1.\" $NetBSD: options.4,v 1.411 2012/01/13 16:05:16 cegger Exp $ 2.\" 3.\" Copyright (c) 1996 4.\" Perry E. Metzger. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgment: 16.\" This product includes software developed for the NetBSD Project 17.\" by Perry E. Metzger. 18.\" 4. The name of the author may not be used to endorse or promote products 19.\" derived from this software without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31.\" 32.\" 33.Dd January 13, 2012 34.Dt OPTIONS 4 35.Os 36.Sh NAME 37.Nm options 38.Nd Miscellaneous kernel configuration options 39.Sh SYNOPSIS 40.Cd cinclude ... 41.Cd config ... 42.Cd [no] file-system ... 43.Cd ident ... 44.Cd include ... 45.Cd [no] makeoptions ... 46.Cd maxusers ... 47.Cd [no] options ... 48.Cd [no] pseudo-device ... 49.Sh DESCRIPTION 50This manual page describes a number of miscellaneous kernel 51configuration options that may be specified in a kernel config 52file. 53See 54.Xr config 1 55and 56.Xr config 5 57for information on how to configure and build kernels. 58.Pp 59The 60.Ar no 61form removes a previously specified option. 62.Ss Keywords 63The following keywords are recognized in a kernel configuration file: 64.Bl -ohang 65.It Sy cinclude Qq Ar filename 66Conditionally includes another kernel configuration file whose name is 67.Ar filename , 68which may be double-quoted and may be an explicit path or relative to 69the kernel source directory. 70Failure to open the named file is ignored. 71.It Sy config Ar exec_name No root on Ar rootdev Oo type Ar fstype Oc \ 72Oo dumps on Ar dumpdev Oc 73Defines a configuration whose kernel executable is named 74.Ar exec_name , 75normally 76.Dq netbsd , 77with its root file system of type 78.Ar fstype 79on the device 80.Ar rootdev , 81and optionally specifying the location of kernel core dumps on the device 82.Ar dumpdev . 83.Ar dev 84or 85.Ar dumpdev 86and 87.Ar fstype 88may be specified as 89.Dq \&? , 90which is a wild card. 91The root 92.Ar fstype 93and 94.Ar dumpdev 95are optional and assumed to be wild carded if they are not specified. 96.It Ar device_instance No at Ar attachment \ 97Oo Ar locators value Oo ... Oc Oc Oo flags Ar value Oc 98Define an instance of the device driver 99.Ar device_instance 100that attaches to the bus or device named 101.Ar attachment . 102An 103.Ar attachment 104may require additional information on where the device can be found, such 105as an address, channel, function, offset, and/or slot, referred to as 106.Ar locators , 107whose 108.Ar value 109often may be a wild card, 110.Dq \&? . 111Some device drivers have one or more 112.Ar flags 113that can be adjusted to affect the way they operate. 114.It Sy file-system Ar fs_name Op , Ar fs_name Op ... 115Include support for the file-system 116.Ar fs_name . 117.It Sy ident Qq Ar string 118Sets the kernel identification string to 119.Ar string . 120.It Sy include Qq Ar filename 121Functions the same as 122.Ar cinclude , 123except failure to open 124.Ar filename 125produces a fatal error. 126.It Sy options Ar option_name Op , Ar option_name=value Op ... 127Specifies (or sets) the option, or comma-separated list of options, 128.Ar option_name . 129Some options expect to be assigned a value, which may be an integer, 130a double-quoted word, a bare word, or an empty string 131.Pq Qq . 132Note that those are eventually handled by the C compiler, so the rules 133of that language apply. 134.Pp 135.Em Note : 136Options that are not defined by device definition files are passed to 137the compile process as 138.Fl D 139flags to the C compiler. 140.It Sy makeoptions Ar name=value 141Defines a 142.Xr make 1 143macro 144.Ar name 145with the value 146.Ar value 147in the kernel Makefile. 148.It Sy maxusers Ar integer 149Set the maxusers variable in the kernel. 150.It Sy no Ar keyword Ar name Op Ar arguments Op ... 151For the 152.Xr config 1 153.Ar keywords 154file-system, makeoptions, options, and pseudo-device, 155.Ar no 156removes the file-system, makeoption, options, or pseudo-device, 157.Ar name . 158This is useful when a kernel configuration file includes another which 159has undesired options. 160.Pp 161For example, a local configuration file that wanted the kitchen sink, but 162not COMPAT_09 or bridging, might be: 163.Bd -literal -offset indent 164include "arch/i386/conf/GENERIC" 165no options COMPAT_09 166no pseudo-device bridge 167.Ed 168.It Sy pseudo-device Ar name Op Ar N 169Includes support for the pseudo-device 170.Ar name . 171Some pseudo-devices can have multiple or 172.Ar N 173instances. 174.El 175.Ss Compatibility Options 176.Bl -ohang 177.It Cd options COMPAT_09 178Enable binary compatibility with 179.Nx 0.9 . 180This enables support for 18116-bit user, group, and process IDs (following revisions support 18232-bit identifiers). 183It also allows the use of the deprecated 184.Xr getdomainname 3 , 185.Xr setdomainname 3 , 186and 187.Xr uname 3 188syscalls. 189This option also allows using numeric file system identifiers rather 190than strings. 191Post 192.Nx 0.9 193versions use string identifiers. 194.It Cd options COMPAT_10 195Enable binary compatibility with 196.Nx 1.0 . 197This option allows the use of the file system name of 198.Dq ufs 199as an alias for 200.Dq ffs . 201The name 202.Dq ffs 203should be used post 1.0 in 204.Pa /etc/fstab 205and other files. 206It also adds old syscalls for the 207.At V 208shared memory interface. 209This was changed post 1.0 to work on 64-bit architectures. 210This option also enables 211.Dq sgtty 212compatibility, without which programs using the old interface produce 213an 214.Dq inappropriate ioctl 215error, and 216.Pa /dev/io 217only works when this option is set in the kernel, 218see 219.Xr io 4 220on ports that support it. 221.It Cd options COMPAT_11 222Enable binary compatibility with 223.Nx 1.1 . 224This allows binaries running on the i386 port to gain direct access to 225the io ports by opening 226.Pa /dev/io 227read/write. 228This functionality was replaced by 229.Xr i386_iopl 2 230post 1.1. 231On the 232.Tn Atari 233port, the location of the disk label was moved after 1.1. 234When the 235.Em COMPAT_11 236option is set, the kernel will read (pre) 1.1 style disk labels as a 237last resort. 238When a disk label is re-written, the old style label will be replaced 239with a post 1.1 style label. 240This also enables the 241.Em EXEC_ELF_NOTELESS 242option. 243.It Cd options COMPAT_12 244Enable binary compatibility with 245.Nx 1.2 . 246This allows the use of old syscalls for 247.Fn reboot 248and 249.Fn swapon . 250The syscall numbers were changed post 1.2 to add functionality to the 251.Xr reboot 2 252syscall, and the new 253.Xr swapctl 2 254interface was introduced. 255This also enables the 256.Em EXEC_ELF_NOTELESS 257option. 258.It Cd options COMPAT_13 259Enable binary compatibility with 260.Nx 1.3 . 261This allows the use of old syscalls for 262.Fn sigaltstack , 263and also enables the old 264.Xr swapctl 2 265command 266.Dv SWAP_STATS 267(now called 268.Dv SWAP_OSTATS ) , 269which does not include the 270.Fa se_path 271member of 272.Va struct swapent . 273.It Cd options COMPAT_14 274Enable binary compatibility with 275.Nx 1.4 . 276This allows some old 277.Xr ioctl 2 278on 279.Xr wscons 4 280to be performed, and allows the 281.Dv NFSSVC_BIOD 282mode of the 283.Xr nfssvc 2 284system call to be used for compatibility with the deprecated nfsiod program. 285.It Cd options COMPAT_15 286Enable binary compatibility with 287.Nx 1.5 . 288Since there were no API changes from 289.Nx 1.5 290and 291.Nx 1.6 , 292this option does nothing. 293.It Cd options COMPAT_16 294Enable binary compatibility with 295.Nx 1.6 . 296This allows the use of old signal trampoline code which has been deprecated 297with the addition of 298.Xr siginfo 2 . 299.It Cd options COMPAT_20 300Enable binary compatibility with 301.Nx 2.0 . 302This allows the use of old syscalls for 303.Fn statfs , 304.Fn fstatfs , 305.Fn getfsstat 306and 307.Fn fhstatfs , 308which have been deprecated with the addition of the 309.Xr statvfs 2 , 310.Xr fstatvfs 2 , 311.Xr getvfsstat 2 312and 313.Xr fhstatvfs 2 314system calls. 315.It Cd options COMPAT_30 316Enable binary compatibility with 317.Nx 3.0 . 318See 319.Xr compat_30 8 320for details about the changes made after the 321.Nx 3.0 322release. 323.It Cd options COMPAT_43 324Enables compatibility with 325.Bx 4.3 . 326This adds an old syscall for 327.Xr lseek 2 . 328It also adds the ioctls for 329.Dv TIOCGETP 330and 331.Dv TIOCSETP . 332The return values for 333.Xr getpid 2 , 334.Xr getgid 2 , 335and 336.Xr getuid 2 337syscalls are modified as well, to return the parent's PID and 338UID as well as the current process's. 339It also enables the deprecated 340.Dv NTTYDISC 341terminal line discipline. 342It also provides backwards compatibility with 343.Dq old 344SIOC[GS]IF{ADDR,DSTADDR,BRDADDR,NETMASK} interface ioctls, including 345binary compatibility with code written before the introduction of the 346sa_len field in sockaddrs. 347It also enables 348support for some older pre 349.Bx 4.4 350socket calls. 351.It Cd options COMPAT_BSDPTY 352This option is currently on by default and enables the pty multiplexer 353.Xr ptm 4 354and 355.Xr ptmx 4 356to find and use ptys named 357.Pa /dev/ptyXX 358(master) and 359.Pa /dev/ttyXX 360(slave). 361Eventually this option will become optional as ptyfs based pseudo-ttys become 362the default, see 363.Xr mount_ptyfs 8 . 364.It Cd options COMPAT_SVR4 365On those architectures that support it, this enables binary 366compatibility with 367.At V.4 368applications built for the same architecture. 369This currently includes the i386, m68k, and sparc ports. 370.It Cd options COMPAT_LINUX 371On those architectures that support it, this enables binary 372compatibility with Linux ELF and 373.Xr a.out 5 374applications built for the same architecture. 375This currently includes the alpha, arm, i386, m68k, mips, powerpc and 376x86_64 ports. 377.It Cd options COMPAT_LINUX32 378On those 64 bit architectures that support it, this enables binary 379compatibility with 32 bit Linux binaries. 380For now this is limited to running i386 ELF Linux binaries on amd64. 381.It Cd options COMPAT_SUNOS 382On those architectures that support it, this enables binary 383compatibility with 384.Tn SunOS 4.1 385applications built for the same architecture. 386This currently includes the sparc, sparc64 and most or all m68k ports. 387Note that the sparc64 requires the 388.Em COMPAT_NETBSD32 389option for 64-bit kernels, in addition to this option. 390.It Cd options COMPAT_ULTRIX 391On those architectures that support it, this enables binary 392compatibility with 393.Tn ULTRIX 394applications built for the same architecture. 395This currently is limited to the pmax. 396The functionality of this option is unknown. 397.It Cd options COMPAT_FREEBSD 398On those architectures that support it, this enables binary 399compatibility with 400.Fx 401applications built for the same architecture. 402At the moment this is limited to the i386 port. 403.It Cd options COMPAT_IBCS2 404On those architectures that support it, this enables binary 405compatibility with iBCS2 or SVR3 applications built for the same architecture. 406This is currently limited to the i386 and vax ports. 407.It Cd options COMPAT_OSF1 408On those architectures that support it, this enables binary 409compatibility with 410.Tn Digital 411.Ux 412.Po 413formerly 414.Tn OSF/1 415.Pc 416applications built for the same architecture. 417This is currently limited to the alpha port. 418.It Cd options COMPAT_NOMID 419Enable compatibility with 420.Xr a.out 5 421executables that lack a machine ID. 422This includes 423.Nx 0.8 Ns 's 424ZMAGIC format, and 386BSD and BSDI's 425QMAGIC, NMAGIC, and OMAGIC 426.Xr a.out 5 427formats. 428.It Cd options COMPAT_NETBSD32 429On those architectures that support it, this enables binary 430compatibility with 32-bit applications built for the same architecture. 431This is currently limited to the amd64 and sparc64 ports, and only 432applicable for 64-bit kernels. 433.It Cd options COMPAT_SVR4_32 434On those architectures that support it, this enables binary 435compatibility with 32-bit SVR4 applications built for the same architecture. 436This is currently limited to the sparc64 port, and only applicable for 43764-bit kernels. 438.It Cd options COMPAT_AOUT_M68K 439On m68k architectures which have switched to ELF, 440this enables binary compatibility with 441.Nx Ns Tn /m68k 442.Xr a.out 5 443executables on 444.Nx Ns Tn /m68k 445ELF kernels. 446This handles alignment incompatibility of m68k ABI between 447a.out and ELF which causes the structure padding differences. 448Currently only some system calls which use 449.Va struct stat 450are adjusted and some binaries which use 451.Xr sysctl 3 452to retrieve network details would not work properly. 453.It Cd options EXEC_ELF_NOTELESS 454Run unidentified ELF binaries as 455.Nx 456binaries. 457This might be needed for very old 458.Nx 459ELF binaries on some archs. 460These old binaries didn't contain an appropriate 461.Li .note.netbsd.ident 462section, and thus can't be identified by the kernel as 463.Nx 464binaries otherwise. 465Beware - if this option is on, the kernel would run 466.Em any 467unknown ELF binaries as if they were 468.Nx 469binaries. 470.It Cd options P1003_1B_SEMAPHORE 471Includes kernel support for the standard C library 472.Pq libc 473functions that implement semaphores as specified in 474.St -p1003.1-96 . 475.El 476.Ss Debugging Options 477.Bl -ohang 478.It Cd options DDB 479Compiles in a kernel debugger for diagnosing kernel problems. 480See 481.Xr ddb 4 482for details. 483.Em NOTE : 484not available on all architectures. 485.It Cd options DDB_FROMCONSOLE=integer 486If set to non-zero, DDB may be entered by sending a break on a serial 487console or by a special key sequence on a graphics console. 488A value of "0" ignores console breaks or key sequences. 489If not explicitly specified, the default value is "1". 490Note that this sets the value of the 491.Em ddb.fromconsole 492.Xr sysctl 3 493variable which may be changed at run time -- see 494.Xr sysctl 8 495for details. 496.It Cd options DDB_HISTORY_SIZE=integer 497If this is non-zero, enable history editing in the kernel debugger 498and set the size of the history to this value. 499.It Cd options DDB_ONPANIC 500The default if not specified is 501.Dq 1 502- just enter into DDB. 503If set to 504.Dq 2 505the kernel will 506attempt to print out a stack trace before entering into DDB. 507If set to 508.Dq 0 509the kernel will attempt to print out a stack trace 510and reboot the system. 511If set to 512.Dq -1 513then neither a stack trace is printed or DDB entered - 514it is as if DDB were not compiled into the kernel. 515Note that this sets the value of the 516.Em ddb.onpanic 517.Xr sysctl 3 518variable which may be changed at run time -- see 519.Xr sysctl 8 520for details. 521.It Cd options DDB_COMMANDONENTER=string 522This option specify commands which will be executed on each entry to DDB. 523This sets the default value of the 524.Em ddb.commandonenter 525.Xr sysctl 3 526variable which may be changed at run time. 527.It Cd options DDB_BREAK_CHAR=integer 528This option overrides using break to enter the kernel debugger 529on the serial console. 530The value given is the ASCII value to be used instead. 531This is currently only supported by the com driver. 532.It Cd options DDB_VERBOSE_HELP 533This option adds more verbose descriptions to the 534.Em help 535command. 536.It Cd options KGDB 537Compiles in a remote kernel debugger stub for diagnosing kernel problems 538using the 539.Dq remote target 540feature of gdb. 541See 542.Xr gdb 1 543for details. 544.Em NOTE : 545not available on all architectures. 546.It Cd options KGDB_DEV 547Device number 548.Po 549as a 550.Dv dev_t 551.Pc 552of kgdb device. 553.It Cd options KGDB_DEVADDR 554Memory address of kgdb device. 555.It Cd options KGDB_DEVMODE 556Permissions of kgdb device. 557.It Cd options KGDB_DEVNAME 558Device name of kgdb device. 559.It Cd options KGDB_DEVRATE 560Baud rate of kgdb device. 561.It Cd makeoptions DEBUG="-g" 562The 563.Fl g 564flag causes 565.Pa netbsd.gdb 566to be built in addition to 567.Pa netbsd . 568.Pa netbsd.gdb 569is useful for debugging kernel crash dumps with gdb. 570See 571.Xr gdb 1 572for details. 573This also turns on 574.Em options DEBUG 575(which see). 576.It Cd options DEBUG 577Turns on miscellaneous kernel debugging. 578Since options are turned into preprocessor defines (see above), 579.Em options DEBUG 580is equivalent to doing a 581.Em #define DEBUG 582throughout the kernel. 583Much of the kernel has 584.Em #ifdef DEBUG 585conditionalized debugging code. 586Note that many parts of the kernel (typically device drivers) include their own 587.Em #ifdef XXX_DEBUG 588conditionals instead. 589This option also turns on certain other options, 590which may decrease system performance. 591.It Cd options DIAGNOSTIC 592Adds code to the kernel that does internal consistency checks. 593This code will cause the kernel to panic if corruption of internal data 594structures is detected. 595These checks can decrease performance up to 15%. 596.It Cd options LOCKDEBUG 597Adds code to the kernel to detect incorrect use of locking primitives 598(mutex, rwlock, simplelock). 599This code will cause the kernel to check for dead lock conditions. 600It will also check for memory being freed to not contain initialised 601lock primitives. 602Functions for use in 603.Xr ddb 4 604to check lock chains etc. are also enabled. 605These checks are very expensive and can decrease performance on 606multi-processor machines by a factor of three. 607.It Cd options KSTACK_CHECK_MAGIC 608Check kernel stack usage and panic if stack overflow is detected. 609This check is performance sensitive because it scans stack on each context 610switch. 611.It Cd options KTRACE 612Add hooks for the system call tracing facility, which allows users to 613watch the system call invocation behavior of processes. 614See 615.Xr ktrace 1 616for details. 617.It Cd options MSGBUFSIZE=integer 618This option sets the size of the kernel message buffer. 619This buffer holds the kernel output of 620.Fn printf 621when not (yet) read by 622.Xr syslogd 8 . 623This is particularly useful when the system has crashed and you wish to lookup 624the kernel output from just before the crash. 625Also, since the autoconfig output becomes more and more verbose, 626it sometimes happens that the message buffer overflows before 627.Xr syslogd 8 628was able to read it. 629Note that not all systems are capable of obtaining a variable sized message 630buffer. 631There are also some systems on which memory contents are not preserved 632across reboots. 633.It Cd options MALLOCLOG 634Enables an event log for 635.Xr malloc 9 . 636Useful for tracking down 637.Dq Data modified on freelist 638and 639.Dq multiple free 640problems. 641.It Cd options MALLOCLOGSIZE=integer 642Defines the number of entries in the malloc log. 643Default is 100000 entries. 644.It Cd options UVMHIST 645Enables the UVM history logs, which create in-memory traces of 646various UVM activities. 647These logs can be displayed be calling 648.Fn uvmhist_dump 649or 650.Fn uvm_hist 651with appropriate arguments from DDB. 652See the kernel source file sys/uvm/uvm_stat.c for details. 653.It Cd options UVMHIST_PRINT 654Prints the UVM history logs on the system console as entries are added. 655Note that the output is 656.Em extremely 657voluminous, so this option is really only useful for debugging 658the very earliest parts of kernel initialization. 659.El 660.Ss File Systems 661.Bl -ohang 662.It Cd file-system FFS 663Includes code implementing the Berkeley Fast File System 664.Po Em FFS Pc . 665Most machines need this if they are not running diskless. 666.It Cd file-system EXT2FS 667Includes code implementing the Second Extended File System 668.Po Em ext2 Pc , 669revision 0 and revision 1 with the 670.Em filetype , 671.Em sparse_super 672and 673.Em large_file 674options. 675This is the most commonly used file system on the Linux operating system, 676and is provided here for compatibility. 677Some of the specific features of 678.Em ext2 679like the "behavior on errors" are not implemented. 680See 681.Xr mount_ext2fs 8 682for details. 683.It Cd file-system LFS 684.Bq Em EXPERIMENTAL 685Include the Log-structured File System 686.Po Em LFS Pc . 687See 688.Xr mount_lfs 8 689and 690.Xr newfs_lfs 8 691for details. 692.It Cd file-system MFS 693Include the Memory File System 694.Po Em MFS Pc . 695This file system stores files in swappable memory, and produces 696notable performance improvements when it is used as the file store 697for 698.Pa /tmp 699and similar file systems. 700See 701.Xr mount_mfs 8 702for details. 703.It Cd file-system NFS 704Include the client side of the Network File System 705.Pq Tn NFS 706remote file sharing protocol. 707Although the bulk of the code implementing 708.Tn NFS 709is kernel based, several user level daemons are needed for it to work. 710See 711.Xr mount_nfs 8 712for details. 713.It Cd file-system CD9660 714Includes code for the 715.Tn ISO 7169660 + Rock Ridge file system, which is the standard file system on many 717.Tn CD-ROM 718discs. 719Useful primarily if you have a 720.Tn CD-ROM 721drive. 722See 723.Xr mount_cd9660 8 724for details. 725.It Cd file-system MSDOSFS 726Includes the 727.Tn MS-DOS 728FAT file system, which is reportedly still used 729by unfortunate people who have not heard about 730.Nx . 731Also implements the 732.Tn Windows 95 733extensions to the same, which permit the use of longer, mixed case 734file names. 735See 736.Xr mount_msdos 8 737and 738.Xr fsck_msdos 8 739for details. 740.It Cd file-system NTFS 741.Bq Em EXPERIMENTAL 742Includes code for the 743.Tn Microsoft Windows NT 744file system. 745See 746.Xr mount_ntfs 8 747for details. 748.It Cd file-system FDESC 749Includes code for a file system, conventionally mounted on 750.Pa /dev/fd , 751which permits access to the per-process file descriptor space via 752special files in the file system. 753See 754.Xr mount_fdesc 8 755for details. 756Note that this facility is redundant, and thus unneeded on most 757.Nx 758systems, since the 759.Xr fd 4 760pseudo-device driver already provides identical functionality. 761On most 762.Nx 763systems, instances of 764.Xr fd 4 765are mknoded under 766.Pa /dev/fd/ 767and on 768.Pa /dev/stdin , 769.Pa /dev/stdout , 770and 771.Pa /dev/stderr . 772.It Cd file-system KERNFS 773Includes code which permits the mounting of a special file system 774(normally mounted on 775.Pa /kern ) 776in which files representing various kernel variables and parameters 777may be found. 778See 779.Xr mount_kernfs 8 780for details. 781.It Cd file-system NULLFS 782Includes code for a loopback file system. 783This permits portions of the file hierarchy to be re-mounted in other places. 784The code really exists to provide an example of a stackable file system layer. 785See 786.Xr mount_null 8 787for details. 788.It Cd file-system OVERLAY 789Includes code for a file system filter. 790This permits the overlay file system to intercept all access to an underlying 791file system. 792This file system is intended to serve as an example of a stacking file 793system which has a need to interpose itself between an underlying file 794system and all other access. 795See 796.Xr mount_overlay 8 797for details. 798.It Cd file-system PROCFS 799Includes code for a special file system (conventionally mounted on 800.Pa /proc ) 801in which the process space becomes visible in the file system. 802Among 803other things, the memory spaces of processes running on the system are 804visible as files, and signals may be sent to processes by writing to 805.Pa ctl 806files in the procfs namespace. 807See 808.Xr mount_procfs 8 809for details. 810.It Cd file-system UDF 811.Bq Em EXPERIMENTAL 812Includes code for the UDF file system commonly found on CD and DVD 813media but also more and more on USB sticks. 814Useful primarily if you have a CD or a DVD drive, be it a read-only 815or a rewritable device. 816Currently only supports read-access. 817See 818.Xr mount_udf 8 819for details. 820.It Cd file-system UMAPFS 821Includes a loopback file system in which user and group IDs may be 822remapped -- this can be useful when mounting alien file systems with 823different UIDs and GIDs than the local system. 824See 825.Xr mount_umap 8 826for details. 827.It Cd file-system UNION 828.Bq Em EXPERIMENTAL 829Includes code for the union file system, which permits directories to 830be mounted on top of each other in such a way that both file systems 831remain visible -- this permits tricks like allowing writing (and the 832deleting of files) on a read-only file system like a 833.Tn CD-ROM 834by mounting a local writable file system on top of the read-only file system. 835See 836.Xr mount_union 8 837for details. 838.It Cd file-system CODA 839.Bq Em EXPERIMENTAL 840Includes code for the Coda file system. 841Coda is a distributed file system like NFS and AFS. 842It is freely available, like NFS, but it functions much like AFS in being a 843.Dq stateful 844file system. 845Both Coda and AFS cache files on your local machine to improve performance. 846Then Coda goes a step further than AFS by letting you access the cached 847files when there is no available network, viz. disconnected laptops and 848network outages. 849In Coda, both the client and server are outside the kernel which makes 850them easier to experiment with. 851Coda is available for several UNIX and non-UNIX platforms. 852See http://www.coda.cs.cmu.edu for more details. 853.Em NOTE : 854You also need to enable the pseudo-device, vcoda, for the Coda 855file system to work. 856.It Cd file-system SMBFS 857.Bq Em EXPERIMENTAL 858Includes code for the SMB/CIFS file system. 859See 860.Xr mount_smbfs 8 861for details. 862.Em NOTE : 863You also need to enable the pseudo-device, nsmb, for the SMB 864file system to work. 865.It Cd file-system PTYFS 866.Bq Em EXPERIMENTAL 867Includes code for a special file system (normally mounted on 868.Pa /dev/pts ) 869in which pseudo-terminal slave devices become visible in the file system. 870See 871.Xr mount_ptyfs 8 872for details. 873.It Cd file-system TMPFS 874Includes code for the efficient memory file system, normally used over 875.Pa /tmp . 876See 877.Xr mount_tmpfs 8 878for details. 879.It Cd file-system PUFFS 880Includes kernel support for the pass-to-userspace framework file system. 881It can be used to implement file system functionality in userspace. 882See 883.Xr puffs 3 884for more details. 885This enables for example sshfs: 886.Xr mount_psshfs 8 . 887.El 888.Ss File System Options 889.Bl -ohang 890.It Cd options MAGICLINKS 891Enables the expansion of special strings 892.Po 893beginning with 894.Dq @ 895.Pc 896when traversing symbolic links. 897See 898.Xr symlink 7 899for a list of supported strings. 900Note that this option only controls the enabling of this feature 901by the kernel at boot-up. 902This feature can still be manipulated with the 903.Xr sysctl 8 904command regardless of the setting of this option. 905.It Cd options NFSSERVER 906Include the server side of the 907.Em NFS 908(Network File System) remote file sharing protocol. 909Although the bulk of the code implementing 910.Em NFS 911is kernel based, several user level daemons are needed for it to 912work. 913See 914.Xr mountd 8 915and 916.Xr nfsd 8 917for details. 918.It Cd options QUOTA 919Enables kernel support for file system quotas. 920See 921.Xr quotaon 8 , 922.Xr edquota 8 , 923and 924.Xr quota 1 925for details. 926Note that quotas only work on 927.Dq ffs 928file systems, although 929.Xr rpc.rquotad 8 930permits them to be accessed over 931.Em NFS . 932.It Cd options QUOTA2 933Enables kernel support for the new file system quotas format. 934See 935.Xr tunefs 8 , 936.Xr newfs 8 , 937.Xr mount_mfs 8 , 938.Xr edquota 8 , 939and 940.Xr quota 1 941for details. 942Note that quota2 is only supported by 943.Dq ffs 944and 945.Dq mfs 946file systems at this time. 947.It Cd options FFS_EI 948Enable ``Endian-Independent'' FFS support. 949This allows a system to mount an FFS file system created for another 950architecture, at a small performance cost for all FFS file systems. 951See also 952.Xr newfs 8 , 953.Xr fsck_ffs 8 , 954.Xr dumpfs 8 955for file system byte order status and manipulation. 956.It Cd options FFS_NO_SNAPSHOT 957Disable the 958.Dq file system snapshot 959support in FFS file systems. 960Maybe useful for install media kernels, small memory systems and 961embedded systems which don't require the snapshot support. 962.It Cd options UFS_EXTATTR 963Enable extended attribute support for UFS1 filesystems. 964.It Cd options WAPBL 965Enable 966.Dq Write Ahead Physical Block Logging file system journaling . 967This provides rapid file system consistency checking after a system outage. 968It also provides better general use performance over regular FFS. 969See also 970.Xr wapbl 4 . 971.It Cd options NVNODE=integer 972This option sets the size of the cache used by the name-to-inode translation 973routines, (a.k.a. the 974.Fn namei 975cache, though called by many other names in the kernel source). 976By default, this cache has 977.Dv NPROC 978(set as 20 + 16 * MAXUSERS) * (80 + NPROC / 8) entries. 979A reasonable way to derive a value of 980.Dv NVNODE , 981should you notice a large number of namei cache misses with a tool such as 982.Xr systat 1 , 983is to examine your system's current computed value with 984.Xr sysctl 8 , 985(which calls this parameter "kern.maxvnodes") and to increase this value 986until either the namei cache hit rate improves or it is determined that 987your system does not benefit substantially from an increase in the size of 988the namei cache. 989.It Cd options NAMECACHE_ENTER_REVERSE 990Causes the namei cache to always enter a reverse mapping (vnode -\*[Gt] name) 991as well as a normal one. 992Normally, this is already done for directory vnodes, to speed up the getcwd 993operation. 994This option will cause longer hash chains in the reverse cache, and thus 995slow down getcwd somewhat. 996However, it does make vnode -\*[Gt] path translations possible in some cases. 997For now, only useful if strict /proc/#/maps emulation for Linux binaries is 998required. 999.It Cd options EXT2FS_SYSTEM_FLAGS 1000This option changes the behavior of the APPEND and IMMUTABLE flags 1001for a file on an 1002.Em ext2 1003file system. 1004Without this option, the superuser or owner of the file can 1005set and clear them. 1006With this option, only the superuser can set them, and 1007they can't be cleared if the securelevel is greater than 0. 1008See also 1009.Xr chflags 1 1010and 1011.Xr secmodel_securelevel 9 . 1012.It Cd options NFS_BOOT_BOOTP 1013Enable use of the BOOTP protocol (RFCs 951 and 1048) to get configuration 1014information if NFS is used to mount the root file system. 1015See 1016.Xr diskless 8 1017for details. 1018.It Cd options NFS_BOOT_DHCP 1019Same as 1020.Dq NFS_BOOT_BOOTP , 1021but use the DHCP extensions to the 1022BOOTP protocol (RFC 1541). 1023.It Cd options NFS_BOOT_BOOTP_REQFILE 1024Specifies the string sent in the bp_file field of the BOOTP / DHCP 1025request packet. 1026.It Cd options NFS_BOOT_BOOTPARAM 1027Enable use of the BOOTPARAM protocol, consisting of RARP and 1028BOOTPARAM RPC, to get configuration information if NFS 1029is used to mount the root file system. 1030See 1031.Xr diskless 8 1032for details. 1033.It Cd options NFS_BOOT_RWSIZE=value 1034Set the initial NFS read and write sizes for diskless-boot requests. 1035The normal default is 8Kbytes. 1036This option provides a way to lower the value (e.g., to 1024 bytes) 1037as a workaround for buggy network interface cards or boot PROMs. 1038Once booted, the read and write request sizes can be increased by 1039remounting the file system. 1040See 1041.Xr mount_nfs 8 1042for details. 1043.It Cd options NFS_V2_ONLY 1044Reduce the size of the NFS client code by omitting code that's only required 1045for NFSv3 and NQNFS support, leaving only that code required to use NFSv2 1046servers. 1047.It Cd options UFS_DIRHASH 1048Increase lookup performance by maintaining in-core hash tables 1049for large directories. 1050.El 1051.Ss Buffer queue strategy options 1052The following options enable alternative buffer queue strategies. 1053.Bl -ohang 1054.It Cd options BUFQ_READPRIO 1055Enable experimental buffer queue strategy for disk I/O. 1056In the default strategy, outstanding disk requests are ordered by 1057sector number and sent to the disk, regardless of whether the 1058operation is a read or write; this option gives priority to issuing 1059read requests over write requests. 1060Although requests may therefore be issued out of sector-order, causing 1061more seeks and thus lower overall throughput, interactive system 1062responsiveness under heavy disk I/O load may be improved, as processes 1063blocking on disk reads are serviced sooner (file writes typically 1064don't cause applications to block). 1065The performance effect varies greatly depending on the hardware, drive 1066firmware, file system configuration, workload, and desired performance 1067trade-off. 1068Systems using drive write-cache (most modern IDE disks, by default) 1069are unlikely to benefit and may well suffer; such disks acknowledge 1070writes very quickly, and optimize them internally according to 1071physical layout. 1072Giving these disks as many requests to work with as possible (the 1073standard strategy) will typically produce the best results, especially 1074if the drive has a large cache; the drive will silently complete 1075writes from cache as it seeks for reads. 1076Disks that support a large number of concurrent tagged requests (SCSI 1077disks and many hardware RAID controllers) expose this internal 1078scheduling with tagged responses, and don't block for reads; such 1079disks may not see a noticeable difference with either strategy. 1080However, if IDE disks are run with write-cache disabled for safety, 1081writes are not acknowledged until actually completed, and only one 1082request can be outstanding; a large number of small writes in one 1083locality can keep the disk busy, starving reads elsewhere on the disk. 1084Such systems are likely to see the most benefit from this option. 1085Finally, the performance interaction of this option with ffs soft 1086dependencies can be subtle, as that mechanism can drastically alter 1087the workload for file system metadata writes. 1088.It Cd options BUFQ_PRIOCSCAN 1089Enable another buffer queue strategy for disk I/O, per-priority cyclical scan. 1090.It Cd options NEW_BUFQ_STRATEGY 1091Synonym of 1092.Em BUFQ_READPRIO . 1093.El 1094.Ss Miscellaneous Options 1095.Bl -ohang 1096.It Cd options CPU_UCODE 1097Support cpu microcode loading via 1098.Xr cpuctl 8 . 1099.It Cd options MEMORY_DISK_DYNAMIC 1100This option makes the 1101.Xr md 4 1102.Tn RAM 1103disk size dynamically sized. 1104It is incompatible with 1105.Xr mdsetimage 8 . 1106.It Cd options MEMORY_DISK_HOOKS 1107This option allows for some machine dependent functions to be called when 1108the 1109.Xr md 4 1110.Tn RAM 1111disk driver is configured. 1112This can result in automatically loading a 1113.Tn RAM 1114disk from floppy on open (among other things). 1115.It Cd options MEMORY_DISK_IS_ROOT 1116Forces the 1117.Xr md 4 1118.Tn RAM 1119disk to be the root device. 1120This can only be overridden when 1121the kernel is booted in the 'ask-for-root' mode. 1122.It Cd options MEMORY_DISK_ROOT_SIZE=integer 1123Allocates the given number of 512 byte blocks as memory for the 1124.Xr md 4 1125.Tn RAM 1126disk, to be populated with 1127.Xr mdsetimage 8 . 1128.It Cd options MEMORY_DISK_SERVER=0 1129Do not include the interface to a userland memory disk server process. 1130Per default, this option is set to 1, including the support code. 1131Useful for install media kernels. 1132.It Cd options MEMORY_DISK_RBFLAGS=value 1133This option sets the 1134.Xr reboot 2 1135flags used when booting with a memory disk as root file system. 1136Possible values include 1137.Dv RB_AUTOBOOT 1138(boot in the usual fashion - default value), and 1139.Dv RB_SINGLE 1140(boot in single-user mode). 1141.It Cd options MODULAR 1142Enables the framework for kernel modules (see 1143.Xr module 7 ) . 1144.It Cd options VND_COMPRESSION 1145Enables the 1146.Xr vnd 4 1147driver to also handle compressed images. 1148See 1149.Xr vndcompress 1 , 1150.Xr vnd 4 1151and 1152.Xr vnconfig 8 1153for more information. 1154.It Cd options SPLDEBUG 1155Help the kernel programmer find bugs related to the interrupt priority 1156level. 1157When 1158.Fn spllower 1159or 1160.Fn splraise 1161changes the current CPU's interrupt priority level to or from 1162.Dv IPL_HIGH , 1163record a backtrace. 1164Read 1165.Xr return_address 9 1166for caveats about collecting backtraces. 1167This feature is experimental, and it is only available on i386. 1168See 1169.Pa sys/kern/subr_spldebug.c . 1170.It Cd options TFTPROOT 1171Download the root memory disk through TFTP at root mount time. 1172This enables the use of a root 1173.Tn RAM 1174disk without requiring it to be embedded in the kernel using 1175.Xr mdsetimage 8 . 1176The 1177.Tn RAM 1178disk name is obtained using DHCP's filename parameter. 1179This option requires 1180.Em MEMORY_DISK_HOOKS , 1181.Em MEMORY_DISK_DYNAMIC , 1182and 1183.Em MEMORY_DISK_IS_ROOT . 1184It is incompatible with 1185.Em MEMORY_DISK_ROOT_SIZE . 1186.It Cd options MALLOC_NOINLINE 1187Time critical fixed size memory allocation is performed with 1188.Fn MALLOC 1189and 1190.Fn FREE . 1191Normally these expand to inline code, but with 1192.Em MALLOC_NOINLINE 1193these call the normal 1194.Fn malloc 1195and 1196.Fn free 1197functions. 1198Useful for install media kernels, small memory systems and embedded systems. 1199.It Cd options HZ=integer 1200On ports that support it, set the system clock frequency (see 1201.Xr hz 9 ) 1202to the supplied value. 1203Handle with care. 1204.It Cd options NTP 1205Turns on in-kernel precision timekeeping support used by software 1206implementing 1207.Em NTP 1208(Network Time Protocol, RFC 1305). 1209The 1210.Em NTP 1211option adds an in-kernel Phase-Locked Loop (PLL) for normal 1212.Em NTP 1213operation, and a Frequency-Locked Loop (FLL) for intermittently-connected 1214operation. 1215.Xr ntpd 8 1216will employ a user-level PLL when kernel support is unavailable, 1217but the in-kernel version has lower latency and more precision, and 1218so typically keeps much better time. 1219.Pp 1220The interface to the kernel 1221.Em NTP 1222support is provided by the 1223.Xr ntp_adjtime 2 1224and 1225.Xr ntp_gettime 2 1226system calls, which are intended for use by 1227.Xr ntpd 8 1228and are enabled by the option. 1229On systems with sub-microsecond resolution timers, or where (HZ / 100000) 1230is not an integer, the 1231.Em NTP 1232option also enables extended-precision arithmetic to keep track of 1233fractional clock ticks at NTP time-format precision. 1234.It Cd options PPS_SYNC 1235This option enables a kernel serial line discipline for receiving time 1236phase signals from an external reference clock such as a radio clock. 1237.Po 1238The 1239.Em NTP 1240option (which see) must be on if the 1241.Em PPS_SYNC 1242option is used 1243.Pc . 1244Some reference clocks generate a Pulse Per Second (PPS) signal in 1245phase with their time source. 1246The 1247.Em PPS 1248line discipline receives this signal on either the data leads 1249or the DCD control lead of a serial port. 1250.Pp 1251.Em NTP 1252uses the PPS signal to discipline the local clock oscillator to a high 1253degree of precision (typically less than 50 microseconds in time and 12540.1 ppm in accuracy). 1255.Em PPS 1256can also generate a serial output pulse when the system receives a PPS 1257interrupt. 1258This can be used to measure the system interrupt latency and thus calibrate 1259.Em NTP 1260to account for it. 1261Using 1262.Em PPS 1263usually requires a gadget box 1264to convert from 1265.Tn TTL 1266to 1267.Tn RS-232 1268signal levels. 1269The gadget box and PPS are described in more detail in the HTML documentation 1270for 1271.Xr ntpd 8 1272in 1273.Pa /usr/share/doc/html/ntp . 1274.Pp 1275.Nx 1276currently supports this option in 1277.Xr com 4 1278and 1279.Xr zsc 4 . 1280.It Cd options SETUIDSCRIPTS 1281Allows scripts with the setuid bit set to execute as the effective 1282user rather than the real user, just like binary executables. 1283.Pp 1284.Em NOTE : 1285Using this option will also enable 1286.Em options FDSCRIPTS 1287.It Cd options FDSCRIPTS 1288Allows execution of scripts with the execute bit set, but not the 1289read bit, by opening the file and passing the file descriptor to 1290the shell, rather than the filename. 1291.Pp 1292.Em NOTE : 1293Execute only (non-readable) scripts will have 1294.Va argv[0] 1295set to 1296.Pa /dev/fd/* . 1297What this option allows as far as security is 1298concerned, is the ability to safely ensure that the correct script 1299is run by the interpreter, as it is passed as an already open file. 1300.It Cd options PUCCN 1301Enables treating serial ports found on PCI boards 1302.Xr puc 4 1303as potential console devices. 1304The method for choosing such a console device is port dependent. 1305.It Cd options RTC_OFFSET=integer 1306The kernel (and typically the hardware battery backed-up clock on 1307those machines that have one) keeps time in 1308.Em UTC 1309(Universal Coordinated Time, once known as 1310.Em GMT , 1311or Greenwich Mean Time) 1312and not in the time of the local time zone. 1313The 1314.Em RTC_OFFSET 1315option is used on some ports (such as the i386) to tell the kernel 1316that the hardware clock is offset from 1317.Em UTC 1318by the specified number of minutes. 1319This is typically used when a machine boots several operating 1320systems and one of them wants the hardware clock to run in the 1321local time zone and not in 1322.Em UTC , 1323e.g. 1324.Em RTC_OFFSET=300 1325means 1326the hardware clock is set to US Eastern Time (300 minutes behind 1327.Em UTC ) , 1328and not 1329.Em UTC . 1330(Note: 1331.Em RTC_OFFSET 1332is used to initialize a kernel variable named 1333.Va rtc_offset 1334which is the source actually used to determine the clock offset, and 1335which may be accessed via the kern.rtc_offset sysctl variable. 1336See 1337.Xr sysctl 8 1338and 1339.Xr sysctl 3 1340for details. 1341Since the kernel clock is initialized from the hardware clock very 1342early in the boot process, it is not possible to meaningfully change 1343.Va rtc_offset 1344in system initialization scripts. 1345Changing this value currently may only be done at kernel compile 1346time or by patching the kernel and rebooting). 1347.Pp 1348.Em NOTE : 1349Unfortunately, in many cases where the hardware clock 1350is kept in local time, it is adjusted for Daylight Savings 1351Time; this means that attempting to use 1352.Em RTC_OFFSET 1353to let 1354.Nx 1355coexist with such an operating system, like Windows, 1356would necessitate changing 1357.Em RTC_OFFSET 1358twice a year. 1359As such, this solution is imperfect. 1360.It Cd options KMEMSTATS 1361The kernel memory allocator, 1362.Xr malloc 9 , 1363will keep statistics on its performance if this option is enabled. 1364Unfortunately, this option therefore essentially disables the 1365.Fn MALLOC 1366and 1367.Fn FREE 1368forms of the memory allocator, which are used to enhance the performance 1369of certain critical sections of code in the kernel. 1370This option therefore can lead to a significant decrease in the 1371performance of certain code in the kernel if enabled. 1372Examples of such code include the 1373.Fn namei 1374routine, the 1375.Xr ccd 4 1376driver, 1377and much of the networking code. 1378.It Cd options MAXUPRC=integer 1379Sets the soft 1380.Dv RLIMIT_NPROC 1381resource limit, which specifies the maximum number of simultaneous 1382processes a user is permitted to run, for process 0; 1383this value is inherited by its child processes. 1384It defaults to 1385.Em CHILD_MAX , 1386which is currently defined to be 160. 1387Setting 1388.Em MAXUPRC 1389to a value less than 1390.Em CHILD_MAX 1391is not permitted, as this would result in a violation of the semantics of 1392.St -p1003.1-90 . 1393.It Cd options NOFILE=integer 1394Sets the soft 1395.Dv RLIMIT_NOFILE 1396resource limit, which specifies the maximum number of open 1397file descriptors for each process; 1398this value is inherited by its child processes. 1399It defaults to 1400.Em OPEN_MAX , 1401which is currently defined to be 64. 1402.It Cd options MAXFILES=integer 1403Sets the default value of the 1404.Em kern.maxfiles 1405sysctl variable, which indicates the maximum number of files that may 1406be open in the system. 1407.It Cd options DEFCORENAME=string 1408Sets the default value of the 1409.Em kern.defcorename 1410sysctl variable, otherwise it is set to 1411.Nm %n.core . 1412See 1413.Xr sysctl 8 1414and 1415.Xr sysctl 3 1416for details. 1417.It Cd options RASOPS_CLIPPING 1418Enables clipping within the 1419.Nm rasops 1420raster-console output system. 1421.Em NOTE : 1422only available on architectures that use 1423.Nm rasops 1424for console output. 1425.It Cd options RASOPS_SMALL 1426Removes optimized character writing code from the 1427.Nm rasops 1428raster-console output system. 1429.Em NOTE : 1430only available on architectures that use 1431.Nm rasops 1432for console output. 1433.It Cd options INCLUDE_CONFIG_FILE 1434Embeds the kernel config file used to define the kernel in the kernel 1435binary itself. 1436The embedded data also includes any files directly included by the config 1437file itself, e.g. 1438.Pa GENERIC.local 1439or 1440.Pa std.$MACHINE . 1441The embedded config file can be extracted from the resulting kernel with 1442.Xr config 1 1443.Fl x , 1444or by the following command: 1445.Bd -literal -offset indent 1446strings netbsd | sed -n 's/^_CFG_//p' | unvis 1447.Ed 1448.It Cd options INCLUDE_JUST_CONFIG 1449Similar to the above option, but includes just the actual config file, 1450not any included files. 1451.It Cd options PIPE_SOCKETPAIR 1452Use slower, but smaller socketpair(2)-based pipe implementation instead 1453of default faster, but bigger one. 1454Primarily useful for installation kernels. 1455.It Cd options USERCONF 1456Compiles in the in-kernel device configuration manager. 1457See 1458.Xr userconf 4 1459for details. 1460.It Cd options PERFCTRS 1461Compiles in kernel support for CPU performance-monitoring counters. 1462See 1463.Xr pmc 1 1464for details. 1465.Em NOTE : 1466not available on all architectures. 1467.It Cd options SYSCALL_STATS 1468Count the number of times each system call number is called. 1469The values can be read through the sysctl interface and displayed using 1470.Xr systat 1 . 1471.Em NOTE : 1472not yet available on all architectures. 1473.It Cd options SYSCALL_TIMES 1474Count the time spent (using 1475.Fn cpu_counter32 ) 1476in each system call. 1477.Em NOTE : 1478Using this option will also enable 1479.Cd options SYSCALL_STATS . 1480.It Cd options SYSCALL_TIMES_HASCOUNTER 1481Force use of 1482.Fn cpu_counter32 1483even if 1484.Fn cpu_hascounter 1485reports false. 1486Useful for systems where the cycle counter doesn't run at a constant rate 1487(e.g. Soekris boxes). 1488.It Cd options XSERVER_DDB 1489A supplement to XSERVER that adds support for entering 1490.Xr ddb 4 1491while in 1492.Tn X11 . 1493.It Cd options FILEASSOC 1494Support for 1495.Xr fileassoc 9 . 1496.It Cd options FILEASSOC_NHOOKS=integer 1497Number of storage slots per file for 1498.Xr fileassoc 9 . 1499Default is 4. 1500.El 1501.Ss Networking Options 1502.Bl -ohang 1503.It Cd options GATEWAY 1504Enables 1505.Em IPFORWARDING 1506(which see) 1507and (on most ports) increases the size of 1508.Em NMBCLUSTERS 1509(which see). 1510In general, 1511.Em GATEWAY 1512is used to indicate that a system should act as a router, and 1513.Em IPFORWARDING 1514is not invoked directly. 1515(Note that 1516.Em GATEWAY 1517has no impact on protocols other than 1518.Tn IP , 1519such as 1520.Tn CLNP ) . 1521.Em GATEWAY 1522option also compiles IPv4 and IPv6 fast forwarding code into the kernel. 1523.It Cd options ICMPPRINTFS 1524The 1525.Em ICMPPRINTFS 1526option will enable debugging information to be printed about 1527the 1528.Xr icmp 4 1529protocol. 1530.It Cd options IPFORWARDING=value 1531If 1532.Em value 1533is 1 this enables IP routing behavior. 1534If 1535.Em value 1536is 0 (the default), it disables it. 1537The 1538.Em GATEWAY 1539option sets this to 1 automatically. 1540With this option enabled, the machine will forward IP datagrams destined 1541for other machines between its interfaces. 1542Note that even without this option, the kernel will 1543still forward some packets (such as source routed packets) -- removing 1544.Em GATEWAY 1545and 1546.Em IPFORWARDING 1547is insufficient to stop all routing through a bastion host on a 1548firewall -- source routing is controlled independently. 1549To turn off source routing, use 1550.Em options IPFORWSRCRT=0 1551(which see). 1552Note that IP forwarding may be turned on and off independently of the 1553setting of the 1554.Em IPFORWARDING 1555option through the use of the 1556.Em net.inet.ip.forwarding 1557sysctl variable. 1558If 1559.Em net.inet.ip.forwarding 1560is 1, IP forwarding is on. 1561See 1562.Xr sysctl 8 1563and 1564.Xr sysctl 3 1565for details. 1566.It Cd options IPFORWSRCRT=value 1567If 1568.Em value 1569is set to zero, source routing of IP datagrams is turned off. 1570If 1571.Em value 1572is set to one (the default) or the option is absent, source routed IP 1573datagrams are forwarded by the machine. 1574Note that source routing of IP packets may be turned on and off 1575independently of the setting of the 1576.Em IPFORWSRCRT 1577option through the use of the 1578.Em net.inet.ip.forwsrcrt 1579sysctl variable. 1580If 1581.Em net.inet.ip.forwsrcrt 1582is 1, forwarding of source routed IP datagrams is on. 1583See 1584.Xr sysctl 8 1585and 1586.Xr sysctl 3 1587for details. 1588.It Cd options IFA_STATS 1589Tells the kernel to maintain per-address statistics on bytes sent 1590and received over (currently) Internet and AppleTalk addresses. 1591.\"This can be a fairly expensive operation, so you probably want to 1592.\"keep this disabled. 1593The option is not recommended as it degrades system stability. 1594.It Cd options IFQ_MAXLEN=value 1595Increases the allowed size of the network interface packet queues. 1596The default queue size is 50 packets, and you do not normally need 1597to increase it. 1598.It Cd options IPSELSRC 1599Includes support for source-address selection policies. 1600See 1601.Xr in_getifa 9 . 1602.It Cd options MROUTING 1603Includes support for IP multicast routers. 1604You certainly want 1605.Em INET 1606with this. 1607Multicast routing is controlled by the 1608.Xr mrouted 8 1609daemon. 1610See also option 1611.Cd PIM . 1612.It Cd options PIM 1613Includes support for Protocol Independent Multicast (PIM) routing. 1614You need 1615.Em MROUTING 1616and 1617.Em INET 1618with this. 1619Software using this can be found e.g. in 1620.Pa pkgsrc/net/xorp . 1621.It Cd options INET 1622Includes support for the 1623.Tn TCP/IP 1624protocol stack. 1625You almost certainly want this. 1626See 1627.Xr inet 4 1628for details. 1629.It Cd options INET6 1630Includes support for the 1631.Tn IPv6 1632protocol stack. 1633See 1634.Xr inet6 4 1635for details. 1636Unlike 1637.Em INET , 1638.Em INET6 1639enables multicast routing code as well. 1640This option requires 1641.Em INET 1642at this moment, but it should not. 1643.It Cd options ND6_DEBUG 1644The option sets the default value of net.inet6.icmp6.nd6_debug to 1, 1645for debugging IPv6 neighbor discovery protocol handling. 1646See 1647.Xr sysctl 3 1648for details. 1649.It Cd options IPSEC 1650Includes support for the 1651.Tn IPsec 1652protocol, using the FAST_IPSEC implementation. 1653See 1654.Xr fast_ipsec 4 1655for details. 1656(This option is an alias for the 1657.Cd FAST_IPSEC 1658option described below.) 1659.It Cd options KAME_IPSEC 1660Includes support for the 1661.Tn IPsec 1662protocol, using the KAME implementation. 1663See 1664.Xr kame_ipsec 4 1665for details. 1666.It Cd options IPSEC_DEBUG 1667Enables debugging code in 1668.Tn IPsec 1669stack. 1670See 1671.Xr ipsec 4 1672for details. 1673.It Cd options IPSEC_ESP 1674Includes support for 1675.Tn IPsec 1676.Tn ESP 1677protocol, using the KAME implementation. 1678See 1679.Xr kame_ipsec 4 1680for details. 1681.It Cd options FAST_IPSEC 1682Includes support for the 1683.Tn IPsec 1684protocol, using the implementation derived from 1685.Ox , 1686relaying on 1687.Xr opencrypto 9 1688to carry out cryptographic operations. 1689See 1690.Xr fast_ipsec 4 1691for details. 1692.It Cd options IPSEC_NAT_T 1693Includes support for 1694.Tn IPsec 1695Network Address Translator traversal (NAT-T), as described in RFCs 3947 1696and 3948. 1697This feature might be patent-encumbered in some countries. 1698.It Cd options ALTQ 1699Enabled ALTQ (Alternate Queueing). 1700For simple rate-limiting, use 1701.Xr tbrconfig 8 1702to set up the interface transmission rate. 1703To use queueing disciplines, their appropriate kernel options should also 1704be defined (documented below). 1705Queueing disciplines are managed by 1706.Xr altqd 8 . 1707See 1708.Xr altq 9 1709for details. 1710.It Cd options ALTQ_HFSC 1711Include support for ALTQ-implemented HFSC (Hierarchical Fair Service Curve) 1712module. 1713HFSC supports both link-sharing and guaranteed real-time services. 1714HFSC employs a service curve based QoS model, and its unique feature 1715is an ability to decouple delay and bandwidth allocation. 1716Requires 1717.Em ALTQ_RED 1718to use the RED queueing discipline on HFSC classes, or 1719.Em ALTQ_RIO 1720to use the RIO queueing discipline on HFSC classes. 1721This option assumes 1722.Em ALTQ . 1723.It Cd options ALTQ_PRIQ 1724Include support for ALTQ-implemented PRIQ (Priority Queueing). 1725PRIQ implements a simple priority-based queueing discipline. 1726A higher priority class is always served first. 1727Requires 1728.Em ALTQ_RED 1729to use the RED queueing discipline on HFSC classes, or 1730.Em ALTQ_RIO 1731to use the RIO queueing discipline on HFSC classes. 1732This option assumes 1733.Em ALTQ . 1734.It Cd options ALTQ_WFQ 1735Include support for ALTQ-implemented WFQ (Weighted Fair Queueing). 1736WFQ implements a weighted-round robin scheduler for a set of queues. 1737A weight can be assigned to each queue to give a different proportion 1738of the link capacity. 1739A hash function is used to map a flow to one of a set of queues. 1740This option assumes 1741.Em ALTQ . 1742.It Cd options ALTQ_FIFOQ 1743Include support for ALTQ-implemented FIFO queueing. 1744FIFOQ is a simple drop-tail FIFO (First In, First Out) queueing discipline. 1745This option assumes 1746.Em ALTQ . 1747.It Cd options ALTQ_RIO 1748Include support for ALTQ-implemented RIO (RED with In/Out). 1749The original RIO has 2 sets of RED parameters; one for in-profile 1750packets and the other for out-of-profile packets. 1751At the ingress of the network, profile meters tag packets as IN or 1752OUT based on contracted profiles for customers. 1753Inside the network, IN packets receive preferential treatment by 1754the RIO dropper. 1755ALTQ/RIO has 3 drop precedence levels defined for the Assured Forwarding 1756PHB of DiffServ (RFC 2597). 1757This option assumes 1758.Em ALTQ . 1759.It Cd options ALTQ_BLUE 1760Include support for ALTQ-implemented Blue buffer management. 1761Blue is another active buffer management mechanism. 1762This option assumes 1763.Em ALTQ . 1764.It Cd options ALTQ_FLOWVALVE 1765Include support for ALTQ-implemented Flowvalve. 1766Flowvalve is a simple implementation of a RED penalty box that identifies 1767and punishes misbehaving flows. 1768This option requires 1769.Em ALTQ_RED 1770and assumes 1771.Em ALTQ . 1772.It Cd options ALTQ_CDNR 1773Include support for ALTQ-implemented CDNR (diffserv traffic conditioner) 1774packet marking/manipulation. 1775Traffic conditioners are components to meter, mark, or drop incoming 1776packets according to some rules. 1777As opposed to queueing disciplines, traffic conditioners handle incoming 1778packets at an input interface. 1779This option assumes 1780.Em ALTQ . 1781.It Cd options ALTQ_NOPCC 1782Disables use of processor cycle counter to measure time in ALTQ. 1783This option should be defined for a non-Pentium i386 CPU which does not 1784have TSC, SMP (per-CPU counters are not in sync), or power management 1785which affects processor cycle counter. 1786This option assumes 1787.Em ALTQ . 1788.It Cd options ALTQ_IPSEC 1789Include support for IPsec in IPv4 ALTQ. 1790This option assumes 1791.Em ALTQ . 1792.It Cd options ALTQ_JOBS 1793Include support for ALTQ-implemented JoBS (Joint Buffer Management 1794and Scheduling). 1795This option assumes 1796.Em ALTQ . 1797.It Cd options ALTQ_AFMAP 1798Include support for an undocumented ALTQ feature that is used to map an IP 1799flow to an ATM VC (Virtual Circuit). 1800This option assumes 1801.Em ALTQ . 1802.It Cd options ALTQ_LOCALQ 1803Include support for ALTQ-implemented local queues. 1804Its practical use is undefined. 1805Assumes 1806.Em ALTQ . 1807.It Cd options SUBNETSARELOCAL 1808Sets default value for net.inet.ip.subnetsarelocal variable, which 1809controls whether non-directly-connected subnets of connected networks 1810are considered "local" for purposes of choosing the MSS for a TCP 1811connection. 1812This is mostly present for historic reasons and completely irrelevant if 1813you enable Path MTU discovery. 1814.It Cd options HOSTZEROBROADCAST 1815Sets default value for net.inet.ip.hostzerobroadcast variable, which 1816controls whether the zeroth host address of each connected subnet is 1817also considered a broadcast address. 1818Default value is "1", for compatibility with old systems; if this is 1819set to zero on all hosts on a subnet, you should be able to fit an extra 1820host per subnet on the 1821".0" address. 1822.It Cd options MCLSHIFT=value 1823This option is the base-2 logarithm of the size of mbuf clusters. 1824The 1825.Bx 1826networking stack keeps network packets in a linked 1827list, or chain, of kernel buffer objects called mbufs. 1828The system provides larger mbuf clusters as an optimization for 1829large packets, instead of using long chains for large packets. 1830The mbuf cluster size, 1831or 1832.Em MCLBYTES , 1833must be a power of two, and is computed as two raised to the power 1834.Em MCLSHIFT . 1835On systems with Ethernet network adapters, 1836.Em MCLSHIFT 1837is often set to 11, giving 2048-byte mbuf clusters, large enough to 1838hold a 1500-byte 1839.Tn Ethernet 1840frame in a single cluster. 1841Systems with network interfaces supporting larger frame sizes like 1842.Tn ATM , 1843.Tn FDDI , 1844or 1845.Tn HIPPI 1846may perform better with 1847.Em MCLSHIFT 1848set to 12 or 13, giving mbuf cluster sizes of 4096 and 8192 bytes, 1849respectively. 1850.It Cd options ISO,TPIP 1851Include support for the ubiquitous 1852.Tn OSI 1853protocol stack. 1854See 1855.Xr iso 4 1856for details. 1857This option assumes 1858.Em INET . 1859.It Cd options EON 1860Include support for tunneling 1861.Tn OSI 1862protocols over 1863.Tn IP . 1864Known to be broken, or at least very fragile, and undocumented. 1865.It Cd options NETATALK 1866Include support for the 1867.Tn AppleTalk 1868protocol stack. 1869The kernel provides provision for the 1870.Em Datagram Delivery Protocol 1871(DDP), providing SOCK_DGRAM support and 1872.Tn AppleTalk 1873routing. 1874This stack is used by the 1875.Em NETATALK 1876package, which adds support for 1877.Tn AppleTalk 1878server services via user libraries and applications. 1879.It Cd options BLUETOOTH 1880Include support for the 1881.Tn Bluetooth 1882protocol stack. 1883See 1884.Xr bluetooth 4 1885for details. 1886.It Cd options IPNOPRIVPORTS 1887Normally, only root can bind a socket descriptor to a so-called 1888.Dq privileged 1889.Tn TCP 1890port, that is, a port number in the range 0-1023. 1891This option eliminates those checks from the kernel. 1892This can be useful if there is a desire to allow daemons without 1893privileges to bind those ports, e.g., on firewalls. 1894The security tradeoffs in doing this are subtle. 1895This option should only be used by experts. 1896.It Cd options TCP_COMPAT_42 1897.Tn TCP 1898bug compatibility with 1899.Bx 4.2 . 1900In 1901.Bx 4.2 , 1902.Tn TCP 1903sequence numbers were 32-bit signed values. 1904Modern implementations of TCP use unsigned values. 1905This option clamps the initial sequence number to start in 1906the range 2^31 rather than the full unsigned range of 2^32. 1907Also, under 1908.Bx 4.2 , 1909keepalive packets must contain at least one byte or else 1910the remote end would not respond. 1911.It Cd options TCP_DEBUG 1912Record the last 1913.Em TCP_NDEBUG 1914TCP packets with SO_DEBUG set, and decode to the console if 1915.Em tcpconsdebug 1916is set. 1917.It Cd options TCP_NDEBUG 1918Number of packets to record for 1919.Em TCP_DEBUG . 1920Defaults to 100. 1921.It Cd options TCP_SENDSPACE=value 1922.It Cd options TCP_RECVSPACE=value 1923These options set the max TCP window size to other sizes than the default. 1924The TCP window sizes can be altered via 1925.Xr sysctl 8 1926as well. 1927.It Cd options TCP_INIT_WIN=value 1928This option sets the initial TCP window size for non-local connections, 1929which is used when the transmission starts. 1930The default size is 1, but if the machine should act more aggressively, 1931the initial size can be set to some other value. 1932The initial TCP window size can be set via 1933.Xr sysctl 8 1934as well. 1935.It Cd options PFIL_HOOKS 1936This option turns on the packet filter interface hooks. 1937See 1938.Xr pfil 9 1939for details. 1940This option assumes 1941.Em INET . 1942.It Cd options IPFILTER_LOG 1943This option, in conjunction with 1944.Em pseudo-device ipfilter , 1945enables logging of IP packets using IP-Filter. 1946.It Cd options IPFILTER_LOOKUP 1947This option enables the 1948IP-Filter 1949.Xr ippool 8 1950functionality to be enabled. 1951.It Cd options IPFILTER_COMPAT 1952This option enables older IP-Filter binaries to work. 1953.It Cd options IPFILTER_DEFAULT_BLOCK 1954This option sets the default policy of IP-Filter. 1955If it is set, IP-Filter will block packets by default. 1956.It Cd options BRIDGE_IPF 1957This option causes 1958.Em bridge 1959devices to use the IP and/or IPv6 filtering hooks, forming 1960a link-layer filter that uses protocol-layer rules. 1961This option assumes the presence of 1962.Em pseudo-device ipfilter . 1963.It Cd options MBUFTRACE 1964This option can help track down mbuf leaks. 1965When enabled, mbufs are tagged with the devices and protocols using them, 1966which slightly decreases network performance. 1967This additional information can be viewed with 1968.Xr netstat 1 : 1969.Dl Ic netstat Fl mssv 1970Not all devices or protocols support this option. 1971.El 1972.Ss Sysctl Related Options 1973.Bl -ohang 1974.It Cd options SYSCTL_DISALLOW_CREATE 1975Disallows the creation or deletion of nodes from the sysctl tree, as 1976well as the assigning of descriptions to nodes that lack them, by any 1977process. 1978These operations are still available to kernel sub-systems, including 1979loadable kernel modules. 1980.It Cd options SYSCTL_DISALLOW_KWRITE 1981Prevents processes from adding nodes to the sysctl tree that make 1982existing kernel memory areas writable. 1983Sections of kernel memory can still be read and new nodes that own 1984their own data may still be writable. 1985.It Cd options SYSCTL_DEBUG_SETUP 1986Causes the SYSCTL_SETUP routines to print a brief message when they 1987are invoked. 1988This is merely meant as an aid in determining the order in which 1989sections of the tree are created. 1990.It Cd options SYSCTL_DEBUG_CREATE 1991Prints a message each time 1992.Fn sysctl_create , 1993the function that adds nodes to the tree, is called. 1994.It Cd options SYSCTL_INCLUDE_DESCR 1995Causes the kernel to include short, human readable descriptions for 1996nodes in the sysctl tree. 1997The descriptions can be retrieved programmatically (see 1998.Xr sysctl 3 ) , 1999or by the sysctl binary itself (see 2000.Xr sysctl 8 ) . 2001The descriptions are meant to give an indication of the purpose and/or 2002effects of a given node's value, not replace the documentation for the 2003given subsystem as a whole. 2004.El 2005.Ss System V IPC Options 2006.Bl -ohang 2007.It Cd options SYSVMSG 2008Includes support for 2009.At V 2010style message queues. 2011See 2012.Xr msgctl 2 , 2013.Xr msgget 2 , 2014.Xr msgrcv 2 , 2015.Xr msgsnd 2 . 2016.It Cd options SYSVSEM 2017Includes support for 2018.At V 2019style semaphores. 2020See 2021.Xr semctl 2 , 2022.Xr semget 2 , 2023.Xr semop 2 . 2024.It Cd options SEMMNI=value 2025Sets the number of 2026.At V 2027style semaphore identifiers. 2028The GENERIC config file for your port will have the default. 2029.It Cd options SEMMNS=value 2030Sets the number of 2031.At V 2032style semaphores in the system. 2033The GENERIC config file for your port will have the default. 2034.It Cd options SEMUME=value 2035Sets the maximum number of undo entries per process for 2036.At V 2037style semaphores. 2038The GENERIC config file for your port will have the default. 2039.It Cd options SEMMNU=value 2040Sets the number of undo structures in the system for 2041.At V 2042style semaphores. 2043The GENERIC config file for your port will have the default. 2044.It Cd options SYSVSHM 2045Includes support for 2046.At V 2047style shared memory. 2048See 2049.Xr shmat 2 , 2050.Xr shmctl 2 , 2051.Xr shmdt 2 , 2052.Xr shmget 2 . 2053.It Cd options SHMMAXPGS=value 2054Sets the maximum number of 2055.At V 2056style shared memory pages that are available through the 2057.Xr shmget 2 2058system call. 2059Default value is 1024 on most ports. 2060See 2061.Pa /usr/include/machine/vmparam.h 2062for the default. 2063.El 2064.Ss VM Related Options 2065.Bl -ohang 2066.It Cd options NMBCLUSTERS=value 2067The number of mbuf clusters the kernel supports. 2068Mbuf clusters are MCLBYTES in size (usually 2k). 2069This is used to compute the size of the kernel VM map 2070.Em mb_map , 2071which maps mbuf clusters. 2072Default on most ports is 1024 (2048 with 2073.Dq options GATEWAY 2074). 2075See 2076.Pa /usr/include/machine/param.h 2077for exact default information. 2078Increase this value if you get 2079.Dq mclpool limit reached 2080messages. 2081.It Cd options NKMEMPAGES=value 2082.It Cd options NKMEMPAGES_MIN=value 2083.It Cd options NKMEMPAGES_MAX=value 2084Size of kernel VM map 2085.Em kmem_map , 2086in PAGE_SIZE-sized chunks (the VM page size; this value may be read 2087from the 2088.Xr sysctl 8 2089variable 2090.Em hw.pagesize 2091). 2092This VM map is used to map the kernel malloc arena. 2093The kernel attempts to auto-size this map based on the amount of 2094physical memory in the system. 2095Platform-specific code may place bounds on this computed size, 2096which may be viewed with the 2097.Xr sysctl 8 2098variable 2099.Em vm.nkmempages . 2100See 2101.Pa /usr/include/machine/param.h 2102for the default upper and lower bounds. 2103The related options 2104.Sq NKMEMPAGES_MIN 2105and 2106.Sq NKMEMPAGES_MAX 2107allow the bounds to be overridden in the kernel configuration file. 2108These options are provided in the event the computed value is 2109insufficient resulting in an 2110.Dq out of space in kmem_map 2111panic. 2112.It Cd options SB_MAX=value 2113Sets the max size in bytes that a socket buffer is allowed to occupy. 2114The default is 256k, but sometimes it needs to be increased, for example 2115when using large TCP windows. 2116This option can be changed via 2117.Xr sysctl 8 2118as well. 2119.It Cd options SOMAXKVA=value 2120Sets the maximum size of kernel virtual memory that the socket buffers 2121are allowed to use. 2122The default is 16MB, but in situations where for example large TCP 2123windows are used this value must also be increased. 2124This option can be changed via 2125.Xr sysctl 8 2126as well. 2127.It Cd options BUFCACHE=value 2128Size of the buffer cache as a percentage of total available 2129.Tn RAM . 2130Ignored if BUFPAGES is also specified. 2131.It Cd options NBUF=value 2132Sets the number of buffer headers available, i.e., the number of 2133open files that may have a buffer cache entry. 2134Each buffer header 2135requires MAXBSIZE (machine dependent, but usually 65536) bytes. 2136The default value is machine dependent, but is usually equal to the 2137value of BUFPAGES. 2138If an architecture dependent VM_MAX_KERNEL_BUF constant is defined 2139then NBUF may be reduced at run time so that the storage allocated 2140for buffer headers doesn't exceed that limit. 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 2145.Tn RAM . 2146.It Cd options MAXTSIZ=bytes 2147Sets the maximum size limit of a process' text segment. 2148See 2149.Pa /usr/include/machine/vmparam.h 2150for the port-specific default. 2151.It Cd options DFLDSIZ=bytes 2152Sets the default size limit of a process' data segment, the value that 2153will be returned as the soft limit for 2154.Dv RLIMIT_DATA 2155(as returned by 2156.Xr getrlimit 2 ) . 2157See 2158.Pa /usr/include/machine/vmparam.h 2159for the port-specific default. 2160.It Cd options MAXDSIZ=bytes 2161Sets the maximum size limit of a process' data segment, the value that 2162will be returned as the hard limit for 2163.Dv RLIMIT_DATA 2164(as returned by 2165.Xr getrlimit 2 ) . 2166See 2167.Pa /usr/include/machine/vmparam.h 2168for the port-specific default. 2169.It Cd options DFLSSIZ=bytes 2170Sets the default size limit of a process' stack segment, the value that 2171will be returned as the soft limit for 2172.Dv RLIMIT_STACK 2173(as returned by 2174.Xr getrlimit 2 ) . 2175See 2176.Pa /usr/include/machine/vmparam.h 2177for the port-specific default. 2178.It Cd options MAXSSIZ=bytes 2179Sets the maximum size limit of a process' stack segment, the value that 2180will be returned as the hard limit for 2181.Dv RLIMIT_STACK 2182(as returned by 2183.Xr getrlimit 2 ) . 2184See 2185.Pa /usr/include/machine/vmparam.h 2186for the port-specific default. 2187.It Cd options DUMP_ON_PANIC=integer 2188Defaults to one. 2189If set to zero, the kernel will not dump to the dump device when 2190it panics, though dumps can still be forced via 2191.Xr ddb 4 2192with the 2193.Dq sync 2194command. 2195Note that this sets the value of the 2196.Em kern.dump_on_panic 2197.Xr sysctl 3 2198variable which may be changed at run time -- see 2199.Xr sysctl 8 2200for details. 2201.It Cd options USE_TOPDOWN_VM 2202User space memory allocations (as made by 2203.Xr mmap 2 ) 2204will be arranged in a 2205.Dq top down 2206fashion instead of the traditional 2207.Dq upwards from MAXDSIZ \&+ vm_daddr 2208method. 2209This includes the placement of 2210.Xr ld.so 1 . 2211Arranging memory in this manner allows either (or both of) the heap or 2212.Xr mmap 2 2213allocated space to grow larger than traditionally possible. 2214This option is not available on all ports, but is instead expected to be 2215offered on a port-by-port basis, after which some ports will commit to 2216using it by default. 2217See the files 2218.Pa /usr/include/uvm/uvm_param.h 2219for some implementation details, and 2220.Pa /usr/include/machine/vmparam.h 2221for port specific details including availability. 2222.It Cd options VMSWAP 2223Enable paging device/file support. 2224This option is on by default. 2225.It Cd options PDPOLICY_CLOCKPRO 2226Use CLOCK-Pro, an alternative page replace policy. 2227.El 2228.Ss Security Options 2229.Bl -ohang 2230.It Cd options INSECURE 2231Hardwires the kernel security level at \-1. 2232This means that the system 2233always runs in secure level \-1 mode, even when running multiuser. 2234See the manual page for 2235.Xr init 8 2236for details on the implications of this. 2237The kernel secure level may manipulated by the superuser by altering the 2238.Em kern.securelevel 2239.Xr sysctl 3 2240variable (the secure level may only be lowered by a call from process ID 1, 2241i.e., 2242.Xr init 8 ) . 2243See also 2244.Xr secmodel_securelevel 9 , 2245.Xr sysctl 8 2246and 2247.Xr sysctl 3 . 2248.It Cd options VERIFIED_EXEC_FP_MD5 2249Enables support for MD5 hashes in Veriexec. 2250.It Cd options VERIFIED_EXEC_FP_SHA1 2251Enables support for SHA1 hashes in Veriexec. 2252.It Cd options VERIFIED_EXEC_FP_RMD160 2253Enables support for RMD160 hashes in Veriexec. 2254.It Cd options VERIFIED_EXEC_FP_SHA256 2255Enables support for SHA256 hashes in Veriexec. 2256.It Cd options VERIFIED_EXEC_FP_SHA384 2257Enables support for SHA384 hashes in Veriexec. 2258.It Cd options VERIFIED_EXEC_FP_SHA512 2259Enables support for SHA512 hashes in Veriexec. 2260.It Cd options PAX_MPROTECT=value 2261Enables PaX MPROTECT, 2262.Xr mprotect 2 2263restrictions from the PaX project. 2264.Pp 2265The 2266.Ar value 2267is the default value for the 2268.Em global 2269knob, see 2270.Xr sysctl 3 . 2271If 0, PaX MPROTECT will be enabled only if explicitly set on programs 2272using 2273.Xr paxctl 8 . 2274If 1, PaX MPROTECT will be enabled for all programs. 2275Programs can be exempted using 2276.Xr paxctl 8 . 2277.Pp 2278See 2279.Xr security 7 2280for more details. 2281.It Cd options PAX_SEGVGUARD=value 2282Enables PaX Segvguard. 2283.Pp 2284The 2285.Ar value 2286is the default value for the 2287.Em global 2288knob, see 2289.Xr sysctl 3 . 2290If 0, PaX Segvguard will be enabled only if explicitly set on programs 2291using 2292.Xr paxctl 8 . 2293If 1, PaX Segvguard will be enabled to all programs, and exemption can 2294be done using 2295.Xr paxctl 8 . 2296.Pp 2297See 2298.Xr security 7 2299for more details. 2300.It Cd options PAX_ASLR=value 2301Enables PaX ASLR. 2302.Pp 2303The 2304.Ar value 2305is the default value for the 2306.Em global 2307knob, see 2308.Xr sysctl 3 . 2309If 0, PaX ASLR will be enabled only if explicitly set on programs 2310using 2311.Xr paxctl 8 . 2312If 1, PaX ASLR will be enabled to all programs, and exemption can 2313be done using 2314.Xr paxctl 8 . 2315.Pp 2316See 2317.Xr security 7 2318for more details. 2319.It Cd options USER_VA0_DISABLE_DEFAULT=value 2320Sets the initial value of the flag which controls whether user programs 2321can map virtual address 0. 2322The flag can be changed at runtime by 2323.Xr sysctl 3 . 2324.El 2325.Ss amiga-specific Options 2326.Bl -ohang 2327.It Cd options BB060STUPIDROM 2328When the bootloader (which passes 2329.Tn AmigaOS 2330.Tn ROM 2331information) claims we have a 68060 2332.Tn CPU 2333without 2334.Tn FPU , 2335go look into the Processor Configuration Register (PCR) to find out. 2336You need this with 2337.Tn Amiga 2338.Tn ROM Ns s 2339up to (at least) V40.xxx (OS3.1), 2340when you boot via the bootblocks and don't have a DraCo. 2341.It Cd options IOBZCLOCK=frequency 2342The IOBlix boards come with two different serial master clocks: older ones 2343use 24 MHz, newer ones use 22.1184 MHz. 2344The driver normally assumes the latter. 2345If your board uses 24 MHz, you can recompile your kernel with 2346options IOBZCLOCK=24000000 2347or patch the kernel variable 2348.Tn iobzclock 2349to the same value. 2350.It Cd options LIMITMEM=value 2351If there, limit the part of the first memory bank used by 2352.Nx 2353to value megabytes. 2354Default is unlimited. 2355.It Cd options NKPTADD=addvalue 2356.It Cd options NKPTADDSHIFT=shiftvalue 2357The 2358.Tn CPU 2359specific 2360.Tn MMU 2361table for the kernel is pre-allocated at kernel startup time. 2362Part of it is scaled with 2363.Va maxproc , 2364to have enough room to hold the user program 2365.Tn MMU 2366tables; the second part is a fixed amount for the kernel itself. 2367.Pp 2368The third part accounts for the size of the file buffer cache. 2369Its size is either 2370.Dv NKPTADD 2371pages (if defined) or memory size in bytes divided by two to 2372the power of 2373.Dv NKPTADDSHIFT . 2374The default is undefined 2375.Dv NKPTADD 2376and 2377.Dv NKPTADDSHIFT=24 , 2378allowing for 16 buffers per megabyte of main memory (while 2379a GENERIC kernel allocates about half of that). 2380When you get "can't get KPT page" panics, you should increase 2381.Dv NKPTADD 2382(if defined), or decrease 2383.Dv NKPTADDSHIFT 2384by one. 2385.It Cd options P5PPC68KBOARD 2386Add special support for Phase5 mixed 68k+PPC boards. 2387Currently, this only affects rebooting from 2388.Nx 2389and is only needed on 68040+PPC, not on 239068060+PPC; without this, affected machines will hang after 2391.Nx 2392has shut 2393down and will only restart after a keyboard reset or a power cycle. 2394.El 2395.Ss arm32-specific Options 2396.Bl -ohang 2397.It Cd options FRENCH_KBD 2398Include translation for French keyboards when using 2399.Em pccons 2400on a Shark. 2401.It Cd options FINNISH_KBD 2402Include translation for Finnish keyboards when using 2403.Em pccons 2404on a Shark. 2405.It Cd options GERMAN_KBD 2406Include translation for German keyboards when using 2407.Em pccons 2408on a Shark. 2409.It Cd options NORWEGIAN_KBD 2410Include translation for French keyboards when using 2411.Em pccons 2412on a Shark. 2413.El 2414.Ss atari-specific Options 2415.Bl -ohang 2416.It Cd options DISKLABEL_AHDI 2417Include support for AHDI (native Atari) disklabels. 2418.It Cd options DISKLABEL_NBDA 2419Include support for 2420.Nx Ns Tn /atari 2421labels. 2422If you don't set this option, it will be set automatically. 2423.Nx Ns Tn /atari 2424will not work without it. 2425.It Cd options FALCON_SCSI 2426Include support for the 5380-SCSI configuration as found on the Falcon. 2427.It Cd options RELOC_KERNEL 2428If set, the kernel will relocate itself to TT-RAM, if possible. 2429This will give you a slightly faster system. 2430.Em Beware 2431that on some TT030 systems, 2432the system will frequently dump with MMU-faults with this option enabled. 2433.It Cd options SERCONSOLE 2434Allow the modem1-port to act as the system-console. 2435A carrier should be active on modem1 during system boot to active 2436the console functionality. 2437.It Cd options TT_SCSI 2438Include support for the 5380-SCSI configuration as found on the TT030 2439and Hades. 2440.El 2441.Ss i386-specific Options 2442.Bl -ohang 2443.It Cd options CPURESET_DELAY=value 2444Specifies the time (in millisecond) to wait before doing a hardware reset 2445in the last phase of a reboot. 2446This gives the user a chance to see error messages from the shutdown 2447operations (like NFS unmounts, buffer cache flush, etc ...). 2448Setting this to 0 will disable the delay. 2449Default is 2 seconds. 2450.It Cd options VM86 2451Include support for virtual 8086 mode, used by 2452.Tn DOS 2453emulators and X servers to run BIOS code, e.g., for some VESA routines. 2454.It Cd options USER_LDT 2455Include i386-specific system calls for modifying the local descriptor table, 2456used by Windows emulators. 2457.It Cd options PAE 2458Enable 2459.Tn PAE (Physical Address Extension) 2460mode. 2461.Tn PAE 2462permits up to 36 bits physical addressing (64GB of physical memory), and 2463turns physical addresses to 64 bits entities in the memory management 2464subsystem. 2465Userland virtual address space remains at 32 bits (4GB). 2466.Tn PAE 2467mode is required to enable the 2468.Tn NX/XD (No-eXecute/eXecute Disable) 2469bit for pages, which allows marking certain ones as not being executable. 2470Any attempt to execute code from such a page will raise an exception. 2471.It Cd options REALBASEMEM=integer 2472Overrides the base memory size passed in from the boot block. 2473(Value given in kilobytes.) 2474Use this option only if the boot block reports the size incorrectly. 2475(Note that some 2476.Tn BIOS Ns es 2477put the extended 2478.Tn BIOS 2479data area at the top of base memory, and therefore report a smaller 2480base memory size to prevent programs overwriting it. 2481This is correct behavior, and you should not use the 2482.Em REALBASEMEM 2483option to access this memory). 2484.It Cd options REALEXTMEM=integer 2485Overrides the extended memory size passed in from the boot block. 2486(Value given in kilobytes. 2487Extended memory does not include the first megabyte.) 2488Use this option only if the boot block reports the size incorrectly. 2489.It Cd options FRENCH_KBD,FINNISH_KBD,GERMAN_KBD,NORWEGIAN_KBD 2490Select a non-US keyboard layout for the 2491.Em pccons 2492console driver. 2493.It Cd options CYRIX_CACHE_WORKS 2494Relevant only to the Cyrix 486DLC CPU. 2495This option is used to turn on the cache in hold-flush mode. 2496It is not turned on by default because it is known to have problems in 2497certain motherboard implementations. 2498.It Cd options CYRIX_CACHE_REALLY_WORKS 2499Relevant only to the Cyrix 486DLC CPU. 2500This option is used to turn on the cache in write-back mode. 2501It is not turned on by default because it is known to have problems in 2502certain motherboard implementations. 2503In order for this option to take effect, option 2504.Em CYRIX_CACHE_WORKS 2505must also be specified. 2506.It Cd options PCIBIOS 2507Enable support for initializing the 2508.Tn PCI 2509bus using information from the 2510.Tn BIOS . 2511See 2512.Xr pcibios 4 2513for details. 2514.It Cd options KSTACK_CHECK_DR0 2515Detect kernel stack overflow using DR0 register. 2516This option uses DR0 register exclusively so you can't use DR0 register for 2517other purpose (e.g., hardware breakpoint) if you turn this on. 2518.It Cd options MTRR 2519Include support for accessing MTRR registers from user-space. 2520See 2521.Xr i386_get_mtrr 2 . 2522.It Cd options BEEP_ONHALT 2523Make the system speaker emit several beeps when it is completely safe to 2524power down the computer after a 2525.Xr halt 8 2526command. 2527Requires 2528.Xr sysbeep 4 2529support. 2530.It Cd options BEEP_ONHALT_COUNT=times 2531Number of times to beep the speaker when 2532.Cd options BEEP_ONHALT 2533is enabled. 2534Defaults to 3. 2535.It Cd options BEEP_ONHALT_PITCH=hz 2536The tone frequency used when 2537.Cd options BEEP_ONHALT 2538option, in hertz. 2539Defaults to 1500. 2540.It Cd options BEEP_ONHALT_PERIOD=msecs 2541The duration of each beep when 2542.Cd options BEEP_ONHALT 2543is enabled, in milliseconds. 2544Defaults to 250. 2545.It Cd options MULTIBOOT 2546Makes the kernel Multiboot-compliant, allowing it to be booted through 2547a Multiboot-compliant boot manager such as GRUB. 2548See 2549.Xr multiboot 8 2550for more information. 2551.It Cd options SPLASHSCREEN 2552Display a splash screen during boot. 2553.It Cd options SPLASHSCREEN_PROGRESS 2554Display a progress bar at the splash screen during boot. 2555This option requires 2556.Em SPLASHSCREEN . 2557.El 2558.Ss isa-specific Options 2559Options specific to 2560.Xr isa 4 2561busses. 2562.Bl -ohang 2563.It Cd options PCIC_ISA_ALLOC_IOBASE=address, PCIC_ISA_ALLOC_IOSIZE=size 2564Control the section of IO bus space used for PCMCIA bus space mapping. 2565Ideally the probed defaults are satisfactory, however in practice 2566that is not always the case. 2567See 2568.Xr pcmcia 4 2569for details. 2570.It Cd options PCIC_ISA_INTR_ALLOC_MASK=mask 2571Controls the allowable interrupts that may be used for 2572.Tn PCMCIA 2573devices. 2574This mask is a logical-or of power-of-2s of allowable interrupts: 2575.Bd -literal -offset 04n 2576.Em "IRQ Val IRQ Val IRQ Val IRQ Val" 2577 0 0x0001 4 0x0010 8 0x0100 12 0x1000 2578 1 0x0002 5 0x0020 9 0x0200 13 0x2000 2579 2 0x0004 6 0x0040 10 0x0400 14 0x4000 2580 3 0x0008 7 0x0080 11 0x0800 15 0x8000 2581.Ed 2582.It Cd options PCKBC_CNATTACH_SELFTEST 2583Perform a self test of the keyboard controller before attaching it as a 2584console. 2585This might be necessary on machines where we boot on cold iron, and 2586pckbc refuses to talk until we request a self test. 2587Currently only the netwinder port uses it. 2588.It Cd options PCKBD_CNATTACH_MAY_FAIL 2589If this option is set the PS/2 keyboard will not be used as the console 2590if it cannot be found during boot. 2591This allows other keyboards, like USB, to be the console keyboard. 2592.It Cd options PCKBD_LAYOUT=layout 2593Sets the default keyboard layout, see 2594.Xr pckbd 4 . 2595.El 2596.Ss m68k-specific Options 2597.Bl -ohang 2598.It Cd options FPU_EMULATE 2599Include support for MC68881/MC68882 emulator. 2600.It Cd options FPSP 2601Include support for 68040 floating point. 2602.It Cd options M68020,M68030,M68040,M68060 2603Include support for a specific 2604.Tn CPU , 2605at least one (the one you are using) should be specified. 2606.It Cd options M060SP 2607Include software support for 68060. 2608This provides emulation of unimplemented 2609integer instructions as well as emulation of unimplemented floating point 2610instructions and data types and software support for floating point traps. 2611.El 2612.Ss powerpc-specific Options (OEA Only) 2613.Bl -ohang 2614.It Cd options PMAP_MEMLIMIT=value 2615Limit the amount of memory seen by the kernel to 2616.Ar value 2617bytes. 2618.It Cd options PTEGCOUNT=value 2619Specify the size of the page table as 2620.Ar value 2621PTE groups. 2622Normally, one PTEG is allocated per physical page frame. 2623.El 2624.Ss sparc-specific Options 2625.Bl -ohang 2626.It Cd options AUDIO_DEBUG 2627Enable simple event debugging of the logging of the 2628.Xr audio 4 2629device. 2630.It Cd options BLINK 2631Enable blinking of LED. 2632Blink rate is full cycle every N seconds for 2633N \*[Lt] then current load average. 2634See 2635.Xr getloadavg 3 . 2636.\" .It Cd options COLORFONT_CACHE 2637.\" What does this do? 2638.It Cd options COUNT_SW_LEFTOVERS 2639Count how many times the sw SCSI device has left 3, 2, 1 and 0 in the 2640sw_3_leftover, sw_2_leftover, sw_1_leftover, and sw_0_leftover 2641variables accessible from 2642.Xr ddb 4 . 2643See 2644.Xr sw 4 . 2645.It Cd options DEBUG_ALIGN 2646Adds debugging messages calls when user-requested alignment fault 2647handling happens. 2648.It Cd options DEBUG_EMUL 2649Adds debugging messages calls for emulated floating point and 2650alignment fixing operations. 2651.It Cd options DEBUG_SVR4 2652Prints registers messages calls for emulated SVR4 getcontext and 2653setcontext operations. 2654See 2655.Em options COMPAT_SVR4 . 2656.It Cd options EXTREME_DEBUG 2657Adds debugging functions callable from 2658.Xr ddb 4 . 2659The debug_pagetables, test_region and print_fe_map 2660functions print information about page tables for the SUN4M 2661platforms only. 2662.It Cd options EXTREME_EXTREME_DEBUG 2663Adds extra info to 2664.Em options EXTREME_DEBUG . 2665.It Cd options FPU_CONTEXT 2666Make 2667.Em options COMPAT_SVR4 2668getcontext and setcontext include floating point registers. 2669.It Cd options MAGMA_DEBUG 2670Adds debugging messages to the 2671.Xr magma 4 2672device. 2673.It Cd options RASTERCONS_FULLSCREEN 2674Use the entire screen for the console. 2675.It Cd options RASTERCONS_SMALLFONT 2676Use the Fixed font on the console, instead of the normal font. 2677.It Cd options SUN4 2678Support sun4 class machines. 2679.It Cd options SUN4C 2680Support sun4c class machines. 2681.It Cd options SUN4M 2682Support sun4m class machines. 2683.It Cd options SUN4_MMU3L 2684.\" XXX ??? 2685Enable support for sun4 3-level MMU machines. 2686.It Cd options V9 2687Enable SPARC V9 assembler in 2688.Xr ddb 4 . 2689.El 2690.Ss sparc64-specific Options 2691.Bl -ohang 2692.It Cd options AUDIO_DEBUG 2693Enable simple event debugging of the logging of the 2694.Xr audio 4 2695device. 2696.It Cd options BLINK 2697Enable blinking of LED. 2698Blink rate is full cycle every N seconds for 2699N \*[Lt] then current load average. 2700See 2701.Xr getloadavg 3 . 2702.El 2703.Ss x68k-specific Options 2704.Bl -ohang 2705.It Cd options EXTENDED_MEMORY 2706Include support for extended memory, e.g., TS-6BE16 and 060turbo on-board. 2707.It Cd options JUPITER 2708Include support for Jupiter-X MPU accelerator 2709.It Cd options ZSCONSOLE,ZSCN_SPEED=value 2710Use the built-in serial port as the system-console. 2711Speed is specified in bps, defaults to 9600. 2712.It Cd options ITE_KERNEL_ATTR=value 2713Set the kernel message attribute for ITE. 2714Value, an integer, is a logical or of the following values: 2715.Bl -tag -width 4n -compact -offset indent 2716.It 1 2717color inversed 2718.It 2 2719underlined 2720.It 4 2721bolded 2722.El 2723.El 2724.\" The following requests should be uncommented and used where appropriate. 2725.\" .Sh FILES 2726.\" .Sh EXAMPLES 2727.Sh SEE ALSO 2728.Xr config 1 , 2729.Xr gdb 1 , 2730.Xr ktrace 1 , 2731.Xr pmc 1 , 2732.Xr quota 1 , 2733.Xr vndcompress 1 , 2734.Xr gettimeofday 2 , 2735.Xr i386_get_mtrr 2 , 2736.Xr i386_iopl 2 , 2737.Xr msgctl 2 , 2738.Xr msgget 2 , 2739.Xr msgrcv 2 , 2740.Xr msgsnd 2 , 2741.Xr ntp_adjtime 2 , 2742.Xr ntp_gettime 2 , 2743.Xr reboot 2 , 2744.Xr semctl 2 , 2745.Xr semget 2 , 2746.Xr semop 2 , 2747.Xr shmat 2 , 2748.Xr shmctl 2 , 2749.Xr shmdt 2 , 2750.Xr shmget 2 , 2751.Xr sysctl 3 , 2752.Xr apm 4 , 2753.Xr ddb 4 , 2754.Xr inet 4 , 2755.Xr iso 4 , 2756.Xr md 4 , 2757.Xr pcibios 4 , 2758.Xr pcmcia 4 , 2759.Xr ppp 4 , 2760.Xr userconf 4 , 2761.Xr vnd 4 , 2762.Xr wscons 4 , 2763.Xr config 5 , 2764.Xr edquota 8 , 2765.Xr init 8 , 2766.Xr mdsetimage 8 , 2767.Xr mount_cd9660 8 , 2768.Xr mount_fdesc 8 , 2769.Xr mount_kernfs 8 , 2770.Xr mount_lfs 8 , 2771.Xr mount_mfs 8 , 2772.Xr mount_msdos 8 , 2773.Xr mount_nfs 8 , 2774.Xr mount_ntfs 8 , 2775.Xr mount_null 8 , 2776.Xr mount_portal 8 , 2777.Xr mount_procfs 8 , 2778.Xr mount_udf 8 , 2779.Xr mount_umap 8 , 2780.Xr mount_union 8 , 2781.Xr mrouted 8 , 2782.Xr newfs_lfs 8 , 2783.Xr ntpd 8 , 2784.Xr quotaon 8 , 2785.Xr rpc.rquotad 8 , 2786.Xr sysctl 8 , 2787.Xr in_getifa 9 2788.Sh HISTORY 2789The 2790.Nm 2791man page first appeared in 2792.Nx 1.3 . 2793.Sh BUGS 2794The 2795.Em EON 2796option should be a pseudo-device, and is also very fragile. 2797