1.\" $NetBSD: options.4,v 1.525 2023/05/14 09:02:05 riastradh 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 7, 2022 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 903.Bq Em EXPERIMENTAL 904Includes code for the UDF file system commonly found on CD and DVD 905media but also on USB sticks. 906Currently supports read and write access up to UDF 2.01 and somewhat limited 907write support for UDF 2.50. 908It is marked experimental since there is no 909.Xr fsck_udf 8 . 910See 911.Xr mount_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 ext2fs File System 1136.Bl -ohang 1137.It Cd options EXT2FS_SYSTEM_FLAGS 1138This option changes the behavior of the APPEND and IMMUTABLE flags 1139for a file on an 1140.Em ext2 1141file system. 1142Without this option, the superuser or owner of the file can 1143set and clear them. 1144With this option, only the superuser can set them, and 1145they can't be cleared if the securelevel is greater than 0. 1146See also 1147.Xr chflags 1 1148and 1149.Xr secmodel_securelevel 9 . 1150.El 1151.Ss Options for the NFS File System 1152.Bl -ohang 1153.It Cd options NFS_BOOT_BOOTP 1154Enable use of the BOOTP protocol (RFCs 951 and 1048) to get configuration 1155information if NFS is used to mount the root file system. 1156See 1157.Xr diskless 8 1158for details. 1159.It Cd options NFS_BOOT_BOOTSTATIC 1160Enable use of static values defined as 1161.Dq NFS_BOOTSTATIC_MYIP , 1162.Dq NFS_BOOTSTATIC_GWIP , 1163.Dq NFS_BOOTSTATIC_SERVADDR , 1164and 1165.Dq NFS_BOOTSTATIC_SERVER 1166in kernel options to get configuration information 1167if NFS is used to mount the root file system. 1168.It Cd options NFS_BOOT_DHCP 1169Same as 1170.Dq NFS_BOOT_BOOTP , 1171but use the DHCP extensions to the 1172BOOTP protocol (RFC 1541). 1173.It Cd options NFS_BOOT_BOOTP_REQFILE 1174Specifies the string sent in the bp_file field of the BOOTP/DHCP 1175request packet. 1176.It Cd options NFS_BOOT_BOOTPARAM 1177Enable use of the BOOTPARAM protocol, consisting of RARP and 1178BOOTPARAM RPC, to get configuration information if NFS 1179is used to mount the root file system. 1180See 1181.Xr diskless 8 1182for details. 1183.It Cd options NFS_BOOT_RWSIZE=value 1184Set the initial NFS read and write sizes for diskless-boot requests. 1185The normal default is 8Kbytes. 1186This option provides a way to lower the value (e.g., to 1024 bytes) 1187as a workaround for buggy network interface cards or boot PROMs. 1188Once booted, the read and write request sizes can be increased by 1189remounting the file system. 1190See 1191.Xr mount_nfs 8 1192for details. 1193.It Cd options NFS_V2_ONLY 1194Reduce the size of the NFS client code by omitting code that's only required 1195for NFSv3 and NQNFS support, leaving only that code required to use NFSv2 1196servers. 1197.It Cd options NFS_BOOT_UDP 1198Use NFS over UDP instead of the default TCP, for mounting root. 1199.El 1200.Ss Buffer queue strategy options 1201The following options enable alternative buffer queue strategies. 1202.Bl -ohang 1203.It Cd options BUFQ_READPRIO 1204Enable alternate buffer queue strategy for disk I/O. 1205In the default strategy, outstanding disk requests are ordered by 1206sector number and sent to the disk, regardless of whether the 1207operation is a read or write; this option gives priority to issuing 1208read requests over write requests. 1209Although requests may therefore be issued out of sector-order, causing 1210more seeks and thus lower overall throughput, interactive system 1211responsiveness under heavy disk I/O load may be improved, as processes 1212blocking on disk reads are serviced sooner (file writes typically 1213don't cause applications to block). 1214The performance effect varies greatly depending on the hardware, drive 1215firmware, file system configuration, workload, and desired performance 1216trade-off. 1217Systems using drive write-cache (most modern IDE disks, by default) 1218are unlikely to benefit and may well suffer; such disks acknowledge 1219writes very quickly, and optimize them internally according to 1220physical layout. 1221Giving these disks as many requests to work with as possible (the 1222standard strategy) will typically produce the best results, especially 1223if the drive has a large cache; the drive will silently complete 1224writes from cache as it seeks for reads. 1225Disks that support a large number of concurrent tagged requests (SCSI 1226disks and many hardware RAID controllers) expose this internal 1227scheduling with tagged responses, and don't block for reads; such 1228disks may not see a noticeable difference with either strategy. 1229However, if IDE disks are run with write-cache disabled for safety, 1230writes are not acknowledged until actually completed, and only one 1231request can be outstanding; a large number of small writes in one 1232locality can keep the disk busy, starving reads elsewhere on the disk. 1233Such systems are likely to see the most benefit from this option. 1234Finally, the performance interaction of this option with ffs soft 1235dependencies can be subtle, as that mechanism can drastically alter 1236the workload for file system metadata writes. 1237.It Cd options BUFQ_PRIOCSCAN 1238Enable another buffer queue strategy for disk I/O, per-priority cyclical scan. 1239.It Cd options NEW_BUFQ_STRATEGY 1240Synonym of 1241.Em BUFQ_READPRIO . 1242.El 1243.Ss Miscellaneous Options 1244.Bl -ohang 1245.It Cd options CPU_UCODE 1246Support cpu microcode loading via 1247.Xr cpuctl 8 . 1248.It Cd options MEMORY_DISK_DYNAMIC 1249This option makes the 1250.Xr md 4 1251RAM disk size dynamically sized. 1252It is incompatible with 1253.Xr mdsetimage 8 . 1254.It Cd options MEMORY_DISK_HOOKS 1255This option allows for some machine dependent functions to be called when 1256the 1257.Xr md 4 1258RAM disk driver is configured. 1259This can result in automatically loading a RAM disk from floppy on 1260open (among other things). 1261.It Cd options MEMORY_DISK_IS_ROOT 1262Forces the 1263.Xr md 4 1264RAM disk to be the root device. 1265This can only be overridden when 1266the kernel is booted in the 'ask-for-root' mode. 1267.It Cd options MEMORY_DISK_ROOT_SIZE=integer 1268Allocates the given number of 512 byte blocks as memory for the 1269.Xr md 4 1270RAM disk, to be populated with 1271.Xr mdsetimage 8 . 1272.It Cd options MEMORY_DISK_SERVER=0 1273Do not include the interface to a userland memory disk server process. 1274Per default, this option is set to 1, including the support code. 1275Useful for install media kernels. 1276.It Cd options MEMORY_DISK_RBFLAGS=value 1277This option sets the 1278.Xr reboot 2 1279flags used when booting with a memory disk as root file system. 1280Possible values include 1281.Dv RB_AUTOBOOT 1282(boot in the usual fashion - default value), and 1283.Dv RB_SINGLE 1284(boot in single-user mode). 1285.It Cd options MODULAR 1286Enables the framework for kernel modules (see 1287.Xr module 7 ) . 1288.It Cd options MODULAR_DEFAULT_AUTOLOAD 1289Enables the autoloading of kernel modules by default. 1290This sets the default value of the 1291.Em kern.module.autoload 1292.Xr sysctl 3 1293variable which may be changed at run time. 1294.It Cd options MODULAR_DEFAULT_VERBOSE 1295Enables verbose debug messages of kernel modules by default. 1296This sets the default value of the 1297.Em kern.module.verbose 1298.Xr sysctl 3 1299variable which may be changed at run time. 1300.It Cd options VND_COMPRESSION 1301Enables the 1302.Xr vnd 4 1303driver to also handle compressed images. 1304See 1305.Xr vndcompress 1 , 1306.Xr vnd 4 1307and 1308.Xr vnconfig 8 1309for more information. 1310.It Cd options SELFRELOC 1311Make the kernel able to self relocate at bootstrap, so that it can 1312run whatever its load address is. 1313This is intented to be used withe the 1314.Ic reloc 1315boostrap command documented in 1316.Xr x86/boot 8 , 1317to workaround UEFI bugs, and is only available on amd64. 1318.It Cd options SPLDEBUG 1319Help the kernel programmer find bugs related to the interrupt priority 1320level. 1321When 1322.Fn spllower 1323or 1324.Fn splraise 1325changes the current CPU's interrupt priority level to or from 1326.Dv IPL_HIGH , 1327record a backtrace. 1328Read 1329.Xr i386/return_address 9 1330for caveats about collecting backtraces. 1331This feature is experimental, and it is only available on i386. 1332See 1333.Pa sys/kern/subr_spldebug.c . 1334.It Cd options TFTPROOT 1335Download the root memory disk through TFTP at root mount time. 1336This enables the use of a root RAM disk without requiring it to be 1337embedded in the kernel using 1338.Xr mdsetimage 8 . 1339The RAM disk name is obtained using DHCP's filename parameter. 1340This option requires 1341.Em MEMORY_DISK_HOOKS 1342and 1343.Em MEMORY_DISK_DYNAMIC . 1344It is incompatible with 1345.Em MEMORY_DISK_ROOT_SIZE . 1346.It Cd options HZ=integer 1347On ports that support it, set the system clock frequency (see 1348.Xr hz 9 ) 1349to the supplied value. 1350Handle with care. 1351.It Cd options NTP 1352Turns on in-kernel precision timekeeping support used by software 1353implementing 1354.Em NTP 1355(Network Time Protocol, RFC 1305). 1356The 1357.Em NTP 1358option adds an in-kernel Phase-Locked Loop (PLL) for normal 1359.Em NTP 1360operation, and a Frequency-Locked Loop (FLL) for intermittently-connected 1361operation. 1362.Xr ntpd 8 1363will employ a user-level PLL when kernel support is unavailable, 1364but the in-kernel version has lower latency and more precision, and 1365so typically keeps much better time. 1366.Pp 1367The interface to the kernel 1368.Em NTP 1369support is provided by the 1370.Xr ntp_adjtime 2 1371and 1372.Xr ntp_gettime 2 1373system calls, which are intended for use by 1374.Xr ntpd 8 1375and are enabled by the option. 1376On systems with sub-microsecond resolution timers, or where (HZ/100000) 1377is not an integer, the 1378.Em NTP 1379option also enables extended-precision arithmetic to keep track of 1380fractional clock ticks at NTP time-format precision. 1381.It Cd options PPS_SYNC 1382This option enables a kernel serial line discipline for receiving time 1383phase signals from an external reference clock such as a radio clock. 1384.Po 1385The 1386.Em NTP 1387option (which see) must be on if the 1388.Em PPS_SYNC 1389option is used 1390.Pc . 1391Some reference clocks generate a Pulse Per Second (PPS) signal in 1392phase with their time source. 1393The 1394.Em PPS 1395line discipline receives this signal on either the data leads 1396or the DCD control lead of a serial port. 1397.Pp 1398.Em NTP 1399uses the PPS signal to discipline the local clock oscillator to a high 1400degree of precision (typically less than 50 microseconds in time and 14010.1 ppm in accuracy). 1402.Em PPS 1403can also generate a serial output pulse when the system receives a PPS 1404interrupt. 1405This can be used to measure the system interrupt latency and thus calibrate 1406.Em NTP 1407to account for it. 1408Using 1409.Em PPS 1410usually requires a gadget box 1411to convert from TTL to RS-232 signal levels. 1412The gadget box and PPS are described in more detail in the HTML documentation 1413for 1414.Xr ntpd 8 1415in 1416.Pa /usr/share/doc/html/ntp . 1417.Pp 1418.Nx 1419currently supports this option in 1420.Xr com 4 1421and 1422.Xr zsc 4 . 1423.It Cd options SETUIDSCRIPTS 1424Allows scripts with the setuid bit set to execute as the effective 1425user rather than the real user, just like binary executables. 1426.Pp 1427.Em NOTE : 1428Using this option will also enable 1429.Em options FDSCRIPTS 1430.It Cd options FDSCRIPTS 1431Allows execution of scripts with the execute bit set, but not the 1432read bit, by opening the file and passing the file descriptor to 1433the shell, rather than the filename. 1434.Pp 1435.Em NOTE : 1436Execute only (non-readable) scripts will have 1437.Va argv[0] 1438set to 1439.Pa /dev/fd/* . 1440What this option allows as far as security is 1441concerned, is the ability to safely ensure that the correct script 1442is run by the interpreter, as it is passed as an already open file. 1443.It Cd options RTC_OFFSET=integer 1444The kernel (and typically the hardware battery backed-up clock on 1445those machines that have one) keeps time in 1446.Em UTC 1447(Universal Coordinated Time, once known as 1448.Em GMT , 1449or Greenwich Mean Time) 1450and not in the time of the local time zone. 1451The 1452.Em RTC_OFFSET 1453option is used on some ports (such as the i386) to tell the kernel 1454that the hardware clock is offset from 1455.Em UTC 1456by the specified number of minutes. 1457This is typically used when a machine boots several operating 1458systems and one of them wants the hardware clock to run in the 1459local time zone and not in 1460.Em UTC , 1461e.g. 1462.Em RTC_OFFSET=300 1463means 1464the hardware clock is set to US Eastern Time (300 minutes behind 1465.Em UTC ) , 1466and not 1467.Em UTC . 1468(Note: 1469.Em RTC_OFFSET 1470is used to initialize a kernel variable named 1471.Va rtc_offset 1472which is the source actually used to determine the clock offset, and 1473which may be accessed via the kern.rtc_offset sysctl variable. 1474See 1475.Xr sysctl 8 1476and 1477.Xr sysctl 3 1478for details. 1479Since the kernel clock is initialized from the hardware clock very 1480early in the boot process, it is not possible to meaningfully change 1481.Va rtc_offset 1482in system initialization scripts. 1483Changing this value currently may only be done at kernel compile 1484time or by patching the kernel and rebooting). 1485.Pp 1486.Em NOTE : 1487Unfortunately, in many cases where the hardware clock 1488is kept in local time, it is adjusted for Daylight Savings 1489Time; this means that attempting to use 1490.Em RTC_OFFSET 1491to let 1492.Nx 1493coexist with such an operating system, like Windows, 1494would necessitate changing 1495.Em RTC_OFFSET 1496twice a year. 1497As such, this solution is imperfect. 1498.It Cd options MAXUPRC=integer 1499Sets the soft 1500.Dv RLIMIT_NPROC 1501resource limit, which specifies the maximum number of simultaneous 1502processes a user is permitted to run, for process 0; 1503this value is inherited by its child processes. 1504It defaults to 1505.Em CHILD_MAX , 1506which is currently defined to be 160. 1507Setting 1508.Em MAXUPRC 1509to a value less than 1510.Em CHILD_MAX 1511is not permitted, as this would result in a violation of the semantics of 1512.St -p1003.1-90 . 1513.It Cd options NOFILE=integer 1514Sets the soft 1515.Dv RLIMIT_NOFILE 1516resource limit, which specifies the maximum number of open 1517file descriptors for each process; 1518this value is inherited by its child processes. 1519It defaults to 1520.Em OPEN_MAX , 1521which is currently defined to be 128. 1522.It Cd options MAXFILES=integer 1523Sets the default value of the 1524.Em kern.maxfiles 1525sysctl variable, which indicates the maximum number of files that may 1526be open in the system. 1527.It Cd options DEFCORENAME=string 1528Sets the default value of the 1529.Em kern.defcorename 1530sysctl variable, otherwise it is set to 1531.Nm %n.core . 1532See 1533.Xr sysctl 8 1534and 1535.Xr sysctl 3 1536for details. 1537.It Cd options RASOPS_CLIPPING 1538Enables clipping within the 1539.Nm rasops 1540raster-console output system. 1541.Em NOTE : 1542only available on architectures that use 1543.Nm rasops 1544for console output. 1545.It Cd options RASOPS_SMALL 1546Removes optimized character writing code from the 1547.Nm rasops 1548raster-console output system. 1549.Em NOTE : 1550only available on architectures that use 1551.Nm rasops 1552for console output. 1553.It Cd options INCLUDE_CONFIG_FILE 1554Embeds the kernel config file used to define the kernel in the kernel 1555binary itself. 1556The embedded data also includes any files directly included by the config 1557file itself, e.g. 1558.Pa GENERIC.local 1559or 1560.Pa std.$MACHINE . 1561The embedded config file can be extracted from the resulting kernel with 1562.Xr config 1 1563.Fl x , 1564or by the following command: 1565.Bd -literal -offset indent 1566strings netbsd | sed -n 's/^_CFG_//p' | unvis 1567.Ed 1568.It Cd options INCLUDE_JUST_CONFIG 1569Similar to the above option, but includes just the actual config file, 1570not any included files. 1571.It Cd options PIPE_SOCKETPAIR 1572Use slower, but smaller socketpair(2)-based pipe implementation instead 1573of default faster, but bigger one. 1574Primarily useful for installation kernels. 1575.It Cd options USERCONF 1576Compiles in the in-kernel device configuration manager. 1577See 1578.Xr userconf 4 1579for details. 1580.It Cd options SCDEBUG_DEFAULT 1581Used with the 1582.Cd options SYSCALL_DEBUG 1583described below to choose which types of events are displayed. 1584.Pp 1585.Bl -tag -width "SCDEBUG_KERNHIST" -compact -offset indent 1586.It Dv SCDEBUG_CALLS 1587Show system call entry points. 1588.It Dv SCDEBUG_RETURNS 1589Show system call exit points. 1590.It Dv SCDEBUG_ALL 1591Show all system call requests, including unimplemented calls. 1592.It Dv SCDEBUG_SHOWARGS 1593Show the arguments provided. 1594.It Dv SCDEBUG_KERNHIST 1595Store a restricted form of the system call debug in a kernel history 1596instead of printing it to the console. 1597This option relies upon 1598.Cd options KERNHIST . 1599.El 1600.Pp 1601The default value is 1602.Dv (SCDEBUG_CALLS|SCDEBUG_RETURNS|SCDEBUG_SHOWARGS) . 1603.It Cd options SYSCALL_DEBUG 1604Useful for debugging system call issues, usually in early single user bringup. 1605By default, writes entries to the system console for most system call events. 1606Can be configured with the 1607.Cd options SCDEBUG_DEFAULT 1608option to to use the 1609.Cd options KERNHIST 1610facility instead. 1611.It Cd options SYSCALL_STATS 1612Count the number of times each system call number is called. 1613The values can be read through the sysctl interface and displayed using 1614.Xr systat 1 . 1615.Em NOTE : 1616not yet available on all architectures. 1617.It Cd options SYSCALL_TIMES 1618Count the time spent (using 1619.Fn cpu_counter32 ) 1620in each system call. 1621.Em NOTE : 1622Using this option will also enable 1623.Cd options SYSCALL_STATS . 1624.It Cd options SYSCALL_TIMES_HASCOUNTER 1625Force use of 1626.Fn cpu_counter32 1627even if 1628.Fn cpu_hascounter 1629reports false. 1630Useful for systems where the cycle counter doesn't run at a constant rate 1631(e.g. Soekris boxes). 1632.It Cd options XSERVER_DDB 1633A supplement to XSERVER that adds support for entering 1634.Xr ddb 4 1635while in X11. 1636.It Cd options FILEASSOC 1637Support for 1638.Xr fileassoc 9 . 1639Required for 1640.Cd options PAX_SEGVGUARD 1641and 1642.Cd pseudo-device veriexec . 1643.It Cd options FILEASSOC_NHOOKS=integer 1644Number of storage slots per file for 1645.Xr fileassoc 9 . 1646Default is 4. 1647.El 1648.Ss Networking Options 1649.Bl -ohang 1650.It Cd options GATEWAY 1651Enables 1652.Em IPFORWARDING 1653and (on most ports) increases the size of 1654.Em NMBCLUSTERS . 1655In general, 1656.Em GATEWAY 1657is used to indicate that a system should act as a router, and 1658.Em IPFORWARDING 1659is not invoked directly. 1660(Note that 1661.Em GATEWAY 1662has no impact on protocols other than IP). 1663.Em GATEWAY 1664option also compiles IPv4 and IPv6 fast forwarding code into the kernel. 1665.It Cd options IPFORWARDING=value 1666If 1667.Em value 1668is 1 this enables IP routing behavior. 1669If 1670.Em value 1671is 0 (the default), it disables it. 1672The 1673.Em GATEWAY 1674option sets this to 1 automatically. 1675With this option enabled, the machine will forward IP datagrams destined 1676for other machines between its interfaces. 1677Note that even without this option, the kernel will 1678still forward some packets (such as source routed packets) \(em removing 1679.Em GATEWAY 1680and 1681.Em IPFORWARDING 1682is insufficient to stop all routing through a bastion host on a 1683firewall \(em source routing is controlled independently. 1684Note that IP forwarding may be turned on and off independently of the 1685setting of the 1686.Em IPFORWARDING 1687option through the use of the 1688.Em net.inet.ip.forwarding 1689sysctl variable. 1690If 1691.Em net.inet.ip.forwarding 1692is 1, IP forwarding is on. 1693See 1694.Xr sysctl 8 1695and 1696.Xr sysctl 3 1697for details. 1698.It Cd options IFA_STATS 1699Tells the kernel to maintain per-address statistics on bytes sent 1700and received over (currently) Internet and AppleTalk addresses. 1701.\"This can be a fairly expensive operation, so you probably want to 1702.\"keep this disabled. 1703The option is not recommended as it degrades system stability. 1704.It Cd options IFQ_MAXLEN=value 1705Increases the allowed size of the network interface packet queues. 1706The default queue size is 50 packets, and you do not normally need 1707to increase it. 1708.It Cd options IPSELSRC 1709Includes support for source-address selection policies. 1710See 1711.Xr in_getifa 9 . 1712.It Cd options MROUTING 1713Includes support for IP multicast routers. 1714You certainly want 1715.Em INET 1716with this. 1717Multicast routing is controlled by the 1718.Xr mrouted 8 1719daemon. 1720See also option 1721.Cd PIM . 1722.It Cd options PIM 1723Includes support for Protocol Independent Multicast (PIM) routing. 1724You need 1725.Em MROUTING 1726and 1727.Em INET 1728with this. 1729Software using this can be found e.g. in 1730.Pa pkgsrc/net/xorp . 1731.It Cd options INET 1732Includes support for the TCP/IP protocol stack. 1733You almost certainly want this. 1734See 1735.Xr inet 4 1736for details. 1737.It Cd options INET6 1738Includes support for the IPv6 protocol stack. 1739See 1740.Xr inet6 4 1741for details. 1742Unlike 1743.Em INET , 1744.Em INET6 1745enables multicast routing code as well. 1746This option requires 1747.Em INET 1748at this moment, but it should not. 1749.It Cd options ND6_DEBUG 1750The option sets the default value of net.inet6.icmp6.nd6_debug to 1, 1751for debugging IPv6 neighbor discovery protocol handling. 1752See 1753.Xr sysctl 3 1754for details. 1755.It Cd options IPSEC 1756Includes support for the IPsec protocol, using the implementation derived from 1757.Ox , 1758relying on 1759.Xr opencrypto 9 1760to carry out cryptographic operations. 1761See 1762.Xr ipsec 4 1763for details. 1764.It Cd options IPSEC_DEBUG 1765Enables debugging code in IPsec stack. 1766See 1767.Xr ipsec 4 1768for details. 1769The 1770.Cd IPSEC 1771option includes support for IPsec Network Address Translator traversal 1772(NAT-T), as described in RFCs 3947 and 3948. 1773This feature might be patent-encumbered in some countries. 1774.It Cd options ALTQ 1775Enabled ALTQ (Alternate Queueing). 1776For simple rate-limiting, use 1777.Xr tbrconfig 8 1778to set up the interface transmission rate. 1779To use queueing disciplines, their appropriate kernel options should also 1780be defined (documented below). 1781Queueing disciplines are managed by 1782.Xr altqd 8 . 1783See 1784.Xr altq 9 1785for details. 1786.It Cd options ALTQ_HFSC 1787Include support for ALTQ-implemented HFSC (Hierarchical Fair Service Curve) 1788module. 1789HFSC supports both link-sharing and guaranteed real-time services. 1790HFSC employs a service curve based QoS model, and its unique feature 1791is an ability to decouple delay and bandwidth allocation. 1792Requires 1793.Em ALTQ_RED 1794to use the RED queueing discipline on HFSC classes, or 1795.Em ALTQ_RIO 1796to use the RIO queueing discipline on HFSC classes. 1797This option assumes 1798.Em ALTQ . 1799.It Cd options ALTQ_PRIQ 1800Include support for ALTQ-implemented PRIQ (Priority Queueing). 1801PRIQ implements a simple priority-based queueing discipline. 1802A higher priority class is always served first. 1803Requires 1804.Em ALTQ_RED 1805to use the RED queueing discipline on HFSC classes, or 1806.Em ALTQ_RIO 1807to use the RIO queueing discipline on HFSC classes. 1808This option assumes 1809.Em ALTQ . 1810.It Cd options ALTQ_WFQ 1811Include support for ALTQ-implemented WFQ (Weighted Fair Queueing). 1812WFQ implements a weighted-round robin scheduler for a set of queues. 1813A weight can be assigned to each queue to give a different proportion 1814of the link capacity. 1815A hash function is used to map a flow to one of a set of queues. 1816This option assumes 1817.Em ALTQ . 1818.It Cd options ALTQ_FIFOQ 1819Include support for ALTQ-implemented FIFO queueing. 1820FIFOQ is a simple drop-tail FIFO (First In, First Out) queueing discipline. 1821This option assumes 1822.Em ALTQ . 1823.It Cd options ALTQ_RIO 1824Include support for ALTQ-implemented RIO (RED with In/Out). 1825The original RIO has 2 sets of RED parameters; one for in-profile 1826packets and the other for out-of-profile packets. 1827At the ingress of the network, profile meters tag packets as IN or 1828OUT based on contracted profiles for customers. 1829Inside the network, IN packets receive preferential treatment by 1830the RIO dropper. 1831ALTQ/RIO has 3 drop precedence levels defined for the Assured Forwarding 1832PHB of DiffServ (RFC 2597). 1833This option assumes 1834.Em ALTQ . 1835.It Cd options ALTQ_BLUE 1836Include support for ALTQ-implemented Blue buffer management. 1837Blue is another active buffer management mechanism. 1838This option assumes 1839.Em ALTQ . 1840.It Cd options ALTQ_FLOWVALVE 1841Include support for ALTQ-implemented Flowvalve. 1842Flowvalve is a simple implementation of a RED penalty box that identifies 1843and punishes misbehaving flows. 1844This option requires 1845.Em ALTQ_RED 1846and assumes 1847.Em ALTQ . 1848.It Cd options ALTQ_CDNR 1849Include support for ALTQ-implemented CDNR (diffserv traffic conditioner) 1850packet marking/manipulation. 1851Traffic conditioners are components to meter, mark, or drop incoming 1852packets according to some rules. 1853As opposed to queueing disciplines, traffic conditioners handle incoming 1854packets at an input interface. 1855This option assumes 1856.Em ALTQ . 1857.It Cd options ALTQ_NOPCC 1858Disables use of processor cycle counter to measure time in ALTQ. 1859This option should be defined for a non-Pentium i386 CPU which does not 1860have TSC, SMP (per-CPU counters are not in sync), or power management 1861which affects processor cycle counter. 1862This option assumes 1863.Em ALTQ . 1864.It Cd options ALTQ_IPSEC 1865Include support for IPsec in IPv4 ALTQ. 1866This option assumes 1867.Em ALTQ . 1868.It Cd options ALTQ_JOBS 1869Include support for ALTQ-implemented JoBS (Joint Buffer Management 1870and Scheduling). 1871This option assumes 1872.Em ALTQ . 1873.It Cd options ALTQ_AFMAP 1874Include support for an undocumented ALTQ feature that is used to map an IP 1875flow to an ATM VC (Virtual Circuit). 1876This option assumes 1877.Em ALTQ . 1878.It Cd options ALTQ_LOCALQ 1879Include support for ALTQ-implemented local queues. 1880Its practical use is undefined. 1881Assumes 1882.Em ALTQ . 1883.It Cd options SUBNETSARELOCAL 1884Sets default value for net.inet.ip.subnetsarelocal variable, which 1885controls whether non-directly-connected subnets of connected networks 1886are considered "local" for purposes of choosing the MSS for a TCP 1887connection. 1888This is mostly present for historic reasons and completely irrelevant if 1889you enable Path MTU discovery. 1890.It Cd options HOSTZEROBROADCAST 1891Sets default value for net.inet.ip.hostzerobroadcast variable, which 1892controls whether the zeroth host address of each connected subnet is 1893also considered a broadcast address. 1894Default value is "1", for compatibility with old systems; if this is 1895set to zero on all hosts on a subnet, you should be able to fit an extra 1896host per subnet on the 1897".0" address. 1898.It Cd options MCLSHIFT=value 1899This option is the base-2 logarithm of the size of mbuf clusters. 1900The 1901.Bx 1902networking stack keeps network packets in a linked 1903list, or chain, of kernel buffer objects called mbufs. 1904The system provides larger mbuf clusters as an optimization for 1905large packets, instead of using long chains for large packets. 1906The mbuf cluster size, 1907or 1908.Em MCLBYTES , 1909must be a power of two, and is computed as two raised to the power 1910.Em MCLSHIFT . 1911On systems with Ethernet network adapters, 1912.Em MCLSHIFT 1913is often set to 11, giving 2048-byte mbuf clusters, large enough to 1914hold a 1500-byte Ethernet frame in a single cluster. 1915Systems with network interfaces supporting larger frame sizes like 1916ATM, FDDI, or HIPPI may perform better with 1917.Em MCLSHIFT 1918set to 12 or 13, giving mbuf cluster sizes of 4096 and 8192 bytes, 1919respectively. 1920.It Cd options NETATALK 1921Include support for the AppleTalk protocol stack. 1922The kernel provides provision for the 1923.Em Datagram Delivery Protocol 1924(DDP), providing SOCK_DGRAM support and AppleTalk routing. 1925This stack is used by the 1926.Em NETATALK 1927package, which adds support for AppleTalk server services via user 1928libraries and applications. 1929.It Cd options BLUETOOTH 1930Include support for the Bluetooth protocol stack. 1931See 1932.Xr bluetooth 4 1933for details. 1934.It Cd options IPNOPRIVPORTS 1935Normally, only root can bind a socket descriptor to a so-called 1936.Dq privileged 1937TCP port, that is, a port number in the range 0-1023. 1938This option eliminates those checks from the kernel. 1939This can be useful if there is a desire to allow daemons without 1940privileges to bind those ports, e.g., on firewalls. 1941The security tradeoffs in doing this are subtle. 1942This option should only be used by experts. 1943.It Cd options TCP_DEBUG 1944Record the last 1945.Em TCP_NDEBUG 1946TCP packets with SO_DEBUG set, and decode to the console if 1947.Em tcpconsdebug 1948is set. 1949.It Cd options TCP_NDEBUG 1950Number of packets to record for 1951.Em TCP_DEBUG . 1952Defaults to 100. 1953.It Cd options TCP_SENDSPACE=value 1954.It Cd options TCP_RECVSPACE=value 1955These options set the max TCP window size to other sizes than the default. 1956The TCP window sizes can be altered via 1957.Xr sysctl 8 1958as well. 1959.It Cd options TCP_INIT_WIN=value 1960This option sets the initial TCP window size for non-local connections, 1961which is used when the transmission starts. 1962The default size is 1, but if the machine should act more aggressively, 1963the initial size can be set to some other value. 1964The initial TCP window size can be set via 1965.Xr sysctl 8 1966as well. 1967.It Cd options TCP_SIGNATURE 1968Enable MD5 TCP signatures (RFC 2385) to protect BGP sessions. 1969.It Cd options IPFILTER_LOG 1970This option, in conjunction with 1971.Em pseudo-device ipfilter , 1972enables logging of IP packets using IP-Filter. 1973.It Cd options IPFILTER_LOOKUP 1974This option enables the 1975IP-Filter 1976.Xr ippool 8 1977functionality to be enabled. 1978.It Cd options IPFILTER_COMPAT 1979This option enables older IP-Filter binaries to work. 1980.It Cd options IPFILTER_DEFAULT_BLOCK 1981This option sets the default policy of IP-Filter. 1982If it is set, IP-Filter will block packets by default. 1983.It Cd options MBUFTRACE 1984This option can help track down mbuf leaks. 1985When enabled, mbufs are tagged with the devices and protocols using them. 1986This can significantly decrease network performance, particularly 1987on MP systems. 1988This additional information can be viewed with 1989.Xr netstat 1 : 1990.Dl Ic netstat Fl mssv 1991Not all devices or protocols support this option. 1992.El 1993.Ss Sysctl Related Options 1994.Bl -ohang 1995.It Cd options SYSCTL_DISALLOW_CREATE 1996Disallows the creation or deletion of nodes from the sysctl tree, as 1997well as the assigning of descriptions to nodes that lack them, by any 1998process. 1999These operations are still available to kernel sub-systems, including 2000loadable kernel modules. 2001.It Cd options SYSCTL_DISALLOW_KWRITE 2002Prevents processes from adding nodes to the sysctl tree that make 2003existing kernel memory areas writable. 2004Sections of kernel memory can still be read and new nodes that own 2005their own data may still be writable. 2006.It Cd options SYSCTL_DEBUG_SETUP 2007Causes the SYSCTL_SETUP routines to print a brief message when they 2008are invoked. 2009This is merely meant as an aid in determining the order in which 2010sections of the tree are created. 2011.It Cd options SYSCTL_DEBUG_CREATE 2012Prints a message each time 2013.Fn sysctl_create , 2014the function that adds nodes to the tree, is called. 2015.It Cd options SYSCTL_INCLUDE_DESCR 2016Causes the kernel to include short, human readable descriptions for 2017nodes in the sysctl tree. 2018The descriptions can be retrieved programmatically (see 2019.Xr sysctl 3 ) , 2020or by the sysctl binary itself (see 2021.Xr sysctl 8 ) . 2022The descriptions are meant to give an indication of the purpose and/or 2023effects of a given node's value, not replace the documentation for the 2024given subsystem as a whole. 2025.El 2026.Ss System V IPC Options 2027.Bl -ohang 2028.It Cd options SYSVMSG 2029Includes support for 2030.At V 2031style message queues. 2032See 2033.Xr msgctl 2 , 2034.Xr msgget 2 , 2035.Xr msgrcv 2 , 2036.Xr msgsnd 2 . 2037.It Cd options SYSVSEM 2038Includes support for 2039.At V 2040style semaphores. 2041See 2042.Xr semctl 2 , 2043.Xr semget 2 , 2044.Xr semop 2 . 2045.It Cd options SEMMNI=value 2046Sets the number of 2047.At V 2048style semaphore identifiers. 2049The GENERIC config file for your port will have the default. 2050.It Cd options SEMMNS=value 2051Sets the number of 2052.At V 2053style semaphores in the system. 2054The GENERIC config file for your port will have the default. 2055.It Cd options SEMUME=value 2056Sets the maximum number of undo entries per process for 2057.At V 2058style semaphores. 2059The GENERIC config file for your port will have the default. 2060.It Cd options SEMMNU=value 2061Sets the number of undo structures in the system for 2062.At V 2063style semaphores. 2064The GENERIC config file for your port will have the default. 2065.It Cd options SYSVSHM 2066Includes support for 2067.At V 2068style shared memory. 2069See 2070.Xr shmat 2 , 2071.Xr shmctl 2 , 2072.Xr shmdt 2 , 2073.Xr shmget 2 . 2074.It Cd options SHMMAXPGS=value 2075Sets the maximum number of 2076.At V 2077style shared memory pages that are available through the 2078.Xr shmget 2 2079system call. 2080Default value is 1024 on most ports. 2081See 2082.Pa /usr/include/machine/vmparam.h 2083for the default. 2084.El 2085.Ss VM Related Options 2086.Bl -ohang 2087.It Cd options NMBCLUSTERS=value 2088The number of mbuf clusters the kernel supports. 2089Mbuf clusters are MCLBYTES in size (usually 2k). 2090The default value is calculated from the amount of physical memory. 2091Architectures without direct mapping also limit it based on the kmem_map size, 2092which is used as backing store. 2093Some archs limit the value with 2094.Sq NMBCLUSTERS_MAX . 2095See 2096.Pa /usr/include/machine/param.h 2097for those archs. 2098This value can be accessed via the kern.mbuf.nmbclusters sysctl variable. 2099Increase this value if you get 2100.Dq mclpool limit reached 2101messages. 2102.It Cd options NMBCLUSTERS_MAX=value 2103The upper limit of NMBCLUSTERS. 2104.It Cd options NKMEMPAGES=value 2105.It Cd options NKMEMPAGES_MIN=value 2106.It Cd options NKMEMPAGES_MAX=value 2107Size of kernel VM map 2108.Em kmem_map , 2109in PAGE_SIZE-sized chunks (the VM page size; this value may be read 2110from the 2111.Xr sysctl 8 2112variable 2113.Em hw.pagesize 2114). 2115This VM map is used to map the kernel malloc arena. 2116The kernel attempts to auto-size this map based on the amount of 2117physical memory in the system. 2118Platform-specific code may place bounds on this computed size, 2119which may be viewed with the 2120.Xr sysctl 8 2121variable 2122.Em vm.nkmempages . 2123See 2124.Pa /usr/include/machine/param.h 2125for the default upper and lower bounds. 2126The related options 2127.Sq NKMEMPAGES_MIN 2128and 2129.Sq NKMEMPAGES_MAX 2130allow the bounds to be overridden in the kernel configuration file. 2131These options are provided in the event the computed value is 2132insufficient resulting in an 2133.Dq out of space in kmem_map 2134panic. 2135.It Cd options SB_MAX=value 2136Sets the max size in bytes that a socket buffer is allowed to occupy. 2137The default is 256k, but sometimes it needs to be increased, for example 2138when using large TCP windows. 2139This option can be changed via 2140.Xr sysctl 8 2141as well. 2142.It Cd options SOMAXKVA=value 2143Sets the maximum size of kernel virtual memory that the socket buffers 2144are allowed to use. 2145The default is 16MB, but in situations where for example large TCP 2146windows are used this value must also be increased. 2147This option can be changed via 2148.Xr sysctl 8 2149as well. 2150.It Cd options BUFCACHE=value 2151Size of the buffer cache as a percentage of total available RAM. 2152Ignored if BUFPAGES is also specified. 2153.It Cd options NBUF=value 2154Sets the number of buffer headers available, i.e., the number of 2155open files that may have a buffer cache entry. 2156Each buffer header 2157requires MAXBSIZE (machine dependent, but usually 65536) bytes. 2158The default value is machine dependent, but is usually equal to the 2159value of BUFPAGES. 2160.It Cd options BUFPAGES=value 2161These options set the number of pages available for the buffer cache. 2162Their default value is a machine dependent value, often calculated as 2163between 5% and 10% of total available RAM. 2164.It Cd options MAXTSIZ=bytes 2165Sets the maximum size limit of a process' text segment. 2166See 2167.Pa /usr/include/machine/vmparam.h 2168for the port-specific default. 2169.It Cd options DFLDSIZ=bytes 2170Sets the default size limit of a process' data segment, the value that 2171will be returned as the soft limit for 2172.Dv RLIMIT_DATA 2173(as returned by 2174.Xr getrlimit 2 ) . 2175See 2176.Pa /usr/include/machine/vmparam.h 2177for the port-specific default. 2178.It Cd options MAXDSIZ=bytes 2179Sets the maximum size limit of a process' data segment, the value that 2180will be returned as the hard limit for 2181.Dv RLIMIT_DATA 2182(as returned by 2183.Xr getrlimit 2 ) . 2184See 2185.Pa /usr/include/machine/vmparam.h 2186for the port-specific default. 2187.It Cd options DFLSSIZ=bytes 2188Sets the default size limit of a process' stack segment, the value that 2189will be returned as the soft limit for 2190.Dv RLIMIT_STACK 2191(as returned by 2192.Xr getrlimit 2 ) . 2193See 2194.Pa /usr/include/machine/vmparam.h 2195for the port-specific default. 2196.It Cd options MAXSSIZ=bytes 2197Sets the maximum size limit of a process' stack segment, the value that 2198will be returned as the hard limit for 2199.Dv RLIMIT_STACK 2200(as returned by 2201.Xr getrlimit 2 ) . 2202See 2203.Pa /usr/include/machine/vmparam.h 2204for the port-specific default. 2205.It Cd options DUMP_ON_PANIC=integer 2206Defaults to one. 2207If set to zero, the kernel will not dump to the dump device when 2208it panics, though dumps can still be forced via 2209.Xr ddb 4 2210with the 2211.Dq sync 2212command. 2213Note that this sets the value of the 2214.Em kern.dump_on_panic 2215.Xr sysctl 3 2216variable which may be changed at run time \(em see 2217.Xr sysctl 8 2218for details. 2219.It Cd options VMSWAP 2220Enable paging device/file support. 2221This option is on by default. 2222.It Cd options VMSWAP_DEFAULT_PLAINTEXT 2223Store swap in plaintext, not encrypted, which may expose secrets if the 2224underlying nonvolatile medium is disclosed. 2225This option is off by default; it is available only for extremely slow 2226machines where the performance impact of swapping early at boot 2227outweighs the security risks. 2228Swap encryption can still be turned on dynamically with the 2229.Em vm.swap_encrypt 2230.Xr sysctl 7 2231knob. 2232.It Cd options PDPOLICY_CLOCKPRO 2233Use CLOCK-Pro, an alternative page replace policy. 2234.El 2235.Ss Security Options 2236.Bl -ohang 2237.It Cd options INSECURE 2238Initializes the kernel security level with \-1 instead of 0. 2239This means that the system always starts in secure level \-1 mode, even when 2240running multiuser, unless the securelevel variable is set to value > \-1 in 2241.Pa /etc/rc.conf . 2242In this case the kernel security level will be raised to that value when the 2243.Pa /etc/rc.d/securelevel 2244script is run during system startup. 2245See the manual page for 2246.Xr init 8 2247for details on the implications of this. 2248The kernel secure level may manipulated by the superuser by altering the 2249.Em kern.securelevel 2250.Xr sysctl 3 2251variable (the secure level may only be lowered by a call from process ID 1, 2252i.e., 2253.Xr init 8 ) . 2254See also 2255.Xr secmodel_securelevel 9 , 2256.Xr sysctl 8 2257and 2258.Xr sysctl 3 . 2259.It Cd options VERIFIED_EXEC_FP_SHA256 2260Enables support for SHA256 hashes in Veriexec. 2261.It Cd options VERIFIED_EXEC_FP_SHA384 2262Enables support for SHA384 hashes in Veriexec. 2263.It Cd options VERIFIED_EXEC_FP_SHA512 2264Enables support for SHA512 hashes in Veriexec. 2265.It Cd options PAX_MPROTECT=value 2266Enables PaX MPROTECT, 2267.Xr mprotect 2 2268restrictions from the PaX project. 2269.Pp 2270The 2271.Ar value 2272is the default value for the 2273.Em global 2274knob, see 2275.Xr sysctl 3 . 2276If 0, PaX MPROTECT will be enabled only if explicitly set on programs 2277using 2278.Xr paxctl 8 . 2279If 1, PaX MPROTECT will be enabled for all programs. 2280Programs can be exempted using 2281.Xr paxctl 8 . 2282.Pp 2283See 2284.Xr security 7 2285for more details. 2286.It Cd options PAX_SEGVGUARD=value 2287Enables PaX Segvguard. 2288Requires 2289.Cd options FILEASSOC . 2290.Pp 2291The 2292.Ar value 2293is the default value for the 2294.Em global 2295knob, see 2296.Xr sysctl 3 . 2297If 0, PaX Segvguard will be enabled only if explicitly set on programs 2298using 2299.Xr paxctl 8 . 2300If 1, PaX Segvguard will be enabled to all programs, and exemption can 2301be done using 2302.Xr paxctl 8 . 2303.Pp 2304See 2305.Xr security 7 2306for more details. 2307.It Cd options PAX_ASLR=value 2308Enables PaX ASLR. 2309.Pp 2310The 2311.Ar value 2312is the default value for the 2313.Em global 2314knob, see 2315.Xr sysctl 3 . 2316If 0, PaX ASLR will be enabled only if explicitly set on programs 2317using 2318.Xr paxctl 8 . 2319If 1, PaX ASLR will be enabled to all programs, and exemption can 2320be done using 2321.Xr paxctl 8 . 2322.Pp 2323See 2324.Xr security 7 2325for more details. 2326.It Cd options USER_VA0_DISABLE_DEFAULT=value 2327Sets the initial value of the flag which controls whether user programs 2328can map virtual address 0. 2329The flag can be changed at runtime by 2330.Xr sysctl 3 . 2331.It Cd options KASAN 2332Enables Kernel Address Sanitizer. 2333.Em NOTE : 2334not available on all architectures. 2335.It Cd options KASLR 2336Enables Kernel ASLR. 2337This randomizes the location of the kernel image in memory. 2338.Em NOTE : 2339not available on all architectures. 2340.It Cd options SVS 2341Enables Separate Virtual Space. 2342On architectures that are designed to function with a shared address 2343space, this option explicitly isolates the kernel and user spaces. 2344.Em NOTE : 2345not available on all architectures. 2346.El 2347.Ss amiga-specific Options 2348.Bl -ohang 2349.It Cd options BB060STUPIDROM 2350When the bootloader (which passes AmigaOS ROM information) claims 2351we have a 68060 CPU without FPU, go look into the Processor 2352Configuration Register (PCR) to find out. 2353You need this with Amiga ROMs up to (at least) V40.xxx (OS3.1), 2354when you boot via the bootblocks and don't have a DraCo. 2355.It Cd options IOBZCLOCK=frequency 2356The IOBlix boards come with two different serial master clocks: older ones 2357use 24 MHz, newer ones use 22.1184 MHz. 2358The driver normally assumes the latter. 2359If your board uses 24 MHz, you can recompile your kernel with 2360options IOBZCLOCK=24000000 2361or patch the kernel variable iobzclock to the same value. 2362.It Cd options LIMITMEM=value 2363If there, limit the part of the first memory bank used by 2364.Nx 2365to value megabytes. 2366Default is unlimited. 2367.It Cd options P5PPC68KBOARD 2368Add special support for Phase5 mixed 68k+PPC boards. 2369Currently, this only affects rebooting from 2370.Nx 2371and is only needed on 68040+PPC, not on 237268060+PPC; without this, affected machines will hang after 2373.Nx 2374has shut 2375down and will only restart after a keyboard reset or a power cycle. 2376.El 2377.Ss atari-specific Options 2378.Bl -ohang 2379.It Cd options DISKLABEL_AHDI 2380Include support for AHDI (native Atari) disklabels. 2381.It Cd options DISKLABEL_NBDA 2382Include support for 2383.Nx Ns /atari 2384labels. 2385If you don't set this option, it will be set automatically. 2386.Nx Ns /atari 2387will not work without it. 2388.It Cd options FALCON_SCSI 2389Include support for the 5380-SCSI configuration as found on the Falcon. 2390.It Cd options RELOC_KERNEL 2391If set, the kernel will relocate itself to TT-RAM, if possible. 2392This will give you a slightly faster system. 2393.Em Beware 2394that on some TT030 systems, 2395the system will frequently dump with MMU-faults with this option enabled. 2396.It Cd options SERCONSOLE 2397Allow the modem1-port to act as the system-console. 2398A carrier should be active on modem1 during system boot to active 2399the console functionality. 2400.It Cd options TT_SCSI 2401Include support for the 5380-SCSI configuration as found on the TT030 2402and Hades. 2403.El 2404.Ss i386-specific Options 2405.Bl -ohang 2406.It Cd options CPURESET_DELAY=value 2407Specifies the time (in millisecond) to wait before doing a hardware reset 2408in the last phase of a reboot. 2409This gives the user a chance to see error messages from the shutdown 2410operations (like NFS unmounts, buffer cache flush, etc ...). 2411Setting this to 0 will disable the delay. 2412Default is 2 seconds. 2413.It Cd options USER_LDT 2414Include i386-specific system calls for modifying the local descriptor table, 2415used by Windows emulators. 2416.It Cd options PAE 2417Enable PAE (Physical Address Extension) mode. 2418PAE permits up to 36 bits physical addressing (64GB of physical 2419memory), and turns physical addresses to 64 bits entities in the 2420memory management subsystem. 2421Userland virtual address space remains at 32 bits (4GB). 2422PAE mode is required to enable the NX/XD (No-eXecute/eXecute Disable) 2423bit for pages, which allows marking certain ones as not being executable. 2424Any attempt to execute code from such a page will raise an exception. 2425.It Cd options REALBASEMEM=integer 2426Overrides the base memory size passed in from the boot block. 2427(Value given in kilobytes.) 2428Use this option only if the boot block reports the size incorrectly. 2429(Note that some BIOSes put the extended BIOS 2430data area at the top of base memory, and therefore report a smaller 2431base memory size to prevent programs overwriting it. 2432This is correct behavior, and you should not use the 2433.Em REALBASEMEM 2434option to access this memory). 2435.It Cd options SPECTRE_V2_GCC_MITIGATION=1 2436Enable GCC-specific Spectre variant 2 mitigations. 2437For 32-bit kernels this means these options: 2438.Bd -literal -offset indent 2439-mindirect-branch=thunk -mindirect-branch-register 2440.Ed 2441.Pp 2442For 64-bit kernels this means these options: 2443.Bd -literal -offset indent 2444-mindirect-branch=thunk-inline -mindirect-branch-register 2445.Ed 2446.It Cd options REALEXTMEM=integer 2447Overrides the extended memory size passed in from the boot block. 2448(Value given in kilobytes. 2449Extended memory does not include the first megabyte.) 2450Use this option only if the boot block reports the size incorrectly. 2451.It Cd options CYRIX_CACHE_WORKS 2452Relevant only to the Cyrix 486DLC CPU. 2453This option is used to turn on the cache in hold-flush mode. 2454It is not turned on by default because it is known to have problems in 2455certain motherboard implementations. 2456.It Cd options CYRIX_CACHE_REALLY_WORKS 2457Relevant only to the Cyrix 486DLC CPU. 2458This option is used to turn on the cache in write-back mode. 2459It is not turned on by default because it is known to have problems in 2460certain motherboard implementations. 2461In order for this option to take effect, option 2462.Em CYRIX_CACHE_WORKS 2463must also be specified. 2464.It Cd options PCIBIOS 2465Enable support for initializing the PCI bus using information from 2466the BIOS. 2467See 2468.Xr pcibios 4 2469for details. 2470.It Cd options MTRR 2471Include support for accessing MTRR registers from user-space. 2472See 2473.Xr i386_get_mtrr 2 . 2474.It Cd options BEEP_ONHALT 2475Make the system speaker emit several beeps when it is completely safe to 2476power down the computer after a 2477.Xr halt 8 2478command. 2479Requires 2480.Xr sysbeep 4 2481support. 2482.It Cd options BEEP_ONHALT_COUNT=times 2483Number of times to beep the speaker when 2484.Cd options BEEP_ONHALT 2485is enabled. 2486Defaults to 3. 2487.It Cd options BEEP_ONHALT_PITCH=hz 2488The tone frequency used when 2489.Cd options BEEP_ONHALT 2490option, in hertz. 2491Defaults to 1500. 2492.It Cd options BEEP_ONHALT_PERIOD=msecs 2493The duration of each beep when 2494.Cd options BEEP_ONHALT 2495is enabled, in milliseconds. 2496Defaults to 250. 2497.It Cd options MULTIBOOT 2498Makes the kernel Multiboot-compliant, allowing it to be booted through 2499a Multiboot-compliant boot manager such as GRUB. 2500See 2501.Xr multiboot 8 2502for more information. 2503.It Cd options SPLASHSCREEN 2504Display a splash screen during boot. 2505.El 2506.Ss isa-specific Options 2507Options specific to 2508.Xr isa 4 2509busses. 2510.Bl -ohang 2511.It Cd options PCIC_ISA_ALLOC_IOBASE=address, PCIC_ISA_ALLOC_IOSIZE=size 2512Control the section of IO bus space used for PCMCIA bus space mapping. 2513Ideally the probed defaults are satisfactory, however in practice 2514that is not always the case. 2515See 2516.Xr pcmcia 4 2517for details. 2518.It Cd options PCIC_ISA_INTR_ALLOC_MASK=mask 2519Controls the allowable interrupts that may be used for PCMCIA 2520devices. 2521This mask is a logical-or of power-of-2s of allowable interrupts: 2522.Bd -literal -offset 04n 2523.Em "IRQ Val IRQ Val IRQ Val IRQ Val" 2524 0 0x0001 4 0x0010 8 0x0100 12 0x1000 2525 1 0x0002 5 0x0020 9 0x0200 13 0x2000 2526 2 0x0004 6 0x0040 10 0x0400 14 0x4000 2527 3 0x0008 7 0x0080 11 0x0800 15 0x8000 2528.Ed 2529.It Cd options PCKBC_CNATTACH_SELFTEST 2530Perform a self test of the keyboard controller before attaching it as a 2531console. 2532This might be necessary on machines where we boot on cold iron, and 2533pckbc refuses to talk until we request a self test. 2534Currently only the netwinder port uses it. 2535.It Cd options PCKBD_CNATTACH_MAY_FAIL 2536If this option is set the PS/2 keyboard will not be used as the console 2537if it cannot be found during boot. 2538This allows other keyboards, like USB, to be the console keyboard. 2539.It Cd options PCKBD_LAYOUT=layout 2540Sets the default keyboard layout, see 2541.Xr pckbd 4 . 2542.El 2543.Ss m68k-specific Options 2544.Bl -ohang 2545.It Cd options FPU_EMULATE 2546Include support for MC68881/MC68882 emulator. 2547.It Cd options FPSP 2548Include support for 68040 floating point. 2549.It Cd options M68020,M68030,M68040,M68060 2550Include support for a specific CPU, 2551at least one (the one you are using) should be specified. 2552.It Cd options M060SP 2553Include software support for 68060. 2554This provides emulation of unimplemented 2555integer instructions as well as emulation of unimplemented floating point 2556instructions and data types and software support for floating point traps. 2557.El 2558.Ss powerpc-specific Options (OEA Only) 2559.Bl -ohang 2560.It Cd options PMAP_MEMLIMIT=value 2561Limit the amount of memory seen by the kernel to 2562.Ar value 2563bytes. 2564.It Cd options PTEGCOUNT=value 2565Specify the size of the page table as 2566.Ar value 2567PTE groups. 2568Normally, one PTEG is allocated per physical page frame. 2569.El 2570.Ss sparc-specific Options 2571.Bl -ohang 2572.It Cd options AUDIO_DEBUG 2573Enable simple event debugging of the logging of the 2574.Xr audio 4 2575device. 2576.It Cd options BLINK 2577Enable blinking of LED. 2578Blink rate is full cycle every N seconds for 2579N < then current load average. 2580See 2581.Xr getloadavg 3 . 2582.\" .It Cd options COLORFONT_CACHE 2583.\" What does this do? 2584.It Cd options COUNT_SW_LEFTOVERS 2585Count how many times the sw SCSI device has left 3, 2, 1 and 0 in the 2586sw_3_leftover, sw_2_leftover, sw_1_leftover, and sw_0_leftover 2587variables accessible from 2588.Xr ddb 4 . 2589See 2590.Xr sw 4 . 2591.It Cd options DEBUG_ALIGN 2592Adds debugging messages calls when user-requested alignment fault 2593handling happens. 2594.It Cd options DEBUG_EMUL 2595Adds debugging messages calls for emulated floating point and 2596alignment fixing operations. 2597.It Cd options EXTREME_DEBUG 2598Adds debugging functions callable from 2599.Xr ddb 4 . 2600The debug_pagetables, test_region and print_fe_map 2601functions print information about page tables for the SUN4M 2602platforms only. 2603.It Cd options EXTREME_EXTREME_DEBUG 2604Adds extra info to 2605.Em options EXTREME_DEBUG . 2606.It Cd options FPU_CONTEXT 2607Make 2608.Em options COMPAT_SVR4 2609getcontext and setcontext include floating point registers. 2610.It Cd options MAGMA_DEBUG 2611Adds debugging messages to the 2612.Xr magma 4 2613device. 2614.It Cd options RASTERCONS_FULLSCREEN 2615Use the entire screen for the console. 2616.It Cd options RASTERCONS_SMALLFONT 2617Use the Fixed font on the console, instead of the normal font. 2618.It Cd options SUN4 2619Support sun4 class machines. 2620.It Cd options SUN4C 2621Support sun4c class machines. 2622.It Cd options SUN4M 2623Support sun4m class machines. 2624.It Cd options SUN4_MMU3L 2625.\" XXX ??? 2626Enable support for sun4 3-level MMU machines. 2627.It Cd options V9 2628Enable SPARC V9 assembler in 2629.Xr ddb 4 . 2630.El 2631.Ss sparc64-specific Options 2632.Bl -ohang 2633.It Cd options AUDIO_DEBUG 2634Enable simple event debugging of the logging of the 2635.Xr audio 4 2636device. 2637.It Cd options BLINK 2638Enable blinking of LED. 2639Blink rate is full cycle every N seconds for 2640N < then current load average. 2641See 2642.Xr getloadavg 3 . 2643.El 2644.Ss x68k-specific Options 2645.Bl -ohang 2646.It Cd options EXTENDED_MEMORY 2647Include support for extended memory, e.g., TS-6BE16 and 060turbo on-board. 2648.It Cd options JUPITER 2649Include support for Jupiter-X MPU accelerator 2650.It Cd options ZSCONSOLE,ZSCN_SPEED=value 2651Use the built-in serial port as the system-console. 2652Speed is specified in bps, defaults to 9600. 2653.It Cd options ITE_KERNEL_ATTR=value 2654Set the kernel message attribute for ITE. 2655Value, an integer, is a logical or of the following values: 2656.Bl -tag -width 4n -compact -offset indent 2657.It 1 2658color inversed 2659.It 2 2660underlined 2661.It 4 2662bolded 2663.El 2664.El 2665.Ss x86-specific Options 2666.Bl -ohang 2667.It Cd options NO_PCI_MSI_MSIX 2668Disable support for MSI/MSIX in the kernel. 2669See 2670.Xr pci_msi 9 2671for details of MSI/MSIX support 2672.It Cd options NO_PREEMPTION 2673Disables 2674.Xr kpreempt 9 2675support in the kernel. 2676.El 2677.\" The following requests should be uncommented and used where appropriate. 2678.\" .Sh FILES 2679.\" .Sh EXAMPLES 2680.Sh SEE ALSO 2681.Xr config 1 , 2682.Xr gcc 1 , 2683.Xr gdb 1 , 2684.Xr ktrace 1 , 2685.Xr quota 1 , 2686.Xr vndcompress 1 , 2687.Xr gettimeofday 2 , 2688.Xr i386_get_mtrr 2 , 2689.Xr i386_iopl 2 , 2690.Xr msgctl 2 , 2691.Xr msgget 2 , 2692.Xr msgrcv 2 , 2693.Xr msgsnd 2 , 2694.Xr ntp_adjtime 2 , 2695.Xr ntp_gettime 2 , 2696.Xr reboot 2 , 2697.Xr semctl 2 , 2698.Xr semget 2 , 2699.Xr semop 2 , 2700.Xr shmat 2 , 2701.Xr shmctl 2 , 2702.Xr shmdt 2 , 2703.Xr shmget 2 , 2704.Xr sysctl 3 , 2705.Xr apm 4 , 2706.Xr ddb 4 , 2707.Xr inet 4 , 2708.Xr md 4 , 2709.Xr pcibios 4 , 2710.Xr pcmcia 4 , 2711.Xr ppp 4 , 2712.Xr userconf 4 , 2713.Xr vnd 4 , 2714.Xr wscons 4 , 2715.Xr config 5 , 2716.Xr edquota 8 , 2717.Xr init 8 , 2718.Xr mdsetimage 8 , 2719.Xr mount_cd9660 8 , 2720.Xr mount_fdesc 8 , 2721.Xr mount_kernfs 8 , 2722.Xr mount_lfs 8 , 2723.Xr mount_mfs 8 , 2724.Xr mount_msdos 8 , 2725.Xr mount_nfs 8 , 2726.Xr mount_ntfs 8 , 2727.Xr mount_null 8 , 2728.Xr mount_portal 8 , 2729.Xr mount_procfs 8 , 2730.Xr mount_udf 8 , 2731.Xr mount_umap 8 , 2732.Xr mount_union 8 , 2733.Xr mrouted 8 , 2734.Xr newfs_lfs 8 , 2735.Xr ntpd 8 , 2736.Xr quotaon 8 , 2737.Xr rpc.rquotad 8 , 2738.Xr sysctl 8 , 2739.Xr cnmagic 9 , 2740.Xr in_getifa 9 , 2741.Xr kernhist 9 2742.Sh HISTORY 2743The 2744.Nm 2745man page first appeared in 2746.Nx 1.3 . 2747