ 2.\" 3.\" Copyright (c) 1996 4.\" Perry E. Metzger. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgment: 16.\" This product includes software developed for the NetBSD Project 17.\" by Perry E. Metzger. 18.\" 4. The name of the author may not be used to endorse or promote products 19.\" derived from this software without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31.\" 32.\" 33.Dd January 10, 2018 34.Dt OPTIONS 4 35.Os 36.Sh NAME 37.Nm options 38.Nd Miscellaneous kernel configuration options 39.Sh SYNOPSIS 40.Cd cinclude ... 41.Cd config ... 42.Cd [no] file-system ... 43.Cd ident ... 44.Cd include ... 45.Cd [no] makeoptions ... 46.Cd maxusers ... 47.Cd [no] options ... 48.Cd [no] pseudo-device ... 49.Sh DESCRIPTION 50This manual page describes a number of miscellaneous kernel 51configuration options that may be specified in a kernel config 52file. 53See 54.Xr config 1 55and 56.Xr config 5 57for information on how to configure and build kernels. 58.Pp 59The 60.Ar no 61form removes a previously specified option. 62.Ss Keywords 63The following keywords are recognized in a kernel configuration file: 64.Bl -ohang 65.It Sy cinclude Qq Ar filename 66Conditionally includes another kernel configuration file whose name is 67.Ar filename , 68which may be double-quoted and may be an explicit path or relative to 69the kernel source directory. 70Failure to open the named file is ignored. 71.It Sy config Ar exec_name No root on Ar rootdev Oo type Ar fstype Oc \ 72Oo dumps on Ar dumpdev Oc 73Defines a configuration whose kernel executable is named 74.Ar exec_name , 75normally 76.Dq netbsd , 77with its root file system of type 78.Ar fstype 79on the device 80.Ar rootdev , 81and optionally specifying the location of kernel core dumps on the device 82.Ar dumpdev . 83.Ar dev 84or 85.Ar dumpdev 86and 87.Ar fstype 88may be specified as 89.Dq \&? , 90which is a wild card. 91The root 92.Ar fstype 93and 94.Ar dumpdev 95are optional and assumed to be wild carded if they are not specified. 96.It Ar device_instance No at Ar attachment \ 97Oo Ar locators value Oo ... Oc Oc Oo flags Ar value Oc 98Define an instance of the device driver 99.Ar device_instance 100that attaches to the bus or device named 101.Ar attachment . 102An 103.Ar attachment 104may require additional information on where the device can be found, such 105as an address, channel, function, offset, and/or slot, referred to as 106.Ar locators , 107whose 108.Ar value 109often may be a wild card, 110.Dq \&? . 111Some device drivers have one or more 112.Ar flags 113that can be adjusted to affect the way they operate. 114.It Sy file-system Ar fs_name Op , Ar fs_name Op ... 115Include support for the file-system 116.Ar fs_name . 117.It Sy ident Qq Ar string 118Sets the kernel identification string to 119.Ar string . 120.It Sy include Qq Ar filename 121Functions the same as 122.Ar cinclude , 123except failure to open 124.Ar filename 125produces a fatal error. 126.It Sy options Ar option_name Op , Ar option_name=value Op ... 127Specifies (or sets) the option, or comma-separated list of options, 128.Ar option_name . 129Some options expect to be assigned a value, which may be an integer, 130a double-quoted word, a bare word, or an empty string 131.Pq Qq . 132Note that those are eventually handled by the C compiler, so the rules 133of that language apply. 134.Pp 135.Em Note : 136Options that are not defined by device definition files are passed to 137the compile process as 138.Fl D 139flags to the C compiler. 140.It Sy makeoptions Ar name=value 141Defines a 142.Xr make 1 143macro 144.Ar name 145with the value 146.Ar value 147in the kernel Makefile. 148.It Sy maxusers Ar integer 149Set the maxusers variable in the kernel. 150.It Sy no Ar keyword Ar name Op Ar arguments Op ... 151For the 152.Xr config 1 153.Ar keywords 154file-system, makeoptions, options, and pseudo-device, 155.Ar no 156removes the file-system, makeoption, options, or pseudo-device, 157.Ar name . 158This is useful when a kernel configuration file includes another which 159has undesired options. 160.Pp 161For example, a local configuration file that wanted the kitchen sink, but 162not COMPAT_09 or bridging, might be: 163.Bd -literal -offset indent 164include "arch/i386/conf/GENERIC" 165no options COMPAT_09 166no pseudo-device bridge 167.Ed 168.It Sy pseudo-device Ar name Op Ar N 169Includes support for the pseudo-device 170.Ar name . 171Some pseudo-devices can have multiple or 172.Ar N 173instances. 174.El 175.Ss Compatibility Options 176Note that compatibility options for older 177.Nx 178releases includes support for newer releases as well. 179This means that typically only one of these is necessary, with the 180.Cd COMPAT_09 181option enabling all 182.Nx 183compatibility. 184This does not include the 185.Cd COMPAT_43 186or 187.Cd COMPAT_44 188options. 189.Bl -ohang 190.It Cd options COMPAT_09 191Enable binary compatibility with 192.Nx 0.9 . 193This enables support for 19416-bit user, group, and process IDs (following revisions support 19532-bit identifiers). 196It also allows the use of the deprecated 197.Xr getdomainname 3 , 198.Xr setdomainname 3 , 199and 200.Xr uname 3 201syscalls. 202This option also allows using numeric file system identifiers rather 203than strings. 204Post 205.Nx 0.9 206versions use string identifiers. 207.It Cd options COMPAT_10 208Enable binary compatibility with 209.Nx 1.0 . 210This option allows the use of the file system name of 211.Dq ufs 212as an alias for 213.Dq ffs . 214The name 215.Dq ffs 216should be used post 1.0 in 217.Pa /etc/fstab 218and other files. 219It also adds old syscalls for the 220.At V 221shared memory interface. 222This was changed post 1.0 to work on 64-bit architectures. 223This option also enables 224.Dq sgtty 225compatibility, without which programs using the old interface produce 226an 227.Dq inappropriate ioctl 228error, and 229.Pa /dev/io 230only works when this option is set in the kernel, 231see 232.Xr io 4 233on ports that support it. 234.It Cd options COMPAT_11 235Enable binary compatibility with 236.Nx 1.1 . 237This allows binaries running on the i386 port to gain direct access to 238the io ports by opening 239.Pa /dev/io 240read/write. 241This functionality was replaced by 242.Xr i386_iopl 2 243post 1.1. 244On the Atari port, the location of the disk label was moved after 1.1. 245When the 246.Em COMPAT_11 247option is set, the kernel will read (pre) 1.1 style disk labels as a 248last resort. 249When a disk label is re-written, the old style label will be replaced 250with a post 1.1 style label. 251This also enables the 252.Em EXEC_ELF_NOTELESS 253option. 254.It Cd options COMPAT_12 255Enable binary compatibility with 256.Nx 1.2 . 257This allows the use of old syscalls for 258.Fn reboot 259and 260.Fn swapon . 261The syscall numbers were changed post 1.2 to add functionality to the 262.Xr reboot 2 263syscall, and the new 264.Xr swapctl 2 265interface was introduced. 266This also enables the 267.Em EXEC_ELF_NOTELESS 268option. 269.It Cd options COMPAT_13 270Enable binary compatibility with 271.Nx 1.3 . 272This allows the use of old syscalls for 273.Fn sigaltstack , 274and also enables the old 275.Xr swapctl 2 276command 277.Dv SWAP_STATS 278(now called 279.Dv SWAP_OSTATS ) , 280which does not include the 281.Fa se_path 282member of 283.Va struct swapent . 284.It Cd options COMPAT_14 285Enable binary compatibility with 286.Nx 1.4 . 287This allows some old 288.Xr ioctl 2 289on 290.Xr wscons 4 291to be performed, and allows the 292.Dv NFSSVC_BIOD 293mode of the 294.Xr nfssvc 2 295system call to be used for compatibility with the deprecated nfsiod program. 296.It Cd options COMPAT_15 297Enable binary compatibility with 298.Nx 1.5 . 299Since there were no API changes from 300.Nx 1.5 301and 302.Nx 1.6 , 303this option does nothing. 304.It Cd options COMPAT_16 305Enable binary compatibility with 306.Nx 1.6 . 307This allows the use of old signal trampoline code which has been deprecated 308with the addition of 309.Xr siginfo 2 . 310.It Cd options COMPAT_20 311Enable binary compatibility with 312.Nx 2.0 . 313This allows the use of old syscalls for 314.Fn statfs , 315.Fn fstatfs , 316.Fn getfsstat 317and 318.Fn fhstatfs , 319which have been deprecated with the addition of the 320.Xr statvfs 2 , 321.Xr fstatvfs 2 , 322.Xr getvfsstat 2 323and 324.Xr fhstatvfs 2 325system calls. 326.It Cd options COMPAT_30 327Enable binary compatibility with 328.Nx 3.0 . 329See 330.Xr compat_30 8 331for details about the changes made after the 332.Nx 3.0 333release. 334.It Cd options COMPAT_40 335Enable binary compatibility with 336.Nx 4.0 . 337This allows the use of old 338.Xr ptrace 2 339calls for the SH3 platform. 340It also enables the old 341.Xr mount 2 342system call that did not include the data length parameter. 343The power_event_t structure's pev_switch is filled in. 344.It Cd options COMPAT_43 345Enables compatibility with 346.Bx 4.3 . 347This adds an old syscall for 348.Xr lseek 2 . 349It also adds the ioctls for 350.Dv TIOCGETP 351and 352.Dv TIOCSETP . 353The return values for 354.Xr getpid 2 , 355.Xr getgid 2 , 356and 357.Xr getuid 2 358syscalls are modified as well, to return the parent's PID and 359UID as well as the current process's. 360It also enables the deprecated 361.Dv NTTYDISC 362terminal line discipline. 363It also provides backwards compatibility with 364.Dq old 365SIOC[GS]IF{ADDR,DSTADDR,BRDADDR,NETMASK} interface ioctls, including 366binary compatibility with code written before the introduction of the 367sa_len field in sockaddrs. 368It also enables 369support for some older pre 370.Bx 4.4 371socket calls. 372.It Cd options COMPAT_50 373Enable binary compatibility with 374.Nx 5.0 . 375This enables support for the old 376.Ft time_t 377and 378.Ft dev_t 379types as 32 bit, and all the associated kernel interface changes. 380It also enables old 381.Xr gpio 4 382and 383.Xr rnd 4 384interfaces. 385.It Cd options COMPAT_60 386Enable binary compatibility with 387.Nx 6.0 . 388This provides old 389.Xr ccd 4 390interfaces, enables support for old 391.Xr cpuctl 8 392microcode interfaces, and support for the old 393.Ft ptmget 394structure. 395.It Cd options COMPAT_70 396Enable binary compatibility with 397.Nx 7.0 . 398This provides support for old 399.Xr route 4 400interfaces. 401.It Cd options COMPAT_BSDPTY 402This option is currently on by default and enables the pty multiplexer 403.Xr ptm 4 404and 405.Xr ptmx 4 406to find and use ptys named 407.Pa /dev/ptyXX 408(master) and 409.Pa /dev/ttyXX 410(slave). 411Eventually this option will become optional as ptyfs based pseudo-ttys become 412the default, see 413.Xr mount_ptyfs 8 . 414.It Cd options COMPAT_SVR4 415On those architectures that support it, this enables binary 416compatibility with 417.At V.4 418applications built for the same architecture. 419This currently includes the m68k and sparc ports. 420.It Cd options COMPAT_LINUX 421On those architectures that support it, this enables binary 422compatibility with Linux ELF and 423.Xr a.out 5 424applications built for the same architecture. 425This currently includes the alpha, arm, i386, m68k, mips, powerpc and 426x86_64 ports. 427.It Cd options COMPAT_LINUX32 428On those 64 bit architectures that support it, this enables binary 429compatibility with 32 bit Linux binaries. 430For now this is limited to running i386 ELF Linux binaries on amd64. 431.It Cd options COMPAT_SUNOS 432On those architectures that support it, this enables binary 433compatibility with SunOS 4.1 applications built for the same architecture. 434This currently includes the sparc, sparc64 and most or all m68k ports. 435Note that the sparc64 requires the 436.Em COMPAT_NETBSD32 437option for 64-bit kernels, in addition to this option. 438.It Cd options COMPAT_ULTRIX 439On those architectures that support it, this enables binary 440compatibility with ULTRIX applications built for the same architecture. 441This currently is limited to the pmax. 442The functionality of this option is unknown. 443.It Cd options COMPAT_FREEBSD 444On those architectures that support it, this enables binary 445compatibility with 446.Fx 447applications built for the same architecture. 448At the moment this is limited to the i386 port. 449.It Cd options COMPAT_IBCS2 450On those architectures that support it, this enables binary 451compatibility with iBCS2 or SVR3 applications built for the same architecture. 452This is currently limited to the i386 and vax ports. 453.It Cd options COMPAT_OSF1 454On those architectures that support it, this enables binary 455compatibility with Digital 456.Ux 457(formerly OSF/1) 458applications built for the same architecture. 459This is currently limited to the alpha port. 460.It Cd options COMPAT_NOMID 461Enable compatibility with 462.Xr a.out 5 463executables that lack a machine ID. 464This includes 465.Nx 0.8 Ns 's 466ZMAGIC format, and 386BSD and BSDI's 467QMAGIC, NMAGIC, and OMAGIC 468.Xr a.out 5 469formats. 470.It Cd options COMPAT_NETBSD32 471On those architectures that support it, this enables binary 472compatibility with 32-bit applications built for the same architecture. 473This is currently limited to the amd64 and sparc64 ports, and only 474applicable for 64-bit kernels. 475.It Cd options COMPAT_SVR4_32 476On those architectures that support it, this enables binary 477compatibility with 32-bit SVR4 applications built for the same architecture. 478This is currently limited to the sparc64 port, and only applicable for 47964-bit kernels. 480.It Cd options COMPAT_AOUT_M68K 481On m68k architectures which have switched to ELF, 482this enables binary compatibility with 483.Nx Ns /m68k 484.Xr a.out 5 485executables on 486.Nx Ns /m68k 487ELF kernels. 488This handles alignment incompatibility of m68k ABI between 489a.out and ELF which causes the structure padding differences. 490Currently only some system calls which use 491.Va struct stat 492are adjusted and some binaries which use 493.Xr sysctl 3 494to retrieve network details would not work properly. 495.It Cd options EMUL_NATIVEROOT=string 496Just like emulated binaries first try looking up files in 497an emulation root (e.g. 498.Pa /emul/linux ) 499before looking them up in real root, this option causes native 500binaries to first look up files in an "emulation" directory too. 501This can be useful to test an amd64 kernel on top of an i386 system 502before full migration: by unpacking the amd64 distribution in e.g. 503.Pa /emul/netbsd64 504and specifying that location as 505.Cd EMUL_NATIVEROOT , 506native amd64 binaries can be run while the root file system remains 507populated with i386 binaries. 508Beware of 509.Pa /dev 510incompatibilities between i386 and amd64 if you do this. 511.It Cd options EXEC_ELF_NOTELESS 512Run unidentified ELF binaries as 513.Nx 514binaries. 515This might be needed for very old 516.Nx 517ELF binaries on some archs. 518These old binaries didn't contain an appropriate 519.Li .note.netbsd.ident 520section, and thus can't be identified by the kernel as 521.Nx 522binaries otherwise. 523Beware - if this option is on, the kernel would run 524.Em any 525unknown ELF binaries as if they were 526.Nx 527binaries. 528.El 529.Ss Debugging Options 530.Bl -ohang 531.It Cd options DDB 532Compiles in a kernel debugger for diagnosing kernel problems. 533See 534.Xr ddb 4 535for details. 536.Em NOTE : 537not available on all architectures. 538.It Cd options DDB_FROMCONSOLE=integer 539If set to non-zero, DDB may be entered by sending a break on a serial 540console or by a special key sequence on a graphics console. 541A value of "0" ignores console breaks or key sequences. 542If not explicitly specified, the default value is "1". 543Note that this sets the value of the 544.Em ddb.fromconsole 545.Xr sysctl 3 546variable which may be changed at run time -- see 547.Xr sysctl 8 548for details. 549.It Cd options DDB_HISTORY_SIZE=integer 550If this is non-zero, enable history editing in the kernel debugger 551and set the size of the history to this value. 552.It Cd options DDB_ONPANIC 553The default if not specified is 554.Dq 1 555- just enter into DDB. 556If set to 557.Dq 2 558the kernel will 559attempt to print out a stack trace before entering into DDB. 560If set to 561.Dq 0 562the kernel will attempt to print out a stack trace 563and reboot the system. 564If set to 565.Dq -1 566then neither a stack trace is printed or DDB entered - 567it is as if DDB were not compiled into the kernel. 568Note that this sets the value of the 569.Em ddb.onpanic 570.Xr sysctl 3 571variable which may be changed at run time -- see 572.Xr sysctl 8 573for details. 574.It Cd options DDB_COMMANDONENTER=string 575This option specify commands which will be executed on each entry to DDB. 576This sets the default value of the 577.Em ddb.commandonenter 578.Xr sysctl 3 579variable which may be changed at run time. 580.It Cd options DDB_BREAK_CHAR=integer 581This option overrides using break to enter the kernel debugger 582on the serial console. 583The value given is the ASCII value to be used instead. 584This is currently only supported by the com driver. 585.It Cd options DDB_VERBOSE_HELP 586This option adds more verbose descriptions to the 587.Em help 588command. 589.It Cd options DDB_PANICSTACKFRAMES=integer 590Number of stack frames to display on panic. 591Useful to avoid scrolling away the interesting frames on a glass tty. 592Default value is 593.Dv 65535 594(all frames), useful value around 595.Dv 10 . 596.It Cd options KGDB 597Compiles in a remote kernel debugger stub for diagnosing kernel problems 598using the 599.Dq remote target 600feature of gdb. 601See 602.Xr gdb 1 603for details. 604.Em NOTE : 605not available on all architectures. 606.It Cd options KGDB_DEV 607Device number 608.Po 609as a 610.Dv dev_t 611.Pc 612of kgdb device. 613.It Cd options KGDB_DEVADDR 614Memory address of kgdb device. 615.It Cd options KGDB_DEVMODE 616Permissions of kgdb device. 617.It Cd options KGDB_DEVNAME 618Device name of kgdb device. 619.It Cd options KGDB_DEVRATE 620Baud rate of kgdb device. 621.It Cd makeoptions DEBUG="-g" 622The 623.Fl g 624flag causes 625.Pa netbsd.gdb 626to be built in addition to 627.Pa netbsd . 628.Pa netbsd.gdb 629is useful for debugging kernel crash dumps with gdb. 630See 631.Xr gdb 1 632for details. 633This also turns on 634.Em options DEBUG 635(which see). 636.It Cd options DEBUG 637Turns on miscellaneous kernel debugging. 638Since options are turned into preprocessor defines (see above), 639.Em options DEBUG 640is equivalent to doing a 641.Em #define DEBUG 642throughout the kernel. 643Much of the kernel has 644.Em #ifdef DEBUG 645conditionalized debugging code. 646Note that many parts of the kernel (typically device drivers) include their own 647.Em #ifdef XXX_DEBUG 648conditionals instead. 649This option also turns on certain other options, 650which may decrease system performance. 651Systems with this option are not suitable for regular use, and are 652intended only for debugging or looking for bugs. 653.It Cd options DIAGNOSTIC 654Adds code to the kernel that does internal consistency checks. 655This code will cause the kernel to panic if corruption of internal data 656structures is detected. 657Historically, the performance degradation is sufficiently small that 658it is reasonable for systems with 659.Em options DIAGNOSTIC 660to be in production use, with the real consideration not being 661performance but instead a preference for more panics versus continued 662operation with undetected problems. 663.It Cd options LOCKDEBUG 664Adds code to the kernel to detect incorrect use of locking primitives 665(mutex, rwlock). 666This code will cause the kernel to check for dead lock conditions. 667It will also check for memory being freed to not contain initialised 668lock primitives. 669Functions for use in 670.Xr ddb 4 671to check lock chains etc. are also enabled. 672These checks are very expensive and can decrease performance on 673multi-processor machines by a factor of three. 674.It Cd options KDTRACE_HOOKS 675Adds hooks for the DTrace tracing facility, which allows users to 676analyze many aspects of system and application behavior. 677See 678.Xr dtrace 1 679for details. 680.It Cd options KSTACK_CHECK_MAGIC 681Check kernel stack usage and panic if stack overflow is detected. 682This check is performance sensitive because it scans stack on each context 683switch. 684.It Cd options KTRACE 685Add hooks for the system call tracing facility, which allows users to 686watch the system call invocation behavior of processes. 687See 688.Xr ktrace 1 689for details. 690.It Cd options MSGBUFSIZE=integer 691This option sets the size of the kernel message buffer. 692This buffer holds the kernel output of 693.Fn printf 694when not (yet) read by 695.Xr syslogd 8 . 696This is particularly useful when the system has crashed and you wish to lookup 697the kernel output from just before the crash. 698Also, since the autoconfig output becomes more and more verbose, 699it sometimes happens that the message buffer overflows before 700.Xr syslogd 8 701was able to read it. 702Note that not all systems are capable of obtaining a variable sized message 703buffer. 704There are also some systems on which memory contents are not preserved 705across reboots. 706.It Cd options KERNHIST 707Enables the kernel history logs, which create in-memory traces of 708various kernel activities. 709These logs can be displayed by using 710.Cm show kernhist 711from DDB. 712See the kernel source file 713.Pa sys/kern/kern_history.c 714and the 715.Xr kernhist 9 716manual for details. 717.It Cd options KERNHIST_PRINT 718Prints the kernel history logs on the system console as entries are added. 719Note that the output is 720.Em extremely 721voluminous, so this option is really only useful for debugging 722the very earliest parts of kernel initialization. 723.It Cd options UVMHIST 724Like 725.Em KERNHIST , 726it enables the UVM history logs. 727These logs can be displayed by using 728.Cm show kernhist 729from DDB. 730See the kernel source file 731.Pa sys/uvm/uvm_stat.c 732for details. 733.It Cd options UVMHIST_PRINT 734Like 735.Em UVMHIST , 736it prints the UVM history logs on the system console as entries are added. 737Note that the output is 738.Em extremely 739voluminous, so this option is really only useful for debugging 740the very earliest parts of kernel initialization. 741.It Cd options UVMHIST_MAPHIST_SIZE 742Set the size of the 743.Dq maphist 744kernel history. 745The default is 100. 746This option depends upon the 747.Em UVMHIST 748option. 749.It Cd options UVMHIST_PDHIST_SIZE 750Set the size of the 751.Dq pdhist 752kernel history. 753The default is 100. 754This option depends upon the 755.Em UVMHIST 756option. 757.It Cd options BIOHIST 758Like 759.Em KERNHIST , 760it enables the BIO history logs. 761These logs can be displayed by using 762.Cm show kernhist 763from DDB, and can help in debugging problems with Buffered I/O operations. 764See the kernel source file 765.Pa sys/kern/vfs_vio.c 766for details. 767.It Cd options BIOHIST_PRINT 768Like 769.Em BIOHIST , 770it prints the BIO history logs on the system console as entries are added. 771Note that the output is 772.Em extremely 773voluminous, so this option is really only useful for debugging 774the very earliest parts of kernel initialization. 775.It Cd options BIOHIST_SIZE 776Set the size of the 777.Dq biohist 778kernel history. 779The default is 500. 780This option depends upon the 781.Em BIOHIST 782option. 783.El 784.Ss File Systems 785.Bl -ohang 786.It Cd file-system FFS 787Includes code implementing the Berkeley Fast File System 788.Po Em FFS Pc . 789Most machines need this if they are not running diskless. 790.It Cd file-system EXT2FS 791Includes code implementing the Second Extended File System 792.Po Em ext2 Pc , 793revision 0 and revision 1 with the 794.Em filetype , 795.Em sparse_super 796and 797.Em large_file 798options. 799This is the most commonly used file system on the Linux operating system, 800and is provided here for compatibility. 801Some of the specific features of 802.Em ext2 803like the "behavior on errors" are not implemented. 804See 805.Xr mount_ext2fs 8 806for details. 807.It Cd file-system LFS 808.Bq Em EXPERIMENTAL 809Include the Log-structured File System 810.Po Em LFS Pc . 811See 812.Xr mount_lfs 8 813and 814.Xr newfs_lfs 8 815for details. 816.It Cd file-system MFS 817Include the Memory File System 818.Po Em MFS Pc . 819This file system stores files in swappable memory, and produces 820notable performance improvements when it is used as the file store 821for 822.Pa /tmp 823and similar file systems. 824See 825.Xr mount_mfs 8 826for details. 827.It Cd file-system NFS 828Include the client side of the Network File System (NFS) 829remote file sharing protocol. 830Although the bulk of the code implementing NFS 831is kernel based, several user level daemons are needed for it to work. 832See 833.Xr mount_nfs 8 834for details. 835.It Cd file-system CD9660 836Includes code for the ISO 9660 + Rock Ridge file system, which is 837the standard file system on many CD-ROM discs. 838Useful primarily if you have a CD-ROM drive. 839See 840.Xr mount_cd9660 8 841for details. 842.It Cd file-system MSDOSFS 843Includes the MS-DOS FAT file system, which is reportedly still used 844by unfortunate people who have not heard about 845.Nx . 846Also implements the Windows 95 extensions to the same, which permit 847the use of longer, mixed case file names. 848See 849.Xr mount_msdos 8 850and 851.Xr fsck_msdos 8 852for details. 853.It Cd file-system NTFS 854.Bq Em EXPERIMENTAL 855Includes code for the Microsoft Windows NT file system. 856See 857.Xr mount_ntfs 8 858for details. 859.It Cd file-system FDESC 860Includes code for a file system, conventionally mounted on 861.Pa /dev/fd , 862which permits access to the per-process file descriptor space via 863special files in the file system. 864See 865.Xr mount_fdesc 8 866for details. 867Note that this facility is redundant, and thus unneeded on most 868.Nx 869systems, since the 870.Xr fd 4 871pseudo-device driver already provides identical functionality. 872On most 873.Nx 874systems, instances of 875.Xr fd 4 876are mknoded under 877.Pa /dev/fd/ 878and on 879.Pa /dev/stdin , 880.Pa /dev/stdout , 881and 882.Pa /dev/stderr . 883.It Cd file-system KERNFS 884Includes code which permits the mounting of a special file system 885(normally mounted on 886.Pa /kern ) 887in which files representing various kernel variables and parameters 888may be found. 889See 890.Xr mount_kernfs 8 891for details. 892.It Cd file-system NULLFS 893Includes code for a loopback file system. 894This permits portions of the file hierarchy to be re-mounted in other places. 895The code really exists to provide an example of a stackable file system layer. 896See 897.Xr mount_null 8 898for details. 899.It Cd file-system OVERLAY 900Includes code for a file system filter. 901This permits the overlay file system to intercept all access to an underlying 902file system. 903This file system is intended to serve as an example of a stacking file 904system which has a need to interpose itself between an underlying file 905system and all other access. 906See 907.Xr mount_overlay 8 908for details. 909.It Cd file-system PROCFS 910Includes code for a special file system (conventionally mounted on 911.Pa /proc ) 912in which the process space becomes visible in the file system. 913Among 914other things, the memory spaces of processes running on the system are 915visible as files, and signals may be sent to processes by writing to 916.Pa ctl 917files in the procfs namespace. 918See 919.Xr mount_procfs 8 920for details. 921.It Cd file-system UDF 922.Bq Em EXPERIMENTAL 923Includes code for the UDF file system commonly found on CD and DVD 924media but also on USB sticks. 925Currently supports read and write access upto UDF 2.01 and somewhat limited 926write support for UDF 2.50. 927It is marked experimental since there is no 928.Xr fsck_udf 8 . 929See 930.Xr mount_udf 8 931for details. 932.It Cd file-system UMAPFS 933Includes a loopback file system in which user and group IDs may be 934remapped -- this can be useful when mounting alien file systems with 935different UIDs and GIDs than the local system. 936See 937.Xr mount_umap 8 938for details. 939.It Cd file-system UNION 940.Bq Em EXPERIMENTAL 941Includes code for the union file system, which permits directories to 942be mounted on top of each other in such a way that both file systems 943remain visible -- this permits tricks like allowing writing (and the 944deleting of files) on a read-only file system like a CD-ROM by 945mounting a local writable file system on top of the read-only file 946system. 947See 948.Xr mount_union 8 949for details. 950.It Cd file-system CODA 951.Bq Em EXPERIMENTAL 952Includes code for the Coda file system. 953Coda is a distributed file system like NFS and AFS. 954It is freely available, like NFS, but it functions much like AFS in being a 955.Dq stateful 956file system. 957Both Coda and AFS cache files on your local machine to improve performance. 958Then Coda goes a step further than AFS by letting you access the cached 959files when there is no available network, viz. disconnected laptops and 960network outages. 961In Coda, both the client and server are outside the kernel which makes 962them easier to experiment with. 963Coda is available for several UNIX and non-UNIX platforms. 964See 965.Lk http://www.coda.cs.cmu.edu 966for more details. 967.Em NOTE : 968You also need to enable the pseudo-device, vcoda, for the Coda 969file system to work. 970.It Cd file-system SMBFS 971.Bq Em EXPERIMENTAL 972Includes code for the SMB/CIFS file system. 973See 974.Xr mount_smbfs 8 975for details. 976.Em NOTE : 977You also need to enable the pseudo-device, nsmb, for the SMB 978file system to work. 979.It Cd file-system PTYFS 980.Bq Em EXPERIMENTAL 981Includes code for a special file system (normally mounted on 982.Pa /dev/pts ) 983in which pseudo-terminal slave devices become visible in the file system. 984See 985.Xr mount_ptyfs 8 986for details. 987.It Cd file-system TMPFS 988Includes code for the efficient memory file system, normally used over 989.Pa /tmp . 990See 991.Xr mount_tmpfs 8 992for details. 993.It Cd file-system PUFFS 994Includes kernel support for the pass-to-userspace framework file system. 995It can be used to implement file system functionality in userspace. 996See 997.Xr puffs 3 998for more details. 999This enables for example sshfs: 1000.Xr mount_psshfs 8 . 1001.El 1002.Ss File System Options 1003.Bl -ohang 1004.It Cd options DISKLABEL_EI 1005Enable 1006.Dq Endian-Independent 1007.Xr disklabel 5 1008support. 1009This allows a system to recognize a disklabel written in the other byte order. 1010For writing, when a label already exists, its byte order is preserved. 1011Otherwise, a new label is written in the native byte order. 1012To specify the byte order explicitly, the 1013.Fl F 1014option of 1015.Xr disklabel 8 1016should be used with the 1017.Fl B 1018option in order to avoid using 1019.Xr ioctl 2 , 1020which results in the default behavior explained above. 1021At the moment this option is restricted to the following ports: 1022amd64, bebox, emips, epoc32, evbarm, i386, ibmnws, landisk, mvmeppc, prep, 1023.\" riscv, 1024rs6000, sandpoint, 1025.\" usermode, 1026xen, and zaurus; 1027also to machines of the 1028.\" evbarm64, 1029evbmips and evbppc ports that support 1030Master Boot Record (MBR). 1031.It Cd options MAGICLINKS 1032Enables the expansion of special strings 1033.Po 1034beginning with 1035.Dq @ 1036.Pc 1037when traversing symbolic links. 1038See 1039.Xr symlink 7 1040for a list of supported strings. 1041Note that this option only controls the enabling of this feature 1042by the kernel at boot-up. 1043This feature can still be manipulated with the 1044.Xr sysctl 8 1045command regardless of the setting of this option. 1046.It Cd options NFSSERVER 1047Include the server side of the 1048.Em NFS 1049(Network File System) remote file sharing protocol. 1050Although the bulk of the code implementing 1051.Em NFS 1052is kernel based, several user level daemons are needed for it to 1053work. 1054See 1055.Xr mountd 8 1056and 1057.Xr nfsd 8 1058for details. 1059.It Cd options NVNODE=integer 1060This option sets the size of the cache used by the name-to-inode translation 1061routines, (a.k.a. the 1062.Fn namei 1063cache, though called by many other names in the kernel source). 1064By default, this cache has 1065.Dv ( NPROC + NTEXT + 100 ) 1066entries (NPROC set as 20 + 16 * MAXUSERS and NTEXT as 80 + NPROC / 8). 1067A reasonable way to derive a value of 1068.Dv NVNODE , 1069should you notice a large number of namei cache misses with a tool such as 1070.Xr systat 1 , 1071is to examine your system's current computed value with 1072.Xr sysctl 8 , 1073(which calls this parameter "kern.maxvnodes") and to increase this value 1074until either the namei cache hit rate improves or it is determined that 1075your system does not benefit substantially from an increase in the size of 1076the namei cache. 1077.It Cd options NAMECACHE_ENTER_REVERSE 1078Causes the namei cache to always enter a reverse mapping (vnode -> name) 1079as well as a normal one. 1080Normally, this is already done for directory vnodes, to speed up the getcwd 1081operation. 1082This option will cause longer hash chains in the reverse cache, and thus 1083slow down getcwd somewhat. 1084However, it does make vnode -> path translations possible in some cases. 1085For now, only useful if strict 1086.Pa /proc/#/maps 1087emulation for Linux binaries is required. 1088.El 1089.Ss Options for FFS/UFS File Systems 1090.Bl -ohang 1091.It Cd options WAPBL 1092Enable 1093.Dq Write Ahead Physical Block Logging file system journaling . 1094This provides rapid file system consistency checking after a system outage. 1095It also provides better general use performance over regular FFS. 1096See also 1097.Xr wapbl 4 . 1098.It Cd options QUOTA 1099Enables kernel support for traditional quotas in FFS. 1100Traditional quotas store the quota information in external files and 1101require 1102.Xr quotacheck 8 1103and 1104.Xr quotaon 8 1105at boot time. 1106Traditional quotas are limited to 32-bit sizes and are at this point 1107considered a legacy feature. 1108.It Cd options QUOTA2 1109Enables kernel support for in-volume quotas in FFS. 1110The quota information is file system metadata maintained by 1111.Xr fsck 8 1112and/or WAPBL journaling. 1113MFS volumes can also use 1114.Dv QUOTA2 1115quotas; see 1116.Xr mount_mfs 8 1117for more information. 1118.It Cd options FFS_EI 1119Enable 1120.Dq Endian-Independent 1121FFS support. 1122This allows a system to mount an FFS file system created for another 1123architecture, at a small performance cost for all FFS file systems. 1124See also 1125.Xr newfs 8 , 1126.Xr fsck_ffs 8 , 1127.Xr dumpfs 8 1128for file system byte order status and manipulation. 1129.It Cd options FFS_NO_SNAPSHOT 1130Disable support for the creation of file system internal snapshot 1131of FFS file systems. 1132Maybe useful for install media kernels, small memory systems and 1133embedded systems which don't require the snapshot support. 1134.It Cd options UFS_EXTATTR 1135Enable extended attribute support for UFS1 file systems. 1136.It Cd options UFS_DIRHASH 1137Increase lookup performance by maintaining in-core hash tables 1138for large directories. 1139.El 1140.Ss Options for the LFS File System 1141.Bl -ohang 1142.\" .It Cd options LFS_KERNEL_RFW 1143.\" There is no documentation for this. (XXX) 1144.\" .It Cd options LFS_QUOTA 1145.\" Enable traditional quota support for LFS. 1146.\" (It is not clear if this works.) 1147.\" .It Cd options LFS_QUOTA2 1148.\" Enable modernized 64-bit quota support for LFS. 1149.\" (This does not work yet.) 1150.It Cd options LFS_EI 1151Enable 1152.Dq Endian-Independent 1153LFS support. 1154This allows (at a small performance cost) mounting an LFS file system 1155created for another architecture. 1156.\" .It Cd options LFS_EXTATTR 1157.\" Enable extended attribute support for LFS. 1158.\" (It is not clear if this works.) 1159.It Cd options LFS_DIRHASH 1160Increase lookup performance by maintaining in-core hash tables 1161for large directories. 1162.El 1163.Ss Options for the ext2fs File System 1164.Bl -ohang 1165.It Cd options EXT2FS_SYSTEM_FLAGS 1166This option changes the behavior of the APPEND and IMMUTABLE flags 1167for a file on an 1168.Em ext2 1169file system. 1170Without this option, the superuser or owner of the file can 1171set and clear them. 1172With this option, only the superuser can set them, and 1173they can't be cleared if the securelevel is greater than 0. 1174See also 1175.Xr chflags 1 1176and 1177.Xr secmodel_securelevel 9 . 1178.El 1179.Ss Options for the NFS File System 1180.Bl -ohang 1181.It Cd options NFS_BOOT_BOOTP 1182Enable use of the BOOTP protocol (RFCs 951 and 1048) to get configuration 1183information if NFS is used to mount the root file system. 1184See 1185.Xr diskless 8 1186for details. 1187.It Cd options NFS_BOOT_BOOTSTATIC 1188Enable use of static values defined as 1189.Dq NFS_BOOTSTATIC_MYIP , 1190.Dq NFS_BOOTSTATIC_GWIP , 1191.Dq NFS_BOOTSTATIC_SERVADDR , 1192and 1193.Dq NFS_BOOTSTATIC_SERVER 1194in kernel options to get configuration information 1195if NFS is used to mount the root file system. 1196.It Cd options NFS_BOOT_DHCP 1197Same as 1198.Dq NFS_BOOT_BOOTP , 1199but use the DHCP extensions to the 1200BOOTP protocol (RFC 1541). 1201.It Cd options NFS_BOOT_BOOTP_REQFILE 1202Specifies the string sent in the bp_file field of the BOOTP/DHCP 1203request packet. 1204.It Cd options NFS_BOOT_BOOTPARAM 1205Enable use of the BOOTPARAM protocol, consisting of RARP and 1206BOOTPARAM RPC, to get configuration information if NFS 1207is used to mount the root file system. 1208See 1209.Xr diskless 8 1210for details. 1211.It Cd options NFS_BOOT_RWSIZE=value 1212Set the initial NFS read and write sizes for diskless-boot requests. 1213The normal default is 8Kbytes. 1214This option provides a way to lower the value (e.g., to 1024 bytes) 1215as a workaround for buggy network interface cards or boot PROMs. 1216Once booted, the read and write request sizes can be increased by 1217remounting the file system. 1218See 1219.Xr mount_nfs 8 1220for details. 1221.It Cd options NFS_V2_ONLY 1222Reduce the size of the NFS client code by omitting code that's only required 1223for NFSv3 and NQNFS support, leaving only that code required to use NFSv2 1224servers. 1225.It Cd options NFS_BOOT_TCP 1226Use NFS over TCP instead of the default UDP, for mounting root. 1227.El 1228.Ss Buffer queue strategy options 1229The following options enable alternative buffer queue strategies. 1230.Bl -ohang 1231.It Cd options BUFQ_READPRIO 1232Enable experimental buffer queue strategy for disk I/O. 1233In the default strategy, outstanding disk requests are ordered by 1234sector number and sent to the disk, regardless of whether the 1235operation is a read or write; this option gives priority to issuing 1236read requests over write requests. 1237Although requests may therefore be issued out of sector-order, causing 1238more seeks and thus lower overall throughput, interactive system 1239responsiveness under heavy disk I/O load may be improved, as processes 1240blocking on disk reads are serviced sooner (file writes typically 1241don't cause applications to block). 1242The performance effect varies greatly depending on the hardware, drive 1243firmware, file system configuration, workload, and desired performance 1244trade-off. 1245Systems using drive write-cache (most modern IDE disks, by default) 1246are unlikely to benefit and may well suffer; such disks acknowledge 1247writes very quickly, and optimize them internally according to 1248physical layout. 1249Giving these disks as many requests to work with as possible (the 1250standard strategy) will typically produce the best results, especially 1251if the drive has a large cache; the drive will silently complete 1252writes from cache as it seeks for reads. 1253Disks that support a large number of concurrent tagged requests (SCSI 1254disks and many hardware RAID controllers) expose this internal 1255scheduling with tagged responses, and don't block for reads; such 1256disks may not see a noticeable difference with either strategy. 1257However, if IDE disks are run with write-cache disabled for safety, 1258writes are not acknowledged until actually completed, and only one 1259request can be outstanding; a large number of small writes in one 1260locality can keep the disk busy, starving reads elsewhere on the disk. 1261Such systems are likely to see the most benefit from this option. 1262Finally, the performance interaction of this option with ffs soft 1263dependencies can be subtle, as that mechanism can drastically alter 1264the workload for file system metadata writes. 1265.It Cd options BUFQ_PRIOCSCAN 1266Enable another buffer queue strategy for disk I/O, per-priority cyclical scan. 1267.It Cd options NEW_BUFQ_STRATEGY 1268Synonym of 1269.Em BUFQ_READPRIO . 1270.El 1271.Ss Miscellaneous Options 1272.Bl -ohang 1273.It Cd options CPU_UCODE 1274Support cpu microcode loading via 1275.Xr cpuctl 8 . 1276.It Cd options MEMORY_DISK_DYNAMIC 1277This option makes the 1278.Xr md 4 1279RAM disk size dynamically sized. 1280It is incompatible with 1281.Xr mdsetimage 8 . 1282.It Cd options MEMORY_DISK_HOOKS 1283This option allows for some machine dependent functions to be called when 1284the 1285.Xr md 4 1286RAM disk driver is configured. 1287This can result in automatically loading a RAM disk from floppy on 1288open (among other things). 1289.It Cd options MEMORY_DISK_IS_ROOT 1290Forces the 1291.Xr md 4 1292RAM disk to be the root device. 1293This can only be overridden when 1294the kernel is booted in the 'ask-for-root' mode. 1295.It Cd options MEMORY_DISK_ROOT_SIZE=integer 1296Allocates the given number of 512 byte blocks as memory for the 1297.Xr md 4 1298RAM disk, to be populated with 1299.Xr mdsetimage 8 . 1300.It Cd options MEMORY_DISK_SERVER=0 1301Do not include the interface to a userland memory disk server process. 1302Per default, this option is set to 1, including the support code. 1303Useful for install media kernels. 1304.It Cd options MEMORY_DISK_RBFLAGS=value 1305This option sets the 1306.Xr reboot 2 1307flags used when booting with a memory disk as root file system. 1308Possible values include 1309.Dv RB_AUTOBOOT 1310(boot in the usual fashion - default value), and 1311.Dv RB_SINGLE 1312(boot in single-user mode). 1313.It Cd options MODULAR 1314Enables the framework for kernel modules (see 1315.Xr module 7 ) . 1316.It Cd options MODULAR_DEFAULT_AUTOLOAD 1317Enables the autoloading of kernel modules by default. 1318This sets the default value of the 1319.Em kern.module.autoload 1320.Xr sysctl 3 1321variable which may be changed at run time. 1322.It Cd options VND_COMPRESSION 1323Enables the 1324.Xr vnd 4 1325driver to also handle compressed images. 1326See 1327.Xr vndcompress 1 , 1328.Xr vnd 4 1329and 1330.Xr vnconfig 8 1331for more information. 1332.It Cd options SPLDEBUG 1333Help the kernel programmer find bugs related to the interrupt priority 1334level. 1335When 1336.Fn spllower 1337or 1338.Fn splraise 1339changes the current CPU's interrupt priority level to or from 1340.Dv IPL_HIGH , 1341record a backtrace. 1342Read 1343.Xr i386/return_address 9 1344for caveats about collecting backtraces. 1345This feature is experimental, and it is only available on i386. 1346See 1347.Pa sys/kern/subr_spldebug.c . 1348.It Cd options TFTPROOT 1349Download the root memory disk through TFTP at root mount time. 1350This enables the use of a root RAM disk without requiring it to be 1351embedded in the kernel using 1352.Xr mdsetimage 8 . 1353The RAM disk name is obtained using DHCP's filename parameter. 1354This option requires 1355.Em MEMORY_DISK_HOOKS , 1356.Em MEMORY_DISK_DYNAMIC , 1357and 1358.Em MEMORY_DISK_IS_ROOT . 1359It is incompatible with 1360.Em MEMORY_DISK_ROOT_SIZE . 1361.It Cd options HZ=integer 1362On ports that support it, set the system clock frequency (see 1363.Xr hz 9 ) 1364to the supplied value. 1365Handle with care. 1366.It Cd options NTP 1367Turns on in-kernel precision timekeeping support used by software 1368implementing 1369.Em NTP 1370(Network Time Protocol, RFC 1305). 1371The 1372.Em NTP 1373option adds an in-kernel Phase-Locked Loop (PLL) for normal 1374.Em NTP 1375operation, and a Frequency-Locked Loop (FLL) for intermittently-connected 1376operation. 1377.Xr ntpd 8 1378will employ a user-level PLL when kernel support is unavailable, 1379but the in-kernel version has lower latency and more precision, and 1380so typically keeps much better time. 1381.Pp 1382The interface to the kernel 1383.Em NTP 1384support is provided by the 1385.Xr ntp_adjtime 2 1386and 1387.Xr ntp_gettime 2 1388system calls, which are intended for use by 1389.Xr ntpd 8 1390and are enabled by the option. 1391On systems with sub-microsecond resolution timers, or where (HZ/100000) 1392is not an integer, the 1393.Em NTP 1394option also enables extended-precision arithmetic to keep track of 1395fractional clock ticks at NTP time-format precision. 1396.It Cd options PPS_SYNC 1397This option enables a kernel serial line discipline for receiving time 1398phase signals from an external reference clock such as a radio clock. 1399.Po 1400The 1401.Em NTP 1402option (which see) must be on if the 1403.Em PPS_SYNC 1404option is used 1405.Pc . 1406Some reference clocks generate a Pulse Per Second (PPS) signal in 1407phase with their time source. 1408The 1409.Em PPS 1410line discipline receives this signal on either the data leads 1411or the DCD control lead of a serial port. 1412.Pp 1413.Em NTP 1414uses the PPS signal to discipline the local clock oscillator to a high 1415degree of precision (typically less than 50 microseconds in time and 14160.1 ppm in accuracy). 1417.Em PPS 1418can also generate a serial output pulse when the system receives a PPS 1419interrupt. 1420This can be used to measure the system interrupt latency and thus calibrate 1421.Em NTP 1422to account for it. 1423Using 1424.Em PPS 1425usually requires a gadget box 1426to convert from TTL to RS-232 signal levels. 1427The gadget box and PPS are described in more detail in the HTML documentation 1428for 1429.Xr ntpd 8 1430in 1431.Pa /usr/share/doc/html/ntp . 1432.Pp 1433.Nx 1434currently supports this option in 1435.Xr com 4 1436and 1437.Xr zsc 4 . 1438.It Cd options SETUIDSCRIPTS 1439Allows scripts with the setuid bit set to execute as the effective 1440user rather than the real user, just like binary executables. 1441.Pp 1442.Em NOTE : 1443Using this option will also enable 1444.Em options FDSCRIPTS 1445.It Cd options FDSCRIPTS 1446Allows execution of scripts with the execute bit set, but not the 1447read bit, by opening the file and passing the file descriptor to 1448the shell, rather than the filename. 1449.Pp 1450.Em NOTE : 1451Execute only (non-readable) scripts will have 1452.Va argv[0] 1453set to 1454.Pa /dev/fd/* . 1455What this option allows as far as security is 1456concerned, is the ability to safely ensure that the correct script 1457is run by the interpreter, as it is passed as an already open file. 1458.It Cd options RTC_OFFSET=integer 1459The kernel (and typically the hardware battery backed-up clock on 1460those machines that have one) keeps time in 1461.Em UTC 1462(Universal Coordinated Time, once known as 1463.Em GMT , 1464or Greenwich Mean Time) 1465and not in the time of the local time zone. 1466The 1467.Em RTC_OFFSET 1468option is used on some ports (such as the i386) to tell the kernel 1469that the hardware clock is offset from 1470.Em UTC 1471by the specified number of minutes. 1472This is typically used when a machine boots several operating 1473systems and one of them wants the hardware clock to run in the 1474local time zone and not in 1475.Em UTC , 1476e.g. 1477.Em RTC_OFFSET=300 1478means 1479the hardware clock is set to US Eastern Time (300 minutes behind 1480.Em UTC ) , 1481and not 1482.Em UTC . 1483(Note: 1484.Em RTC_OFFSET 1485is used to initialize a kernel variable named 1486.Va rtc_offset 1487which is the source actually used to determine the clock offset, and 1488which may be accessed via the kern.rtc_offset sysctl variable. 1489See 1490.Xr sysctl 8 1491and 1492.Xr sysctl 3 1493for details. 1494Since the kernel clock is initialized from the hardware clock very 1495early in the boot process, it is not possible to meaningfully change 1496.Va rtc_offset 1497in system initialization scripts. 1498Changing this value currently may only be done at kernel compile 1499time or by patching the kernel and rebooting). 1500.Pp 1501.Em NOTE : 1502Unfortunately, in many cases where the hardware clock 1503is kept in local time, it is adjusted for Daylight Savings 1504Time; this means that attempting to use 1505.Em RTC_OFFSET 1506to let 1507.Nx 1508coexist with such an operating system, like Windows, 1509would necessitate changing 1510.Em RTC_OFFSET 1511twice a year. 1512As such, this solution is imperfect. 1513.It Cd options MAXUPRC=integer 1514Sets the soft 1515.Dv RLIMIT_NPROC 1516resource limit, which specifies the maximum number of simultaneous 1517processes a user is permitted to run, for process 0; 1518this value is inherited by its child processes. 1519It defaults to 1520.Em CHILD_MAX , 1521which is currently defined to be 160. 1522Setting 1523.Em MAXUPRC 1524to a value less than 1525.Em CHILD_MAX 1526is not permitted, as this would result in a violation of the semantics of 1527.St -p1003.1-90 . 1528.It Cd options NOFILE=integer 1529Sets the soft 1530.Dv RLIMIT_NOFILE 1531resource limit, which specifies the maximum number of open 1532file descriptors for each process; 1533this value is inherited by its child processes. 1534It defaults to 1535.Em OPEN_MAX , 1536which is currently defined to be 128. 1537.It Cd options MAXFILES=integer 1538Sets the default value of the 1539.Em kern.maxfiles 1540sysctl variable, which indicates the maximum number of files that may 1541be open in the system. 1542.It Cd options DEFCORENAME=string 1543Sets the default value of the 1544.Em kern.defcorename 1545sysctl variable, otherwise it is set to 1546.Nm %n.core . 1547See 1548.Xr sysctl 8 1549and 1550.Xr sysctl 3 1551for details. 1552.It Cd options RASOPS_CLIPPING 1553Enables clipping within the 1554.Nm rasops 1555raster-console output system. 1556.Em NOTE : 1557only available on architectures that use 1558.Nm rasops 1559for console output. 1560.It Cd options RASOPS_SMALL 1561Removes optimized character writing code from the 1562.Nm rasops 1563raster-console output system. 1564.Em NOTE : 1565only available on architectures that use 1566.Nm rasops 1567for console output. 1568.It Cd options INCLUDE_CONFIG_FILE 1569Embeds the kernel config file used to define the kernel in the kernel 1570binary itself. 1571The embedded data also includes any files directly included by the config 1572file itself, e.g. 1573.Pa GENERIC.local 1574or 1575.Pa std.$MACHINE . 1576The embedded config file can be extracted from the resulting kernel with 1577.Xr config 1 1578.Fl x , 1579or by the following command: 1580.Bd -literal -offset indent 1581strings netbsd | sed -n 's/^_CFG_//p' | unvis 1582.Ed 1583.It Cd options INCLUDE_JUST_CONFIG 1584Similar to the above option, but includes just the actual config file, 1585not any included files. 1586.It Cd options PIPE_SOCKETPAIR 1587Use slower, but smaller socketpair(2)-based pipe implementation instead 1588of default faster, but bigger one. 1589Primarily useful for installation kernels. 1590.It Cd options USERCONF 1591Compiles in the in-kernel device configuration manager. 1592See 1593.Xr userconf 4 1594for details. 1595.It Cd options PERFCTRS 1596Compiles in kernel support for CPU performance-monitoring counters. 1597See 1598.Xr pmc 1 1599for details. 1600.Em NOTE : 1601not available on all architectures. 1602.It Cd options SCDEBUG_DEFAULT 1603Used with the 1604.Cd options SYSCALL_DEBUG 1605described below to choose which types of events are displayed. 1606.Pp 1607.Bl -tag -width "SCDEBUG_KERNHIST" -compact -offset indent 1608.It Dv SCDEBUG_CALLS 1609Show system call entry points. 1610.It Dv SCDEBUG_RETURNS 1611Show system call exit points. 1612.It Dv SCDEBUG_ALL 1613Show all system call requestes, including unimplemented calls. 1614.It Dv SCDEBUG_SHOWARGS 1615Show the arguments provided. 1616.It Dv SCDEBUG_KERNHIST 1617Store a restricted form of the system call debug in a kernel history 1618instead of printing it to the console. 1619This option relies upon 1620.Cd options KERNHIST . 1621.El 1622.Pp 1623The default value is 1624.Dv (SCDEBUG_CALLS|SCDEBUG_RETURNS|SCDEBUG_SHOWARGS) . 1625.It Cd options SYSCALL_DEBUG 1626Useful for debugging system call issues, usually in early single user bringup. 1627By default, writes entries to the system console for most system call events. 1628Can be configured with the 1629.Cd options SCDEBUG_DEFAULT 1630option to to use the 1631.Cd options KERNHIST 1632facility instead. 1633.It Cd options SYSCALL_STATS 1634Count the number of times each system call number is called. 1635The values can be read through the sysctl interface and displayed using 1636.Xr systat 1 . 1637.Em NOTE : 1638not yet available on all architectures. 1639.It Cd options SYSCALL_TIMES 1640Count the time spent (using 1641.Fn cpu_counter32 ) 1642in each system call. 1643.Em NOTE : 1644Using this option will also enable 1645.Cd options SYSCALL_STATS . 1646.It Cd options SYSCALL_TIMES_HASCOUNTER 1647Force use of 1648.Fn cpu_counter32 1649even if 1650.Fn cpu_hascounter 1651reports false. 1652Useful for systems where the cycle counter doesn't run at a constant rate 1653(e.g. Soekris boxes). 1654.It Cd options XSERVER_DDB 1655A supplement to XSERVER that adds support for entering 1656.Xr ddb 4 1657while in X11. 1658.It Cd options FILEASSOC 1659Support for 1660.Xr fileassoc 9 . 1661Required for 1662.Cd options PAX_SEGVGUARD 1663and 1664.Cd pseudo-device veriexec . 1665.It Cd options FILEASSOC_NHOOKS=integer 1666Number of storage slots per file for 1667.Xr fileassoc 9 . 1668Default is 4. 1669.El 1670.Ss Networking Options 1671.Bl -ohang 1672.It Cd options GATEWAY 1673Enables 1674.Em IPFORWARDING 1675(which see) 1676and (on most ports) increases the size of 1677.Em NMBCLUSTERS 1678(which see). 1679In general, 1680.Em GATEWAY 1681is used to indicate that a system should act as a router, and 1682.Em IPFORWARDING 1683is not invoked directly. 1684(Note that 1685.Em GATEWAY 1686has no impact on protocols other than IP, such as CLNP). 1687.Em GATEWAY 1688option also compiles IPv4 and IPv6 fast forwarding code into the kernel. 1689.It Cd options ICMPPRINTFS 1690The 1691.Em ICMPPRINTFS 1692option will enable debugging information to be printed about 1693the 1694.Xr icmp 4 1695protocol. 1696.It Cd options IPFORWARDING=value 1697If 1698.Em value 1699is 1 this enables IP routing behavior. 1700If 1701.Em value 1702is 0 (the default), it disables it. 1703The 1704.Em GATEWAY 1705option sets this to 1 automatically. 1706With this option enabled, the machine will forward IP datagrams destined 1707for other machines between its interfaces. 1708Note that even without this option, the kernel will 1709still forward some packets (such as source routed packets) -- removing 1710.Em GATEWAY 1711and 1712.Em IPFORWARDING 1713is insufficient to stop all routing through a bastion host on a 1714firewall -- source routing is controlled independently. 1715To turn off source routing, use 1716.Em options IPFORWSRCRT=0 1717(which see). 1718Note that IP forwarding may be turned on and off independently of the 1719setting of the 1720.Em IPFORWARDING 1721option through the use of the 1722.Em net.inet.ip.forwarding 1723sysctl variable. 1724If 1725.Em net.inet.ip.forwarding 1726is 1, IP forwarding is on. 1727See 1728.Xr sysctl 8 1729and 1730.Xr sysctl 3 1731for details. 1732.It Cd options IPFORWSRCRT=value 1733If 1734.Em value 1735is set to zero, source routing of IP datagrams is turned off. 1736If 1737.Em value 1738is set to one (the default) or the option is absent, source routed IP 1739datagrams are forwarded by the machine. 1740Note that source routing of IP packets may be turned on and off 1741independently of the setting of the 1742.Em IPFORWSRCRT 1743option through the use of the 1744.Em net.inet.ip.forwsrcrt 1745sysctl variable. 1746If 1747.Em net.inet.ip.forwsrcrt 1748is 1, forwarding of source routed IP datagrams is on. 1749See 1750.Xr sysctl 8 1751and 1752.Xr sysctl 3 1753for details. 1754.It Cd options IFA_STATS 1755Tells the kernel to maintain per-address statistics on bytes sent 1756and received over (currently) Internet and AppleTalk addresses. 1757.\"This can be a fairly expensive operation, so you probably want to 1758.\"keep this disabled. 1759The option is not recommended as it degrades system stability. 1760.It Cd options IFQ_MAXLEN=value 1761Increases the allowed size of the network interface packet queues. 1762The default queue size is 50 packets, and you do not normally need 1763to increase it. 1764.It Cd options IPSELSRC 1765Includes support for source-address selection policies. 1766See 1767.Xr in_getifa 9 . 1768.It Cd options MROUTING 1769Includes support for IP multicast routers. 1770You certainly want 1771.Em INET 1772with this. 1773Multicast routing is controlled by the 1774.Xr mrouted 8 1775daemon. 1776See also option 1777.Cd PIM . 1778.It Cd options PIM 1779Includes support for Protocol Independent Multicast (PIM) routing. 1780You need 1781.Em MROUTING 1782and 1783.Em INET 1784with this. 1785Software using this can be found e.g. in 1786.Pa pkgsrc/net/xorp . 1787.It Cd options INET 1788Includes support for the TCP/IP protocol stack. 1789You almost certainly want this. 1790See 1791.Xr inet 4 1792for details. 1793.It Cd options INET6 1794Includes support for the IPv6 protocol stack. 1795See 1796.Xr inet6 4 1797for details. 1798Unlike 1799.Em INET , 1800.Em INET6 1801enables multicast routing code as well. 1802This option requires 1803.Em INET 1804at this moment, but it should not. 1805.It Cd options ND6_DEBUG 1806The option sets the default value of net.inet6.icmp6.nd6_debug to 1, 1807for debugging IPv6 neighbor discovery protocol handling. 1808See 1809.Xr sysctl 3 1810for details. 1811.It Cd options IPSEC 1812Includes support for the IPsec protocol, using the implementation derived from 1813.Ox , 1814relying on 1815.Xr opencrypto 9 1816to carry out cryptographic operations. 1817See 1818.Xr fast_ipsec 4 1819for details. 1820.It Cd options IPSEC_DEBUG 1821Enables debugging code in IPsec stack. 1822See 1823.Xr ipsec 4 1824for details. 1825The 1826.Cd IPSEC 1827option includes support for IPsec Network Address Translator traversal 1828(NAT-T), as described in RFCs 3947 and 3948. 1829This feature might be patent-encumbered in some countries. 1830.It Cd options ALTQ 1831Enabled ALTQ (Alternate Queueing). 1832For simple rate-limiting, use 1833.Xr tbrconfig 8 1834to set up the interface transmission rate. 1835To use queueing disciplines, their appropriate kernel options should also 1836be defined (documented below). 1837Queueing disciplines are managed by 1838.Xr altqd 8 . 1839See 1840.Xr altq 9 1841for details. 1842.It Cd options ALTQ_HFSC 1843Include support for ALTQ-implemented HFSC (Hierarchical Fair Service Curve) 1844module. 1845HFSC supports both link-sharing and guaranteed real-time services. 1846HFSC employs a service curve based QoS model, and its unique feature 1847is an ability to decouple delay and bandwidth allocation. 1848Requires 1849.Em ALTQ_RED 1850to use the RED queueing discipline on HFSC classes, or 1851.Em ALTQ_RIO 1852to use the RIO queueing discipline on HFSC classes. 1853This option assumes 1854.Em ALTQ . 1855.It Cd options ALTQ_PRIQ 1856Include support for ALTQ-implemented PRIQ (Priority Queueing). 1857PRIQ implements a simple priority-based queueing discipline. 1858A higher priority class is always served first. 1859Requires 1860.Em ALTQ_RED 1861to use the RED queueing discipline on HFSC classes, or 1862.Em ALTQ_RIO 1863to use the RIO queueing discipline on HFSC classes. 1864This option assumes 1865.Em ALTQ . 1866.It Cd options ALTQ_WFQ 1867Include support for ALTQ-implemented WFQ (Weighted Fair Queueing). 1868WFQ implements a weighted-round robin scheduler for a set of queues. 1869A weight can be assigned to each queue to give a different proportion 1870of the link capacity. 1871A hash function is used to map a flow to one of a set of queues. 1872This option assumes 1873.Em ALTQ . 1874.It Cd options ALTQ_FIFOQ 1875Include support for ALTQ-implemented FIFO queueing. 1876FIFOQ is a simple drop-tail FIFO (First In, First Out) queueing discipline. 1877This option assumes 1878.Em ALTQ . 1879.It Cd options ALTQ_RIO 1880Include support for ALTQ-implemented RIO (RED with In/Out). 1881The original RIO has 2 sets of RED parameters; one for in-profile 1882packets and the other for out-of-profile packets. 1883At the ingress of the network, profile meters tag packets as IN or 1884OUT based on contracted profiles for customers. 1885Inside the network, IN packets receive preferential treatment by 1886the RIO dropper. 1887ALTQ/RIO has 3 drop precedence levels defined for the Assured Forwarding 1888PHB of DiffServ (RFC 2597). 1889This option assumes 1890.Em ALTQ . 1891.It Cd options ALTQ_BLUE 1892Include support for ALTQ-implemented Blue buffer management. 1893Blue is another active buffer management mechanism. 1894This option assumes 1895.Em ALTQ . 1896.It Cd options ALTQ_FLOWVALVE 1897Include support for ALTQ-implemented Flowvalve. 1898Flowvalve is a simple implementation of a RED penalty box that identifies 1899and punishes misbehaving flows. 1900This option requires 1901.Em ALTQ_RED 1902and assumes 1903.Em ALTQ . 1904.It Cd options ALTQ_CDNR 1905Include support for ALTQ-implemented CDNR (diffserv traffic conditioner) 1906packet marking/manipulation. 1907Traffic conditioners are components to meter, mark, or drop incoming 1908packets according to some rules. 1909As opposed to queueing disciplines, traffic conditioners handle incoming 1910packets at an input interface. 1911This option assumes 1912.Em ALTQ . 1913.It Cd options ALTQ_NOPCC 1914Disables use of processor cycle counter to measure time in ALTQ. 1915This option should be defined for a non-Pentium i386 CPU which does not 1916have TSC, SMP (per-CPU counters are not in sync), or power management 1917which affects processor cycle counter. 1918This option assumes 1919.Em ALTQ . 1920.It Cd options ALTQ_IPSEC 1921Include support for IPsec in IPv4 ALTQ. 1922This option assumes 1923.Em ALTQ . 1924.It Cd options ALTQ_JOBS 1925Include support for ALTQ-implemented JoBS (Joint Buffer Management 1926and Scheduling). 1927This option assumes 1928.Em ALTQ . 1929.It Cd options ALTQ_AFMAP 1930Include support for an undocumented ALTQ feature that is used to map an IP 1931flow to an ATM VC (Virtual Circuit). 1932This option assumes 1933.Em ALTQ . 1934.It Cd options ALTQ_LOCALQ 1935Include support for ALTQ-implemented local queues. 1936Its practical use is undefined. 1937Assumes 1938.Em ALTQ . 1939.It Cd options SUBNETSARELOCAL 1940Sets default value for net.inet.ip.subnetsarelocal variable, which 1941controls whether non-directly-connected subnets of connected networks 1942are considered "local" for purposes of choosing the MSS for a TCP 1943connection. 1944This is mostly present for historic reasons and completely irrelevant if 1945you enable Path MTU discovery. 1946.It Cd options HOSTZEROBROADCAST 1947Sets default value for net.inet.ip.hostzerobroadcast variable, which 1948controls whether the zeroth host address of each connected subnet is 1949also considered a broadcast address. 1950Default value is "1", for compatibility with old systems; if this is 1951set to zero on all hosts on a subnet, you should be able to fit an extra 1952host per subnet on the 1953".0" address. 1954.It Cd options MCLSHIFT=value 1955This option is the base-2 logarithm of the size of mbuf clusters. 1956The 1957.Bx 1958networking stack keeps network packets in a linked 1959list, or chain, of kernel buffer objects called mbufs. 1960The system provides larger mbuf clusters as an optimization for 1961large packets, instead of using long chains for large packets. 1962The mbuf cluster size, 1963or 1964.Em MCLBYTES , 1965must be a power of two, and is computed as two raised to the power 1966.Em MCLSHIFT . 1967On systems with Ethernet network adapters, 1968.Em MCLSHIFT 1969is often set to 11, giving 2048-byte mbuf clusters, large enough to 1970hold a 1500-byte Ethernet frame in a single cluster. 1971Systems with network interfaces supporting larger frame sizes like 1972ATM, FDDI, or HIPPI may perform better with 1973.Em MCLSHIFT 1974set to 12 or 13, giving mbuf cluster sizes of 4096 and 8192 bytes, 1975respectively. 1976.It Cd options NETATALK 1977Include support for the AppleTalk protocol stack. 1978The kernel provides provision for the 1979.Em Datagram Delivery Protocol 1980(DDP), providing SOCK_DGRAM support and AppleTalk routing. 1981This stack is used by the 1982.Em NETATALK 1983package, which adds support for AppleTalk server services via user 1984libraries and applications. 1985.It Cd options BLUETOOTH 1986Include support for the Bluetooth protocol stack. 1987See 1988.Xr bluetooth 4 1989for details. 1990.It Cd options IPNOPRIVPORTS 1991Normally, only root can bind a socket descriptor to a so-called 1992.Dq privileged 1993TCP port, that is, a port number in the range 0-1023. 1994This option eliminates those checks from the kernel. 1995This can be useful if there is a desire to allow daemons without 1996privileges to bind those ports, e.g., on firewalls. 1997The security tradeoffs in doing this are subtle. 1998This option should only be used by experts. 1999.It Cd options TCP_DEBUG 2000Record the last 2001.Em TCP_NDEBUG 2002TCP packets with SO_DEBUG set, and decode to the console if 2003.Em tcpconsdebug 2004is set. 2005.It Cd options TCP_NDEBUG 2006Number of packets to record for 2007.Em TCP_DEBUG . 2008Defaults to 100. 2009.It Cd options TCP_SENDSPACE=value 2010.It Cd options TCP_RECVSPACE=value 2011These options set the max TCP window size to other sizes than the default. 2012The TCP window sizes can be altered via 2013.Xr sysctl 8 2014as well. 2015.It Cd options TCP_INIT_WIN=value 2016This option sets the initial TCP window size for non-local connections, 2017which is used when the transmission starts. 2018The default size is 1, but if the machine should act more aggressively, 2019the initial size can be set to some other value. 2020The initial TCP window size can be set via 2021.Xr sysctl 8 2022as well. 2023.It Cd options TCP_SIGNATURE 2024Enable MD5 TCP signatures (RFC 2385) to protect BGP sessions. 2025.It Cd options IPFILTER_LOG 2026This option, in conjunction with 2027.Em pseudo-device ipfilter , 2028enables logging of IP packets using IP-Filter. 2029.It Cd options IPFILTER_LOOKUP 2030This option enables the 2031IP-Filter 2032.Xr ippool 8 2033functionality to be enabled. 2034.It Cd options IPFILTER_COMPAT 2035This option enables older IP-Filter binaries to work. 2036.It Cd options IPFILTER_DEFAULT_BLOCK 2037This option sets the default policy of IP-Filter. 2038If it is set, IP-Filter will block packets by default. 2039.It Cd options BRIDGE_IPF 2040This option causes 2041.Em bridge 2042devices to use the IP and/or IPv6 filtering hooks, forming 2043a link-layer filter that uses protocol-layer rules. 2044This option assumes the presence of 2045.Em pseudo-device ipfilter . 2046.It Cd options MBUFTRACE 2047This option can help track down mbuf leaks. 2048When enabled, mbufs are tagged with the devices and protocols using them, 2049which slightly decreases network performance. 2050This additional information can be viewed with 2051.Xr netstat 1 : 2052.Dl Ic netstat Fl mssv 2053Not all devices or protocols support this option. 2054.El 2055.Ss Sysctl Related Options 2056.Bl -ohang 2057.It Cd options SYSCTL_DISALLOW_CREATE 2058Disallows the creation or deletion of nodes from the sysctl tree, as 2059well as the assigning of descriptions to nodes that lack them, by any 2060process. 2061These operations are still available to kernel sub-systems, including 2062loadable kernel modules. 2063.It Cd options SYSCTL_DISALLOW_KWRITE 2064Prevents processes from adding nodes to the sysctl tree that make 2065existing kernel memory areas writable. 2066Sections of kernel memory can still be read and new nodes that own 2067their own data may still be writable. 2068.It Cd options SYSCTL_DEBUG_SETUP 2069Causes the SYSCTL_SETUP routines to print a brief message when they 2070are invoked. 2071This is merely meant as an aid in determining the order in which 2072sections of the tree are created. 2073.It Cd options SYSCTL_DEBUG_CREATE 2074Prints a message each time 2075.Fn sysctl_create , 2076the function that adds nodes to the tree, is called. 2077.It Cd options SYSCTL_INCLUDE_DESCR 2078Causes the kernel to include short, human readable descriptions for 2079nodes in the sysctl tree. 2080The descriptions can be retrieved programmatically (see 2081.Xr sysctl 3 ) , 2082or by the sysctl binary itself (see 2083.Xr sysctl 8 ) . 2084The descriptions are meant to give an indication of the purpose and/or 2085effects of a given node's value, not replace the documentation for the 2086given subsystem as a whole. 2087.El 2088.Ss System V IPC Options 2089.Bl -ohang 2090.It Cd options SYSVMSG 2091Includes support for 2092.At V 2093style message queues. 2094See 2095.Xr msgctl 2 , 2096.Xr msgget 2 , 2097.Xr msgrcv 2 , 2098.Xr msgsnd 2 . 2099.It Cd options SYSVSEM 2100Includes support for 2101.At V 2102style semaphores. 2103See 2104.Xr semctl 2 , 2105.Xr semget 2 , 2106.Xr semop 2 . 2107.It Cd options SEMMNI=value 2108Sets the number of 2109.At V 2110style semaphore identifiers. 2111The GENERIC config file for your port will have the default. 2112.It Cd options SEMMNS=value 2113Sets the number of 2114.At V 2115style semaphores in the system. 2116The GENERIC config file for your port will have the default. 2117.It Cd options SEMUME=value 2118Sets the maximum number of undo entries per process for 2119.At V 2120style semaphores. 2121The GENERIC config file for your port will have the default. 2122.It Cd options SEMMNU=value 2123Sets the number of undo structures in the system for 2124.At V 2125style semaphores. 2126The GENERIC config file for your port will have the default. 2127.It Cd options SYSVSHM 2128Includes support for 2129.At V 2130style shared memory. 2131See 2132.Xr shmat 2 , 2133.Xr shmctl 2 , 2134.Xr shmdt 2 , 2135.Xr shmget 2 . 2136.It Cd options SHMMAXPGS=value 2137Sets the maximum number of 2138.At V 2139style shared memory pages that are available through the 2140.Xr shmget 2 2141system call. 2142Default value is 1024 on most ports. 2143See 2144.Pa /usr/include/machine/vmparam.h 2145for the default. 2146.El 2147.Ss VM Related Options 2148.Bl -ohang 2149.It Cd options NMBCLUSTERS=value 2150The number of mbuf clusters the kernel supports. 2151Mbuf clusters are MCLBYTES in size (usually 2k). 2152This is used to compute the size of the kernel VM map 2153.Em mb_map , 2154which maps mbuf clusters. 2155Default on most ports is 1024 (2048 with 2156.Dq options GATEWAY 2157). 2158See 2159.Pa /usr/include/machine/param.h 2160for exact default information. 2161Increase this value if you get 2162.Dq mclpool limit reached 2163messages. 2164.It Cd options NKMEMPAGES=value 2165.It Cd options NKMEMPAGES_MIN=value 2166.It Cd options NKMEMPAGES_MAX=value 2167Size of kernel VM map 2168.Em kmem_map , 2169in PAGE_SIZE-sized chunks (the VM page size; this value may be read 2170from the 2171.Xr sysctl 8 2172variable 2173.Em hw.pagesize 2174). 2175This VM map is used to map the kernel malloc arena. 2176The kernel attempts to auto-size this map based on the amount of 2177physical memory in the system. 2178Platform-specific code may place bounds on this computed size, 2179which may be viewed with the 2180.Xr sysctl 8 2181variable 2182.Em vm.nkmempages . 2183See 2184.Pa /usr/include/machine/param.h 2185for the default upper and lower bounds. 2186The related options 2187.Sq NKMEMPAGES_MIN 2188and 2189.Sq NKMEMPAGES_MAX 2190allow the bounds to be overridden in the kernel configuration file. 2191These options are provided in the event the computed value is 2192insufficient resulting in an 2193.Dq out of space in kmem_map 2194panic. 2195.It Cd options SB_MAX=value 2196Sets the max size in bytes that a socket buffer is allowed to occupy. 2197The default is 256k, but sometimes it needs to be increased, for example 2198when using large TCP windows. 2199This option can be changed via 2200.Xr sysctl 8 2201as well. 2202.It Cd options SOMAXKVA=value 2203Sets the maximum size of kernel virtual memory that the socket buffers 2204are allowed to use. 2205The default is 16MB, but in situations where for example large TCP 2206windows are used this value must also be increased. 2207This option can be changed via 2208.Xr sysctl 8 2209as well. 2210.It Cd options BUFCACHE=value 2211Size of the buffer cache as a percentage of total available RAM. 2212Ignored if BUFPAGES is also specified. 2213.It Cd options NBUF=value 2214Sets the number of buffer headers available, i.e., the number of 2215open files that may have a buffer cache entry. 2216Each buffer header 2217requires MAXBSIZE (machine dependent, but usually 65536) bytes. 2218The default value is machine dependent, but is usually equal to the 2219value of BUFPAGES. 2220.It Cd options BUFPAGES=value 2221These options set the number of pages available for the buffer cache. 2222Their default value is a machine dependent value, often calculated as 2223between 5% and 10% of total available RAM. 2224.It Cd options MAXTSIZ=bytes 2225Sets the maximum size limit of a process' text segment. 2226See 2227.Pa /usr/include/machine/vmparam.h 2228for the port-specific default. 2229.It Cd options DFLDSIZ=bytes 2230Sets the default size limit of a process' data segment, the value that 2231will be returned as the soft limit for 2232.Dv RLIMIT_DATA 2233(as returned by 2234.Xr getrlimit 2 ) . 2235See 2236.Pa /usr/include/machine/vmparam.h 2237for the port-specific default. 2238.It Cd options MAXDSIZ=bytes 2239Sets the maximum size limit of a process' data segment, the value that 2240will be returned as the hard limit for 2241.Dv RLIMIT_DATA 2242(as returned by 2243.Xr getrlimit 2 ) . 2244See 2245.Pa /usr/include/machine/vmparam.h 2246for the port-specific default. 2247.It Cd options DFLSSIZ=bytes 2248Sets the default size limit of a process' stack segment, the value that 2249will be returned as the soft limit for 2250.Dv RLIMIT_STACK 2251(as returned by 2252.Xr getrlimit 2 ) . 2253See 2254.Pa /usr/include/machine/vmparam.h 2255for the port-specific default. 2256.It Cd options MAXSSIZ=bytes 2257Sets the maximum size limit of a process' stack segment, the value that 2258will be returned as the hard limit for 2259.Dv RLIMIT_STACK 2260(as returned by 2261.Xr getrlimit 2 ) . 2262See 2263.Pa /usr/include/machine/vmparam.h 2264for the port-specific default. 2265.It Cd options DUMP_ON_PANIC=integer 2266Defaults to one. 2267If set to zero, the kernel will not dump to the dump device when 2268it panics, though dumps can still be forced via 2269.Xr ddb 4 2270with the 2271.Dq sync 2272command. 2273Note that this sets the value of the 2274.Em kern.dump_on_panic 2275.Xr sysctl 3 2276variable which may be changed at run time -- see 2277.Xr sysctl 8 2278for details. 2279.It Cd options USE_TOPDOWN_VM 2280User space memory allocations (as made by 2281.Xr mmap 2 ) 2282will be arranged in a 2283.Dq top down 2284fashion instead of the traditional 2285.Dq upwards from MAXDSIZ \&+ vm_daddr 2286method. 2287This includes the placement of 2288.Xr ld.so 1 . 2289Arranging memory in this manner allows either (or both of) the heap or 2290.Xr mmap 2 2291allocated space to grow larger than traditionally possible. 2292This option is not available on all ports, but is instead expected to be 2293offered on a port-by-port basis, after which some ports will commit to 2294using it by default. 2295See the files 2296.Pa /usr/include/uvm/uvm_param.h 2297for some implementation details, and 2298.Pa /usr/include/machine/vmparam.h 2299for port specific details including availability. 2300.It Cd options VMSWAP 2301Enable paging device/file support. 2302This option is on by default. 2303.It Cd options PDPOLICY_CLOCKPRO 2304Use CLOCK-Pro, an alternative page replace policy. 2305.El 2306.Ss Security Options 2307.Bl -ohang 2308.It Cd options INSECURE 2309Initializes the kernel security level with \-1 instead of 0. 2310This means that the system always starts in secure level \-1 mode, even when 2311running multiuser, unless the securelevel variable is set to value > \-1 in 2312.Pa /etc/rc.conf . 2313In this case the kernel security level will be raised to that value when the 2314.Pa /etc/rc.d/securelevel 2315script is run during system startup. 2316See the manual page for 2317.Xr init 8 2318for details on the implications of this. 2319The kernel secure level may manipulated by the superuser by altering the 2320.Em kern.securelevel 2321.Xr sysctl 3 2322variable (the secure level may only be lowered by a call from process ID 1, 2323i.e., 2324.Xr init 8 ) . 2325See also 2326.Xr secmodel_securelevel 9 , 2327.Xr sysctl 8 2328and 2329.Xr sysctl 3 . 2330.It Cd options VERIFIED_EXEC_FP_SHA256 2331Enables support for SHA256 hashes in Veriexec. 2332.It Cd options VERIFIED_EXEC_FP_SHA384 2333Enables support for SHA384 hashes in Veriexec. 2334.It Cd options VERIFIED_EXEC_FP_SHA512 2335Enables support for SHA512 hashes in Veriexec. 2336.It Cd options PAX_MPROTECT=value 2337Enables PaX MPROTECT, 2338.Xr mprotect 2 2339restrictions from the PaX project. 2340.Pp 2341The 2342.Ar value 2343is the default value for the 2344.Em global 2345knob, see 2346.Xr sysctl 3 . 2347If 0, PaX MPROTECT will be enabled only if explicitly set on programs 2348using 2349.Xr paxctl 8 . 2350If 1, PaX MPROTECT will be enabled for all programs. 2351Programs can be exempted using 2352.Xr paxctl 8 . 2353.Pp 2354See 2355.Xr security 7 2356for more details. 2357.It Cd options PAX_SEGVGUARD=value 2358Enables PaX Segvguard. 2359Requires 2360.Cd options FILEASSOC . 2361.Pp 2362The 2363.Ar value 2364is the default value for the 2365.Em global 2366knob, see 2367.Xr sysctl 3 . 2368If 0, PaX Segvguard will be enabled only if explicitly set on programs 2369using 2370.Xr paxctl 8 . 2371If 1, PaX Segvguard will be enabled to all programs, and exemption can 2372be done using 2373.Xr paxctl 8 . 2374.Pp 2375See 2376.Xr security 7 2377for more details. 2378.It Cd options PAX_ASLR=value 2379Enables PaX ASLR. 2380.Pp 2381The 2382.Ar value 2383is the default value for the 2384.Em global 2385knob, see 2386.Xr sysctl 3 . 2387If 0, PaX ASLR will be enabled only if explicitly set on programs 2388using 2389.Xr paxctl 8 . 2390If 1, PaX ASLR will be enabled to all programs, and exemption can 2391be done using 2392.Xr paxctl 8 . 2393.Pp 2394See 2395.Xr security 7 2396for more details. 2397.It Cd options USER_VA0_DISABLE_DEFAULT=value 2398Sets the initial value of the flag which controls whether user programs 2399can map virtual address 0. 2400The flag can be changed at runtime by 2401.Xr sysctl 3 . 2402.It Cd options KASLR 2403Enables Kernel ASLR. 2404This randomizes the location of the kernel image in memory. 2405.Em NOTE : 2406not available on all architectures. 2407.It Cd options SVS 2408Enables Separate Virtual Space. 2409On architectures that are designed to function with a shared address 2410space, this option explicitly isolates the kernel and user spaces. 2411.Em NOTE : 2412not available on all architectures. 2413.El 2414.Ss amiga-specific Options 2415.Bl -ohang 2416.It Cd options BB060STUPIDROM 2417When the bootloader (which passes AmigaOS ROM information) claims 2418we have a 68060 CPU without FPU, go look into the Processor 2419Configuration Register (PCR) to find out. 2420You need this with Amiga ROMs up to (at least) V40.xxx (OS3.1), 2421when you boot via the bootblocks and don't have a DraCo. 2422.It Cd options IOBZCLOCK=frequency 2423The IOBlix boards come with two different serial master clocks: older ones 2424use 24 MHz, newer ones use 22.1184 MHz. 2425The driver normally assumes the latter. 2426If your board uses 24 MHz, you can recompile your kernel with 2427options IOBZCLOCK=24000000 2428or patch the kernel variable iobzclock to the same value. 2429.It Cd options LIMITMEM=value 2430If there, limit the part of the first memory bank used by 2431.Nx 2432to value megabytes. 2433Default is unlimited. 2434.It Cd options P5PPC68KBOARD 2435Add special support for Phase5 mixed 68k+PPC boards. 2436Currently, this only affects rebooting from 2437.Nx 2438and is only needed on 68040+PPC, not on 243968060+PPC; without this, affected machines will hang after 2440.Nx 2441has shut 2442down and will only restart after a keyboard reset or a power cycle. 2443.El 2444.Ss atari-specific Options 2445.Bl -ohang 2446.It Cd options DISKLABEL_AHDI 2447Include support for AHDI (native Atari) disklabels. 2448.It Cd options DISKLABEL_NBDA 2449Include support for 2450.Nx Ns /atari 2451labels. 2452If you don't set this option, it will be set automatically. 2453.Nx Ns /atari 2454will not work without it. 2455.It Cd options FALCON_SCSI 2456Include support for the 5380-SCSI configuration as found on the Falcon. 2457.It Cd options RELOC_KERNEL 2458If set, the kernel will relocate itself to TT-RAM, if possible. 2459This will give you a slightly faster system. 2460.Em Beware 2461that on some TT030 systems, 2462the system will frequently dump with MMU-faults with this option enabled. 2463.It Cd options SERCONSOLE 2464Allow the modem1-port to act as the system-console. 2465A carrier should be active on modem1 during system boot to active 2466the console functionality. 2467.It Cd options TT_SCSI 2468Include support for the 5380-SCSI configuration as found on the TT030 2469and Hades. 2470.El 2471.Ss i386-specific Options 2472.Bl -ohang 2473.It Cd options CPURESET_DELAY=value 2474Specifies the time (in millisecond) to wait before doing a hardware reset 2475in the last phase of a reboot. 2476This gives the user a chance to see error messages from the shutdown 2477operations (like NFS unmounts, buffer cache flush, etc ...). 2478Setting this to 0 will disable the delay. 2479Default is 2 seconds. 2480.It Cd options USER_LDT 2481Include i386-specific system calls for modifying the local descriptor table, 2482used by Windows emulators. 2483.It Cd options PAE 2484Enable PAE (Physical Address Extension) mode. 2485PAE permits up to 36 bits physical addressing (64GB of physical 2486memory), and turns physical addresses to 64 bits entities in the 2487memory management subsystem. 2488Userland virtual address space remains at 32 bits (4GB). 2489PAE mode is required to enable the NX/XD (No-eXecute/eXecute Disable) 2490bit for pages, which allows marking certain ones as not being executable. 2491Any attempt to execute code from such a page will raise an exception. 2492.It Cd options REALBASEMEM=integer 2493Overrides the base memory size passed in from the boot block. 2494(Value given in kilobytes.) 2495Use this option only if the boot block reports the size incorrectly. 2496(Note that some BIOSes put the extended BIOS 2497data area at the top of base memory, and therefore report a smaller 2498base memory size to prevent programs overwriting it. 2499This is correct behavior, and you should not use the 2500.Em REALBASEMEM 2501option to access this memory). 2502.It Cd options REALEXTMEM=integer 2503Overrides the extended memory size passed in from the boot block. 2504(Value given in kilobytes. 2505Extended memory does not include the first megabyte.) 2506Use this option only if the boot block reports the size incorrectly. 2507.It Cd options CYRIX_CACHE_WORKS 2508Relevant only to the Cyrix 486DLC CPU. 2509This option is used to turn on the cache in hold-flush mode. 2510It is not turned on by default because it is known to have problems in 2511certain motherboard implementations. 2512.It Cd options CYRIX_CACHE_REALLY_WORKS 2513Relevant only to the Cyrix 486DLC CPU. 2514This option is used to turn on the cache in write-back mode. 2515It is not turned on by default because it is known to have problems in 2516certain motherboard implementations. 2517In order for this option to take effect, option 2518.Em CYRIX_CACHE_WORKS 2519must also be specified. 2520.It Cd options PCIBIOS 2521Enable support for initializing the PCI bus using information from 2522the BIOS. 2523See 2524.Xr pcibios 4 2525for details. 2526.It Cd options MTRR 2527Include support for accessing MTRR registers from user-space. 2528See 2529.Xr i386_get_mtrr 2 . 2530.It Cd options BEEP_ONHALT 2531Make the system speaker emit several beeps when it is completely safe to 2532power down the computer after a 2533.Xr halt 8 2534command. 2535Requires 2536.Xr sysbeep 4 2537support. 2538.It Cd options BEEP_ONHALT_COUNT=times 2539Number of times to beep the speaker when 2540.Cd options BEEP_ONHALT 2541is enabled. 2542Defaults to 3. 2543.It Cd options BEEP_ONHALT_PITCH=hz 2544The tone frequency used when 2545.Cd options BEEP_ONHALT 2546option, in hertz. 2547Defaults to 1500. 2548.It Cd options BEEP_ONHALT_PERIOD=msecs 2549The duration of each beep when 2550.Cd options BEEP_ONHALT 2551is enabled, in milliseconds. 2552Defaults to 250. 2553.It Cd options MULTIBOOT 2554Makes the kernel Multiboot-compliant, allowing it to be booted through 2555a Multiboot-compliant boot manager such as GRUB. 2556See 2557.Xr multiboot 8 2558for more information. 2559.It Cd options SPLASHSCREEN 2560Display a splash screen during boot. 2561.It Cd options SPLASHSCREEN_PROGRESS 2562Display a progress bar at the splash screen during boot. 2563This option requires 2564.Em SPLASHSCREEN . 2565.El 2566.Ss isa-specific Options 2567Options specific to 2568.Xr isa 4 2569busses. 2570.Bl -ohang 2571.It Cd options PCIC_ISA_ALLOC_IOBASE=address, PCIC_ISA_ALLOC_IOSIZE=size 2572Control the section of IO bus space used for PCMCIA bus space mapping. 2573Ideally the probed defaults are satisfactory, however in practice 2574that is not always the case. 2575See 2576.Xr pcmcia 4 2577for details. 2578.It Cd options PCIC_ISA_INTR_ALLOC_MASK=mask 2579Controls the allowable interrupts that may be used for PCMCIA 2580devices. 2581This mask is a logical-or of power-of-2s of allowable interrupts: 2582.Bd -literal -offset 04n 2583.Em "IRQ Val IRQ Val IRQ Val IRQ Val" 2584 0 0x0001 4 0x0010 8 0x0100 12 0x1000 2585 1 0x0002 5 0x0020 9 0x0200 13 0x2000 2586 2 0x0004 6 0x0040 10 0x0400 14 0x4000 2587 3 0x0008 7 0x0080 11 0x0800 15 0x8000 2588.Ed 2589.It Cd options PCKBC_CNATTACH_SELFTEST 2590Perform a self test of the keyboard controller before attaching it as a 2591console. 2592This might be necessary on machines where we boot on cold iron, and 2593pckbc refuses to talk until we request a self test. 2594Currently only the netwinder port uses it. 2595.It Cd options PCKBD_CNATTACH_MAY_FAIL 2596If this option is set the PS/2 keyboard will not be used as the console 2597if it cannot be found during boot. 2598This allows other keyboards, like USB, to be the console keyboard. 2599.It Cd options PCKBD_LAYOUT=layout 2600Sets the default keyboard layout, see 2601.Xr pckbd 4 . 2602.El 2603.Ss m68k-specific Options 2604.Bl -ohang 2605.It Cd options FPU_EMULATE 2606Include support for MC68881/MC68882 emulator. 2607.It Cd options FPSP 2608Include support for 68040 floating point. 2609.It Cd options M68020,M68030,M68040,M68060 2610Include support for a specific CPU, 2611at least one (the one you are using) should be specified. 2612.It Cd options M060SP 2613Include software support for 68060. 2614This provides emulation of unimplemented 2615integer instructions as well as emulation of unimplemented floating point 2616instructions and data types and software support for floating point traps. 2617.El 2618.Ss powerpc-specific Options (OEA Only) 2619.Bl -ohang 2620.It Cd options PMAP_MEMLIMIT=value 2621Limit the amount of memory seen by the kernel to 2622.Ar value 2623bytes. 2624.It Cd options PTEGCOUNT=value 2625Specify the size of the page table as 2626.Ar value 2627PTE groups. 2628Normally, one PTEG is allocated per physical page frame. 2629.El 2630.Ss sparc-specific Options 2631.Bl -ohang 2632.It Cd options AUDIO_DEBUG 2633Enable simple event debugging of the logging of the 2634.Xr audio 4 2635device. 2636.It Cd options BLINK 2637Enable blinking of LED. 2638Blink rate is full cycle every N seconds for 2639N < then current load average. 2640See 2641.Xr getloadavg 3 . 2642.\" .It Cd options COLORFONT_CACHE 2643.\" What does this do? 2644.It Cd options COUNT_SW_LEFTOVERS 2645Count how many times the sw SCSI device has left 3, 2, 1 and 0 in the 2646sw_3_leftover, sw_2_leftover, sw_1_leftover, and sw_0_leftover 2647variables accessible from 2648.Xr ddb 4 . 2649See 2650.Xr sw 4 . 2651.It Cd options DEBUG_ALIGN 2652Adds debugging messages calls when user-requested alignment fault 2653handling happens. 2654.It Cd options DEBUG_EMUL 2655Adds debugging messages calls for emulated floating point and 2656alignment fixing operations. 2657.It Cd options DEBUG_SVR4 2658Prints registers messages calls for emulated SVR4 getcontext and 2659setcontext operations. 2660See 2661.Em options COMPAT_SVR4 . 2662.It Cd options EXTREME_DEBUG 2663Adds debugging functions callable from 2664.Xr ddb 4 . 2665The debug_pagetables, test_region and print_fe_map 2666functions print information about page tables for the SUN4M 2667platforms only. 2668.It Cd options EXTREME_EXTREME_DEBUG 2669Adds extra info to 2670.Em options EXTREME_DEBUG . 2671.It Cd options FPU_CONTEXT 2672Make 2673.Em options COMPAT_SVR4 2674getcontext and setcontext include floating point registers. 2675.It Cd options MAGMA_DEBUG 2676Adds debugging messages to the 2677.Xr magma 4 2678device. 2679.It Cd options RASTERCONS_FULLSCREEN 2680Use the entire screen for the console. 2681.It Cd options RASTERCONS_SMALLFONT 2682Use the Fixed font on the console, instead of the normal font. 2683.It Cd options SUN4 2684Support sun4 class machines. 2685.It Cd options SUN4C 2686Support sun4c class machines. 2687.It Cd options SUN4M 2688Support sun4m class machines. 2689.It Cd options SUN4_MMU3L 2690.\" XXX ??? 2691Enable support for sun4 3-level MMU machines. 2692.It Cd options V9 2693Enable SPARC V9 assembler in 2694.Xr ddb 4 . 2695.El 2696.Ss sparc64-specific Options 2697.Bl -ohang 2698.It Cd options AUDIO_DEBUG 2699Enable simple event debugging of the logging of the 2700.Xr audio 4 2701device. 2702.It Cd options BLINK 2703Enable blinking of LED. 2704Blink rate is full cycle every N seconds for 2705N < then current load average. 2706See 2707.Xr getloadavg 3 . 2708.El 2709.Ss x68k-specific Options 2710.Bl -ohang 2711.It Cd options EXTENDED_MEMORY 2712Include support for extended memory, e.g., TS-6BE16 and 060turbo on-board. 2713.It Cd options JUPITER 2714Include support for Jupiter-X MPU accelerator 2715.It Cd options ZSCONSOLE,ZSCN_SPEED=value 2716Use the built-in serial port as the system-console. 2717Speed is specified in bps, defaults to 9600. 2718.It Cd options ITE_KERNEL_ATTR=value 2719Set the kernel message attribute for ITE. 2720Value, an integer, is a logical or of the following values: 2721.Bl -tag -width 4n -compact -offset indent 2722.It 1 2723color inversed 2724.It 2 2725underlined 2726.It 4 2727bolded 2728.El 2729.El 2730.\" The following requests should be uncommented and used where appropriate. 2731.\" .Sh FILES 2732.\" .Sh EXAMPLES 2733.Sh SEE ALSO 2734.Xr config 1 , 2735.Xr gdb 1 , 2736.Xr ktrace 1 , 2737.Xr pmc 1 , 2738.Xr quota 1 , 2739.Xr vndcompress 1 , 2740.Xr gettimeofday 2 , 2741.Xr i386_get_mtrr 2 , 2742.Xr i386_iopl 2 , 2743.Xr msgctl 2 , 2744.Xr msgget 2 , 2745.Xr msgrcv 2 , 2746.Xr msgsnd 2 , 2747.Xr ntp_adjtime 2 , 2748.Xr ntp_gettime 2 , 2749.Xr reboot 2 , 2750.Xr semctl 2 , 2751.Xr semget 2 , 2752.Xr semop 2 , 2753.Xr shmat 2 , 2754.Xr shmctl 2 , 2755.Xr shmdt 2 , 2756.Xr shmget 2 , 2757.Xr sysctl 3 , 2758.Xr apm 4 , 2759.Xr ddb 4 , 2760.Xr inet 4 , 2761.Xr md 4 , 2762.Xr pcibios 4 , 2763.Xr pcmcia 4 , 2764.Xr ppp 4 , 2765.Xr userconf 4 , 2766.Xr vnd 4 , 2767.Xr wscons 4 , 2768.Xr config 5 , 2769.Xr edquota 8 , 2770.Xr init 8 , 2771.Xr mdsetimage 8 , 2772.Xr mount_cd9660 8 , 2773.Xr mount_fdesc 8 , 2774.Xr mount_kernfs 8 , 2775.Xr mount_lfs 8 , 2776.Xr mount_mfs 8 , 2777.Xr mount_msdos 8 , 2778.Xr mount_nfs 8 , 2779.Xr mount_ntfs 8 , 2780.Xr mount_null 8 , 2781.Xr mount_portal 8 , 2782.Xr mount_procfs 8 , 2783.Xr mount_udf 8 , 2784.Xr mount_umap 8 , 2785.Xr mount_union 8 , 2786.Xr mrouted 8 , 2787.Xr newfs_lfs 8 , 2788.Xr ntpd 8 , 2789.Xr quotaon 8 , 2790.Xr rpc.rquotad 8 , 2791.Xr sysctl 8 , 2792.Xr in_getifa 9 , 2793.Xr kernhist 9 2794.Sh HISTORY 2795The 2796.Nm 2797man page first appeared in 2798.Nx 1.3 . 2799.Sh BUGS 2800The 2801.Em EON 2802option should be a pseudo-device, and is also very fragile. 2803