1.\" $NetBSD: options.4,v 1.531 2024/07/05 13:02:55 reinoud 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 May 12, 2024 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 makeoptions Ar name=value 127Defines a 128.Xr make 1 129macro 130.Ar name 131with the value 132.Ar value 133in the kernel Makefile. 134.It Sy maxusers Ar integer 135Set the maxusers variable in the kernel. 136.It Sy no Ar keyword Ar name Op Ar arguments Op ... 137For the 138.Xr config 1 139.Ar keywords 140file-system, makeoptions, options, and pseudo-device, 141.Ar no 142removes the file-system, makeoption, options, or pseudo-device, 143.Ar name . 144This is useful when a kernel configuration file includes another which 145has undesired options. 146.Pp 147For example, a local configuration file that wanted the kitchen sink, but 148not COMPAT_09 or bridging, might be: 149.Bd -literal -offset indent 150include "arch/i386/conf/GENERIC" 151no options COMPAT_09 152no pseudo-device bridge 153.Ed 154.It Sy options Ar option_name Op , Ar option_name=value Op ... 155Specifies (or sets) the option, or comma-separated list of options, 156.Ar option_name . 157Some options expect to be assigned a value, which may be an integer, 158a double-quoted word, a bare word, or an empty string 159.Pq Qq . 160Note that those are eventually handled by the C compiler, so the rules 161of that language apply. 162.Pp 163.Em Note : 164Options that are not defined by device definition files are passed to 165the compile process as 166.Fl D 167flags to the C compiler. 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_80 402Enable binary compatibility with 403.Nx 8.0 . 404.It Cd options COMPAT_90 405Enable binary compatibility with 406.Nx 9.0 . 407.It Cd options COMPAT_BSDPTY 408This option is currently on by default and enables the pty multiplexer 409.Xr ptm 4 410and 411.Xr ptmx 4 412to find and use ptys named 413.Pa /dev/ptyXX 414(master) and 415.Pa /dev/ttyXX 416(slave). 417Eventually this option will become optional as ptyfs based pseudo-ttys become 418the default, see 419.Xr mount_ptyfs 8 . 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_NOMID 450Enable compatibility with 451.Xr a.out 5 452executables that lack a machine ID. 453This includes 454.Nx 0.8 Ns 's 455ZMAGIC format, and 386BSD and BSDI's 456QMAGIC, NMAGIC, and OMAGIC 457.Xr a.out 5 458formats. 459.It Cd options COMPAT_NETBSD32 460On those architectures that support it, this enables binary 461compatibility with 32-bit applications built for the same architecture. 462This is currently limited to the amd64 and sparc64 ports, and only 463applicable for 64-bit kernels. 464.It Cd options COMPAT_AOUT_M68K 465On m68k architectures which have switched to ELF, 466this enables binary compatibility with 467.Nx Ns /m68k 468.Xr a.out 5 469executables on 470.Nx Ns /m68k 471ELF kernels. 472This handles alignment incompatibility of m68k ABI between 473a.out and ELF which causes the structure padding differences. 474Currently only some system calls which use 475.Va struct stat 476are adjusted and some binaries which use 477.Xr sysctl 3 478to retrieve network details would not work properly. 479.It Cd options EMUL_NATIVEROOT=string 480Just like emulated binaries first try looking up files in 481an emulation root (e.g. 482.Pa /emul/linux ) 483before looking them up in real root, this option causes native 484binaries to first look up files in an "emulation" directory too. 485This can be useful to test an amd64 kernel on top of an i386 system 486before full migration: by unpacking the amd64 distribution in e.g. 487.Pa /emul/netbsd64 488and specifying that location as 489.Cd EMUL_NATIVEROOT , 490native amd64 binaries can be run while the root file system remains 491populated with i386 binaries. 492Beware of 493.Pa /dev 494incompatibilities between i386 and amd64 if you do this. 495.It Cd options EXEC_ELF_NOTELESS 496Run unidentified ELF binaries as 497.Nx 498binaries. 499This might be needed for very old 500.Nx 501ELF binaries on some archs. 502These old binaries didn't contain an appropriate 503.Li .note.netbsd.ident 504section, and thus can't be identified by the kernel as 505.Nx 506binaries otherwise. 507Beware - if this option is on, the kernel would run 508.Em any 509unknown ELF binaries as if they were 510.Nx 511binaries. 512.El 513.Ss Debugging Options 514.Bl -ohang 515.It Cd options DDB 516Compiles in a kernel debugger for diagnosing kernel problems. 517See 518.Xr ddb 4 519for details. 520.Em NOTE : 521not available on all architectures. 522.It Cd options DDB_FROMCONSOLE=integer 523If set to non-zero, DDB may be entered by sending a break on a serial 524console or by a special key sequence on a graphics console. 525A value of "0" ignores console breaks or key sequences. 526If not explicitly specified, the default value is "1". 527Note that this sets the value of the 528.Em ddb.fromconsole 529.Xr sysctl 3 530variable which may be changed at run time \(em see 531.Xr sysctl 8 532for details. 533.It Cd options DDB_HISTORY_SIZE=integer 534If this is non-zero, enable history editing in the kernel debugger 535and set the size of the history to this value. 536.It Cd options DDB_ONPANIC 537The default if not specified is 538.Dq 1 539- just enter into DDB. 540If set to 541.Dq 0 542the kernel will attempt to print out a stack trace 543and reboot the system. 544If set to 545.Dq -1 546then neither a stack trace is printed or DDB entered - 547it is as if DDB were not compiled into the kernel. 548Note that this sets the value of the 549.Em ddb.onpanic 550.Xr sysctl 3 551variable which may be changed at run time \(em see 552.Xr sysctl 8 553for details. 554.It Cd options DDB_COMMANDONENTER=string 555This option specify commands which will be executed on each entry to DDB. 556This sets the default value of the 557.Em ddb.commandonenter 558.Xr sysctl 3 559variable which may be changed at run time. 560.It Cd options DDB_BREAK_CHAR=integer 561This option overrides using break to enter the kernel debugger 562on the serial console. 563The value given is the ASCII value to be used instead. 564This is currently only supported by the com driver. 565.It Cd options CNMAGIC=string 566This option overrides the 567.Xr cnmagic 9 568string used to enter the kernel debugger. 569.It Cd options DDB_VERBOSE_HELP 570This option adds more verbose descriptions to the 571.Em help 572command. 573.It Cd options DDB_PANICSTACKFRAMES=integer 574Number of stack frames to display on panic. 575Useful to avoid scrolling away the interesting frames on a glass tty. 576Default value is 577.Dv 65535 578(all frames), useful value around 579.Dv 10 . 580.It Cd options KGDB 581Compiles in a remote kernel debugger stub for diagnosing kernel problems 582using the 583.Dq remote target 584feature of gdb. 585See 586.Xr gdb 1 587for details. 588.Em NOTE : 589not available on all architectures. 590.It Cd options KGDB_DEV 591Device number 592.Po 593as a 594.Dv dev_t 595.Pc 596of kgdb device. 597.It Cd options KGDB_DEVADDR 598Memory address of kgdb device. 599.It Cd options KGDB_DEVMODE 600Permissions of kgdb device. 601.It Cd options KGDB_DEVNAME 602Device name of kgdb device. 603.It Cd options KGDB_DEVRATE 604Baud rate of kgdb device. 605.It Cd makeoptions DEBUG="-g" 606The 607.Fl g 608flag causes 609.Pa netbsd.gdb 610to be built in addition to 611.Pa netbsd . 612.Pa netbsd.gdb 613is useful for debugging kernel crash dumps with gdb. 614See 615.Xr gdb 1 616for details. 617.It Cd options DEBUG 618Turns on miscellaneous kernel debugging. 619Since options are turned into preprocessor defines (see above), 620.Em options DEBUG 621is equivalent to doing a 622.Em #define DEBUG 623throughout the kernel. 624Much of the kernel has 625.Em #ifdef DEBUG 626conditionalized debugging code. 627Note that many parts of the kernel (typically device drivers) include their own 628.Em #ifdef XXX_DEBUG 629conditionals instead. 630This option also turns on certain other options, 631which may decrease system performance. 632Systems with this option are not suitable for regular use, and are 633intended only for debugging or looking for bugs. 634.It Cd options DIAGNOSTIC 635Adds code to the kernel that does internal consistency checks. 636This code will cause the kernel to panic if corruption of internal data 637structures is detected. 638Historically, the performance degradation is sufficiently small that 639it is reasonable for systems with 640.Em options DIAGNOSTIC 641to be in production use, with the real consideration not being 642performance but instead a preference for more panics versus continued 643operation with undetected problems. 644.It Cd options LOCKDEBUG 645Adds code to the kernel to detect incorrect use of locking primitives 646(mutex, rwlock). 647This code will cause the kernel to check for dead lock conditions. 648It will also check for memory being freed to not contain initialised 649lock primitives. 650Functions for use in 651.Xr ddb 4 652to check lock chains etc. are also enabled. 653These checks are very expensive and can decrease performance on 654multi-processor machines by a factor of three. 655.It Cd options KDTRACE_HOOKS 656Adds hooks for the DTrace tracing facility, which allows users to 657analyze many aspects of system and application behavior. 658See 659.Xr dtrace 1 660for details. 661.It Cd options KSTACK_CHECK_MAGIC 662Check kernel stack usage and panic if stack overflow is detected. 663This check is performance sensitive because it scans stack on each context 664switch. 665.It Cd options KTRACE 666Add hooks for the system call tracing facility, which allows users to 667watch the system call invocation behavior of processes. 668See 669.Xr ktrace 1 670for details. 671.It Cd options MSGBUFSIZE=integer 672This option sets the size of the kernel message buffer in bytes. 673This buffer holds the kernel output of 674.Fn printf 675when not (yet) read by 676.Xr syslogd 8 . 677This is particularly useful when the system has crashed and you wish to lookup 678the kernel output from just before the crash. 679Also, since the autoconfig output becomes more and more verbose, 680it sometimes happens that the message buffer overflows before 681.Xr syslogd 8 682was able to read it. 683Note that not all systems are capable of obtaining a variable sized message 684buffer. 685There are also some systems on which memory contents are not preserved 686across reboots. 687.It Cd options KERNHIST 688Enables the kernel history logs, which create in-memory traces of 689various kernel activities. 690These logs can be displayed by using 691.Cm show kernhist 692from DDB. 693See the kernel source file 694.Pa sys/kern/kern_history.c 695and the 696.Xr kernhist 9 697manual for details. 698.It Cd options KERNHIST_PRINT 699Prints the kernel history logs on the system console as entries are added. 700Note that the output is 701.Em extremely 702voluminous, so this option is really only useful for debugging 703the very earliest parts of kernel initialization. 704.It Cd options UVMHIST 705Like 706.Em KERNHIST , 707it enables the UVM history logs. 708These logs can be displayed by using 709.Cm show kernhist 710from DDB. 711See the kernel source file 712.Pa sys/uvm/uvm_stat.c 713for details. 714.It Cd options UVMHIST_PRINT 715Like 716.Em UVMHIST , 717it prints the UVM history logs on the system console as entries are added. 718Note that the output is 719.Em extremely 720voluminous, so this option is really only useful for debugging 721the very earliest parts of kernel initialization. 722.It Cd options UVMHIST_MAPHIST_SIZE 723Set the size of the 724.Dq maphist 725kernel history. 726The default is 100. 727This option depends upon the 728.Em UVMHIST 729option. 730.It Cd options UVMHIST_PDHIST_SIZE 731Set the size of the 732.Dq pdhist 733kernel history. 734The default is 100. 735This option depends upon the 736.Em UVMHIST 737option. 738.It Cd options BIOHIST 739Like 740.Em KERNHIST , 741it enables the BIO history logs. 742These logs can be displayed by using 743.Cm show kernhist 744from DDB, and can help in debugging problems with Buffered I/O operations. 745See the kernel source file 746.Pa sys/kern/vfs_vio.c 747for details. 748.It Cd options BIOHIST_PRINT 749Like 750.Em BIOHIST , 751it prints the BIO history logs on the system console as entries are added. 752Note that the output is 753.Em extremely 754voluminous, so this option is really only useful for debugging 755the very earliest parts of kernel initialization. 756.It Cd options BIOHIST_SIZE 757Set the size of the 758.Dq biohist 759kernel history. 760The default is 500. 761This option depends upon the 762.Em BIOHIST 763option. 764.El 765.Ss File Systems 766.Bl -ohang 767.It Cd file-system FFS 768Includes code implementing the Berkeley Fast File System 769.Po Em FFS Pc . 770Most machines need this if they are not running diskless. 771.It Cd file-system EXT2FS 772Includes code implementing the Second Extended File System 773.Po Em ext2 Pc , 774revision 0 and revision 1 with the 775.Em filetype , 776.Em sparse_super 777and 778.Em large_file 779options. 780This is the most commonly used file system on the Linux operating system, 781and is provided here for compatibility. 782Some of the specific features of 783.Em ext2 784like the "behavior on errors" are not implemented. 785See 786.Xr mount_ext2fs 8 787for details. 788.It Cd file-system LFS 789.Bq Em EXPERIMENTAL 790Include the Log-structured File System 791.Po Em LFS Pc . 792See 793.Xr mount_lfs 8 794and 795.Xr newfs_lfs 8 796for details. 797.It Cd file-system MFS 798Include the Memory File System 799.Po Em MFS Pc . 800This file system stores files in swappable memory, and produces 801notable performance improvements when it is used as the file store 802for 803.Pa /tmp 804and similar file systems. 805See 806.Xr mount_mfs 8 807for details. 808.It Cd file-system NFS 809Include the client side of the Network File System (NFS) 810remote file sharing protocol. 811Although the bulk of the code implementing NFS 812is kernel based, several user level daemons are needed for it to work. 813See 814.Xr mount_nfs 8 815for details. 816.It Cd file-system CD9660 817Includes code for the ISO 9660 + Rock Ridge file system, which is 818the standard file system on many CD-ROM discs. 819Useful primarily if you have a CD-ROM drive. 820See 821.Xr mount_cd9660 8 822for details. 823.It Cd file-system MSDOSFS 824Includes the MS-DOS FAT file system, which is reportedly still used 825by unfortunate people who have not heard about 826.Nx . 827Also implements the Windows 95 extensions to the same, which permit 828the use of longer, mixed case file names. 829See 830.Xr mount_msdos 8 831and 832.Xr fsck_msdos 8 833for details. 834.It Cd file-system NTFS 835.Bq Em EXPERIMENTAL 836Includes code for the Microsoft Windows NT file system. 837See 838.Xr mount_ntfs 8 839for details. 840.It Cd file-system FDESC 841Includes code for a file system, conventionally mounted on 842.Pa /dev/fd , 843which permits access to the per-process file descriptor space via 844special files in the file system. 845See 846.Xr mount_fdesc 8 847for details. 848Note that this facility is redundant, and thus unneeded on most 849.Nx 850systems, since the 851.Xr fd 4 852pseudo-device driver already provides identical functionality. 853On most 854.Nx 855systems, instances of 856.Xr fd 4 857are mknoded under 858.Pa /dev/fd/ 859and on 860.Pa /dev/stdin , 861.Pa /dev/stdout , 862and 863.Pa /dev/stderr . 864.It Cd file-system KERNFS 865Includes code which permits the mounting of a special file system 866(normally mounted on 867.Pa /kern ) 868in which files representing various kernel variables and parameters 869may be found. 870See 871.Xr mount_kernfs 8 872for details. 873.It Cd file-system NULLFS 874Includes code for a loopback file system. 875This permits portions of the file hierarchy to be re-mounted in other places. 876The code really exists to provide an example of a stackable file system layer. 877See 878.Xr mount_null 8 879for details. 880.It Cd file-system OVERLAY 881Includes code for a file system filter. 882This permits the overlay file system to intercept all access to an underlying 883file system. 884This file system is intended to serve as an example of a stacking file 885system which has a need to interpose itself between an underlying file 886system and all other access. 887See 888.Xr mount_overlay 8 889for details. 890.It Cd file-system PROCFS 891Includes code for a special file system (conventionally mounted on 892.Pa /proc ) 893in which the process space becomes visible in the file system. 894Among 895other things, the memory spaces of processes running on the system are 896visible as files, and signals may be sent to processes by writing to 897.Pa ctl 898files in the procfs namespace. 899See 900.Xr mount_procfs 8 901for details. 902.It Cd file-system UDF 903Includes code for the UDF file system commonly found on CD and DVD media but 904also on USB sticks and harddiscs for interchange and backup. Supports read and 905write access for all formats on discs and on rewritable and recordable 906CD/DVD/BD media. It has a somewhat limited write support for UDF 2.50 as it 907can't expand the metadata partion. 908See 909.Xr mount_udf 8 910and 911.Xr fsck_udf 8 912for details. 913.It Cd file-system UMAPFS 914Includes a loopback file system in which user and group IDs may be 915remapped \(em this can be useful when mounting alien file systems with 916different UIDs and GIDs than the local system. 917See 918.Xr mount_umap 8 919for details. 920.It Cd file-system UNION 921.Bq Em EXPERIMENTAL 922Includes code for the union file system, which permits directories to 923be mounted on top of each other in such a way that both file systems 924remain visible \(em this permits tricks like allowing writing (and the 925deleting of files) on a read-only file system like a CD-ROM by 926mounting a local writable file system on top of the read-only file 927system. 928See 929.Xr mount_union 8 930for details. 931.It Cd file-system CODA 932.Bq Em EXPERIMENTAL 933Includes code for the Coda file system. 934Coda is a distributed file system like NFS and AFS. 935It is freely available, like NFS, but it functions much like AFS in being a 936.Dq stateful 937file system. 938Both Coda and AFS cache files on your local machine to improve performance. 939Then Coda goes a step further than AFS by letting you access the cached 940files when there is no available network, viz. disconnected laptops and 941network outages. 942In Coda, both the client and server are outside the kernel which makes 943them easier to experiment with. 944Coda is available for several UNIX and non-UNIX platforms. 945See 946.Lk http://www.coda.cs.cmu.edu 947for more details. 948.Em NOTE : 949You also need to enable the pseudo-device, vcoda, for the Coda 950file system to work. 951.It Cd file-system PTYFS 952Includes code for a special file system (normally mounted on 953.Pa /dev/pts ) 954in which pseudo-terminal slave devices become visible in the file system. 955See 956.Xr mount_ptyfs 8 957for details. 958.It Cd file-system TMPFS 959Includes code for the efficient memory file system, normally used over 960.Pa /tmp . 961See 962.Xr mount_tmpfs 8 963for details. 964.It Cd file-system PUFFS 965Includes kernel support for the pass-to-userspace framework file system. 966It can be used to implement file system functionality in userspace. 967See 968.Xr puffs 3 969for more details. 970This enables for example sshfs: 971.Xr mount_psshfs 8 . 972.El 973.Ss File System Options 974.Bl -ohang 975.It Cd options DISKLABEL_EI 976Enable 977.Dq Endian-Independent 978.Xr disklabel 5 979support. 980This allows a system to recognize a disklabel written in the other byte order. 981For writing, when a label already exists, its byte order is preserved. 982Otherwise, a new label is written in the native byte order. 983To specify the byte order explicitly, the 984.Fl F 985option of 986.Xr disklabel 8 987should be used with the 988.Fl B 989option in order to avoid using 990.Xr ioctl 2 , 991which results in the default behavior explained above. 992At the moment this option is restricted to the following ports: 993amd64, bebox, emips, epoc32, evbarm, i386, ibmnws, landisk, mvmeppc, prep, 994.\" riscv, 995rs6000, sandpoint, 996.\" usermode, 997xen, and zaurus; 998also to machines of the 999evbmips and evbppc ports that support 1000Master Boot Record (MBR). 1001.It Cd options MAGICLINKS 1002Enables the expansion of special strings 1003.Po 1004beginning with 1005.Dq @ 1006.Pc 1007when traversing symbolic links. 1008See 1009.Xr symlink 7 1010for a list of supported strings. 1011Note that this option only controls the enabling of this feature 1012by the kernel at boot-up. 1013This feature can still be manipulated with the 1014.Xr sysctl 8 1015command regardless of the setting of this option. 1016.It Cd options NFSSERVER 1017Include the server side of the 1018.Em NFS 1019(Network File System) remote file sharing protocol. 1020Although the bulk of the code implementing 1021.Em NFS 1022is kernel based, several user level daemons are needed for it to 1023work. 1024See 1025.Xr mountd 8 1026and 1027.Xr nfsd 8 1028for details. 1029.It Cd options NVNODE=integer 1030This option sets the size of the cache used by the name-to-inode translation 1031routines, (a.k.a. the 1032.Fn namei 1033cache, though called by many other names in the kernel source). 1034By default, this cache has 1035.Dv ( NPROC + NTEXT + 100 ) 1036entries (NPROC set as 20 + 16 * MAXUSERS and NTEXT as 80 + NPROC / 8). 1037A reasonable way to derive a value of 1038.Dv NVNODE , 1039should you notice a large number of namei cache misses with a tool such as 1040.Xr systat 1 , 1041is to examine your system's current computed value with 1042.Xr sysctl 8 , 1043(which calls this parameter "kern.maxvnodes") and to increase this value 1044until either the namei cache hit rate improves or it is determined that 1045your system does not benefit substantially from an increase in the size of 1046the namei cache. 1047.It Cd options NAMECACHE_ENTER_REVERSE 1048Causes the namei cache to always enter a reverse mapping (vnode -> name) 1049as well as a normal one. 1050Normally, this is already done for directory vnodes, to speed up the getcwd 1051operation. 1052This option will cause longer hash chains in the reverse cache, and thus 1053slow down getcwd somewhat. 1054However, it does make vnode -> path translations possible in some cases. 1055For now, only useful if strict 1056.Pa /proc/#/maps 1057emulation for Linux binaries is required. 1058.El 1059.Ss Options for FFS/UFS File Systems 1060.Bl -ohang 1061.It Cd options APPLE_UFS 1062Enable support for UFS file systems created on Mac OS X. 1063.It Cd options FFS_EI 1064Enable 1065.Dq Endian-Independent 1066FFS support. 1067This allows a system to mount an FFS file system created for another 1068architecture, at a small performance cost for all FFS file systems. 1069See also 1070.Xr newfs 8 , 1071.Xr fsck_ffs 8 , 1072.Xr dumpfs 8 1073for file system byte order status and manipulation. 1074.It Cd options FFS_NO_SNAPSHOT 1075Disable support for the creation of file system internal snapshot 1076of FFS file systems. 1077Maybe useful for install media kernels, small memory systems and 1078embedded systems which don't require the snapshot support. 1079.It Cd options QUOTA 1080Enables kernel support for traditional quotas in FFS. 1081Traditional quotas store the quota information in external files and 1082require 1083.Xr quotacheck 8 1084and 1085.Xr quotaon 8 1086at boot time. 1087Traditional quotas are limited to 32-bit sizes and are at this point 1088considered a legacy feature. 1089.It Cd options QUOTA2 1090Enables kernel support for in-volume quotas in FFS. 1091The quota information is file system metadata maintained by 1092.Xr fsck 8 1093and/or WAPBL journaling. 1094MFS volumes can also use 1095.Dv QUOTA2 1096quotas; see 1097.Xr mount_mfs 8 1098for more information. 1099.It Cd options UFS_DIRHASH 1100Increase lookup performance by maintaining in-core hash tables 1101for large directories. 1102.It Cd options UFS_EXTATTR 1103Enable extended attribute support for UFS1 file systems. 1104.It Cd options WAPBL 1105Enable 1106.Dq Write Ahead Physical Block Logging file system journaling . 1107This provides rapid file system consistency checking after a system outage. 1108It also provides better general use performance over regular FFS. 1109See also 1110.Xr wapbl 4 . 1111.El 1112.Ss Options for the LFS File System 1113.Bl -ohang 1114.\" .It Cd options LFS_KERNEL_RFW 1115.\" There is no documentation for this. (XXX) 1116.\" .It Cd options LFS_QUOTA 1117.\" Enable traditional quota support for LFS. 1118.\" (It is not clear if this works.) 1119.\" .It Cd options LFS_QUOTA2 1120.\" Enable modernized 64-bit quota support for LFS. 1121.\" (This does not work yet.) 1122.It Cd options LFS_EI 1123Enable 1124.Dq Endian-Independent 1125LFS support. 1126This allows (at a small performance cost) mounting an LFS file system 1127created for another architecture. 1128.\" .It Cd options LFS_EXTATTR 1129.\" Enable extended attribute support for LFS. 1130.\" (It is not clear if this works.) 1131.It Cd options LFS_DIRHASH 1132Increase lookup performance by maintaining in-core hash tables 1133for large directories. 1134.El 1135.Ss Options for the NFS File System 1136.Bl -ohang 1137.It Cd options NFS_BOOT_BOOTP 1138Enable use of the BOOTP protocol (RFCs 951 and 1048) to get configuration 1139information if NFS is used to mount the root file system. 1140See 1141.Xr diskless 8 1142for details. 1143.It Cd options NFS_BOOT_BOOTSTATIC 1144Enable use of static values defined as 1145.Dq NFS_BOOTSTATIC_MYIP , 1146.Dq NFS_BOOTSTATIC_GWIP , 1147.Dq NFS_BOOTSTATIC_SERVADDR , 1148and 1149.Dq NFS_BOOTSTATIC_SERVER 1150in kernel options to get configuration information 1151if NFS is used to mount the root file system. 1152.It Cd options NFS_BOOT_DHCP 1153Same as 1154.Dq NFS_BOOT_BOOTP , 1155but use the DHCP extensions to the 1156BOOTP protocol (RFC 1541). 1157.It Cd options NFS_BOOT_BOOTP_REQFILE 1158Specifies the string sent in the bp_file field of the BOOTP/DHCP 1159request packet. 1160.It Cd options NFS_BOOT_BOOTPARAM 1161Enable use of the BOOTPARAM protocol, consisting of RARP and 1162BOOTPARAM RPC, to get configuration information if NFS 1163is used to mount the root file system. 1164See 1165.Xr diskless 8 1166for details. 1167.It Cd options NFS_BOOT_RWSIZE=value 1168Set the initial NFS read and write sizes for diskless-boot requests. 1169The normal default is 8Kbytes. 1170This option provides a way to lower the value (e.g., to 1024 bytes) 1171as a workaround for buggy network interface cards or boot PROMs. 1172Once booted, the read and write request sizes can be increased by 1173remounting the file system. 1174See 1175.Xr mount_nfs 8 1176for details. 1177.It Cd options NFS_V2_ONLY 1178Reduce the size of the NFS client code by omitting code that's only required 1179for NFSv3 and NQNFS support, leaving only that code required to use NFSv2 1180servers. 1181.It Cd options NFS_BOOT_UDP 1182Use NFS over UDP instead of the default TCP, for mounting root. 1183.El 1184.Ss Buffer queue strategy options 1185The following options enable alternative buffer queue strategies. 1186.Bl -ohang 1187.It Cd options BUFQ_READPRIO 1188Enable alternate buffer queue strategy for disk I/O. 1189In the default strategy, outstanding disk requests are ordered by 1190sector number and sent to the disk, regardless of whether the 1191operation is a read or write; this option gives priority to issuing 1192read requests over write requests. 1193Although requests may therefore be issued out of sector-order, causing 1194more seeks and thus lower overall throughput, interactive system 1195responsiveness under heavy disk I/O load may be improved, as processes 1196blocking on disk reads are serviced sooner (file writes typically 1197don't cause applications to block). 1198The performance effect varies greatly depending on the hardware, drive 1199firmware, file system configuration, workload, and desired performance 1200trade-off. 1201Systems using drive write-cache (most modern IDE disks, by default) 1202are unlikely to benefit and may well suffer; such disks acknowledge 1203writes very quickly, and optimize them internally according to 1204physical layout. 1205Giving these disks as many requests to work with as possible (the 1206standard strategy) will typically produce the best results, especially 1207if the drive has a large cache; the drive will silently complete 1208writes from cache as it seeks for reads. 1209Disks that support a large number of concurrent tagged requests (SCSI 1210disks and many hardware RAID controllers) expose this internal 1211scheduling with tagged responses, and don't block for reads; such 1212disks may not see a noticeable difference with either strategy. 1213However, if IDE disks are run with write-cache disabled for safety, 1214writes are not acknowledged until actually completed, and only one 1215request can be outstanding; a large number of small writes in one 1216locality can keep the disk busy, starving reads elsewhere on the disk. 1217Such systems are likely to see the most benefit from this option. 1218Finally, the performance interaction of this option with ffs soft 1219dependencies can be subtle, as that mechanism can drastically alter 1220the workload for file system metadata writes. 1221.It Cd options BUFQ_PRIOCSCAN 1222Enable another buffer queue strategy for disk I/O, per-priority cyclical scan. 1223.It Cd options NEW_BUFQ_STRATEGY 1224Synonym of 1225.Em BUFQ_READPRIO . 1226.El 1227.Ss Miscellaneous Options 1228.Bl -ohang 1229.It Cd options CPU_UCODE 1230Support cpu microcode loading via 1231.Xr cpuctl 8 . 1232.It Cd options MEMORY_DISK_DYNAMIC 1233This option makes the 1234.Xr md 4 1235RAM disk size dynamically sized. 1236It is incompatible with 1237.Xr mdsetimage 8 . 1238.It Cd options MEMORY_DISK_HOOKS 1239This option allows for some machine dependent functions to be called when 1240the 1241.Xr md 4 1242RAM disk driver is configured. 1243This can result in automatically loading a RAM disk from floppy on 1244open (among other things). 1245.It Cd options MEMORY_DISK_IS_ROOT 1246Forces the 1247.Xr md 4 1248RAM disk to be the root device. 1249This can only be overridden when 1250the kernel is booted in the 'ask-for-root' mode. 1251.It Cd options MEMORY_DISK_ROOT_SIZE=integer 1252Allocates the given number of 512 byte blocks as memory for the 1253.Xr md 4 1254RAM disk, to be populated with 1255.Xr mdsetimage 8 . 1256.It Cd options MEMORY_DISK_SERVER=0 1257Do not include the interface to a userland memory disk server process. 1258Per default, this option is set to 1, including the support code. 1259Useful for install media kernels. 1260.It Cd options MEMORY_DISK_RBFLAGS=value 1261This option sets the 1262.Xr reboot 2 1263flags used when booting with a memory disk as root file system. 1264Possible values include 1265.Dv RB_AUTOBOOT 1266(boot in the usual fashion - default value), and 1267.Dv RB_SINGLE 1268(boot in single-user mode). 1269.It Cd options MODULAR 1270Enables the framework for kernel modules (see 1271.Xr module 7 ) . 1272.It Cd options MODULAR_DEFAULT_AUTOLOAD 1273Enables the autoloading of kernel modules by default. 1274This sets the default value of the 1275.Em kern.module.autoload 1276.Xr sysctl 3 1277variable which may be changed at run time. 1278.It Cd options MODULAR_DEFAULT_VERBOSE 1279Enables verbose debug messages of kernel modules by default. 1280This sets the default value of the 1281.Em kern.module.verbose 1282.Xr sysctl 3 1283variable which may be changed at run time. 1284.It Cd options VND_COMPRESSION 1285Enables the 1286.Xr vnd 4 1287driver to also handle compressed images. 1288See 1289.Xr vndcompress 1 , 1290.Xr vnd 4 1291and 1292.Xr vnconfig 8 1293for more information. 1294.It Cd options SELFRELOC 1295Make the kernel able to self relocate at bootstrap, so that it can 1296run whatever its load address is. 1297This is intented to be used with the 1298.Ic reloc 1299bootstrap command documented in 1300.Xr x86/boot 8 , 1301to workaround UEFI bugs, and is only available on amd64. 1302.It Cd options SPLDEBUG 1303Help the kernel programmer find bugs related to the interrupt priority 1304level. 1305When 1306.Fn spllower 1307or 1308.Fn splraise 1309changes the current CPU's interrupt priority level to or from 1310.Dv IPL_HIGH , 1311record a backtrace. 1312Read 1313.Xr i386/return_address 9 1314for caveats about collecting backtraces. 1315This feature is experimental, and it is only available on i386. 1316See 1317.Pa sys/kern/subr_spldebug.c . 1318.It Cd options TFTPROOT 1319Download the root memory disk through TFTP at root mount time. 1320This enables the use of a root RAM disk without requiring it to be 1321embedded in the kernel using 1322.Xr mdsetimage 8 . 1323The RAM disk name is obtained using DHCP's filename parameter. 1324This option requires 1325.Em MEMORY_DISK_HOOKS 1326and 1327.Em MEMORY_DISK_DYNAMIC . 1328It is incompatible with 1329.Em MEMORY_DISK_ROOT_SIZE . 1330.It Cd options HEARTBEAT 1331Turns on heartbeat checks to panic if any CPU in the system or the 1332timecounter appears stuck. 1333.Pp 1334Each CPU will periodically check in hard interrupt context that the 1335timecounter has advanced and soft interrupts have run on the current 1336CPU, and each CPU will also be periodically checked for progress by 1337another CPU. 1338.Pp 1339If a CPU detects no progress has been made after 1340.Dv HEARTBEAT_MAX_PERIOD 1341seconds, 1342.Nx 1343will panic, giving the opportunity to enter ddb or get a crash dump 1344even if the system has become totally unresponsive to keyboard input. 1345.Pp 1346This is different from a hardware watchdog timer 1347.Pq Xr wdogctl 8 : 1348.Bl -bullet 1349.It 1350.Cd options HEARTBEAT 1351is purely a software mechanism, so if hard interrupts are stuck on all 1352CPUs, then 1353.Cd options HEARTBEAT 1354cannot trigger, but a hardware watchdog timer can. 1355.It 1356A hardware watchdog timer won't notice if a single CPU is stuck, or if 1357the system timecounter is stuck, as long as at least one CPU is not 1358stuck and able to run 1359.Xr wdogctl 8 1360or the kernel watchdog tickle thread. 1361In contrast, 1362.Cd options HEARTBEAT 1363uses hard interrupts on each CPU to cross-check soft interrupt progress 1364on another CPU as well as the timecounter, so it can detect when a 1365single CPU is unable to make progress when others are able. 1366.El 1367.It Cd options HEARTBEAT_MAX_PERIOD_DEFAULT=integer 1368Time in seconds since the last 1369.Cd options HEARTBEAT 1370progress check has passed before it will trigger a panic. 1371Default: 15. 1372.Pp 1373Can be changed at runtime via the 1374.Li kern.heartbeat.max_period 1375.Xr sysctl 7 1376knob. 1377.It Cd options HZ=integer 1378On ports that support it, set the system clock frequency (see 1379.Xr hz 9 ) 1380to the supplied value. 1381Handle with care. 1382.It Cd options NTP 1383Turns on in-kernel precision timekeeping support used by software 1384implementing 1385.Em NTP 1386(Network Time Protocol, RFC 1305). 1387The 1388.Em NTP 1389option adds an in-kernel Phase-Locked Loop (PLL) for normal 1390.Em NTP 1391operation, and a Frequency-Locked Loop (FLL) for intermittently-connected 1392operation. 1393.Xr ntpd 8 1394will employ a user-level PLL when kernel support is unavailable, 1395but the in-kernel version has lower latency and more precision, and 1396so typically keeps much better time. 1397.Pp 1398The interface to the kernel 1399.Em NTP 1400support is provided by the 1401.Xr ntp_adjtime 2 1402and 1403.Xr ntp_gettime 2 1404system calls, which are intended for use by 1405.Xr ntpd 8 1406and are enabled by the option. 1407On systems with sub-microsecond resolution timers, or where (HZ/100000) 1408is not an integer, the 1409.Em NTP 1410option also enables extended-precision arithmetic to keep track of 1411fractional clock ticks at NTP time-format precision. 1412.It Cd options PPS_SYNC 1413This option enables a kernel serial line discipline for receiving time 1414phase signals from an external reference clock such as a radio clock. 1415Some reference clocks generate a Pulse Per Second (PPS) signal in 1416phase with their time source. 1417The 1418.Em PPS 1419line discipline receives this signal on either the data leads 1420or the DCD control lead of a serial port. 1421.Pp 1422.Em NTP 1423uses the PPS signal to discipline the local clock oscillator to a high 1424degree of precision (typically less than 50 microseconds in time and 14250.1 ppm in accuracy). 1426.Em PPS 1427can also generate a serial output pulse when the system receives a PPS 1428interrupt. 1429This can be used to measure the system interrupt latency and thus calibrate 1430.Em NTP 1431to account for it. 1432Using 1433.Em PPS 1434usually requires a gadget box 1435to convert from TTL to RS-232 signal levels. 1436The gadget box and PPS are described in more detail in the HTML documentation 1437for 1438.Xr ntpd 8 1439in 1440.Pa /usr/share/doc/html/ntp . 1441.Pp 1442.Nx 1443currently supports this option in 1444.Xr com 4 1445and 1446.Xr zsc 4 . 1447.Pp 1448.Em NOTE : 1449Using this option will also enable 1450.Em options NTP . 1451.It Cd options SETUIDSCRIPTS 1452Allows scripts with the setuid bit set to execute as the effective 1453user rather than the real user, just like binary executables. 1454.Pp 1455.Em NOTE : 1456Using this option will also enable 1457.Em options FDSCRIPTS 1458.It Cd options FDSCRIPTS 1459Allows execution of scripts with the execute bit set, but not the 1460read bit, by opening the file and passing the file descriptor to 1461the shell, rather than the filename. 1462.Pp 1463.Em NOTE : 1464Execute only (non-readable) scripts will have 1465.Va argv[0] 1466set to 1467.Pa /dev/fd/* . 1468What this option allows as far as security is 1469concerned, is the ability to safely ensure that the correct script 1470is run by the interpreter, as it is passed as an already open file. 1471.It Cd options RTC_OFFSET=integer 1472The kernel (and typically the hardware battery backed-up clock on 1473those machines that have one) keeps time in 1474.Em UTC 1475(Universal Coordinated Time, once known as 1476.Em GMT , 1477or Greenwich Mean Time) 1478and not in the time of the local time zone. 1479The 1480.Em RTC_OFFSET 1481option is used on some ports (such as the i386) to tell the kernel 1482that the hardware clock is offset from 1483.Em UTC 1484by the specified number of minutes. 1485This is typically used when a machine boots several operating 1486systems and one of them wants the hardware clock to run in the 1487local time zone and not in 1488.Em UTC , 1489e.g. 1490.Em RTC_OFFSET=300 1491means 1492the hardware clock is set to US Eastern Time (300 minutes behind 1493.Em UTC ) , 1494and not 1495.Em UTC . 1496(Note: 1497.Em RTC_OFFSET 1498is used to initialize a kernel variable named 1499.Va rtc_offset 1500which is the source actually used to determine the clock offset, and 1501which may be accessed via the kern.rtc_offset sysctl variable. 1502See 1503.Xr sysctl 8 1504and 1505.Xr sysctl 3 1506for details. 1507Since the kernel clock is initialized from the hardware clock very 1508early in the boot process, it is not possible to meaningfully change 1509.Va rtc_offset 1510in system initialization scripts. 1511Changing this value currently may only be done at kernel compile 1512time or by patching the kernel and rebooting). 1513.Pp 1514.Em NOTE : 1515Unfortunately, in many cases where the hardware clock 1516is kept in local time, it is adjusted for Daylight Savings 1517Time; this means that attempting to use 1518.Em RTC_OFFSET 1519to let 1520.Nx 1521coexist with such an operating system, like Windows, 1522would necessitate changing 1523.Em RTC_OFFSET 1524twice a year. 1525As such, this solution is imperfect. 1526.It Cd options MAXUPRC=integer 1527Sets the soft 1528.Dv RLIMIT_NPROC 1529resource limit, which specifies the maximum number of simultaneous 1530processes a user is permitted to run, for process 0; 1531this value is inherited by its child processes. 1532It defaults to 1533.Em CHILD_MAX , 1534which is currently defined to be 160. 1535Setting 1536.Em MAXUPRC 1537to a value less than 1538.Em CHILD_MAX 1539is not permitted, as this would result in a violation of the semantics of 1540.St -p1003.1-90 . 1541.It Cd options NOFILE=integer 1542Sets the soft 1543.Dv RLIMIT_NOFILE 1544resource limit, which specifies the maximum number of open 1545file descriptors for each process; 1546this value is inherited by its child processes. 1547It defaults to 1548.Em OPEN_MAX , 1549which is currently defined to be 128. 1550.It Cd options MAXFILES=integer 1551Sets the default value of the 1552.Em kern.maxfiles 1553sysctl variable, which indicates the maximum number of files that may 1554be open in the system. 1555.It Cd options DEFCORENAME=string 1556Sets the default value of the 1557.Em kern.defcorename 1558sysctl variable, otherwise it is set to 1559.Nm %n.core . 1560See 1561.Xr sysctl 8 1562and 1563.Xr sysctl 3 1564for details. 1565.It Cd options RASOPS_CLIPPING 1566Enables clipping within the 1567.Nm rasops 1568raster-console output system. 1569.Em NOTE : 1570only available on architectures that use 1571.Nm rasops 1572for console output. 1573.It Cd options RASOPS_SMALL 1574Removes optimized character writing code from the 1575.Nm rasops 1576raster-console output system. 1577.Em NOTE : 1578only available on architectures that use 1579.Nm rasops 1580for console output. 1581.It Cd options INCLUDE_CONFIG_FILE 1582Embeds the kernel config file used to define the kernel in the kernel 1583binary itself. 1584The embedded data also includes any files directly included by the config 1585file itself, e.g. 1586.Pa GENERIC.local 1587or 1588.Pa std.$MACHINE . 1589The embedded config file can be extracted from the resulting kernel with 1590.Xr config 1 1591.Fl x , 1592or by the following command: 1593.Bd -literal -offset indent 1594strings netbsd | sed -n 's/^_CFG_//p' | unvis 1595.Ed 1596.It Cd options INCLUDE_JUST_CONFIG 1597Similar to the above option, but includes just the actual config file, 1598not any included files. 1599.It Cd options PIPE_SOCKETPAIR 1600Use slower, but smaller socketpair(2)-based pipe implementation instead 1601of default faster, but bigger one. 1602Primarily useful for installation kernels. 1603.It Cd options USERCONF 1604Compiles in the in-kernel device configuration manager. 1605See 1606.Xr userconf 4 1607for details. 1608.It Cd options SCDEBUG_DEFAULT 1609Used with the 1610.Cd options SYSCALL_DEBUG 1611described below to choose which types of events are displayed. 1612.Pp 1613.Bl -tag -width "SCDEBUG_KERNHIST" -compact -offset indent 1614.It Dv SCDEBUG_CALLS 1615Show system call entry points. 1616.It Dv SCDEBUG_RETURNS 1617Show system call exit points. 1618.It Dv SCDEBUG_ALL 1619Show all system call requests, including unimplemented calls. 1620.It Dv SCDEBUG_SHOWARGS 1621Show the arguments provided. 1622.It Dv SCDEBUG_KERNHIST 1623Store a restricted form of the system call debug in a kernel history 1624instead of printing it to the console. 1625This option relies upon 1626.Cd options KERNHIST . 1627.El 1628.Pp 1629The default value is 1630.Dv (SCDEBUG_CALLS|SCDEBUG_RETURNS|SCDEBUG_SHOWARGS) . 1631.It Cd options SYSCALL_DEBUG 1632Useful for debugging system call issues, usually in early single user bringup. 1633By default, writes entries to the system console for most system call events. 1634Can be configured with the 1635.Cd options SCDEBUG_DEFAULT 1636option to to use the 1637.Cd options KERNHIST 1638facility instead. 1639.It Cd options SYSCALL_STATS 1640Count the number of times each system call number is called. 1641The values can be read through the sysctl interface and displayed using 1642.Xr systat 1 . 1643.Em NOTE : 1644not yet available on all architectures. 1645.It Cd options SYSCALL_TIMES 1646Count the time spent (using 1647.Fn cpu_counter32 ) 1648in each system call. 1649.Em NOTE : 1650Using this option will also enable 1651.Cd options SYSCALL_STATS . 1652.It Cd options SYSCALL_TIMES_HASCOUNTER 1653Force use of 1654.Fn cpu_counter32 1655even if 1656.Fn cpu_hascounter 1657reports false. 1658Useful for systems where the cycle counter doesn't run at a constant rate 1659(e.g. Soekris boxes). 1660.It Cd options XSERVER_DDB 1661A supplement to XSERVER that adds support for entering 1662.Xr ddb 4 1663while in X11. 1664.It Cd options FILEASSOC 1665Support for 1666.Xr fileassoc 9 . 1667Required for 1668.Cd options PAX_SEGVGUARD 1669and 1670.Cd pseudo-device veriexec . 1671.It Cd options FILEASSOC_NHOOKS=integer 1672Number of storage slots per file for 1673.Xr fileassoc 9 . 1674Default is 4. 1675.El 1676.Ss Networking Options 1677.Bl -ohang 1678.It Cd options GATEWAY 1679Enables 1680.Em IPFORWARDING 1681and (on most ports) increases the size of 1682.Em NMBCLUSTERS . 1683In general, 1684.Em GATEWAY 1685is used to indicate that a system should act as a router, and 1686.Em IPFORWARDING 1687is not invoked directly. 1688(Note that 1689.Em GATEWAY 1690has no impact on protocols other than IP). 1691.Em GATEWAY 1692option also compiles IPv4 and IPv6 fast forwarding code into the kernel. 1693.It Cd options IPFORWARDING=value 1694If 1695.Em value 1696is 1 this enables IP routing behavior. 1697If 1698.Em value 1699is 0 (the default), it disables it. 1700The 1701.Em GATEWAY 1702option sets this to 1 automatically. 1703With this option enabled, the machine will forward IP datagrams destined 1704for other machines between its interfaces. 1705Note that even without this option, the kernel will 1706still forward some packets (such as source routed packets) \(em removing 1707.Em GATEWAY 1708and 1709.Em IPFORWARDING 1710is insufficient to stop all routing through a bastion host on a 1711firewall \(em source routing is controlled independently. 1712Note that IP forwarding may be turned on and off independently of the 1713setting of the 1714.Em IPFORWARDING 1715option through the use of the 1716.Em net.inet.ip.forwarding 1717sysctl variable. 1718If 1719.Em net.inet.ip.forwarding 1720is 1, IP forwarding is on. 1721See 1722.Xr sysctl 8 1723and 1724.Xr sysctl 3 1725for details. 1726.It Cd options IFA_STATS 1727Tells the kernel to maintain per-address statistics on bytes sent 1728and received over (currently) Internet and AppleTalk addresses. 1729.\"This can be a fairly expensive operation, so you probably want to 1730.\"keep this disabled. 1731The option is not recommended as it degrades system stability. 1732.It Cd options IFQ_MAXLEN=value 1733Increases the allowed size of the network interface packet queues. 1734The default queue size is 50 packets, and you do not normally need 1735to increase it. 1736.It Cd options IPSELSRC 1737Includes support for source-address selection policies. 1738See 1739.Xr in_getifa 9 . 1740.It Cd options MROUTING 1741Includes support for IP multicast routers. 1742You certainly want 1743.Em INET 1744with this. 1745Multicast routing is controlled by the 1746.Xr mrouted 8 1747daemon. 1748See also option 1749.Cd PIM . 1750.It Cd options PIM 1751Includes support for Protocol Independent Multicast (PIM) routing. 1752You need 1753.Em MROUTING 1754and 1755.Em INET 1756with this. 1757Software using this can be found e.g. in 1758.Pa pkgsrc/net/xorp . 1759.It Cd options INET 1760Includes support for the TCP/IP protocol stack. 1761You almost certainly want this. 1762See 1763.Xr inet 4 1764for details. 1765.It Cd options INET6 1766Includes support for the IPv6 protocol stack. 1767See 1768.Xr inet6 4 1769for details. 1770Unlike 1771.Em INET , 1772.Em INET6 1773enables multicast routing code as well. 1774This option requires 1775.Em INET 1776at this moment, but it should not. 1777.It Cd options ND6_DEBUG 1778The option sets the default value of net.inet6.icmp6.nd6_debug to 1, 1779for debugging IPv6 neighbor discovery protocol handling. 1780See 1781.Xr sysctl 3 1782for details. 1783.It Cd options IPSEC 1784Includes support for the IPsec protocol, using the implementation derived from 1785.Ox , 1786relying on 1787.Xr opencrypto 9 1788to carry out cryptographic operations. 1789See 1790.Xr ipsec 4 1791for details. 1792.It Cd options IPSEC_DEBUG 1793Enables debugging code in IPsec stack. 1794See 1795.Xr ipsec 4 1796for details. 1797The 1798.Cd IPSEC 1799option includes support for IPsec Network Address Translator traversal 1800(NAT-T), as described in RFCs 3947 and 3948. 1801This feature might be patent-encumbered in some countries. 1802.It Cd options ALTQ 1803Enabled ALTQ (Alternate Queueing). 1804For simple rate-limiting, use 1805.Xr tbrconfig 8 1806to set up the interface transmission rate. 1807To use queueing disciplines, their appropriate kernel options should also 1808be defined (documented below). 1809Queueing disciplines are managed by 1810.Xr altqd 8 . 1811See 1812.Xr altq 9 1813for details. 1814.It Cd options ALTQ_HFSC 1815Include support for ALTQ-implemented HFSC (Hierarchical Fair Service Curve) 1816module. 1817HFSC supports both link-sharing and guaranteed real-time services. 1818HFSC employs a service curve based QoS model, and its unique feature 1819is an ability to decouple delay and bandwidth allocation. 1820Requires 1821.Em ALTQ_RED 1822to use the RED queueing discipline on HFSC classes, or 1823.Em ALTQ_RIO 1824to use the RIO queueing discipline on HFSC classes. 1825This option assumes 1826.Em ALTQ . 1827.It Cd options ALTQ_PRIQ 1828Include support for ALTQ-implemented PRIQ (Priority Queueing). 1829PRIQ implements a simple priority-based queueing discipline. 1830A higher priority class is always served first. 1831Requires 1832.Em ALTQ_RED 1833to use the RED queueing discipline on HFSC classes, or 1834.Em ALTQ_RIO 1835to use the RIO queueing discipline on HFSC classes. 1836This option assumes 1837.Em ALTQ . 1838.It Cd options ALTQ_WFQ 1839Include support for ALTQ-implemented WFQ (Weighted Fair Queueing). 1840WFQ implements a weighted-round robin scheduler for a set of queues. 1841A weight can be assigned to each queue to give a different proportion 1842of the link capacity. 1843A hash function is used to map a flow to one of a set of queues. 1844This option assumes 1845.Em ALTQ . 1846.It Cd options ALTQ_FIFOQ 1847Include support for ALTQ-implemented FIFO queueing. 1848FIFOQ is a simple drop-tail FIFO (First In, First Out) queueing discipline. 1849This option assumes 1850.Em ALTQ . 1851.It Cd options ALTQ_RIO 1852Include support for ALTQ-implemented RIO (RED with In/Out). 1853The original RIO has 2 sets of RED parameters; one for in-profile 1854packets and the other for out-of-profile packets. 1855At the ingress of the network, profile meters tag packets as IN or 1856OUT based on contracted profiles for customers. 1857Inside the network, IN packets receive preferential treatment by 1858the RIO dropper. 1859ALTQ/RIO has 3 drop precedence levels defined for the Assured Forwarding 1860PHB of DiffServ (RFC 2597). 1861This option assumes 1862.Em ALTQ . 1863.It Cd options ALTQ_BLUE 1864Include support for ALTQ-implemented Blue buffer management. 1865Blue is another active buffer management mechanism. 1866This option assumes 1867.Em ALTQ . 1868.It Cd options ALTQ_FLOWVALVE 1869Include support for ALTQ-implemented Flowvalve. 1870Flowvalve is a simple implementation of a RED penalty box that identifies 1871and punishes misbehaving flows. 1872This option requires 1873.Em ALTQ_RED 1874and assumes 1875.Em ALTQ . 1876.It Cd options ALTQ_CDNR 1877Include support for ALTQ-implemented CDNR (diffserv traffic conditioner) 1878packet marking/manipulation. 1879Traffic conditioners are components to meter, mark, or drop incoming 1880packets according to some rules. 1881As opposed to queueing disciplines, traffic conditioners handle incoming 1882packets at an input interface. 1883This option assumes 1884.Em ALTQ . 1885.It Cd options ALTQ_NOPCC 1886Disables use of processor cycle counter to measure time in ALTQ. 1887This option should be defined for a non-Pentium i386 CPU which does not 1888have TSC, SMP (per-CPU counters are not in sync), or power management 1889which affects processor cycle counter. 1890This option assumes 1891.Em ALTQ . 1892.It Cd options ALTQ_IPSEC 1893Include support for IPsec in IPv4 ALTQ. 1894This option assumes 1895.Em ALTQ . 1896.It Cd options ALTQ_JOBS 1897Include support for ALTQ-implemented JoBS (Joint Buffer Management 1898and Scheduling). 1899This option assumes 1900.Em ALTQ . 1901.It Cd options ALTQ_AFMAP 1902Include support for an undocumented ALTQ feature that is used to map an IP 1903flow to an ATM VC (Virtual Circuit). 1904This option assumes 1905.Em ALTQ . 1906.It Cd options ALTQ_LOCALQ 1907Include support for ALTQ-implemented local queues. 1908Its practical use is undefined. 1909Assumes 1910.Em ALTQ . 1911.It Cd options SUBNETSARELOCAL 1912Sets default value for net.inet.ip.subnetsarelocal variable, which 1913controls whether non-directly-connected subnets of connected networks 1914are considered "local" for purposes of choosing the MSS for a TCP 1915connection. 1916This is mostly present for historic reasons and completely irrelevant if 1917you enable Path MTU discovery. 1918.It Cd options HOSTZEROBROADCAST 1919Sets default value for net.inet.ip.hostzerobroadcast variable, which 1920controls whether the zeroth host address of each connected subnet is 1921also considered a broadcast address. 1922Default value is "1", for compatibility with old systems; if this is 1923set to zero on all hosts on a subnet, you should be able to fit an extra 1924host per subnet on the 1925".0" address. 1926.It Cd options MCLSHIFT=value 1927This option is the base-2 logarithm of the size of mbuf clusters. 1928The 1929.Bx 1930networking stack keeps network packets in a linked 1931list, or chain, of kernel buffer objects called mbufs. 1932The system provides larger mbuf clusters as an optimization for 1933large packets, instead of using long chains for large packets. 1934The mbuf cluster size, 1935or 1936.Em MCLBYTES , 1937must be a power of two, and is computed as two raised to the power 1938.Em MCLSHIFT . 1939On systems with Ethernet network adapters, 1940.Em MCLSHIFT 1941is often set to 11, giving 2048-byte mbuf clusters, large enough to 1942hold a 1500-byte Ethernet frame in a single cluster. 1943Systems with network interfaces supporting larger frame sizes like 1944ATM, FDDI, or HIPPI may perform better with 1945.Em MCLSHIFT 1946set to 12 or 13, giving mbuf cluster sizes of 4096 and 8192 bytes, 1947respectively. 1948.It Cd options NETATALK 1949Include support for the AppleTalk protocol stack. 1950The kernel provides provision for the 1951.Em Datagram Delivery Protocol 1952(DDP), providing SOCK_DGRAM support and AppleTalk routing. 1953This stack is used by the 1954.Em NETATALK 1955package, which adds support for AppleTalk server services via user 1956libraries and applications. 1957.It Cd options BLUETOOTH 1958Include support for the Bluetooth protocol stack. 1959See 1960.Xr bluetooth 4 1961for details. 1962.It Cd options IPNOPRIVPORTS 1963Normally, only root can bind a socket descriptor to a so-called 1964.Dq privileged 1965TCP port, that is, a port number in the range 0-1023. 1966This option eliminates those checks from the kernel. 1967This can be useful if there is a desire to allow daemons without 1968privileges to bind those ports, e.g., on firewalls. 1969The security tradeoffs in doing this are subtle. 1970This option should only be used by experts. 1971.It Cd options TCP_DEBUG 1972Record the last 1973.Em TCP_NDEBUG 1974TCP packets with SO_DEBUG set, and decode to the console if 1975.Em tcpconsdebug 1976is set. 1977.It Cd options TCP_NDEBUG 1978Number of packets to record for 1979.Em TCP_DEBUG . 1980Defaults to 100. 1981.It Cd options TCP_SENDSPACE=value 1982.It Cd options TCP_RECVSPACE=value 1983These options set the max TCP window size to other sizes than the default. 1984The TCP window sizes can be altered via 1985.Xr sysctl 8 1986as well. 1987.It Cd options TCP_INIT_WIN=value 1988This option sets the initial TCP window size for non-local connections, 1989which is used when the transmission starts. 1990The default size is 1, but if the machine should act more aggressively, 1991the initial size can be set to some other value. 1992The initial TCP window size can be set via 1993.Xr sysctl 8 1994as well. 1995.It Cd options TCP_SIGNATURE 1996Enable MD5 TCP signatures (RFC 2385) to protect BGP sessions. 1997.It Cd options IPFILTER_LOG 1998This option, in conjunction with 1999.Em pseudo-device ipfilter , 2000enables logging of IP packets using IP-Filter. 2001.It Cd options IPFILTER_LOOKUP 2002This option enables the 2003IP-Filter 2004.Xr ippool 8 2005functionality to be enabled. 2006.It Cd options IPFILTER_COMPAT 2007This option enables older IP-Filter binaries to work. 2008.It Cd options IPFILTER_DEFAULT_BLOCK 2009This option sets the default policy of IP-Filter. 2010If it is set, IP-Filter will block packets by default. 2011.It Cd options MBUFTRACE 2012This option can help track down mbuf leaks. 2013When enabled, mbufs are tagged with the devices and protocols using them. 2014This can significantly decrease network performance, particularly 2015on MP systems. 2016This additional information can be viewed with 2017.Xr netstat 1 : 2018.Dl Ic netstat Fl mssv 2019Not all devices or protocols support this option. 2020.El 2021.Ss Sysctl Related Options 2022.Bl -ohang 2023.It Cd options SYSCTL_DISALLOW_CREATE 2024Disallows the creation or deletion of nodes from the sysctl tree, as 2025well as the assigning of descriptions to nodes that lack them, by any 2026process. 2027These operations are still available to kernel sub-systems, including 2028loadable kernel modules. 2029.It Cd options SYSCTL_DISALLOW_KWRITE 2030Prevents processes from adding nodes to the sysctl tree that make 2031existing kernel memory areas writable. 2032Sections of kernel memory can still be read and new nodes that own 2033their own data may still be writable. 2034.It Cd options SYSCTL_DEBUG_SETUP 2035Causes the SYSCTL_SETUP routines to print a brief message when they 2036are invoked. 2037This is merely meant as an aid in determining the order in which 2038sections of the tree are created. 2039.It Cd options SYSCTL_DEBUG_CREATE 2040Prints a message each time 2041.Fn sysctl_create , 2042the function that adds nodes to the tree, is called. 2043.It Cd options SYSCTL_INCLUDE_DESCR 2044Causes the kernel to include short, human readable descriptions for 2045nodes in the sysctl tree. 2046The descriptions can be retrieved programmatically (see 2047.Xr sysctl 3 ) , 2048or by the sysctl binary itself (see 2049.Xr sysctl 8 ) . 2050The descriptions are meant to give an indication of the purpose and/or 2051effects of a given node's value, not replace the documentation for the 2052given subsystem as a whole. 2053.El 2054.Ss System V IPC Options 2055.Bl -ohang 2056.It Cd options SYSVMSG 2057Includes support for 2058.At V 2059style message queues. 2060See 2061.Xr msgctl 2 , 2062.Xr msgget 2 , 2063.Xr msgrcv 2 , 2064.Xr msgsnd 2 . 2065.It Cd options SYSVSEM 2066Includes support for 2067.At V 2068style semaphores. 2069See 2070.Xr semctl 2 , 2071.Xr semget 2 , 2072.Xr semop 2 . 2073.It Cd options SEMMNI=value 2074Sets the number of 2075.At V 2076style semaphore identifiers. 2077The GENERIC config file for your port will have the default. 2078.It Cd options SEMMNS=value 2079Sets the number of 2080.At V 2081style semaphores in the system. 2082The GENERIC config file for your port will have the default. 2083.It Cd options SEMUME=value 2084Sets the maximum number of undo entries per process for 2085.At V 2086style semaphores. 2087The GENERIC config file for your port will have the default. 2088.It Cd options SEMMNU=value 2089Sets the number of undo structures in the system for 2090.At V 2091style semaphores. 2092The GENERIC config file for your port will have the default. 2093.It Cd options SYSVSHM 2094Includes support for 2095.At V 2096style shared memory. 2097See 2098.Xr shmat 2 , 2099.Xr shmctl 2 , 2100.Xr shmdt 2 , 2101.Xr shmget 2 . 2102.It Cd options SHMMAXPGS=value 2103Sets the maximum number of 2104.At V 2105style shared memory pages that are available through the 2106.Xr shmget 2 2107system call. 2108Default value is 1024 on most ports. 2109See 2110.Pa /usr/include/machine/vmparam.h 2111for the default. 2112.El 2113.Ss VM Related Options 2114.Bl -ohang 2115.It Cd options NMBCLUSTERS=value 2116The number of mbuf clusters the kernel supports. 2117Mbuf clusters are MCLBYTES in size (usually 2k). 2118The default value is calculated from the amount of physical memory. 2119Architectures without direct mapping also limit it based on the kmem_map size, 2120which is used as backing store. 2121Some archs limit the value with 2122.Sq NMBCLUSTERS_MAX . 2123See 2124.Pa /usr/include/machine/param.h 2125for those archs. 2126This value can be accessed via the kern.mbuf.nmbclusters sysctl variable. 2127Increase this value if you get 2128.Dq mclpool limit reached 2129messages. 2130.It Cd options NMBCLUSTERS_MAX=value 2131The upper limit of NMBCLUSTERS. 2132.It Cd options NKMEMPAGES=value 2133.It Cd options NKMEMPAGES_MIN=value 2134.It Cd options NKMEMPAGES_MAX=value 2135Size of kernel VM map 2136.Em kmem_map , 2137in PAGE_SIZE-sized chunks (the VM page size; this value may be read 2138from the 2139.Xr sysctl 8 2140variable 2141.Em hw.pagesize 2142). 2143This VM map is used to map the kernel malloc arena. 2144The kernel attempts to auto-size this map based on the amount of 2145physical memory in the system. 2146Platform-specific code may place bounds on this computed size, 2147which may be viewed with the 2148.Xr sysctl 8 2149variable 2150.Em vm.nkmempages . 2151See 2152.Pa /usr/include/machine/param.h 2153for the default upper and lower bounds. 2154The related options 2155.Sq NKMEMPAGES_MIN 2156and 2157.Sq NKMEMPAGES_MAX 2158allow the bounds to be overridden in the kernel configuration file. 2159These options are provided in the event the computed value is 2160insufficient resulting in an 2161.Dq out of space in kmem_map 2162panic. 2163.It Cd options SB_MAX=value 2164Sets the max size in bytes that a socket buffer is allowed to occupy. 2165The default is 256k, but sometimes it needs to be increased, for example 2166when using large TCP windows. 2167This option can be changed via 2168.Xr sysctl 8 2169as well. 2170.It Cd options SOMAXKVA=value 2171Sets the maximum size of kernel virtual memory that the socket buffers 2172are allowed to use. 2173The default is 16MB, but in situations where for example large TCP 2174windows are used this value must also be increased. 2175This option can be changed via 2176.Xr sysctl 8 2177as well. 2178.It Cd options BUFCACHE=value 2179Size of the buffer cache as a percentage of total available RAM. 2180Ignored if BUFPAGES is also specified. 2181.It Cd options NBUF=value 2182Sets the number of buffer headers available, i.e., the number of 2183open files that may have a buffer cache entry. 2184Each buffer header 2185requires MAXBSIZE (machine dependent, but usually 65536) bytes. 2186The default value is machine dependent, but is usually equal to the 2187value of BUFPAGES. 2188.It Cd options BUFPAGES=value 2189These options set the number of pages available for the buffer cache. 2190Their default value is a machine dependent value, often calculated as 2191between 5% and 10% of total available RAM. 2192.It Cd options MAXTSIZ=bytes 2193Sets the maximum size limit of a process' text segment. 2194See 2195.Pa /usr/include/machine/vmparam.h 2196for the port-specific default. 2197.It Cd options DFLDSIZ=bytes 2198Sets the default size limit of a process' data segment, the value that 2199will be returned as the soft limit for 2200.Dv RLIMIT_DATA 2201(as returned by 2202.Xr getrlimit 2 ) . 2203See 2204.Pa /usr/include/machine/vmparam.h 2205for the port-specific default. 2206.It Cd options MAXDSIZ=bytes 2207Sets the maximum size limit of a process' data segment, the value that 2208will be returned as the hard limit for 2209.Dv RLIMIT_DATA 2210(as returned by 2211.Xr getrlimit 2 ) . 2212See 2213.Pa /usr/include/machine/vmparam.h 2214for the port-specific default. 2215.It Cd options DFLSSIZ=bytes 2216Sets the default size limit of a process' stack segment, the value that 2217will be returned as the soft limit for 2218.Dv RLIMIT_STACK 2219(as returned by 2220.Xr getrlimit 2 ) . 2221See 2222.Pa /usr/include/machine/vmparam.h 2223for the port-specific default. 2224.It Cd options MAXSSIZ=bytes 2225Sets the maximum size limit of a process' stack segment, the value that 2226will be returned as the hard limit for 2227.Dv RLIMIT_STACK 2228(as returned by 2229.Xr getrlimit 2 ) . 2230See 2231.Pa /usr/include/machine/vmparam.h 2232for the port-specific default. 2233.It Cd options DUMP_ON_PANIC=integer 2234Defaults to one. 2235If set to zero, the kernel will not dump to the dump device when 2236it panics, though dumps can still be forced via 2237.Xr ddb 4 2238with the 2239.Dq sync 2240command. 2241Note that this sets the value of the 2242.Em kern.dump_on_panic 2243.Xr sysctl 3 2244variable which may be changed at run time \(em see 2245.Xr sysctl 8 2246for details. 2247.It Cd options VMSWAP 2248Enable paging device/file support. 2249This option is on by default. 2250.It Cd options VMSWAP_DEFAULT_PLAINTEXT 2251Store swap in plaintext, not encrypted, which may expose secrets if the 2252underlying nonvolatile medium is disclosed. 2253This option is off by default; it is available only for extremely slow 2254machines where the performance impact of swapping early at boot 2255outweighs the security risks. 2256Swap encryption can still be turned on dynamically with the 2257.Em vm.swap_encrypt 2258.Xr sysctl 7 2259knob. 2260.It Cd options PDPOLICY_CLOCKPRO 2261Use CLOCK-Pro, an alternative page replace policy. 2262.El 2263.Ss Security Options 2264.Bl -ohang 2265.It Cd options INSECURE 2266Initializes the kernel security level with \-1 instead of 0. 2267This means that the system always starts in secure level \-1 mode, even when 2268running multiuser, unless the securelevel variable is set to value > \-1 in 2269.Pa /etc/rc.conf . 2270In this case the kernel security level will be raised to that value when the 2271.Pa /etc/rc.d/securelevel 2272script is run during system startup. 2273See the manual page for 2274.Xr init 8 2275for details on the implications of this. 2276The kernel secure level may manipulated by the superuser by altering the 2277.Em kern.securelevel 2278.Xr sysctl 3 2279variable (the secure level may only be lowered by a call from process ID 1, 2280i.e., 2281.Xr init 8 ) . 2282See also 2283.Xr secmodel_securelevel 9 , 2284.Xr sysctl 8 2285and 2286.Xr sysctl 3 . 2287.It Cd options VERIFIED_EXEC_FP_SHA256 2288Enables support for SHA256 hashes in Veriexec. 2289.It Cd options VERIFIED_EXEC_FP_SHA384 2290Enables support for SHA384 hashes in Veriexec. 2291.It Cd options VERIFIED_EXEC_FP_SHA512 2292Enables support for SHA512 hashes in Veriexec. 2293.It Cd options PAX_MPROTECT=value 2294Enables PaX MPROTECT, 2295.Xr mprotect 2 2296restrictions from the PaX project. 2297.Pp 2298The 2299.Ar value 2300is the default value for the 2301.Em global 2302knob, see 2303.Xr sysctl 3 . 2304If 0, PaX MPROTECT will be enabled only if explicitly set on programs 2305using 2306.Xr paxctl 8 . 2307If 1, PaX MPROTECT will be enabled for all programs. 2308Programs can be exempted using 2309.Xr paxctl 8 . 2310.Pp 2311See 2312.Xr security 7 2313for more details. 2314.It Cd options PAX_SEGVGUARD=value 2315Enables PaX Segvguard. 2316Requires 2317.Cd options FILEASSOC . 2318.Pp 2319The 2320.Ar value 2321is the default value for the 2322.Em global 2323knob, see 2324.Xr sysctl 3 . 2325If 0, PaX Segvguard will be enabled only if explicitly set on programs 2326using 2327.Xr paxctl 8 . 2328If 1, PaX Segvguard will be enabled to all programs, and exemption can 2329be done using 2330.Xr paxctl 8 . 2331.Pp 2332See 2333.Xr security 7 2334for more details. 2335.It Cd options PAX_ASLR=value 2336Enables PaX ASLR. 2337.Pp 2338The 2339.Ar value 2340is the default value for the 2341.Em global 2342knob, see 2343.Xr sysctl 3 . 2344If 0, PaX ASLR will be enabled only if explicitly set on programs 2345using 2346.Xr paxctl 8 . 2347If 1, PaX ASLR will be enabled to all programs, and exemption can 2348be done using 2349.Xr paxctl 8 . 2350.Pp 2351See 2352.Xr security 7 2353for more details. 2354.It Cd options USER_VA0_DISABLE_DEFAULT=value 2355Sets the initial value of the flag which controls whether user programs 2356can map virtual address 0. 2357The flag can be changed at runtime by 2358.Xr sysctl 3 . 2359.It Cd options KASAN 2360Enables Kernel Address Sanitizer. 2361.Em NOTE : 2362not available on all architectures. 2363.It Cd options KASLR 2364Enables Kernel ASLR. 2365This randomizes the location of the kernel image in memory. 2366.Em NOTE : 2367not available on all architectures. 2368.It Cd options SVS 2369Enables Separate Virtual Space. 2370On architectures that are designed to function with a shared address 2371space, this option explicitly isolates the kernel and user spaces. 2372.Em NOTE : 2373not available on all architectures. 2374.El 2375.Ss amiga-specific Options 2376.Bl -ohang 2377.It Cd options BB060STUPIDROM 2378When the bootloader (which passes AmigaOS ROM information) claims 2379we have a 68060 CPU without FPU, go look into the Processor 2380Configuration Register (PCR) to find out. 2381You need this with Amiga ROMs up to (at least) V40.xxx (OS3.1), 2382when you boot via the bootblocks and don't have a DraCo. 2383.It Cd options IOBZCLOCK=frequency 2384The IOBlix boards come with two different serial master clocks: older ones 2385use 24 MHz, newer ones use 22.1184 MHz. 2386The driver normally assumes the latter. 2387If your board uses 24 MHz, you can recompile your kernel with 2388options IOBZCLOCK=24000000 2389or patch the kernel variable iobzclock to the same value. 2390.It Cd options LIMITMEM=value 2391If there, limit the part of the first memory bank used by 2392.Nx 2393to value megabytes. 2394Default is unlimited. 2395.It Cd options P5PPC68KBOARD 2396Add special support for Phase5 mixed 68k+PPC boards. 2397Currently, this only affects rebooting from 2398.Nx 2399and is only needed on 68040+PPC, not on 240068060+PPC; without this, affected machines will hang after 2401.Nx 2402has shut 2403down and will only restart after a keyboard reset or a power cycle. 2404.El 2405.Ss atari-specific Options 2406.Bl -ohang 2407.It Cd options DISKLABEL_AHDI 2408Include support for AHDI (native Atari) disklabels. 2409.It Cd options DISKLABEL_NBDA 2410Include support for 2411.Nx Ns /atari 2412labels. 2413If you don't set this option, it will be set automatically. 2414.Nx Ns /atari 2415will not work without it. 2416.It Cd options FALCON_SCSI 2417Include support for the 5380-SCSI configuration as found on the Falcon. 2418.It Cd options RELOC_KERNEL 2419If set, the kernel will relocate itself to TT-RAM, if possible. 2420This will give you a slightly faster system. 2421.Em Beware 2422that on some TT030 systems, 2423the system will frequently dump with MMU-faults with this option enabled. 2424.It Cd options SERCONSOLE 2425Allow the modem1-port to act as the system-console. 2426A carrier should be active on modem1 during system boot to active 2427the console functionality. 2428.It Cd options TT_SCSI 2429Include support for the 5380-SCSI configuration as found on the TT030 2430and Hades. 2431.El 2432.Ss i386-specific Options 2433.Bl -ohang 2434.It Cd options CPURESET_DELAY=value 2435Specifies the time (in millisecond) to wait before doing a hardware reset 2436in the last phase of a reboot. 2437This gives the user a chance to see error messages from the shutdown 2438operations (like NFS unmounts, buffer cache flush, etc ...). 2439Setting this to 0 will disable the delay. 2440Default is 2 seconds. 2441.It Cd options USER_LDT 2442Include i386-specific system calls for modifying the local descriptor table, 2443used by Windows emulators. 2444.It Cd options PAE 2445Enable PAE (Physical Address Extension) mode. 2446PAE permits up to 36 bits physical addressing (64GB of physical 2447memory), and turns physical addresses to 64 bits entities in the 2448memory management subsystem. 2449Userland virtual address space remains at 32 bits (4GB). 2450PAE mode is required to enable the NX/XD (No-eXecute/eXecute Disable) 2451bit for pages, which allows marking certain ones as not being executable. 2452Any attempt to execute code from such a page will raise an exception. 2453.It Cd options REALBASEMEM=integer 2454Overrides the base memory size passed in from the boot block. 2455(Value given in kilobytes.) 2456Use this option only if the boot block reports the size incorrectly. 2457(Note that some BIOSes put the extended BIOS 2458data area at the top of base memory, and therefore report a smaller 2459base memory size to prevent programs overwriting it. 2460This is correct behavior, and you should not use the 2461.Em REALBASEMEM 2462option to access this memory). 2463.It Cd options SPECTRE_V2_GCC_MITIGATION=1 2464Enable GCC-specific Spectre variant 2 mitigations. 2465For 32-bit kernels this means these options: 2466.Bd -literal -offset indent 2467-mindirect-branch=thunk -mindirect-branch-register 2468.Ed 2469.Pp 2470For 64-bit kernels this means these options: 2471.Bd -literal -offset indent 2472-mindirect-branch=thunk-inline -mindirect-branch-register 2473.Ed 2474.It Cd options REALEXTMEM=integer 2475Overrides the extended memory size passed in from the boot block. 2476(Value given in kilobytes. 2477Extended memory does not include the first megabyte.) 2478Use this option only if the boot block reports the size incorrectly. 2479.It Cd options CYRIX_CACHE_WORKS 2480Relevant only to the Cyrix 486DLC CPU. 2481This option is used to turn on the cache in hold-flush mode. 2482It is not turned on by default because it is known to have problems in 2483certain motherboard implementations. 2484.It Cd options CYRIX_CACHE_REALLY_WORKS 2485Relevant only to the Cyrix 486DLC CPU. 2486This option is used to turn on the cache in write-back mode. 2487It is not turned on by default because it is known to have problems in 2488certain motherboard implementations. 2489In order for this option to take effect, option 2490.Em CYRIX_CACHE_WORKS 2491must also be specified. 2492.It Cd options PCIBIOS 2493Enable support for initializing the PCI bus using information from 2494the BIOS. 2495See 2496.Xr pcibios 4 2497for details. 2498.It Cd options MTRR 2499Include support for accessing MTRR registers from user-space. 2500See 2501.Xr i386_get_mtrr 2 . 2502.It Cd options BEEP_ONHALT 2503Make the system speaker emit several beeps when it is completely safe to 2504power down the computer after a 2505.Xr halt 8 2506command. 2507Requires 2508.Xr sysbeep 4 2509support. 2510.It Cd options BEEP_ONHALT_COUNT=times 2511Number of times to beep the speaker when 2512.Cd options BEEP_ONHALT 2513is enabled. 2514Defaults to 3. 2515.It Cd options BEEP_ONHALT_PITCH=hz 2516The tone frequency used when 2517.Cd options BEEP_ONHALT 2518option, in hertz. 2519Defaults to 1500. 2520.It Cd options BEEP_ONHALT_PERIOD=msecs 2521The duration of each beep when 2522.Cd options BEEP_ONHALT 2523is enabled, in milliseconds. 2524Defaults to 250. 2525.It Cd options MULTIBOOT 2526Makes the kernel Multiboot-compliant, allowing it to be booted through 2527a Multiboot-compliant boot manager such as GRUB. 2528See 2529.Xr multiboot 8 2530for more information. 2531.It Cd options SPLASHSCREEN 2532Display a splash screen during boot. 2533.El 2534.Ss isa-specific Options 2535Options specific to 2536.Xr isa 4 2537busses. 2538.Bl -ohang 2539.It Cd options PCIC_ISA_ALLOC_IOBASE=address, PCIC_ISA_ALLOC_IOSIZE=size 2540Control the section of IO bus space used for PCMCIA bus space mapping. 2541Ideally the probed defaults are satisfactory, however in practice 2542that is not always the case. 2543See 2544.Xr pcmcia 4 2545for details. 2546.It Cd options PCIC_ISA_INTR_ALLOC_MASK=mask 2547Controls the allowable interrupts that may be used for PCMCIA 2548devices. 2549This mask is a logical-or of power-of-2s of allowable interrupts: 2550.Bd -literal -offset 04n 2551.Em "IRQ Val IRQ Val IRQ Val IRQ Val" 2552 0 0x0001 4 0x0010 8 0x0100 12 0x1000 2553 1 0x0002 5 0x0020 9 0x0200 13 0x2000 2554 2 0x0004 6 0x0040 10 0x0400 14 0x4000 2555 3 0x0008 7 0x0080 11 0x0800 15 0x8000 2556.Ed 2557.It Cd options PCKBC_CNATTACH_SELFTEST 2558Perform a self test of the keyboard controller before attaching it as a 2559console. 2560This might be necessary on machines where we boot on cold iron, and 2561pckbc refuses to talk until we request a self test. 2562Currently only the netwinder port uses it. 2563.It Cd options PCKBD_CNATTACH_MAY_FAIL 2564If this option is set the PS/2 keyboard will not be used as the console 2565if it cannot be found during boot. 2566This allows other keyboards, like USB, to be the console keyboard. 2567.It Cd options PCKBD_LAYOUT=layout 2568Sets the default keyboard layout, see 2569.Xr pckbd 4 . 2570.El 2571.Ss m68k-specific Options 2572.Bl -ohang 2573.It Cd options FPU_EMULATE 2574Include support for MC68881/MC68882 emulator. 2575.It Cd options FPSP 2576Include support for 68040 floating point. 2577.It Cd options M68020,M68030,M68040,M68060 2578Include support for a specific CPU, 2579at least one (the one you are using) should be specified. 2580.It Cd options M060SP 2581Include software support for 68060. 2582This provides emulation of unimplemented 2583integer instructions as well as emulation of unimplemented floating point 2584instructions and data types and software support for floating point traps. 2585.El 2586.Ss powerpc-specific Options (OEA Only) 2587.Bl -ohang 2588.It Cd options PMAP_MEMLIMIT=value 2589Limit the amount of memory seen by the kernel to 2590.Ar value 2591bytes. 2592.It Cd options PTEGCOUNT=value 2593Specify the size of the page table as 2594.Ar value 2595PTE groups. 2596Normally, one PTEG is allocated per physical page frame. 2597.El 2598.Ss sparc-specific Options 2599.Bl -ohang 2600.It Cd options AUDIO_DEBUG 2601Enable simple event debugging of the logging of the 2602.Xr audio 4 2603device. 2604.It Cd options BLINK 2605Enable blinking of LED. 2606Blink rate is full cycle every N seconds for 2607N < then current load average. 2608See 2609.Xr getloadavg 3 . 2610.\" .It Cd options COLORFONT_CACHE 2611.\" What does this do? 2612.It Cd options COUNT_SW_LEFTOVERS 2613Count how many times the sw SCSI device has left 3, 2, 1 and 0 in the 2614sw_3_leftover, sw_2_leftover, sw_1_leftover, and sw_0_leftover 2615variables accessible from 2616.Xr ddb 4 . 2617See 2618.Xr sw 4 . 2619.It Cd options DEBUG_ALIGN 2620Adds debugging messages calls when user-requested alignment fault 2621handling happens. 2622.It Cd options DEBUG_EMUL 2623Adds debugging messages calls for emulated floating point and 2624alignment fixing operations. 2625.It Cd options EXTREME_DEBUG 2626Adds debugging functions callable from 2627.Xr ddb 4 . 2628The debug_pagetables, test_region and print_fe_map 2629functions print information about page tables for the SUN4M 2630platforms only. 2631.It Cd options EXTREME_EXTREME_DEBUG 2632Adds extra info to 2633.Em options EXTREME_DEBUG . 2634.It Cd options FPU_CONTEXT 2635Make 2636.Em options COMPAT_SVR4 2637getcontext and setcontext include floating point registers. 2638.It Cd options MAGMA_DEBUG 2639Adds debugging messages to the 2640.Xr magma 4 2641device. 2642.It Cd options RASTERCONS_FULLSCREEN 2643Use the entire screen for the console. 2644.It Cd options RASTERCONS_SMALLFONT 2645Use the Fixed font on the console, instead of the normal font. 2646.It Cd options SUN4 2647Support sun4 class machines. 2648.It Cd options SUN4C 2649Support sun4c class machines. 2650.It Cd options SUN4M 2651Support sun4m class machines. 2652.It Cd options SUN4_MMU3L 2653.\" XXX ??? 2654Enable support for sun4 3-level MMU machines. 2655.It Cd options V9 2656Enable SPARC V9 assembler in 2657.Xr ddb 4 . 2658.El 2659.Ss sparc64-specific Options 2660.Bl -ohang 2661.It Cd options AUDIO_DEBUG 2662Enable simple event debugging of the logging of the 2663.Xr audio 4 2664device. 2665.It Cd options BLINK 2666Enable blinking of LED. 2667Blink rate is full cycle every N seconds for 2668N < then current load average. 2669See 2670.Xr getloadavg 3 . 2671.El 2672.Ss x68k-specific Options 2673.Bl -ohang 2674.It Cd options EXTENDED_MEMORY 2675Include support for extended memory, e.g., TS-6BE16 and 060turbo on-board. 2676.It Cd options JUPITER 2677Include support for Jupiter-X MPU accelerator 2678.It Cd options ZSCONSOLE,ZSCN_SPEED=value 2679Use the built-in serial port as the system-console. 2680Speed is specified in bps, defaults to 9600. 2681.It Cd options ITE_KERNEL_ATTR=value 2682Set the kernel message attribute for ITE. 2683Value, an integer, is a logical or of the following values: 2684.Bl -tag -width 4n -compact -offset indent 2685.It 1 2686color inversed 2687.It 2 2688underlined 2689.It 4 2690bolded 2691.El 2692.El 2693.Ss x86-specific Options 2694.Bl -ohang 2695.It Cd options NO_PCI_MSI_MSIX 2696Disable support for MSI/MSIX in the kernel. 2697See 2698.Xr pci_msi 9 2699for details of MSI/MSIX support 2700.It Cd options NO_PREEMPTION 2701Disables 2702.Xr kpreempt 9 2703support in the kernel. 2704.El 2705.\" The following requests should be uncommented and used where appropriate. 2706.\" .Sh FILES 2707.\" .Sh EXAMPLES 2708.Sh SEE ALSO 2709.Xr config 1 , 2710.Xr gcc 1 , 2711.Xr gdb 1 , 2712.Xr ktrace 1 , 2713.Xr quota 1 , 2714.Xr vndcompress 1 , 2715.Xr gettimeofday 2 , 2716.Xr i386_get_mtrr 2 , 2717.Xr i386_iopl 2 , 2718.Xr msgctl 2 , 2719.Xr msgget 2 , 2720.Xr msgrcv 2 , 2721.Xr msgsnd 2 , 2722.Xr ntp_adjtime 2 , 2723.Xr ntp_gettime 2 , 2724.Xr reboot 2 , 2725.Xr semctl 2 , 2726.Xr semget 2 , 2727.Xr semop 2 , 2728.Xr shmat 2 , 2729.Xr shmctl 2 , 2730.Xr shmdt 2 , 2731.Xr shmget 2 , 2732.Xr sysctl 3 , 2733.Xr apm 4 , 2734.Xr ddb 4 , 2735.Xr inet 4 , 2736.Xr md 4 , 2737.Xr pcibios 4 , 2738.Xr pcmcia 4 , 2739.Xr ppp 4 , 2740.Xr userconf 4 , 2741.Xr vnd 4 , 2742.Xr wscons 4 , 2743.Xr config 5 , 2744.Xr edquota 8 , 2745.Xr init 8 , 2746.Xr mdsetimage 8 , 2747.Xr mount_cd9660 8 , 2748.Xr mount_fdesc 8 , 2749.Xr mount_kernfs 8 , 2750.Xr mount_lfs 8 , 2751.Xr mount_mfs 8 , 2752.Xr mount_msdos 8 , 2753.Xr mount_nfs 8 , 2754.Xr mount_ntfs 8 , 2755.Xr mount_null 8 , 2756.Xr mount_portal 8 , 2757.Xr mount_procfs 8 , 2758.Xr mount_udf 8 , 2759.Xr mount_umap 8 , 2760.Xr mount_union 8 , 2761.Xr mrouted 8 , 2762.Xr newfs_lfs 8 , 2763.Xr ntpd 8 , 2764.Xr quotaon 8 , 2765.Xr rpc.rquotad 8 , 2766.Xr sysctl 8 , 2767.Xr cnmagic 9 , 2768.Xr in_getifa 9 , 2769.Xr kernhist 9 2770.Sh HISTORY 2771The 2772.Nm 2773man page first appeared in 2774.Nx 1.3 . 2775