1.\" $NetBSD: options.4,v 1.512 2020/04/24 13:54:56 jdolecek 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 April 24, 2020 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_BSDPTY 402This option is currently on by default and enables the pty multiplexer 403.Xr ptm 4 404and 405.Xr ptmx 4 406to find and use ptys named 407.Pa /dev/ptyXX 408(master) and 409.Pa /dev/ttyXX 410(slave). 411Eventually this option will become optional as ptyfs based pseudo-ttys become 412the default, see 413.Xr mount_ptyfs 8 . 414.It Cd options COMPAT_LINUX 415On those architectures that support it, this enables binary 416compatibility with Linux ELF and 417.Xr a.out 5 418applications built for the same architecture. 419This currently includes the alpha, arm, i386, m68k, mips, powerpc and 420x86_64 ports. 421.It Cd options COMPAT_LINUX32 422On those 64 bit architectures that support it, this enables binary 423compatibility with 32 bit Linux binaries. 424For now this is limited to running i386 ELF Linux binaries on amd64. 425.It Cd options COMPAT_SUNOS 426On those architectures that support it, this enables binary 427compatibility with SunOS 4.1 applications built for the same architecture. 428This currently includes the sparc, sparc64 and most or all m68k ports. 429Note that the sparc64 requires the 430.Em COMPAT_NETBSD32 431option for 64-bit kernels, in addition to this option. 432.It Cd options COMPAT_ULTRIX 433On those architectures that support it, this enables binary 434compatibility with ULTRIX applications built for the same architecture. 435This currently is limited to the pmax. 436The functionality of this option is unknown. 437.It Cd options COMPAT_FREEBSD 438On those architectures that support it, this enables binary 439compatibility with 440.Fx 441applications built for the same architecture. 442At the moment this is limited to the i386 port. 443.It Cd options COMPAT_NOMID 444Enable compatibility with 445.Xr a.out 5 446executables that lack a machine ID. 447This includes 448.Nx 0.8 Ns 's 449ZMAGIC format, and 386BSD and BSDI's 450QMAGIC, NMAGIC, and OMAGIC 451.Xr a.out 5 452formats. 453.It Cd options COMPAT_NETBSD32 454On those architectures that support it, this enables binary 455compatibility with 32-bit applications built for the same architecture. 456This is currently limited to the amd64 and sparc64 ports, and only 457applicable for 64-bit kernels. 458.It Cd options COMPAT_AOUT_M68K 459On m68k architectures which have switched to ELF, 460this enables binary compatibility with 461.Nx Ns /m68k 462.Xr a.out 5 463executables on 464.Nx Ns /m68k 465ELF kernels. 466This handles alignment incompatibility of m68k ABI between 467a.out and ELF which causes the structure padding differences. 468Currently only some system calls which use 469.Va struct stat 470are adjusted and some binaries which use 471.Xr sysctl 3 472to retrieve network details would not work properly. 473.It Cd options EMUL_NATIVEROOT=string 474Just like emulated binaries first try looking up files in 475an emulation root (e.g. 476.Pa /emul/linux ) 477before looking them up in real root, this option causes native 478binaries to first look up files in an "emulation" directory too. 479This can be useful to test an amd64 kernel on top of an i386 system 480before full migration: by unpacking the amd64 distribution in e.g. 481.Pa /emul/netbsd64 482and specifying that location as 483.Cd EMUL_NATIVEROOT , 484native amd64 binaries can be run while the root file system remains 485populated with i386 binaries. 486Beware of 487.Pa /dev 488incompatibilities between i386 and amd64 if you do this. 489.It Cd options EXEC_ELF_NOTELESS 490Run unidentified ELF binaries as 491.Nx 492binaries. 493This might be needed for very old 494.Nx 495ELF binaries on some archs. 496These old binaries didn't contain an appropriate 497.Li .note.netbsd.ident 498section, and thus can't be identified by the kernel as 499.Nx 500binaries otherwise. 501Beware - if this option is on, the kernel would run 502.Em any 503unknown ELF binaries as if they were 504.Nx 505binaries. 506.El 507.Ss Debugging Options 508.Bl -ohang 509.It Cd options DDB 510Compiles in a kernel debugger for diagnosing kernel problems. 511See 512.Xr ddb 4 513for details. 514.Em NOTE : 515not available on all architectures. 516.It Cd options DDB_FROMCONSOLE=integer 517If set to non-zero, DDB may be entered by sending a break on a serial 518console or by a special key sequence on a graphics console. 519A value of "0" ignores console breaks or key sequences. 520If not explicitly specified, the default value is "1". 521Note that this sets the value of the 522.Em ddb.fromconsole 523.Xr sysctl 3 524variable which may be changed at run time \(em see 525.Xr sysctl 8 526for details. 527.It Cd options DDB_HISTORY_SIZE=integer 528If this is non-zero, enable history editing in the kernel debugger 529and set the size of the history to this value. 530.It Cd options DDB_ONPANIC 531The default if not specified is 532.Dq 1 533- just enter into DDB. 534If set to 535.Dq 0 536the kernel will attempt to print out a stack trace 537and reboot the system. 538If set to 539.Dq -1 540then neither a stack trace is printed or DDB entered - 541it is as if DDB were not compiled into the kernel. 542Note that this sets the value of the 543.Em ddb.onpanic 544.Xr sysctl 3 545variable which may be changed at run time \(em see 546.Xr sysctl 8 547for details. 548.It Cd options DDB_COMMANDONENTER=string 549This option specify commands which will be executed on each entry to DDB. 550This sets the default value of the 551.Em ddb.commandonenter 552.Xr sysctl 3 553variable which may be changed at run time. 554.It Cd options DDB_BREAK_CHAR=integer 555This option overrides using break to enter the kernel debugger 556on the serial console. 557The value given is the ASCII value to be used instead. 558This is currently only supported by the com driver. 559.It Cd options DDB_VERBOSE_HELP 560This option adds more verbose descriptions to the 561.Em help 562command. 563.It Cd options DDB_PANICSTACKFRAMES=integer 564Number of stack frames to display on panic. 565Useful to avoid scrolling away the interesting frames on a glass tty. 566Default value is 567.Dv 65535 568(all frames), useful value around 569.Dv 10 . 570.It Cd options KGDB 571Compiles in a remote kernel debugger stub for diagnosing kernel problems 572using the 573.Dq remote target 574feature of gdb. 575See 576.Xr gdb 1 577for details. 578.Em NOTE : 579not available on all architectures. 580.It Cd options KGDB_DEV 581Device number 582.Po 583as a 584.Dv dev_t 585.Pc 586of kgdb device. 587.It Cd options KGDB_DEVADDR 588Memory address of kgdb device. 589.It Cd options KGDB_DEVMODE 590Permissions of kgdb device. 591.It Cd options KGDB_DEVNAME 592Device name of kgdb device. 593.It Cd options KGDB_DEVRATE 594Baud rate of kgdb device. 595.It Cd makeoptions DEBUG="-g" 596The 597.Fl g 598flag causes 599.Pa netbsd.gdb 600to be built in addition to 601.Pa netbsd . 602.Pa netbsd.gdb 603is useful for debugging kernel crash dumps with gdb. 604See 605.Xr gdb 1 606for details. 607.It Cd options DEBUG 608Turns on miscellaneous kernel debugging. 609Since options are turned into preprocessor defines (see above), 610.Em options DEBUG 611is equivalent to doing a 612.Em #define DEBUG 613throughout the kernel. 614Much of the kernel has 615.Em #ifdef DEBUG 616conditionalized debugging code. 617Note that many parts of the kernel (typically device drivers) include their own 618.Em #ifdef XXX_DEBUG 619conditionals instead. 620This option also turns on certain other options, 621which may decrease system performance. 622Systems with this option are not suitable for regular use, and are 623intended only for debugging or looking for bugs. 624.It Cd options DIAGNOSTIC 625Adds code to the kernel that does internal consistency checks. 626This code will cause the kernel to panic if corruption of internal data 627structures is detected. 628Historically, the performance degradation is sufficiently small that 629it is reasonable for systems with 630.Em options DIAGNOSTIC 631to be in production use, with the real consideration not being 632performance but instead a preference for more panics versus continued 633operation with undetected problems. 634.It Cd options LOCKDEBUG 635Adds code to the kernel to detect incorrect use of locking primitives 636(mutex, rwlock). 637This code will cause the kernel to check for dead lock conditions. 638It will also check for memory being freed to not contain initialised 639lock primitives. 640Functions for use in 641.Xr ddb 4 642to check lock chains etc. are also enabled. 643These checks are very expensive and can decrease performance on 644multi-processor machines by a factor of three. 645.It Cd options KDTRACE_HOOKS 646Adds hooks for the DTrace tracing facility, which allows users to 647analyze many aspects of system and application behavior. 648See 649.Xr dtrace 1 650for details. 651.It Cd options KSTACK_CHECK_MAGIC 652Check kernel stack usage and panic if stack overflow is detected. 653This check is performance sensitive because it scans stack on each context 654switch. 655.It Cd options KTRACE 656Add hooks for the system call tracing facility, which allows users to 657watch the system call invocation behavior of processes. 658See 659.Xr ktrace 1 660for details. 661.It Cd options MSGBUFSIZE=integer 662This option sets the size of the kernel message buffer. 663This buffer holds the kernel output of 664.Fn printf 665when not (yet) read by 666.Xr syslogd 8 . 667This is particularly useful when the system has crashed and you wish to lookup 668the kernel output from just before the crash. 669Also, since the autoconfig output becomes more and more verbose, 670it sometimes happens that the message buffer overflows before 671.Xr syslogd 8 672was able to read it. 673Note that not all systems are capable of obtaining a variable sized message 674buffer. 675There are also some systems on which memory contents are not preserved 676across reboots. 677.It Cd options KERNHIST 678Enables the kernel history logs, which create in-memory traces of 679various kernel activities. 680These logs can be displayed by using 681.Cm show kernhist 682from DDB. 683See the kernel source file 684.Pa sys/kern/kern_history.c 685and the 686.Xr kernhist 9 687manual for details. 688.It Cd options KERNHIST_PRINT 689Prints the kernel history logs on the system console as entries are added. 690Note that the output is 691.Em extremely 692voluminous, so this option is really only useful for debugging 693the very earliest parts of kernel initialization. 694.It Cd options UVMHIST 695Like 696.Em KERNHIST , 697it enables the UVM history logs. 698These logs can be displayed by using 699.Cm show kernhist 700from DDB. 701See the kernel source file 702.Pa sys/uvm/uvm_stat.c 703for details. 704.It Cd options UVMHIST_PRINT 705Like 706.Em UVMHIST , 707it prints the UVM history logs on the system console as entries are added. 708Note that the output is 709.Em extremely 710voluminous, so this option is really only useful for debugging 711the very earliest parts of kernel initialization. 712.It Cd options UVMHIST_MAPHIST_SIZE 713Set the size of the 714.Dq maphist 715kernel history. 716The default is 100. 717This option depends upon the 718.Em UVMHIST 719option. 720.It Cd options UVMHIST_PDHIST_SIZE 721Set the size of the 722.Dq pdhist 723kernel history. 724The default is 100. 725This option depends upon the 726.Em UVMHIST 727option. 728.It Cd options BIOHIST 729Like 730.Em KERNHIST , 731it enables the BIO history logs. 732These logs can be displayed by using 733.Cm show kernhist 734from DDB, and can help in debugging problems with Buffered I/O operations. 735See the kernel source file 736.Pa sys/kern/vfs_vio.c 737for details. 738.It Cd options BIOHIST_PRINT 739Like 740.Em BIOHIST , 741it prints the BIO history logs on the system console as entries are added. 742Note that the output is 743.Em extremely 744voluminous, so this option is really only useful for debugging 745the very earliest parts of kernel initialization. 746.It Cd options BIOHIST_SIZE 747Set the size of the 748.Dq biohist 749kernel history. 750The default is 500. 751This option depends upon the 752.Em BIOHIST 753option. 754.El 755.Ss File Systems 756.Bl -ohang 757.It Cd file-system FFS 758Includes code implementing the Berkeley Fast File System 759.Po Em FFS Pc . 760Most machines need this if they are not running diskless. 761.It Cd file-system EXT2FS 762Includes code implementing the Second Extended File System 763.Po Em ext2 Pc , 764revision 0 and revision 1 with the 765.Em filetype , 766.Em sparse_super 767and 768.Em large_file 769options. 770This is the most commonly used file system on the Linux operating system, 771and is provided here for compatibility. 772Some of the specific features of 773.Em ext2 774like the "behavior on errors" are not implemented. 775See 776.Xr mount_ext2fs 8 777for details. 778.It Cd file-system LFS 779.Bq Em EXPERIMENTAL 780Include the Log-structured File System 781.Po Em LFS Pc . 782See 783.Xr mount_lfs 8 784and 785.Xr newfs_lfs 8 786for details. 787.It Cd file-system MFS 788Include the Memory File System 789.Po Em MFS Pc . 790This file system stores files in swappable memory, and produces 791notable performance improvements when it is used as the file store 792for 793.Pa /tmp 794and similar file systems. 795See 796.Xr mount_mfs 8 797for details. 798.It Cd file-system NFS 799Include the client side of the Network File System (NFS) 800remote file sharing protocol. 801Although the bulk of the code implementing NFS 802is kernel based, several user level daemons are needed for it to work. 803See 804.Xr mount_nfs 8 805for details. 806.It Cd file-system CD9660 807Includes code for the ISO 9660 + Rock Ridge file system, which is 808the standard file system on many CD-ROM discs. 809Useful primarily if you have a CD-ROM drive. 810See 811.Xr mount_cd9660 8 812for details. 813.It Cd file-system MSDOSFS 814Includes the MS-DOS FAT file system, which is reportedly still used 815by unfortunate people who have not heard about 816.Nx . 817Also implements the Windows 95 extensions to the same, which permit 818the use of longer, mixed case file names. 819See 820.Xr mount_msdos 8 821and 822.Xr fsck_msdos 8 823for details. 824.It Cd file-system NTFS 825.Bq Em EXPERIMENTAL 826Includes code for the Microsoft Windows NT file system. 827See 828.Xr mount_ntfs 8 829for details. 830.It Cd file-system FDESC 831Includes code for a file system, conventionally mounted on 832.Pa /dev/fd , 833which permits access to the per-process file descriptor space via 834special files in the file system. 835See 836.Xr mount_fdesc 8 837for details. 838Note that this facility is redundant, and thus unneeded on most 839.Nx 840systems, since the 841.Xr fd 4 842pseudo-device driver already provides identical functionality. 843On most 844.Nx 845systems, instances of 846.Xr fd 4 847are mknoded under 848.Pa /dev/fd/ 849and on 850.Pa /dev/stdin , 851.Pa /dev/stdout , 852and 853.Pa /dev/stderr . 854.It Cd file-system KERNFS 855Includes code which permits the mounting of a special file system 856(normally mounted on 857.Pa /kern ) 858in which files representing various kernel variables and parameters 859may be found. 860See 861.Xr mount_kernfs 8 862for details. 863.It Cd file-system NULLFS 864Includes code for a loopback file system. 865This permits portions of the file hierarchy to be re-mounted in other places. 866The code really exists to provide an example of a stackable file system layer. 867See 868.Xr mount_null 8 869for details. 870.It Cd file-system OVERLAY 871Includes code for a file system filter. 872This permits the overlay file system to intercept all access to an underlying 873file system. 874This file system is intended to serve as an example of a stacking file 875system which has a need to interpose itself between an underlying file 876system and all other access. 877See 878.Xr mount_overlay 8 879for details. 880.It Cd file-system PROCFS 881Includes code for a special file system (conventionally mounted on 882.Pa /proc ) 883in which the process space becomes visible in the file system. 884Among 885other things, the memory spaces of processes running on the system are 886visible as files, and signals may be sent to processes by writing to 887.Pa ctl 888files in the procfs namespace. 889See 890.Xr mount_procfs 8 891for details. 892.It Cd file-system UDF 893.Bq Em EXPERIMENTAL 894Includes code for the UDF file system commonly found on CD and DVD 895media but also on USB sticks. 896Currently supports read and write access upto UDF 2.01 and somewhat limited 897write support for UDF 2.50. 898It is marked experimental since there is no 899.Xr fsck_udf 8 . 900See 901.Xr mount_udf 8 902for details. 903.It Cd file-system UMAPFS 904Includes a loopback file system in which user and group IDs may be 905remapped \(em this can be useful when mounting alien file systems with 906different UIDs and GIDs than the local system. 907See 908.Xr mount_umap 8 909for details. 910.It Cd file-system UNION 911.Bq Em EXPERIMENTAL 912Includes code for the union file system, which permits directories to 913be mounted on top of each other in such a way that both file systems 914remain visible \(em this permits tricks like allowing writing (and the 915deleting of files) on a read-only file system like a CD-ROM by 916mounting a local writable file system on top of the read-only file 917system. 918See 919.Xr mount_union 8 920for details. 921.It Cd file-system CODA 922.Bq Em EXPERIMENTAL 923Includes code for the Coda file system. 924Coda is a distributed file system like NFS and AFS. 925It is freely available, like NFS, but it functions much like AFS in being a 926.Dq stateful 927file system. 928Both Coda and AFS cache files on your local machine to improve performance. 929Then Coda goes a step further than AFS by letting you access the cached 930files when there is no available network, viz. disconnected laptops and 931network outages. 932In Coda, both the client and server are outside the kernel which makes 933them easier to experiment with. 934Coda is available for several UNIX and non-UNIX platforms. 935See 936.Lk http://www.coda.cs.cmu.edu 937for more details. 938.Em NOTE : 939You also need to enable the pseudo-device, vcoda, for the Coda 940file system to work. 941.It Cd file-system PTYFS 942Includes code for a special file system (normally mounted on 943.Pa /dev/pts ) 944in which pseudo-terminal slave devices become visible in the file system. 945See 946.Xr mount_ptyfs 8 947for details. 948.It Cd file-system TMPFS 949Includes code for the efficient memory file system, normally used over 950.Pa /tmp . 951See 952.Xr mount_tmpfs 8 953for details. 954.It Cd file-system PUFFS 955Includes kernel support for the pass-to-userspace framework file system. 956It can be used to implement file system functionality in userspace. 957See 958.Xr puffs 3 959for more details. 960This enables for example sshfs: 961.Xr mount_psshfs 8 . 962.El 963.Ss File System Options 964.Bl -ohang 965.It Cd options DISKLABEL_EI 966Enable 967.Dq Endian-Independent 968.Xr disklabel 5 969support. 970This allows a system to recognize a disklabel written in the other byte order. 971For writing, when a label already exists, its byte order is preserved. 972Otherwise, a new label is written in the native byte order. 973To specify the byte order explicitly, the 974.Fl F 975option of 976.Xr disklabel 8 977should be used with the 978.Fl B 979option in order to avoid using 980.Xr ioctl 2 , 981which results in the default behavior explained above. 982At the moment this option is restricted to the following ports: 983amd64, bebox, emips, epoc32, evbarm, i386, ibmnws, landisk, mvmeppc, prep, 984.\" riscv, 985rs6000, sandpoint, 986.\" usermode, 987xen, and zaurus; 988also to machines of the 989evbmips and evbppc ports that support 990Master Boot Record (MBR). 991.It Cd options MAGICLINKS 992Enables the expansion of special strings 993.Po 994beginning with 995.Dq @ 996.Pc 997when traversing symbolic links. 998See 999.Xr symlink 7 1000for a list of supported strings. 1001Note that this option only controls the enabling of this feature 1002by the kernel at boot-up. 1003This feature can still be manipulated with the 1004.Xr sysctl 8 1005command regardless of the setting of this option. 1006.It Cd options NFSSERVER 1007Include the server side of the 1008.Em NFS 1009(Network File System) remote file sharing protocol. 1010Although the bulk of the code implementing 1011.Em NFS 1012is kernel based, several user level daemons are needed for it to 1013work. 1014See 1015.Xr mountd 8 1016and 1017.Xr nfsd 8 1018for details. 1019.It Cd options NVNODE=integer 1020This option sets the size of the cache used by the name-to-inode translation 1021routines, (a.k.a. the 1022.Fn namei 1023cache, though called by many other names in the kernel source). 1024By default, this cache has 1025.Dv ( NPROC + NTEXT + 100 ) 1026entries (NPROC set as 20 + 16 * MAXUSERS and NTEXT as 80 + NPROC / 8). 1027A reasonable way to derive a value of 1028.Dv NVNODE , 1029should you notice a large number of namei cache misses with a tool such as 1030.Xr systat 1 , 1031is to examine your system's current computed value with 1032.Xr sysctl 8 , 1033(which calls this parameter "kern.maxvnodes") and to increase this value 1034until either the namei cache hit rate improves or it is determined that 1035your system does not benefit substantially from an increase in the size of 1036the namei cache. 1037.It Cd options NAMECACHE_ENTER_REVERSE 1038Causes the namei cache to always enter a reverse mapping (vnode -> name) 1039as well as a normal one. 1040Normally, this is already done for directory vnodes, to speed up the getcwd 1041operation. 1042This option will cause longer hash chains in the reverse cache, and thus 1043slow down getcwd somewhat. 1044However, it does make vnode -> path translations possible in some cases. 1045For now, only useful if strict 1046.Pa /proc/#/maps 1047emulation for Linux binaries is required. 1048.El 1049.Ss Options for FFS/UFS File Systems 1050.Bl -ohang 1051.It Cd options APPLE_UFS 1052Enable support for UFS file systems created on Mac OS X. 1053.It Cd options FFS_EI 1054Enable 1055.Dq Endian-Independent 1056FFS support. 1057This allows a system to mount an FFS file system created for another 1058architecture, at a small performance cost for all FFS file systems. 1059See also 1060.Xr newfs 8 , 1061.Xr fsck_ffs 8 , 1062.Xr dumpfs 8 1063for file system byte order status and manipulation. 1064.It Cd options FFS_NO_SNAPSHOT 1065Disable support for the creation of file system internal snapshot 1066of FFS file systems. 1067Maybe useful for install media kernels, small memory systems and 1068embedded systems which don't require the snapshot support. 1069.It Cd options QUOTA 1070Enables kernel support for traditional quotas in FFS. 1071Traditional quotas store the quota information in external files and 1072require 1073.Xr quotacheck 8 1074and 1075.Xr quotaon 8 1076at boot time. 1077Traditional quotas are limited to 32-bit sizes and are at this point 1078considered a legacy feature. 1079.It Cd options QUOTA2 1080Enables kernel support for in-volume quotas in FFS. 1081The quota information is file system metadata maintained by 1082.Xr fsck 8 1083and/or WAPBL journaling. 1084MFS volumes can also use 1085.Dv QUOTA2 1086quotas; see 1087.Xr mount_mfs 8 1088for more information. 1089.It Cd options UFS_DIRHASH 1090Increase lookup performance by maintaining in-core hash tables 1091for large directories. 1092.It Cd options UFS_EXTATTR 1093Enable extended attribute support for UFS1 file systems. 1094.It Cd options WAPBL 1095Enable 1096.Dq Write Ahead Physical Block Logging file system journaling . 1097This provides rapid file system consistency checking after a system outage. 1098It also provides better general use performance over regular FFS. 1099See also 1100.Xr wapbl 4 . 1101.El 1102.Ss Options for the LFS File System 1103.Bl -ohang 1104.\" .It Cd options LFS_KERNEL_RFW 1105.\" There is no documentation for this. (XXX) 1106.\" .It Cd options LFS_QUOTA 1107.\" Enable traditional quota support for LFS. 1108.\" (It is not clear if this works.) 1109.\" .It Cd options LFS_QUOTA2 1110.\" Enable modernized 64-bit quota support for LFS. 1111.\" (This does not work yet.) 1112.It Cd options LFS_EI 1113Enable 1114.Dq Endian-Independent 1115LFS support. 1116This allows (at a small performance cost) mounting an LFS file system 1117created for another architecture. 1118.\" .It Cd options LFS_EXTATTR 1119.\" Enable extended attribute support for LFS. 1120.\" (It is not clear if this works.) 1121.It Cd options LFS_DIRHASH 1122Increase lookup performance by maintaining in-core hash tables 1123for large directories. 1124.El 1125.Ss Options for the ext2fs File System 1126.Bl -ohang 1127.It Cd options EXT2FS_SYSTEM_FLAGS 1128This option changes the behavior of the APPEND and IMMUTABLE flags 1129for a file on an 1130.Em ext2 1131file system. 1132Without this option, the superuser or owner of the file can 1133set and clear them. 1134With this option, only the superuser can set them, and 1135they can't be cleared if the securelevel is greater than 0. 1136See also 1137.Xr chflags 1 1138and 1139.Xr secmodel_securelevel 9 . 1140.El 1141.Ss Options for the NFS File System 1142.Bl -ohang 1143.It Cd options NFS_BOOT_BOOTP 1144Enable use of the BOOTP protocol (RFCs 951 and 1048) to get configuration 1145information if NFS is used to mount the root file system. 1146See 1147.Xr diskless 8 1148for details. 1149.It Cd options NFS_BOOT_BOOTSTATIC 1150Enable use of static values defined as 1151.Dq NFS_BOOTSTATIC_MYIP , 1152.Dq NFS_BOOTSTATIC_GWIP , 1153.Dq NFS_BOOTSTATIC_SERVADDR , 1154and 1155.Dq NFS_BOOTSTATIC_SERVER 1156in kernel options to get configuration information 1157if NFS is used to mount the root file system. 1158.It Cd options NFS_BOOT_DHCP 1159Same as 1160.Dq NFS_BOOT_BOOTP , 1161but use the DHCP extensions to the 1162BOOTP protocol (RFC 1541). 1163.It Cd options NFS_BOOT_BOOTP_REQFILE 1164Specifies the string sent in the bp_file field of the BOOTP/DHCP 1165request packet. 1166.It Cd options NFS_BOOT_BOOTPARAM 1167Enable use of the BOOTPARAM protocol, consisting of RARP and 1168BOOTPARAM RPC, to get configuration information if NFS 1169is used to mount the root file system. 1170See 1171.Xr diskless 8 1172for details. 1173.It Cd options NFS_BOOT_RWSIZE=value 1174Set the initial NFS read and write sizes for diskless-boot requests. 1175The normal default is 8Kbytes. 1176This option provides a way to lower the value (e.g., to 1024 bytes) 1177as a workaround for buggy network interface cards or boot PROMs. 1178Once booted, the read and write request sizes can be increased by 1179remounting the file system. 1180See 1181.Xr mount_nfs 8 1182for details. 1183.It Cd options NFS_V2_ONLY 1184Reduce the size of the NFS client code by omitting code that's only required 1185for NFSv3 and NQNFS support, leaving only that code required to use NFSv2 1186servers. 1187.It Cd options NFS_BOOT_TCP 1188Use NFS over TCP instead of the default UDP, for mounting root. 1189.El 1190.Ss Buffer queue strategy options 1191The following options enable alternative buffer queue strategies. 1192.Bl -ohang 1193.It Cd options BUFQ_READPRIO 1194Enable alternate buffer queue strategy for disk I/O. 1195In the default strategy, outstanding disk requests are ordered by 1196sector number and sent to the disk, regardless of whether the 1197operation is a read or write; this option gives priority to issuing 1198read requests over write requests. 1199Although requests may therefore be issued out of sector-order, causing 1200more seeks and thus lower overall throughput, interactive system 1201responsiveness under heavy disk I/O load may be improved, as processes 1202blocking on disk reads are serviced sooner (file writes typically 1203don't cause applications to block). 1204The performance effect varies greatly depending on the hardware, drive 1205firmware, file system configuration, workload, and desired performance 1206trade-off. 1207Systems using drive write-cache (most modern IDE disks, by default) 1208are unlikely to benefit and may well suffer; such disks acknowledge 1209writes very quickly, and optimize them internally according to 1210physical layout. 1211Giving these disks as many requests to work with as possible (the 1212standard strategy) will typically produce the best results, especially 1213if the drive has a large cache; the drive will silently complete 1214writes from cache as it seeks for reads. 1215Disks that support a large number of concurrent tagged requests (SCSI 1216disks and many hardware RAID controllers) expose this internal 1217scheduling with tagged responses, and don't block for reads; such 1218disks may not see a noticeable difference with either strategy. 1219However, if IDE disks are run with write-cache disabled for safety, 1220writes are not acknowledged until actually completed, and only one 1221request can be outstanding; a large number of small writes in one 1222locality can keep the disk busy, starving reads elsewhere on the disk. 1223Such systems are likely to see the most benefit from this option. 1224Finally, the performance interaction of this option with ffs soft 1225dependencies can be subtle, as that mechanism can drastically alter 1226the workload for file system metadata writes. 1227.It Cd options BUFQ_PRIOCSCAN 1228Enable another buffer queue strategy for disk I/O, per-priority cyclical scan. 1229.It Cd options NEW_BUFQ_STRATEGY 1230Synonym of 1231.Em BUFQ_READPRIO . 1232.El 1233.Ss Miscellaneous Options 1234.Bl -ohang 1235.It Cd options CPU_UCODE 1236Support cpu microcode loading via 1237.Xr cpuctl 8 . 1238.It Cd options MEMORY_DISK_DYNAMIC 1239This option makes the 1240.Xr md 4 1241RAM disk size dynamically sized. 1242It is incompatible with 1243.Xr mdsetimage 8 . 1244.It Cd options MEMORY_DISK_HOOKS 1245This option allows for some machine dependent functions to be called when 1246the 1247.Xr md 4 1248RAM disk driver is configured. 1249This can result in automatically loading a RAM disk from floppy on 1250open (among other things). 1251.It Cd options MEMORY_DISK_IS_ROOT 1252Forces the 1253.Xr md 4 1254RAM disk to be the root device. 1255This can only be overridden when 1256the kernel is booted in the 'ask-for-root' mode. 1257.It Cd options MEMORY_DISK_ROOT_SIZE=integer 1258Allocates the given number of 512 byte blocks as memory for the 1259.Xr md 4 1260RAM disk, to be populated with 1261.Xr mdsetimage 8 . 1262.It Cd options MEMORY_DISK_SERVER=0 1263Do not include the interface to a userland memory disk server process. 1264Per default, this option is set to 1, including the support code. 1265Useful for install media kernels. 1266.It Cd options MEMORY_DISK_RBFLAGS=value 1267This option sets the 1268.Xr reboot 2 1269flags used when booting with a memory disk as root file system. 1270Possible values include 1271.Dv RB_AUTOBOOT 1272(boot in the usual fashion - default value), and 1273.Dv RB_SINGLE 1274(boot in single-user mode). 1275.It Cd options MODULAR 1276Enables the framework for kernel modules (see 1277.Xr module 7 ) . 1278.It Cd options MODULAR_DEFAULT_AUTOLOAD 1279Enables the autoloading of kernel modules by default. 1280This sets the default value of the 1281.Em kern.module.autoload 1282.Xr sysctl 3 1283variable which may be changed at run time. 1284.It Cd options VND_COMPRESSION 1285Enables the 1286.Xr vnd 4 1287driver to also handle compressed images. 1288See 1289.Xr vndcompress 1 , 1290.Xr vnd 4 1291and 1292.Xr vnconfig 8 1293for more information. 1294.It Cd options SPLDEBUG 1295Help the kernel programmer find bugs related to the interrupt priority 1296level. 1297When 1298.Fn spllower 1299or 1300.Fn splraise 1301changes the current CPU's interrupt priority level to or from 1302.Dv IPL_HIGH , 1303record a backtrace. 1304Read 1305.Xr i386/return_address 9 1306for caveats about collecting backtraces. 1307This feature is experimental, and it is only available on i386. 1308See 1309.Pa sys/kern/subr_spldebug.c . 1310.It Cd options TFTPROOT 1311Download the root memory disk through TFTP at root mount time. 1312This enables the use of a root RAM disk without requiring it to be 1313embedded in the kernel using 1314.Xr mdsetimage 8 . 1315The RAM disk name is obtained using DHCP's filename parameter. 1316This option requires 1317.Em MEMORY_DISK_HOOKS 1318and 1319.Em MEMORY_DISK_DYNAMIC . 1320It is incompatible with 1321.Em MEMORY_DISK_ROOT_SIZE . 1322.It Cd options HZ=integer 1323On ports that support it, set the system clock frequency (see 1324.Xr hz 9 ) 1325to the supplied value. 1326Handle with care. 1327.It Cd options NTP 1328Turns on in-kernel precision timekeeping support used by software 1329implementing 1330.Em NTP 1331(Network Time Protocol, RFC 1305). 1332The 1333.Em NTP 1334option adds an in-kernel Phase-Locked Loop (PLL) for normal 1335.Em NTP 1336operation, and a Frequency-Locked Loop (FLL) for intermittently-connected 1337operation. 1338.Xr ntpd 8 1339will employ a user-level PLL when kernel support is unavailable, 1340but the in-kernel version has lower latency and more precision, and 1341so typically keeps much better time. 1342.Pp 1343The interface to the kernel 1344.Em NTP 1345support is provided by the 1346.Xr ntp_adjtime 2 1347and 1348.Xr ntp_gettime 2 1349system calls, which are intended for use by 1350.Xr ntpd 8 1351and are enabled by the option. 1352On systems with sub-microsecond resolution timers, or where (HZ/100000) 1353is not an integer, the 1354.Em NTP 1355option also enables extended-precision arithmetic to keep track of 1356fractional clock ticks at NTP time-format precision. 1357.It Cd options PPS_SYNC 1358This option enables a kernel serial line discipline for receiving time 1359phase signals from an external reference clock such as a radio clock. 1360.Po 1361The 1362.Em NTP 1363option (which see) must be on if the 1364.Em PPS_SYNC 1365option is used 1366.Pc . 1367Some reference clocks generate a Pulse Per Second (PPS) signal in 1368phase with their time source. 1369The 1370.Em PPS 1371line discipline receives this signal on either the data leads 1372or the DCD control lead of a serial port. 1373.Pp 1374.Em NTP 1375uses the PPS signal to discipline the local clock oscillator to a high 1376degree of precision (typically less than 50 microseconds in time and 13770.1 ppm in accuracy). 1378.Em PPS 1379can also generate a serial output pulse when the system receives a PPS 1380interrupt. 1381This can be used to measure the system interrupt latency and thus calibrate 1382.Em NTP 1383to account for it. 1384Using 1385.Em PPS 1386usually requires a gadget box 1387to convert from TTL to RS-232 signal levels. 1388The gadget box and PPS are described in more detail in the HTML documentation 1389for 1390.Xr ntpd 8 1391in 1392.Pa /usr/share/doc/html/ntp . 1393.Pp 1394.Nx 1395currently supports this option in 1396.Xr com 4 1397and 1398.Xr zsc 4 . 1399.It Cd options SETUIDSCRIPTS 1400Allows scripts with the setuid bit set to execute as the effective 1401user rather than the real user, just like binary executables. 1402.Pp 1403.Em NOTE : 1404Using this option will also enable 1405.Em options FDSCRIPTS 1406.It Cd options FDSCRIPTS 1407Allows execution of scripts with the execute bit set, but not the 1408read bit, by opening the file and passing the file descriptor to 1409the shell, rather than the filename. 1410.Pp 1411.Em NOTE : 1412Execute only (non-readable) scripts will have 1413.Va argv[0] 1414set to 1415.Pa /dev/fd/* . 1416What this option allows as far as security is 1417concerned, is the ability to safely ensure that the correct script 1418is run by the interpreter, as it is passed as an already open file. 1419.It Cd options RTC_OFFSET=integer 1420The kernel (and typically the hardware battery backed-up clock on 1421those machines that have one) keeps time in 1422.Em UTC 1423(Universal Coordinated Time, once known as 1424.Em GMT , 1425or Greenwich Mean Time) 1426and not in the time of the local time zone. 1427The 1428.Em RTC_OFFSET 1429option is used on some ports (such as the i386) to tell the kernel 1430that the hardware clock is offset from 1431.Em UTC 1432by the specified number of minutes. 1433This is typically used when a machine boots several operating 1434systems and one of them wants the hardware clock to run in the 1435local time zone and not in 1436.Em UTC , 1437e.g. 1438.Em RTC_OFFSET=300 1439means 1440the hardware clock is set to US Eastern Time (300 minutes behind 1441.Em UTC ) , 1442and not 1443.Em UTC . 1444(Note: 1445.Em RTC_OFFSET 1446is used to initialize a kernel variable named 1447.Va rtc_offset 1448which is the source actually used to determine the clock offset, and 1449which may be accessed via the kern.rtc_offset sysctl variable. 1450See 1451.Xr sysctl 8 1452and 1453.Xr sysctl 3 1454for details. 1455Since the kernel clock is initialized from the hardware clock very 1456early in the boot process, it is not possible to meaningfully change 1457.Va rtc_offset 1458in system initialization scripts. 1459Changing this value currently may only be done at kernel compile 1460time or by patching the kernel and rebooting). 1461.Pp 1462.Em NOTE : 1463Unfortunately, in many cases where the hardware clock 1464is kept in local time, it is adjusted for Daylight Savings 1465Time; this means that attempting to use 1466.Em RTC_OFFSET 1467to let 1468.Nx 1469coexist with such an operating system, like Windows, 1470would necessitate changing 1471.Em RTC_OFFSET 1472twice a year. 1473As such, this solution is imperfect. 1474.It Cd options MAXUPRC=integer 1475Sets the soft 1476.Dv RLIMIT_NPROC 1477resource limit, which specifies the maximum number of simultaneous 1478processes a user is permitted to run, for process 0; 1479this value is inherited by its child processes. 1480It defaults to 1481.Em CHILD_MAX , 1482which is currently defined to be 160. 1483Setting 1484.Em MAXUPRC 1485to a value less than 1486.Em CHILD_MAX 1487is not permitted, as this would result in a violation of the semantics of 1488.St -p1003.1-90 . 1489.It Cd options NOFILE=integer 1490Sets the soft 1491.Dv RLIMIT_NOFILE 1492resource limit, which specifies the maximum number of open 1493file descriptors for each process; 1494this value is inherited by its child processes. 1495It defaults to 1496.Em OPEN_MAX , 1497which is currently defined to be 128. 1498.It Cd options MAXFILES=integer 1499Sets the default value of the 1500.Em kern.maxfiles 1501sysctl variable, which indicates the maximum number of files that may 1502be open in the system. 1503.It Cd options DEFCORENAME=string 1504Sets the default value of the 1505.Em kern.defcorename 1506sysctl variable, otherwise it is set to 1507.Nm %n.core . 1508See 1509.Xr sysctl 8 1510and 1511.Xr sysctl 3 1512for details. 1513.It Cd options RASOPS_CLIPPING 1514Enables clipping within the 1515.Nm rasops 1516raster-console output system. 1517.Em NOTE : 1518only available on architectures that use 1519.Nm rasops 1520for console output. 1521.It Cd options RASOPS_SMALL 1522Removes optimized character writing code from the 1523.Nm rasops 1524raster-console output system. 1525.Em NOTE : 1526only available on architectures that use 1527.Nm rasops 1528for console output. 1529.It Cd options INCLUDE_CONFIG_FILE 1530Embeds the kernel config file used to define the kernel in the kernel 1531binary itself. 1532The embedded data also includes any files directly included by the config 1533file itself, e.g. 1534.Pa GENERIC.local 1535or 1536.Pa std.$MACHINE . 1537The embedded config file can be extracted from the resulting kernel with 1538.Xr config 1 1539.Fl x , 1540or by the following command: 1541.Bd -literal -offset indent 1542strings netbsd | sed -n 's/^_CFG_//p' | unvis 1543.Ed 1544.It Cd options INCLUDE_JUST_CONFIG 1545Similar to the above option, but includes just the actual config file, 1546not any included files. 1547.It Cd options PIPE_SOCKETPAIR 1548Use slower, but smaller socketpair(2)-based pipe implementation instead 1549of default faster, but bigger one. 1550Primarily useful for installation kernels. 1551.It Cd options USERCONF 1552Compiles in the in-kernel device configuration manager. 1553See 1554.Xr userconf 4 1555for details. 1556.It Cd options SCDEBUG_DEFAULT 1557Used with the 1558.Cd options SYSCALL_DEBUG 1559described below to choose which types of events are displayed. 1560.Pp 1561.Bl -tag -width "SCDEBUG_KERNHIST" -compact -offset indent 1562.It Dv SCDEBUG_CALLS 1563Show system call entry points. 1564.It Dv SCDEBUG_RETURNS 1565Show system call exit points. 1566.It Dv SCDEBUG_ALL 1567Show all system call requestes, including unimplemented calls. 1568.It Dv SCDEBUG_SHOWARGS 1569Show the arguments provided. 1570.It Dv SCDEBUG_KERNHIST 1571Store a restricted form of the system call debug in a kernel history 1572instead of printing it to the console. 1573This option relies upon 1574.Cd options KERNHIST . 1575.El 1576.Pp 1577The default value is 1578.Dv (SCDEBUG_CALLS|SCDEBUG_RETURNS|SCDEBUG_SHOWARGS) . 1579.It Cd options SYSCALL_DEBUG 1580Useful for debugging system call issues, usually in early single user bringup. 1581By default, writes entries to the system console for most system call events. 1582Can be configured with the 1583.Cd options SCDEBUG_DEFAULT 1584option to to use the 1585.Cd options KERNHIST 1586facility instead. 1587.It Cd options SYSCALL_STATS 1588Count the number of times each system call number is called. 1589The values can be read through the sysctl interface and displayed using 1590.Xr systat 1 . 1591.Em NOTE : 1592not yet available on all architectures. 1593.It Cd options SYSCALL_TIMES 1594Count the time spent (using 1595.Fn cpu_counter32 ) 1596in each system call. 1597.Em NOTE : 1598Using this option will also enable 1599.Cd options SYSCALL_STATS . 1600.It Cd options SYSCALL_TIMES_HASCOUNTER 1601Force use of 1602.Fn cpu_counter32 1603even if 1604.Fn cpu_hascounter 1605reports false. 1606Useful for systems where the cycle counter doesn't run at a constant rate 1607(e.g. Soekris boxes). 1608.It Cd options XSERVER_DDB 1609A supplement to XSERVER that adds support for entering 1610.Xr ddb 4 1611while in X11. 1612.It Cd options FILEASSOC 1613Support for 1614.Xr fileassoc 9 . 1615Required for 1616.Cd options PAX_SEGVGUARD 1617and 1618.Cd pseudo-device veriexec . 1619.It Cd options FILEASSOC_NHOOKS=integer 1620Number of storage slots per file for 1621.Xr fileassoc 9 . 1622Default is 4. 1623.El 1624.Ss Networking Options 1625.Bl -ohang 1626.It Cd options GATEWAY 1627Enables 1628.Em IPFORWARDING 1629and (on most ports) increases the size of 1630.Em NMBCLUSTERS . 1631In general, 1632.Em GATEWAY 1633is used to indicate that a system should act as a router, and 1634.Em IPFORWARDING 1635is not invoked directly. 1636(Note that 1637.Em GATEWAY 1638has no impact on protocols other than IP). 1639.Em GATEWAY 1640option also compiles IPv4 and IPv6 fast forwarding code into the kernel. 1641.It Cd options IPFORWARDING=value 1642If 1643.Em value 1644is 1 this enables IP routing behavior. 1645If 1646.Em value 1647is 0 (the default), it disables it. 1648The 1649.Em GATEWAY 1650option sets this to 1 automatically. 1651With this option enabled, the machine will forward IP datagrams destined 1652for other machines between its interfaces. 1653Note that even without this option, the kernel will 1654still forward some packets (such as source routed packets) \(em removing 1655.Em GATEWAY 1656and 1657.Em IPFORWARDING 1658is insufficient to stop all routing through a bastion host on a 1659firewall \(em source routing is controlled independently. 1660Note that IP forwarding may be turned on and off independently of the 1661setting of the 1662.Em IPFORWARDING 1663option through the use of the 1664.Em net.inet.ip.forwarding 1665sysctl variable. 1666If 1667.Em net.inet.ip.forwarding 1668is 1, IP forwarding is on. 1669See 1670.Xr sysctl 8 1671and 1672.Xr sysctl 3 1673for details. 1674.It Cd options IFA_STATS 1675Tells the kernel to maintain per-address statistics on bytes sent 1676and received over (currently) Internet and AppleTalk addresses. 1677.\"This can be a fairly expensive operation, so you probably want to 1678.\"keep this disabled. 1679The option is not recommended as it degrades system stability. 1680.It Cd options IFQ_MAXLEN=value 1681Increases the allowed size of the network interface packet queues. 1682The default queue size is 50 packets, and you do not normally need 1683to increase it. 1684.It Cd options IPSELSRC 1685Includes support for source-address selection policies. 1686See 1687.Xr in_getifa 9 . 1688.It Cd options MROUTING 1689Includes support for IP multicast routers. 1690You certainly want 1691.Em INET 1692with this. 1693Multicast routing is controlled by the 1694.Xr mrouted 8 1695daemon. 1696See also option 1697.Cd PIM . 1698.It Cd options PIM 1699Includes support for Protocol Independent Multicast (PIM) routing. 1700You need 1701.Em MROUTING 1702and 1703.Em INET 1704with this. 1705Software using this can be found e.g. in 1706.Pa pkgsrc/net/xorp . 1707.It Cd options INET 1708Includes support for the TCP/IP protocol stack. 1709You almost certainly want this. 1710See 1711.Xr inet 4 1712for details. 1713.It Cd options INET6 1714Includes support for the IPv6 protocol stack. 1715See 1716.Xr inet6 4 1717for details. 1718Unlike 1719.Em INET , 1720.Em INET6 1721enables multicast routing code as well. 1722This option requires 1723.Em INET 1724at this moment, but it should not. 1725.It Cd options ND6_DEBUG 1726The option sets the default value of net.inet6.icmp6.nd6_debug to 1, 1727for debugging IPv6 neighbor discovery protocol handling. 1728See 1729.Xr sysctl 3 1730for details. 1731.It Cd options IPSEC 1732Includes support for the IPsec protocol, using the implementation derived from 1733.Ox , 1734relying on 1735.Xr opencrypto 9 1736to carry out cryptographic operations. 1737See 1738.Xr ipsec 4 1739for details. 1740.It Cd options IPSEC_DEBUG 1741Enables debugging code in IPsec stack. 1742See 1743.Xr ipsec 4 1744for details. 1745The 1746.Cd IPSEC 1747option includes support for IPsec Network Address Translator traversal 1748(NAT-T), as described in RFCs 3947 and 3948. 1749This feature might be patent-encumbered in some countries. 1750.It Cd options ALTQ 1751Enabled ALTQ (Alternate Queueing). 1752For simple rate-limiting, use 1753.Xr tbrconfig 8 1754to set up the interface transmission rate. 1755To use queueing disciplines, their appropriate kernel options should also 1756be defined (documented below). 1757Queueing disciplines are managed by 1758.Xr altqd 8 . 1759See 1760.Xr altq 9 1761for details. 1762.It Cd options ALTQ_HFSC 1763Include support for ALTQ-implemented HFSC (Hierarchical Fair Service Curve) 1764module. 1765HFSC supports both link-sharing and guaranteed real-time services. 1766HFSC employs a service curve based QoS model, and its unique feature 1767is an ability to decouple delay and bandwidth allocation. 1768Requires 1769.Em ALTQ_RED 1770to use the RED queueing discipline on HFSC classes, or 1771.Em ALTQ_RIO 1772to use the RIO queueing discipline on HFSC classes. 1773This option assumes 1774.Em ALTQ . 1775.It Cd options ALTQ_PRIQ 1776Include support for ALTQ-implemented PRIQ (Priority Queueing). 1777PRIQ implements a simple priority-based queueing discipline. 1778A higher priority class is always served first. 1779Requires 1780.Em ALTQ_RED 1781to use the RED queueing discipline on HFSC classes, or 1782.Em ALTQ_RIO 1783to use the RIO queueing discipline on HFSC classes. 1784This option assumes 1785.Em ALTQ . 1786.It Cd options ALTQ_WFQ 1787Include support for ALTQ-implemented WFQ (Weighted Fair Queueing). 1788WFQ implements a weighted-round robin scheduler for a set of queues. 1789A weight can be assigned to each queue to give a different proportion 1790of the link capacity. 1791A hash function is used to map a flow to one of a set of queues. 1792This option assumes 1793.Em ALTQ . 1794.It Cd options ALTQ_FIFOQ 1795Include support for ALTQ-implemented FIFO queueing. 1796FIFOQ is a simple drop-tail FIFO (First In, First Out) queueing discipline. 1797This option assumes 1798.Em ALTQ . 1799.It Cd options ALTQ_RIO 1800Include support for ALTQ-implemented RIO (RED with In/Out). 1801The original RIO has 2 sets of RED parameters; one for in-profile 1802packets and the other for out-of-profile packets. 1803At the ingress of the network, profile meters tag packets as IN or 1804OUT based on contracted profiles for customers. 1805Inside the network, IN packets receive preferential treatment by 1806the RIO dropper. 1807ALTQ/RIO has 3 drop precedence levels defined for the Assured Forwarding 1808PHB of DiffServ (RFC 2597). 1809This option assumes 1810.Em ALTQ . 1811.It Cd options ALTQ_BLUE 1812Include support for ALTQ-implemented Blue buffer management. 1813Blue is another active buffer management mechanism. 1814This option assumes 1815.Em ALTQ . 1816.It Cd options ALTQ_FLOWVALVE 1817Include support for ALTQ-implemented Flowvalve. 1818Flowvalve is a simple implementation of a RED penalty box that identifies 1819and punishes misbehaving flows. 1820This option requires 1821.Em ALTQ_RED 1822and assumes 1823.Em ALTQ . 1824.It Cd options ALTQ_CDNR 1825Include support for ALTQ-implemented CDNR (diffserv traffic conditioner) 1826packet marking/manipulation. 1827Traffic conditioners are components to meter, mark, or drop incoming 1828packets according to some rules. 1829As opposed to queueing disciplines, traffic conditioners handle incoming 1830packets at an input interface. 1831This option assumes 1832.Em ALTQ . 1833.It Cd options ALTQ_NOPCC 1834Disables use of processor cycle counter to measure time in ALTQ. 1835This option should be defined for a non-Pentium i386 CPU which does not 1836have TSC, SMP (per-CPU counters are not in sync), or power management 1837which affects processor cycle counter. 1838This option assumes 1839.Em ALTQ . 1840.It Cd options ALTQ_IPSEC 1841Include support for IPsec in IPv4 ALTQ. 1842This option assumes 1843.Em ALTQ . 1844.It Cd options ALTQ_JOBS 1845Include support for ALTQ-implemented JoBS (Joint Buffer Management 1846and Scheduling). 1847This option assumes 1848.Em ALTQ . 1849.It Cd options ALTQ_AFMAP 1850Include support for an undocumented ALTQ feature that is used to map an IP 1851flow to an ATM VC (Virtual Circuit). 1852This option assumes 1853.Em ALTQ . 1854.It Cd options ALTQ_LOCALQ 1855Include support for ALTQ-implemented local queues. 1856Its practical use is undefined. 1857Assumes 1858.Em ALTQ . 1859.It Cd options SUBNETSARELOCAL 1860Sets default value for net.inet.ip.subnetsarelocal variable, which 1861controls whether non-directly-connected subnets of connected networks 1862are considered "local" for purposes of choosing the MSS for a TCP 1863connection. 1864This is mostly present for historic reasons and completely irrelevant if 1865you enable Path MTU discovery. 1866.It Cd options HOSTZEROBROADCAST 1867Sets default value for net.inet.ip.hostzerobroadcast variable, which 1868controls whether the zeroth host address of each connected subnet is 1869also considered a broadcast address. 1870Default value is "1", for compatibility with old systems; if this is 1871set to zero on all hosts on a subnet, you should be able to fit an extra 1872host per subnet on the 1873".0" address. 1874.It Cd options MCLSHIFT=value 1875This option is the base-2 logarithm of the size of mbuf clusters. 1876The 1877.Bx 1878networking stack keeps network packets in a linked 1879list, or chain, of kernel buffer objects called mbufs. 1880The system provides larger mbuf clusters as an optimization for 1881large packets, instead of using long chains for large packets. 1882The mbuf cluster size, 1883or 1884.Em MCLBYTES , 1885must be a power of two, and is computed as two raised to the power 1886.Em MCLSHIFT . 1887On systems with Ethernet network adapters, 1888.Em MCLSHIFT 1889is often set to 11, giving 2048-byte mbuf clusters, large enough to 1890hold a 1500-byte Ethernet frame in a single cluster. 1891Systems with network interfaces supporting larger frame sizes like 1892ATM, FDDI, or HIPPI may perform better with 1893.Em MCLSHIFT 1894set to 12 or 13, giving mbuf cluster sizes of 4096 and 8192 bytes, 1895respectively. 1896.It Cd options NETATALK 1897Include support for the AppleTalk protocol stack. 1898The kernel provides provision for the 1899.Em Datagram Delivery Protocol 1900(DDP), providing SOCK_DGRAM support and AppleTalk routing. 1901This stack is used by the 1902.Em NETATALK 1903package, which adds support for AppleTalk server services via user 1904libraries and applications. 1905.It Cd options BLUETOOTH 1906Include support for the Bluetooth protocol stack. 1907See 1908.Xr bluetooth 4 1909for details. 1910.It Cd options IPNOPRIVPORTS 1911Normally, only root can bind a socket descriptor to a so-called 1912.Dq privileged 1913TCP port, that is, a port number in the range 0-1023. 1914This option eliminates those checks from the kernel. 1915This can be useful if there is a desire to allow daemons without 1916privileges to bind those ports, e.g., on firewalls. 1917The security tradeoffs in doing this are subtle. 1918This option should only be used by experts. 1919.It Cd options TCP_DEBUG 1920Record the last 1921.Em TCP_NDEBUG 1922TCP packets with SO_DEBUG set, and decode to the console if 1923.Em tcpconsdebug 1924is set. 1925.It Cd options TCP_NDEBUG 1926Number of packets to record for 1927.Em TCP_DEBUG . 1928Defaults to 100. 1929.It Cd options TCP_SENDSPACE=value 1930.It Cd options TCP_RECVSPACE=value 1931These options set the max TCP window size to other sizes than the default. 1932The TCP window sizes can be altered via 1933.Xr sysctl 8 1934as well. 1935.It Cd options TCP_INIT_WIN=value 1936This option sets the initial TCP window size for non-local connections, 1937which is used when the transmission starts. 1938The default size is 1, but if the machine should act more aggressively, 1939the initial size can be set to some other value. 1940The initial TCP window size can be set via 1941.Xr sysctl 8 1942as well. 1943.It Cd options TCP_SIGNATURE 1944Enable MD5 TCP signatures (RFC 2385) to protect BGP sessions. 1945.It Cd options IPFILTER_LOG 1946This option, in conjunction with 1947.Em pseudo-device ipfilter , 1948enables logging of IP packets using IP-Filter. 1949.It Cd options IPFILTER_LOOKUP 1950This option enables the 1951IP-Filter 1952.Xr ippool 8 1953functionality to be enabled. 1954.It Cd options IPFILTER_COMPAT 1955This option enables older IP-Filter binaries to work. 1956.It Cd options IPFILTER_DEFAULT_BLOCK 1957This option sets the default policy of IP-Filter. 1958If it is set, IP-Filter will block packets by default. 1959.It Cd options BRIDGE_IPF 1960This option causes 1961.Em bridge 1962devices to use the IP and/or IPv6 filtering hooks, forming 1963a link-layer filter that uses protocol-layer rules. 1964This option assumes the presence of 1965.Em pseudo-device ipfilter . 1966.It Cd options MBUFTRACE 1967This option can help track down mbuf leaks. 1968When enabled, mbufs are tagged with the devices and protocols using them. 1969This can significantly decrease network performance, particularly 1970on MP systems. 1971This additional information can be viewed with 1972.Xr netstat 1 : 1973.Dl Ic netstat Fl mssv 1974Not all devices or protocols support this option. 1975.El 1976.Ss Sysctl Related Options 1977.Bl -ohang 1978.It Cd options SYSCTL_DISALLOW_CREATE 1979Disallows the creation or deletion of nodes from the sysctl tree, as 1980well as the assigning of descriptions to nodes that lack them, by any 1981process. 1982These operations are still available to kernel sub-systems, including 1983loadable kernel modules. 1984.It Cd options SYSCTL_DISALLOW_KWRITE 1985Prevents processes from adding nodes to the sysctl tree that make 1986existing kernel memory areas writable. 1987Sections of kernel memory can still be read and new nodes that own 1988their own data may still be writable. 1989.It Cd options SYSCTL_DEBUG_SETUP 1990Causes the SYSCTL_SETUP routines to print a brief message when they 1991are invoked. 1992This is merely meant as an aid in determining the order in which 1993sections of the tree are created. 1994.It Cd options SYSCTL_DEBUG_CREATE 1995Prints a message each time 1996.Fn sysctl_create , 1997the function that adds nodes to the tree, is called. 1998.It Cd options SYSCTL_INCLUDE_DESCR 1999Causes the kernel to include short, human readable descriptions for 2000nodes in the sysctl tree. 2001The descriptions can be retrieved programmatically (see 2002.Xr sysctl 3 ) , 2003or by the sysctl binary itself (see 2004.Xr sysctl 8 ) . 2005The descriptions are meant to give an indication of the purpose and/or 2006effects of a given node's value, not replace the documentation for the 2007given subsystem as a whole. 2008.El 2009.Ss System V IPC Options 2010.Bl -ohang 2011.It Cd options SYSVMSG 2012Includes support for 2013.At V 2014style message queues. 2015See 2016.Xr msgctl 2 , 2017.Xr msgget 2 , 2018.Xr msgrcv 2 , 2019.Xr msgsnd 2 . 2020.It Cd options SYSVSEM 2021Includes support for 2022.At V 2023style semaphores. 2024See 2025.Xr semctl 2 , 2026.Xr semget 2 , 2027.Xr semop 2 . 2028.It Cd options SEMMNI=value 2029Sets the number of 2030.At V 2031style semaphore identifiers. 2032The GENERIC config file for your port will have the default. 2033.It Cd options SEMMNS=value 2034Sets the number of 2035.At V 2036style semaphores in the system. 2037The GENERIC config file for your port will have the default. 2038.It Cd options SEMUME=value 2039Sets the maximum number of undo entries per process for 2040.At V 2041style semaphores. 2042The GENERIC config file for your port will have the default. 2043.It Cd options SEMMNU=value 2044Sets the number of undo structures in the system for 2045.At V 2046style semaphores. 2047The GENERIC config file for your port will have the default. 2048.It Cd options SYSVSHM 2049Includes support for 2050.At V 2051style shared memory. 2052See 2053.Xr shmat 2 , 2054.Xr shmctl 2 , 2055.Xr shmdt 2 , 2056.Xr shmget 2 . 2057.It Cd options SHMMAXPGS=value 2058Sets the maximum number of 2059.At V 2060style shared memory pages that are available through the 2061.Xr shmget 2 2062system call. 2063Default value is 1024 on most ports. 2064See 2065.Pa /usr/include/machine/vmparam.h 2066for the default. 2067.El 2068.Ss VM Related Options 2069.Bl -ohang 2070.It Cd options NMBCLUSTERS=value 2071The number of mbuf clusters the kernel supports. 2072Mbuf clusters are MCLBYTES in size (usually 2k). 2073This is used to compute the size of the kernel VM map 2074.Em mb_map , 2075which maps mbuf clusters. 2076Default on most ports is 1024 (2048 with 2077.Dq options GATEWAY 2078). 2079See 2080.Pa /usr/include/machine/param.h 2081for exact default information. 2082Increase this value if you get 2083.Dq mclpool limit reached 2084messages. 2085.It Cd options NKMEMPAGES=value 2086.It Cd options NKMEMPAGES_MIN=value 2087.It Cd options NKMEMPAGES_MAX=value 2088Size of kernel VM map 2089.Em kmem_map , 2090in PAGE_SIZE-sized chunks (the VM page size; this value may be read 2091from the 2092.Xr sysctl 8 2093variable 2094.Em hw.pagesize 2095). 2096This VM map is used to map the kernel malloc arena. 2097The kernel attempts to auto-size this map based on the amount of 2098physical memory in the system. 2099Platform-specific code may place bounds on this computed size, 2100which may be viewed with the 2101.Xr sysctl 8 2102variable 2103.Em vm.nkmempages . 2104See 2105.Pa /usr/include/machine/param.h 2106for the default upper and lower bounds. 2107The related options 2108.Sq NKMEMPAGES_MIN 2109and 2110.Sq NKMEMPAGES_MAX 2111allow the bounds to be overridden in the kernel configuration file. 2112These options are provided in the event the computed value is 2113insufficient resulting in an 2114.Dq out of space in kmem_map 2115panic. 2116.It Cd options SB_MAX=value 2117Sets the max size in bytes that a socket buffer is allowed to occupy. 2118The default is 256k, but sometimes it needs to be increased, for example 2119when using large TCP windows. 2120This option can be changed via 2121.Xr sysctl 8 2122as well. 2123.It Cd options SOMAXKVA=value 2124Sets the maximum size of kernel virtual memory that the socket buffers 2125are allowed to use. 2126The default is 16MB, but in situations where for example large TCP 2127windows are used this value must also be increased. 2128This option can be changed via 2129.Xr sysctl 8 2130as well. 2131.It Cd options BUFCACHE=value 2132Size of the buffer cache as a percentage of total available RAM. 2133Ignored if BUFPAGES is also specified. 2134.It Cd options NBUF=value 2135Sets the number of buffer headers available, i.e., the number of 2136open files that may have a buffer cache entry. 2137Each buffer header 2138requires MAXBSIZE (machine dependent, but usually 65536) bytes. 2139The default value is machine dependent, but is usually equal to the 2140value of BUFPAGES. 2141.It Cd options BUFPAGES=value 2142These options set the number of pages available for the buffer cache. 2143Their default value is a machine dependent value, often calculated as 2144between 5% and 10% of total available RAM. 2145.It Cd options MAXTSIZ=bytes 2146Sets the maximum size limit of a process' text segment. 2147See 2148.Pa /usr/include/machine/vmparam.h 2149for the port-specific default. 2150.It Cd options DFLDSIZ=bytes 2151Sets the default size limit of a process' data segment, the value that 2152will be returned as the soft limit for 2153.Dv RLIMIT_DATA 2154(as returned by 2155.Xr getrlimit 2 ) . 2156See 2157.Pa /usr/include/machine/vmparam.h 2158for the port-specific default. 2159.It Cd options MAXDSIZ=bytes 2160Sets the maximum size limit of a process' data segment, the value that 2161will be returned as the hard limit for 2162.Dv RLIMIT_DATA 2163(as returned by 2164.Xr getrlimit 2 ) . 2165See 2166.Pa /usr/include/machine/vmparam.h 2167for the port-specific default. 2168.It Cd options DFLSSIZ=bytes 2169Sets the default size limit of a process' stack segment, the value that 2170will be returned as the soft limit for 2171.Dv RLIMIT_STACK 2172(as returned by 2173.Xr getrlimit 2 ) . 2174See 2175.Pa /usr/include/machine/vmparam.h 2176for the port-specific default. 2177.It Cd options MAXSSIZ=bytes 2178Sets the maximum size limit of a process' stack segment, the value that 2179will be returned as the hard limit for 2180.Dv RLIMIT_STACK 2181(as returned by 2182.Xr getrlimit 2 ) . 2183See 2184.Pa /usr/include/machine/vmparam.h 2185for the port-specific default. 2186.It Cd options DUMP_ON_PANIC=integer 2187Defaults to one. 2188If set to zero, the kernel will not dump to the dump device when 2189it panics, though dumps can still be forced via 2190.Xr ddb 4 2191with the 2192.Dq sync 2193command. 2194Note that this sets the value of the 2195.Em kern.dump_on_panic 2196.Xr sysctl 3 2197variable which may be changed at run time \(em see 2198.Xr sysctl 8 2199for details. 2200.It Cd options USE_TOPDOWN_VM 2201User space memory allocations (as made by 2202.Xr mmap 2 ) 2203will be arranged in a 2204.Dq top down 2205fashion instead of the traditional 2206.Dq upwards from MAXDSIZ \&+ vm_daddr 2207method. 2208This includes the placement of 2209.Xr ld.so 1 . 2210Arranging memory in this manner allows either (or both of) the heap or 2211.Xr mmap 2 2212allocated space to grow larger than traditionally possible. 2213This option is not available on all ports, but is instead expected to be 2214offered on a port-by-port basis, after which some ports will commit to 2215using it by default. 2216See the files 2217.Pa /usr/include/uvm/uvm_param.h 2218for some implementation details, and 2219.Pa /usr/include/machine/vmparam.h 2220for port specific details including availability. 2221.It Cd options VMSWAP 2222Enable paging device/file support. 2223This option is on by default. 2224.It Cd options PDPOLICY_CLOCKPRO 2225Use CLOCK-Pro, an alternative page replace policy. 2226.El 2227.Ss Security Options 2228.Bl -ohang 2229.It Cd options INSECURE 2230Initializes the kernel security level with \-1 instead of 0. 2231This means that the system always starts in secure level \-1 mode, even when 2232running multiuser, unless the securelevel variable is set to value > \-1 in 2233.Pa /etc/rc.conf . 2234In this case the kernel security level will be raised to that value when the 2235.Pa /etc/rc.d/securelevel 2236script is run during system startup. 2237See the manual page for 2238.Xr init 8 2239for details on the implications of this. 2240The kernel secure level may manipulated by the superuser by altering the 2241.Em kern.securelevel 2242.Xr sysctl 3 2243variable (the secure level may only be lowered by a call from process ID 1, 2244i.e., 2245.Xr init 8 ) . 2246See also 2247.Xr secmodel_securelevel 9 , 2248.Xr sysctl 8 2249and 2250.Xr sysctl 3 . 2251.It Cd options VERIFIED_EXEC_FP_SHA256 2252Enables support for SHA256 hashes in Veriexec. 2253.It Cd options VERIFIED_EXEC_FP_SHA384 2254Enables support for SHA384 hashes in Veriexec. 2255.It Cd options VERIFIED_EXEC_FP_SHA512 2256Enables support for SHA512 hashes in Veriexec. 2257.It Cd options PAX_MPROTECT=value 2258Enables PaX MPROTECT, 2259.Xr mprotect 2 2260restrictions from the PaX project. 2261.Pp 2262The 2263.Ar value 2264is the default value for the 2265.Em global 2266knob, see 2267.Xr sysctl 3 . 2268If 0, PaX MPROTECT will be enabled only if explicitly set on programs 2269using 2270.Xr paxctl 8 . 2271If 1, PaX MPROTECT will be enabled for all programs. 2272Programs can be exempted using 2273.Xr paxctl 8 . 2274.Pp 2275See 2276.Xr security 7 2277for more details. 2278.It Cd options PAX_SEGVGUARD=value 2279Enables PaX Segvguard. 2280Requires 2281.Cd options FILEASSOC . 2282.Pp 2283The 2284.Ar value 2285is the default value for the 2286.Em global 2287knob, see 2288.Xr sysctl 3 . 2289If 0, PaX Segvguard will be enabled only if explicitly set on programs 2290using 2291.Xr paxctl 8 . 2292If 1, PaX Segvguard will be enabled to all programs, and exemption can 2293be done using 2294.Xr paxctl 8 . 2295.Pp 2296See 2297.Xr security 7 2298for more details. 2299.It Cd options PAX_ASLR=value 2300Enables PaX ASLR. 2301.Pp 2302The 2303.Ar value 2304is the default value for the 2305.Em global 2306knob, see 2307.Xr sysctl 3 . 2308If 0, PaX ASLR will be enabled only if explicitly set on programs 2309using 2310.Xr paxctl 8 . 2311If 1, PaX ASLR will be enabled to all programs, and exemption can 2312be done using 2313.Xr paxctl 8 . 2314.Pp 2315See 2316.Xr security 7 2317for more details. 2318.It Cd options USER_VA0_DISABLE_DEFAULT=value 2319Sets the initial value of the flag which controls whether user programs 2320can map virtual address 0. 2321The flag can be changed at runtime by 2322.Xr sysctl 3 . 2323.It Cd options KASAN 2324Enables Kernel Address Sanitizer. 2325.Em NOTE : 2326not available on all architectures. 2327.It Cd options KASLR 2328Enables Kernel ASLR. 2329This randomizes the location of the kernel image in memory. 2330.Em NOTE : 2331not available on all architectures. 2332.It Cd options SVS 2333Enables Separate Virtual Space. 2334On architectures that are designed to function with a shared address 2335space, this option explicitly isolates the kernel and user spaces. 2336.Em NOTE : 2337not available on all architectures. 2338.El 2339.Ss amiga-specific Options 2340.Bl -ohang 2341.It Cd options BB060STUPIDROM 2342When the bootloader (which passes AmigaOS ROM information) claims 2343we have a 68060 CPU without FPU, go look into the Processor 2344Configuration Register (PCR) to find out. 2345You need this with Amiga ROMs up to (at least) V40.xxx (OS3.1), 2346when you boot via the bootblocks and don't have a DraCo. 2347.It Cd options IOBZCLOCK=frequency 2348The IOBlix boards come with two different serial master clocks: older ones 2349use 24 MHz, newer ones use 22.1184 MHz. 2350The driver normally assumes the latter. 2351If your board uses 24 MHz, you can recompile your kernel with 2352options IOBZCLOCK=24000000 2353or patch the kernel variable iobzclock to the same value. 2354.It Cd options LIMITMEM=value 2355If there, limit the part of the first memory bank used by 2356.Nx 2357to value megabytes. 2358Default is unlimited. 2359.It Cd options P5PPC68KBOARD 2360Add special support for Phase5 mixed 68k+PPC boards. 2361Currently, this only affects rebooting from 2362.Nx 2363and is only needed on 68040+PPC, not on 236468060+PPC; without this, affected machines will hang after 2365.Nx 2366has shut 2367down and will only restart after a keyboard reset or a power cycle. 2368.El 2369.Ss atari-specific Options 2370.Bl -ohang 2371.It Cd options DISKLABEL_AHDI 2372Include support for AHDI (native Atari) disklabels. 2373.It Cd options DISKLABEL_NBDA 2374Include support for 2375.Nx Ns /atari 2376labels. 2377If you don't set this option, it will be set automatically. 2378.Nx Ns /atari 2379will not work without it. 2380.It Cd options FALCON_SCSI 2381Include support for the 5380-SCSI configuration as found on the Falcon. 2382.It Cd options RELOC_KERNEL 2383If set, the kernel will relocate itself to TT-RAM, if possible. 2384This will give you a slightly faster system. 2385.Em Beware 2386that on some TT030 systems, 2387the system will frequently dump with MMU-faults with this option enabled. 2388.It Cd options SERCONSOLE 2389Allow the modem1-port to act as the system-console. 2390A carrier should be active on modem1 during system boot to active 2391the console functionality. 2392.It Cd options TT_SCSI 2393Include support for the 5380-SCSI configuration as found on the TT030 2394and Hades. 2395.El 2396.Ss i386-specific Options 2397.Bl -ohang 2398.It Cd options CPURESET_DELAY=value 2399Specifies the time (in millisecond) to wait before doing a hardware reset 2400in the last phase of a reboot. 2401This gives the user a chance to see error messages from the shutdown 2402operations (like NFS unmounts, buffer cache flush, etc ...). 2403Setting this to 0 will disable the delay. 2404Default is 2 seconds. 2405.It Cd options USER_LDT 2406Include i386-specific system calls for modifying the local descriptor table, 2407used by Windows emulators. 2408.It Cd options PAE 2409Enable PAE (Physical Address Extension) mode. 2410PAE permits up to 36 bits physical addressing (64GB of physical 2411memory), and turns physical addresses to 64 bits entities in the 2412memory management subsystem. 2413Userland virtual address space remains at 32 bits (4GB). 2414PAE mode is required to enable the NX/XD (No-eXecute/eXecute Disable) 2415bit for pages, which allows marking certain ones as not being executable. 2416Any attempt to execute code from such a page will raise an exception. 2417.It Cd options REALBASEMEM=integer 2418Overrides the base memory size passed in from the boot block. 2419(Value given in kilobytes.) 2420Use this option only if the boot block reports the size incorrectly. 2421(Note that some BIOSes put the extended BIOS 2422data area at the top of base memory, and therefore report a smaller 2423base memory size to prevent programs overwriting it. 2424This is correct behavior, and you should not use the 2425.Em REALBASEMEM 2426option to access this memory). 2427.It Cd options SPECTRE_V2_GCC_MITIGATION=1 2428Enable GCC-specific Spectre variant 2 mitigations. 2429For 32-bit kernels this means these options: 2430.Bd -literal -offset indent 2431-mindirect-branch=thunk -mindirect-branch-register 2432.Ed 2433.Pp 2434For 64-bit kernels this means these options: 2435.Bd -literal -offset indent 2436-mindirect-branch=thunk-inline -mindirect-branch-register 2437.Ed 2438.It Cd options REALEXTMEM=integer 2439Overrides the extended memory size passed in from the boot block. 2440(Value given in kilobytes. 2441Extended memory does not include the first megabyte.) 2442Use this option only if the boot block reports the size incorrectly. 2443.It Cd options CYRIX_CACHE_WORKS 2444Relevant only to the Cyrix 486DLC CPU. 2445This option is used to turn on the cache in hold-flush mode. 2446It is not turned on by default because it is known to have problems in 2447certain motherboard implementations. 2448.It Cd options CYRIX_CACHE_REALLY_WORKS 2449Relevant only to the Cyrix 486DLC CPU. 2450This option is used to turn on the cache in write-back mode. 2451It is not turned on by default because it is known to have problems in 2452certain motherboard implementations. 2453In order for this option to take effect, option 2454.Em CYRIX_CACHE_WORKS 2455must also be specified. 2456.It Cd options PCIBIOS 2457Enable support for initializing the PCI bus using information from 2458the BIOS. 2459See 2460.Xr pcibios 4 2461for details. 2462.It Cd options MTRR 2463Include support for accessing MTRR registers from user-space. 2464See 2465.Xr i386_get_mtrr 2 . 2466.It Cd options BEEP_ONHALT 2467Make the system speaker emit several beeps when it is completely safe to 2468power down the computer after a 2469.Xr halt 8 2470command. 2471Requires 2472.Xr sysbeep 4 2473support. 2474.It Cd options BEEP_ONHALT_COUNT=times 2475Number of times to beep the speaker when 2476.Cd options BEEP_ONHALT 2477is enabled. 2478Defaults to 3. 2479.It Cd options BEEP_ONHALT_PITCH=hz 2480The tone frequency used when 2481.Cd options BEEP_ONHALT 2482option, in hertz. 2483Defaults to 1500. 2484.It Cd options BEEP_ONHALT_PERIOD=msecs 2485The duration of each beep when 2486.Cd options BEEP_ONHALT 2487is enabled, in milliseconds. 2488Defaults to 250. 2489.It Cd options MULTIBOOT 2490Makes the kernel Multiboot-compliant, allowing it to be booted through 2491a Multiboot-compliant boot manager such as GRUB. 2492See 2493.Xr multiboot 8 2494for more information. 2495.It Cd options SPLASHSCREEN 2496Display a splash screen during boot. 2497.El 2498.Ss isa-specific Options 2499Options specific to 2500.Xr isa 4 2501busses. 2502.Bl -ohang 2503.It Cd options PCIC_ISA_ALLOC_IOBASE=address, PCIC_ISA_ALLOC_IOSIZE=size 2504Control the section of IO bus space used for PCMCIA bus space mapping. 2505Ideally the probed defaults are satisfactory, however in practice 2506that is not always the case. 2507See 2508.Xr pcmcia 4 2509for details. 2510.It Cd options PCIC_ISA_INTR_ALLOC_MASK=mask 2511Controls the allowable interrupts that may be used for PCMCIA 2512devices. 2513This mask is a logical-or of power-of-2s of allowable interrupts: 2514.Bd -literal -offset 04n 2515.Em "IRQ Val IRQ Val IRQ Val IRQ Val" 2516 0 0x0001 4 0x0010 8 0x0100 12 0x1000 2517 1 0x0002 5 0x0020 9 0x0200 13 0x2000 2518 2 0x0004 6 0x0040 10 0x0400 14 0x4000 2519 3 0x0008 7 0x0080 11 0x0800 15 0x8000 2520.Ed 2521.It Cd options PCKBC_CNATTACH_SELFTEST 2522Perform a self test of the keyboard controller before attaching it as a 2523console. 2524This might be necessary on machines where we boot on cold iron, and 2525pckbc refuses to talk until we request a self test. 2526Currently only the netwinder port uses it. 2527.It Cd options PCKBD_CNATTACH_MAY_FAIL 2528If this option is set the PS/2 keyboard will not be used as the console 2529if it cannot be found during boot. 2530This allows other keyboards, like USB, to be the console keyboard. 2531.It Cd options PCKBD_LAYOUT=layout 2532Sets the default keyboard layout, see 2533.Xr pckbd 4 . 2534.El 2535.Ss m68k-specific Options 2536.Bl -ohang 2537.It Cd options FPU_EMULATE 2538Include support for MC68881/MC68882 emulator. 2539.It Cd options FPSP 2540Include support for 68040 floating point. 2541.It Cd options M68020,M68030,M68040,M68060 2542Include support for a specific CPU, 2543at least one (the one you are using) should be specified. 2544.It Cd options M060SP 2545Include software support for 68060. 2546This provides emulation of unimplemented 2547integer instructions as well as emulation of unimplemented floating point 2548instructions and data types and software support for floating point traps. 2549.El 2550.Ss powerpc-specific Options (OEA Only) 2551.Bl -ohang 2552.It Cd options PMAP_MEMLIMIT=value 2553Limit the amount of memory seen by the kernel to 2554.Ar value 2555bytes. 2556.It Cd options PTEGCOUNT=value 2557Specify the size of the page table as 2558.Ar value 2559PTE groups. 2560Normally, one PTEG is allocated per physical page frame. 2561.El 2562.Ss sparc-specific Options 2563.Bl -ohang 2564.It Cd options AUDIO_DEBUG 2565Enable simple event debugging of the logging of the 2566.Xr audio 4 2567device. 2568.It Cd options BLINK 2569Enable blinking of LED. 2570Blink rate is full cycle every N seconds for 2571N < then current load average. 2572See 2573.Xr getloadavg 3 . 2574.\" .It Cd options COLORFONT_CACHE 2575.\" What does this do? 2576.It Cd options COUNT_SW_LEFTOVERS 2577Count how many times the sw SCSI device has left 3, 2, 1 and 0 in the 2578sw_3_leftover, sw_2_leftover, sw_1_leftover, and sw_0_leftover 2579variables accessible from 2580.Xr ddb 4 . 2581See 2582.Xr sw 4 . 2583.It Cd options DEBUG_ALIGN 2584Adds debugging messages calls when user-requested alignment fault 2585handling happens. 2586.It Cd options DEBUG_EMUL 2587Adds debugging messages calls for emulated floating point and 2588alignment fixing operations. 2589.It Cd options EXTREME_DEBUG 2590Adds debugging functions callable from 2591.Xr ddb 4 . 2592The debug_pagetables, test_region and print_fe_map 2593functions print information about page tables for the SUN4M 2594platforms only. 2595.It Cd options EXTREME_EXTREME_DEBUG 2596Adds extra info to 2597.Em options EXTREME_DEBUG . 2598.It Cd options FPU_CONTEXT 2599Make 2600.Em options COMPAT_SVR4 2601getcontext and setcontext include floating point registers. 2602.It Cd options MAGMA_DEBUG 2603Adds debugging messages to the 2604.Xr magma 4 2605device. 2606.It Cd options RASTERCONS_FULLSCREEN 2607Use the entire screen for the console. 2608.It Cd options RASTERCONS_SMALLFONT 2609Use the Fixed font on the console, instead of the normal font. 2610.It Cd options SUN4 2611Support sun4 class machines. 2612.It Cd options SUN4C 2613Support sun4c class machines. 2614.It Cd options SUN4M 2615Support sun4m class machines. 2616.It Cd options SUN4_MMU3L 2617.\" XXX ??? 2618Enable support for sun4 3-level MMU machines. 2619.It Cd options V9 2620Enable SPARC V9 assembler in 2621.Xr ddb 4 . 2622.El 2623.Ss sparc64-specific Options 2624.Bl -ohang 2625.It Cd options AUDIO_DEBUG 2626Enable simple event debugging of the logging of the 2627.Xr audio 4 2628device. 2629.It Cd options BLINK 2630Enable blinking of LED. 2631Blink rate is full cycle every N seconds for 2632N < then current load average. 2633See 2634.Xr getloadavg 3 . 2635.El 2636.Ss x68k-specific Options 2637.Bl -ohang 2638.It Cd options EXTENDED_MEMORY 2639Include support for extended memory, e.g., TS-6BE16 and 060turbo on-board. 2640.It Cd options JUPITER 2641Include support for Jupiter-X MPU accelerator 2642.It Cd options ZSCONSOLE,ZSCN_SPEED=value 2643Use the built-in serial port as the system-console. 2644Speed is specified in bps, defaults to 9600. 2645.It Cd options ITE_KERNEL_ATTR=value 2646Set the kernel message attribute for ITE. 2647Value, an integer, is a logical or of the following values: 2648.Bl -tag -width 4n -compact -offset indent 2649.It 1 2650color inversed 2651.It 2 2652underlined 2653.It 4 2654bolded 2655.El 2656.El 2657.Ss x86-specific Options 2658.Bl -ohang 2659.It Cd options NO_PCI_MSI_MSIX 2660Disable support for MSI/MSIX in the kernel. 2661See 2662.Xr pci_msi 9 2663for details of MSI/MSIX support 2664.It Cd options NO_PREEMPTION 2665Disables 2666.Xr kpreempt 9 2667support in the kernel. 2668.El 2669.\" The following requests should be uncommented and used where appropriate. 2670.\" .Sh FILES 2671.\" .Sh EXAMPLES 2672.Sh SEE ALSO 2673.Xr config 1 , 2674.Xr gcc 1 , 2675.Xr gdb 1 , 2676.Xr ktrace 1 , 2677.Xr quota 1 , 2678.Xr vndcompress 1 , 2679.Xr gettimeofday 2 , 2680.Xr i386_get_mtrr 2 , 2681.Xr i386_iopl 2 , 2682.Xr msgctl 2 , 2683.Xr msgget 2 , 2684.Xr msgrcv 2 , 2685.Xr msgsnd 2 , 2686.Xr ntp_adjtime 2 , 2687.Xr ntp_gettime 2 , 2688.Xr reboot 2 , 2689.Xr semctl 2 , 2690.Xr semget 2 , 2691.Xr semop 2 , 2692.Xr shmat 2 , 2693.Xr shmctl 2 , 2694.Xr shmdt 2 , 2695.Xr shmget 2 , 2696.Xr sysctl 3 , 2697.Xr apm 4 , 2698.Xr ddb 4 , 2699.Xr inet 4 , 2700.Xr md 4 , 2701.Xr pcibios 4 , 2702.Xr pcmcia 4 , 2703.Xr ppp 4 , 2704.Xr userconf 4 , 2705.Xr vnd 4 , 2706.Xr wscons 4 , 2707.Xr config 5 , 2708.Xr edquota 8 , 2709.Xr init 8 , 2710.Xr mdsetimage 8 , 2711.Xr mount_cd9660 8 , 2712.Xr mount_fdesc 8 , 2713.Xr mount_kernfs 8 , 2714.Xr mount_lfs 8 , 2715.Xr mount_mfs 8 , 2716.Xr mount_msdos 8 , 2717.Xr mount_nfs 8 , 2718.Xr mount_ntfs 8 , 2719.Xr mount_null 8 , 2720.Xr mount_portal 8 , 2721.Xr mount_procfs 8 , 2722.Xr mount_udf 8 , 2723.Xr mount_umap 8 , 2724.Xr mount_union 8 , 2725.Xr mrouted 8 , 2726.Xr newfs_lfs 8 , 2727.Xr ntpd 8 , 2728.Xr quotaon 8 , 2729.Xr rpc.rquotad 8 , 2730.Xr sysctl 8 , 2731.Xr in_getifa 9 , 2732.Xr kernhist 9 2733.Sh HISTORY 2734The 2735.Nm 2736man page first appeared in 2737.Nx 1.3 . 2738