1.\" $NetBSD: options.4,v 1.404 2011/04/26 22:17:17 wiz 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 27, 2011 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 WAPBL 963Enable 964.Dq Write Ahead Physical Block Logging file system journaling . 965This provides rapid file system consistency checking after a system outage. 966It also provides better general use performance over regular FFS. 967See also 968.Xr wapbl 4 . 969.It Cd options NVNODE=integer 970This option sets the size of the cache used by the name-to-inode translation 971routines, (a.k.a. the 972.Fn namei 973cache, though called by many other names in the kernel source). 974By default, this cache has 975.Dv NPROC 976(set as 20 + 16 * MAXUSERS) * (80 + NPROC / 8) entries. 977A reasonable way to derive a value of 978.Dv NVNODE , 979should you notice a large number of namei cache misses with a tool such as 980.Xr systat 1 , 981is to examine your system's current computed value with 982.Xr sysctl 8 , 983(which calls this parameter "kern.maxvnodes") and to increase this value 984until either the namei cache hit rate improves or it is determined that 985your system does not benefit substantially from an increase in the size of 986the namei cache. 987.It Cd options NAMECACHE_ENTER_REVERSE 988Causes the namei cache to always enter a reverse mapping (vnode -\*[Gt] name) 989as well as a normal one. 990Normally, this is already done for directory vnodes, to speed up the getcwd 991operation. 992This option will cause longer hash chains in the reverse cache, and thus 993slow down getcwd somewhat. 994However, it does make vnode -\*[Gt] path translations possible in some cases. 995For now, only useful if strict /proc/#/maps emulation for Linux binaries is 996required. 997.It Cd options EXT2FS_SYSTEM_FLAGS 998This option changes the behavior of the APPEND and IMMUTABLE flags 999for a file on an 1000.Em ext2 1001file system. 1002Without this option, the superuser or owner of the file can 1003set and clear them. 1004With this option, only the superuser can set them, and 1005they can't be cleared if the securelevel is greater than 0. 1006See also 1007.Xr chflags 1 1008and 1009.Xr secmodel_securelevel 9 . 1010.It Cd options NFS_BOOT_BOOTP 1011Enable use of the BOOTP protocol (RFCs 951 and 1048) to get configuration 1012information if NFS is used to mount the root file system. 1013See 1014.Xr diskless 8 1015for details. 1016.It Cd options NFS_BOOT_DHCP 1017Same as 1018.Dq NFS_BOOT_BOOTP , 1019but use the DHCP extensions to the 1020BOOTP protocol (RFC 1541). 1021.It Cd options NFS_BOOT_BOOTP_REQFILE 1022Specifies the string sent in the bp_file field of the BOOTP / DHCP 1023request packet. 1024.It Cd options NFS_BOOT_BOOTPARAM 1025Enable use of the BOOTPARAM protocol, consisting of RARP and 1026BOOTPARAM RPC, to get configuration information if NFS 1027is used to mount the root file system. 1028See 1029.Xr diskless 8 1030for details. 1031.It Cd options NFS_BOOT_RWSIZE=value 1032Set the initial NFS read and write sizes for diskless-boot requests. 1033The normal default is 8Kbytes. 1034This option provides a way to lower the value (e.g., to 1024 bytes) 1035as a workaround for buggy network interface cards or boot PROMs. 1036Once booted, the read and write request sizes can be increased by 1037remounting the file system. 1038See 1039.Xr mount_nfs 8 1040for details. 1041.It Cd options NFS_V2_ONLY 1042Reduce the size of the NFS client code by omitting code that's only required 1043for NFSv3 and NQNFS support, leaving only that code required to use NFSv2 1044servers. 1045.It Cd options UFS_DIRHASH 1046Increase lookup performance by maintaining in-core hash tables 1047for large directories. 1048.El 1049.Ss Buffer queue strategy options 1050The following options enable alternative buffer queue strategies. 1051.Bl -ohang 1052.It Cd options BUFQ_READPRIO 1053Enable experimental buffer queue strategy for disk I/O. 1054In the default strategy, outstanding disk requests are ordered by 1055sector number and sent to the disk, regardless of whether the 1056operation is a read or write; this option gives priority to issuing 1057read requests over write requests. 1058Although requests may therefore be issued out of sector-order, causing 1059more seeks and thus lower overall throughput, interactive system 1060responsiveness under heavy disk I/O load may be improved, as processes 1061blocking on disk reads are serviced sooner (file writes typically 1062don't cause applications to block). 1063The performance effect varies greatly depending on the hardware, drive 1064firmware, file system configuration, workload, and desired performance 1065trade-off. 1066Systems using drive write-cache (most modern IDE disks, by default) 1067are unlikely to benefit and may well suffer; such disks acknowledge 1068writes very quickly, and optimize them internally according to 1069physical layout. 1070Giving these disks as many requests to work with as possible (the 1071standard strategy) will typically produce the best results, especially 1072if the drive has a large cache; the drive will silently complete 1073writes from cache as it seeks for reads. 1074Disks that support a large number of concurrent tagged requests (SCSI 1075disks and many hardware RAID controllers) expose this internal 1076scheduling with tagged responses, and don't block for reads; such 1077disks may not see a noticeable difference with either strategy. 1078However, if IDE disks are run with write-cache disabled for safety, 1079writes are not acknowledged until actually completed, and only one 1080request can be outstanding; a large number of small writes in one 1081locality can keep the disk busy, starving reads elsewhere on the disk. 1082Such systems are likely to see the most benefit from this option. 1083Finally, the performance interaction of this option with ffs soft 1084dependencies can be subtle, as that mechanism can drastically alter 1085the workload for file system metadata writes. 1086.It Cd options BUFQ_PRIOCSCAN 1087Enable another buffer queue strategy for disk I/O, per-priority cyclical scan. 1088.It Cd options NEW_BUFQ_STRATEGY 1089Synonym of 1090.Em BUFQ_READPRIO . 1091.El 1092.Ss Miscellaneous Options 1093.Bl -ohang 1094.It Cd options MEMORY_DISK_DYNAMIC 1095This option makes the 1096.Xr md 4 1097.Tn RAM 1098disk size dynamically sized. 1099It is incompatible with 1100.Xr mdsetimage 8 . 1101.It Cd options MEMORY_DISK_HOOKS 1102This option allows for some machine dependent functions to be called when 1103the 1104.Xr md 4 1105.Tn RAM 1106disk driver is configured. 1107This can result in automatically loading a 1108.Tn RAM 1109disk from floppy on open (among other things). 1110.It Cd options MEMORY_DISK_IS_ROOT 1111Forces the 1112.Xr md 4 1113.Tn RAM 1114disk to be the root device. 1115This can only be overridden when 1116the kernel is booted in the 'ask-for-root' mode. 1117.It Cd options MEMORY_DISK_ROOT_SIZE=integer 1118Allocates the given number of 512 byte blocks as memory for the 1119.Xr md 4 1120.Tn RAM 1121disk, to be populated with 1122.Xr mdsetimage 8 . 1123.It Cd options MEMORY_DISK_SERVER=0 1124Do not include the interface to a userland memory disk server process. 1125Per default, this option is set to 1, including the support code. 1126Useful for install media kernels. 1127.It Cd options MEMORY_DISK_RBFLAGS=value 1128This option sets the 1129.Xr reboot 2 1130flags used when booting with a memory disk as root file system. 1131Possible values include 1132.Dv RB_AUTOBOOT 1133(boot in the usual fashion - default value), and 1134.Dv RB_SINGLE 1135(boot in single-user mode). 1136.It Cd options MODULAR 1137Enables the framework for kernel modules (see 1138.Xr module 7 ) . 1139.It Cd options VND_COMPRESSION 1140Enables the 1141.Xr vnd 4 1142driver to also handle compressed images. 1143See 1144.Xr vndcompress 1 , 1145.Xr vnd 4 1146and 1147.Xr vnconfig 8 1148for more information. 1149.It Cd options SPLDEBUG 1150Help the kernel programmer find bugs related to the interrupt priority 1151level. 1152When 1153.Fn spllower 1154or 1155.Fn splraise 1156changes the current CPU's interrupt priority level to or from 1157.Dv IPL_HIGH , 1158record a backtrace. 1159Read 1160.Xr return_address 9 1161for caveats about collecting backtraces. 1162This feature is experimental, and it is only available on i386. 1163See 1164.Pa sys/kern/subr_spldebug.c . 1165.It Cd options TFTPROOT 1166Download the root memory disk through TFTP at root mount time. 1167This enables the use of a root 1168.Tn RAM 1169disk without requiring it to be embedded in the kernel using 1170.Xr mdsetimage 8 . 1171The 1172.Tn RAM 1173disk name is obtained using DHCP's filename parameter. 1174This option requires 1175.Em MEMORY_DISK_HOOKS , 1176.Em MEMORY_DISK_DYNAMIC , 1177and 1178.Em MEMORY_DISK_IS_ROOT . 1179It is incompatible with 1180.Em MEMORY_DISK_ROOT_SIZE . 1181.It Cd options MALLOC_NOINLINE 1182Time critical fixed size memory allocation is performed with 1183.Fn MALLOC 1184and 1185.Fn FREE . 1186Normally these expand to inline code, but with 1187.Em MALLOC_NOINLINE 1188these call the normal 1189.Fn malloc 1190and 1191.Fn free 1192functions. 1193Useful for install media kernels, small memory systems and embedded systems. 1194.It Cd options HZ=integer 1195On ports that support it, set the system clock frequency (see 1196.Xr hz 9 ) 1197to the supplied value. 1198Handle with care. 1199.It Cd options NTP 1200Turns on in-kernel precision timekeeping support used by software 1201implementing 1202.Em NTP 1203(Network Time Protocol, RFC 1305). 1204The 1205.Em NTP 1206option adds an in-kernel Phase-Locked Loop (PLL) for normal 1207.Em NTP 1208operation, and a Frequency-Locked Loop (FLL) for intermittently-connected 1209operation. 1210.Xr ntpd 8 1211will employ a user-level PLL when kernel support is unavailable, 1212but the in-kernel version has lower latency and more precision, and 1213so typically keeps much better time. 1214The interface to the kernel 1215.Em NTP 1216support is provided by the 1217.Xr ntp_adjtime 2 1218and 1219.Xr ntp_gettime 2 1220system calls, which are intended for use by 1221.Xr ntpd 8 1222and are enabled by the option. 1223On systems with sub-microsecond resolution timers, or where (HZ / 100000) 1224is not an integer, the 1225.Em NTP 1226option also enables extended-precision arithmetic to keep track of 1227fractional clock ticks at NTP time-format precision. 1228.It Cd options PPS_SYNC 1229This option enables a kernel serial line discipline for receiving time 1230phase signals from an external reference clock such as a radio clock. 1231(The 1232.Em NTP 1233option (which see) must be on if the 1234.Em PPS_SYNC 1235option is used.) 1236Some reference clocks generate a Pulse Per Second (PPS) signal in 1237phase with their time source. 1238The 1239.Em PPS 1240line discipline receives this signal on either the data leads 1241or the DCD control lead of a serial port. 1242.Em NTP 1243uses the PPS signal to discipline the local clock oscillator to a high 1244degree of precision (typically less than 50 microseconds in time and 12450.1 ppm in accuracy). 1246.Em PPS 1247can also generate a serial output pulse when the system receives a PPS 1248interrupt. 1249This can be used to measure the system interrupt latency and thus calibrate 1250.Em NTP 1251to account for it. 1252Using 1253.Em PPS 1254usually requires a 1255gadget box 1256to convert from TTL to RS-232 signal levels. 1257The gadget box and PPS are described in more detail in the HTML documentation 1258for 1259.Xr ntpd 8 1260in 1261.Pa /usr/share/doc/html/ntp . 1262.It Cd options SETUIDSCRIPTS 1263Allows scripts with the setuid bit set to execute as the effective 1264user rather than the real user, just like binary executables. 1265.Pp 1266.Em NOTE : 1267Using this option will also enable 1268.Em options FDSCRIPTS 1269.It Cd options FDSCRIPTS 1270Allows execution of scripts with the execute bit set, but not the 1271read bit, by opening the file and passing the file descriptor to 1272the shell, rather than the filename. 1273.Pp 1274.Em NOTE : 1275Execute only (non-readable) scripts will have 1276.Va argv[0] 1277set to 1278.Pa /dev/fd/* . 1279What this option allows as far as security is 1280concerned, is the ability to safely ensure that the correct script 1281is run by the interpreter, as it is passed as an already open file. 1282.It Cd options PUCCN 1283Enables treating serial ports found on PCI boards 1284.Xr puc 4 1285as potential console devices. 1286The method for choosing such a console device is port dependent. 1287.It Cd options RTC_OFFSET=integer 1288The kernel (and typically the hardware battery backed-up clock on 1289those machines that have one) keeps time in 1290.Em UTC 1291(Universal Coordinated Time, once known as 1292.Em GMT , 1293or Greenwich Mean Time) 1294and not in the time of the local time zone. 1295The 1296.Em RTC_OFFSET 1297option is used on some ports (such as the i386) to tell the kernel 1298that the hardware clock is offset from 1299.Em UTC 1300by the specified number of minutes. 1301This is typically used when a machine boots several operating 1302systems and one of them wants the hardware clock to run in the 1303local time zone and not in 1304.Em UTC , 1305e.g. 1306.Em RTC_OFFSET=300 1307means 1308the hardware clock is set to US Eastern Time (300 minutes behind 1309.Em UTC ) , 1310and not 1311.Em UTC . 1312(Note: 1313.Em RTC_OFFSET 1314is used to initialize a kernel variable named 1315.Va rtc_offset 1316which is the source actually used to determine the clock offset, and 1317which may be accessed via the kern.rtc_offset sysctl variable. 1318See 1319.Xr sysctl 8 1320and 1321.Xr sysctl 3 1322for details. 1323Since the kernel clock is initialized from the hardware clock very 1324early in the boot process, it is not possible to meaningfully change 1325.Va rtc_offset 1326in system initialization scripts. 1327Changing this value currently may only be done at kernel compile 1328time or by patching the kernel and rebooting). 1329.Pp 1330.Em NOTE : 1331Unfortunately, in many cases where the hardware clock 1332is kept in local time, it is adjusted for Daylight Savings 1333Time; this means that attempting to use 1334.Em RTC_OFFSET 1335to let 1336.Nx 1337coexist with such an operating system, like Windows, 1338would necessitate changing 1339.Em RTC_OFFSET 1340twice a year. 1341As such, this solution is imperfect. 1342.It Cd options KMEMSTATS 1343The kernel memory allocator, 1344.Xr malloc 9 , 1345will keep statistics on its performance if this option is enabled. 1346Unfortunately, this option therefore essentially disables the 1347.Fn MALLOC 1348and 1349.Fn FREE 1350forms of the memory allocator, which are used to enhance the performance 1351of certain critical sections of code in the kernel. 1352This option therefore can lead to a significant decrease in the 1353performance of certain code in the kernel if enabled. 1354Examples of such code include the 1355.Fn namei 1356routine, the 1357.Xr ccd 4 1358driver, 1359and much of the networking code. 1360.It Cd options MAXUPRC=integer 1361Sets the soft 1362.Dv RLIMIT_NPROC 1363resource limit, which specifies the maximum number of simultaneous 1364processes a user is permitted to run, for process 0; 1365this value is inherited by its child processes. 1366It defaults to 1367.Em CHILD_MAX , 1368which is currently defined to be 160. 1369Setting 1370.Em MAXUPRC 1371to a value less than 1372.Em CHILD_MAX 1373is not permitted, as this would result in a violation of the semantics of 1374.St -p1003.1-90 . 1375.It Cd options NOFILE=integer 1376Sets the soft 1377.Dv RLIMIT_NOFILE 1378resource limit, which specifies the maximum number of open 1379file descriptors for each process; 1380this value is inherited by its child processes. 1381It defaults to 1382.Em OPEN_MAX , 1383which is currently defined to be 64. 1384.It Cd options MAXFILES=integer 1385Sets the default value of the 1386.Em kern.maxfiles 1387sysctl variable, which indicates the maximum number of files that may 1388be open in the system. 1389.It Cd options DEFCORENAME=string 1390Sets the default value of the 1391.Em kern.defcorename 1392sysctl variable, otherwise it is set to 1393.Nm %n.core . 1394See 1395.Xr sysctl 8 1396and 1397.Xr sysctl 3 1398for details. 1399.It Cd options RASOPS_CLIPPING 1400Enables clipping within the 1401.Nm rasops 1402raster-console output system. 1403.Em NOTE : 1404only available on architectures that use 1405.Nm rasops 1406for console output. 1407.It Cd options RASOPS_SMALL 1408Removes optimized character writing code from the 1409.Nm rasops 1410raster-console output system. 1411.Em NOTE : 1412only available on architectures that use 1413.Nm rasops 1414for console output. 1415.It Cd options INCLUDE_CONFIG_FILE 1416Embeds the kernel config file used to define the kernel in the kernel 1417binary itself. 1418The embedded data also includes any files directly included by the config 1419file itself, e.g. 1420.Pa GENERIC.local 1421or 1422.Pa std.$MACHINE . 1423The embedded config file can be extracted from the resulting kernel with 1424.Xr config 1 1425.Fl x , 1426or by the following command: 1427.Bd -literal -offset indent 1428strings netbsd | sed -n 's/^_CFG_//p' | unvis 1429.Ed 1430.It Cd options INCLUDE_JUST_CONFIG 1431Similar to the above option, but includes just the actual config file, 1432not any included files. 1433.It Cd options PIPE_SOCKETPAIR 1434Use slower, but smaller socketpair(2)-based pipe implementation instead 1435of default faster, but bigger one. 1436Primarily useful for installation kernels. 1437.It Cd options USERCONF 1438Compiles in the in-kernel device configuration manager. 1439See 1440.Xr userconf 4 1441for details. 1442.It Cd options PERFCTRS 1443Compiles in kernel support for CPU performance-monitoring counters. 1444See 1445.Xr pmc 1 1446for details. 1447.Em NOTE : 1448not available on all architectures. 1449.It Cd options SYSCALL_STATS 1450Count the number of times each system call number is called. 1451The values can be read through the sysctl interface and displayed using 1452.Xr systat 1 . 1453.Em NOTE : 1454not yet available on all architectures. 1455.It Cd options SYSCALL_TIMES 1456Count the time spent (using 1457.Fn cpu_counter32 ) 1458in each system call. 1459.Em NOTE : 1460Using this option will also enable 1461.Cd options SYSCALL_STATS . 1462.It Cd options SYSCALL_TIMES_HASCOUNTER 1463Force use of 1464.Fn cpu_counter32 1465even if 1466.Fn cpu_hascounter 1467reports false. 1468Useful for systems where the cycle counter doesn't run at a constant rate 1469(e.g. Soekris boxes). 1470.It Cd options XSERVER_DDB 1471A supplement to XSERVER that adds support for entering 1472.Xr ddb 4 1473while in 1474.Tn X11 . 1475.It Cd options FILEASSOC 1476Support for 1477.Xr fileassoc 9 . 1478.It Cd options FILEASSOC_NHOOKS=integer 1479Number of storage slots per file for 1480.Xr fileassoc 9 . 1481Default is 4. 1482.It Cd options I2C_SCAN 1483Scan each i2c bus to determine which addresses respond. 1484.Pp 1485.Em WARNING ! 1486Using this option can access some devices in such a 1487manner as to leave them in an unstable or unuseable state, and 1488can prevent those devices from being properly matched and/or 1489attached. 1490It can also lock up the entire 1491.Xr iic 4 1492bus and even prevent a machine from completing the boot process. 1493Don't use this option unless you know what you're doing and can 1494accept all sorts of unforeseen consequences. 1495.El 1496.Ss Networking Options 1497.Bl -ohang 1498.It Cd options GATEWAY 1499Enables 1500.Em IPFORWARDING 1501(which see) 1502and (on most ports) increases the size of 1503.Em NMBCLUSTERS 1504(which see). 1505In general, 1506.Em GATEWAY 1507is used to indicate that a system should act as a router, and 1508.Em IPFORWARDING 1509is not invoked directly. 1510(Note that 1511.Em GATEWAY 1512has no impact on protocols other than 1513.Tn IP , 1514such as 1515.Tn CLNP ) . 1516.Em GATEWAY 1517option also compiles IPv4 and IPv6 fast forwarding code into the kernel. 1518.It Cd options ICMPPRINTFS 1519The 1520.Em ICMPPRINTFS 1521option will enable debugging information to be printed about 1522the 1523.Xr icmp 4 1524protocol. 1525.It Cd options IPFORWARDING=value 1526If 1527.Em value 1528is 1 this enables IP routing behavior. 1529If 1530.Em value 1531is 0 (the default), it disables it. 1532The 1533.Em GATEWAY 1534option sets this to 1 automatically. 1535With this option enabled, the machine will forward IP datagrams destined 1536for other machines between its interfaces. 1537Note that even without this option, the kernel will 1538still forward some packets (such as source routed packets) -- removing 1539.Em GATEWAY 1540and 1541.Em IPFORWARDING 1542is insufficient to stop all routing through a bastion host on a 1543firewall -- source routing is controlled independently. 1544To turn off source routing, use 1545.Em options IPFORWSRCRT=0 1546(which see). 1547Note that IP forwarding may be turned on and off independently of the 1548setting of the 1549.Em IPFORWARDING 1550option through the use of the 1551.Em net.inet.ip.forwarding 1552sysctl variable. 1553If 1554.Em net.inet.ip.forwarding 1555is 1, IP forwarding is on. 1556See 1557.Xr sysctl 8 1558and 1559.Xr sysctl 3 1560for details. 1561.It Cd options IPFORWSRCRT=value 1562If 1563.Em value 1564is set to zero, source routing of IP datagrams is turned off. 1565If 1566.Em value 1567is set to one (the default) or the option is absent, source routed IP 1568datagrams are forwarded by the machine. 1569Note that source routing of IP packets may be turned on and off 1570independently of the setting of the 1571.Em IPFORWSRCRT 1572option through the use of the 1573.Em net.inet.ip.forwsrcrt 1574sysctl variable. 1575If 1576.Em net.inet.ip.forwsrcrt 1577is 1, forwarding of source routed IP datagrams is on. 1578See 1579.Xr sysctl 8 1580and 1581.Xr sysctl 3 1582for details. 1583.It Cd options IFA_STATS 1584Tells the kernel to maintain per-address statistics on bytes sent 1585and received over (currently) Internet and AppleTalk addresses. 1586.\"This can be a fairly expensive operation, so you probably want to 1587.\"keep this disabled. 1588The option is not recommended as it degrades system stability. 1589.It Cd options IFQ_MAXLEN=value 1590Increases the allowed size of the network interface packet queues. 1591The default queue size is 50 packets, and you do not normally need 1592to increase it. 1593.It Cd options IPSELSRC 1594Includes support for source-address selection policies. 1595See 1596.Xr in_getifa 9 . 1597.It Cd options MROUTING 1598Includes support for IP multicast routers. 1599You certainly want 1600.Em INET 1601with this. 1602Multicast routing is controlled by the 1603.Xr mrouted 8 1604daemon. 1605See also option 1606.Cd PIM . 1607.It Cd options PIM 1608Includes support for Protocol Independent Multicast (PIM) routing. 1609You need 1610.Em MROUTING 1611and 1612.Em INET 1613with this. 1614Software using this can be found e.g. in 1615.Pa pkgsrc/net/xorp . 1616.It Cd options INET 1617Includes support for the 1618.Tn TCP/IP 1619protocol stack. 1620You almost certainly want this. 1621See 1622.Xr inet 4 1623for details. 1624.It Cd options INET6 1625Includes support for the 1626.Tn IPv6 1627protocol stack. 1628See 1629.Xr inet6 4 1630for details. 1631Unlike 1632.Em INET , 1633.Em INET6 1634enables multicast routing code as well. 1635This option requires 1636.Em INET 1637at this moment, but it should not. 1638.It Cd options ND6_DEBUG 1639The option sets the default value of net.inet6.icmp6.nd6_debug to 1, 1640for debugging IPv6 neighbor discovery protocol handling. 1641See 1642.Xr sysctl 3 1643for details. 1644.It Cd options IPSEC 1645Includes support for the 1646.Tn IPsec 1647protocol, using the KAME implementation. 1648See 1649.Xr ipsec 4 1650for details. 1651.It Cd options IPSEC_DEBUG 1652Enables debugging code in 1653.Tn IPsec 1654stack. 1655See 1656.Xr ipsec 4 1657for details. 1658.It Cd options IPSEC_ESP 1659Includes support for 1660.Tn IPsec 1661.Tn ESP 1662protocol, using the KAME implementation. 1663See 1664.Xr ipsec 4 1665for details. 1666.It Cd options FAST_IPSEC 1667Includes support for the 1668.Tn IPsec 1669protocol, using the implementation derived from 1670.Ox , 1671relaying on 1672.Xr opencrypto 9 1673to carry out cryptographic operations. 1674See 1675.Xr fast_ipsec 4 1676for details. 1677.It Cd options IPSEC_NAT_T 1678Includes support for 1679.Tn IPsec 1680Network Address Translator traversal (NAT-T), as described in RFCs 3947 1681and 3948. 1682This feature might be patent-encumbered in some countries. 1683.It Cd options ALTQ 1684Enabled ALTQ (Alternate Queueing). 1685For simple rate-limiting, use 1686.Xr tbrconfig 8 1687to set up the interface transmission rate. 1688To use queueing disciplines, their appropriate kernel options should also 1689be defined (documented below). 1690Queueing disciplines are managed by 1691.Xr altqd 8 . 1692See 1693.Xr altq 9 1694for details. 1695.It Cd options ALTQ_HFSC 1696Include support for ALTQ-implemented HFSC (Hierarchical Fair Service Curve) 1697module. 1698HFSC supports both link-sharing and guaranteed real-time services. 1699HFSC employs a service curve based QoS model, and its unique feature 1700is an ability to decouple delay and bandwidth allocation. 1701Requires 1702.Em ALTQ_RED 1703to use the RED queueing discipline on HFSC classes, or 1704.Em ALTQ_RIO 1705to use the RIO queueing discipline on HFSC classes. 1706This option assumes 1707.Em ALTQ . 1708.It Cd options ALTQ_PRIQ 1709Include support for ALTQ-implemented PRIQ (Priority Queueing). 1710PRIQ implements a simple priority-based queueing discipline. 1711A higher priority class is always served first. 1712Requires 1713.Em ALTQ_RED 1714to use the RED queueing discipline on HFSC classes, or 1715.Em ALTQ_RIO 1716to use the RIO queueing discipline on HFSC classes. 1717This option assumes 1718.Em ALTQ . 1719.It Cd options ALTQ_WFQ 1720Include support for ALTQ-implemented WFQ (Weighted Fair Queueing). 1721WFQ implements a weighted-round robin scheduler for a set of queues. 1722A weight can be assigned to each queue to give a different proportion 1723of the link capacity. 1724A hash function is used to map a flow to one of a set of queues. 1725This option assumes 1726.Em ALTQ . 1727.It Cd options ALTQ_FIFOQ 1728Include support for ALTQ-implemented FIFO queueing. 1729FIFOQ is a simple drop-tail FIFO (First In, First Out) queueing discipline. 1730This option assumes 1731.Em ALTQ . 1732.It Cd options ALTQ_RIO 1733Include support for ALTQ-implemented RIO (RED with In/Out). 1734The original RIO has 2 sets of RED parameters; one for in-profile 1735packets and the other for out-of-profile packets. 1736At the ingress of the network, profile meters tag packets as IN or 1737OUT based on contracted profiles for customers. 1738Inside the network, IN packets receive preferential treatment by 1739the RIO dropper. 1740ALTQ/RIO has 3 drop precedence levels defined for the Assured Forwarding 1741PHB of DiffServ (RFC 2597). 1742This option assumes 1743.Em ALTQ . 1744.It Cd options ALTQ_BLUE 1745Include support for ALTQ-implemented Blue buffer management. 1746Blue is another active buffer management mechanism. 1747This option assumes 1748.Em ALTQ . 1749.It Cd options ALTQ_FLOWVALVE 1750Include support for ALTQ-implemented Flowvalve. 1751Flowvalve is a simple implementation of a RED penalty box that identifies 1752and punishes misbehaving flows. 1753This option requires 1754.Em ALTQ_RED 1755and assumes 1756.Em ALTQ . 1757.It Cd options ALTQ_CDNR 1758Include support for ALTQ-implemented CDNR (diffserv traffic conditioner) 1759packet marking/manipulation. 1760Traffic conditioners are components to meter, mark, or drop incoming 1761packets according to some rules. 1762As opposed to queueing disciplines, traffic conditioners handle incoming 1763packets at an input interface. 1764This option assumes 1765.Em ALTQ . 1766.It Cd options ALTQ_NOPCC 1767Disables use of processor cycle counter to measure time in ALTQ. 1768This option should be defined for a non-Pentium i386 CPU which does not 1769have TSC, SMP (per-CPU counters are not in sync), or power management 1770which affects processor cycle counter. 1771This option assumes 1772.Em ALTQ . 1773.It Cd options ALTQ_IPSEC 1774Include support for IPsec in IPv4 ALTQ. 1775This option assumes 1776.Em ALTQ . 1777.It Cd options ALTQ_JOBS 1778Include support for ALTQ-implemented JoBS (Joint Buffer Management 1779and Scheduling). 1780This option assumes 1781.Em ALTQ . 1782.It Cd options ALTQ_AFMAP 1783Include support for an undocumented ALTQ feature that is used to map an IP 1784flow to an ATM VC (Virtual Circuit). 1785This option assumes 1786.Em ALTQ . 1787.It Cd options ALTQ_LOCALQ 1788Include support for ALTQ-implemented local queues. 1789Its practical use is undefined. 1790Assumes 1791.Em ALTQ . 1792.It Cd options SUBNETSARELOCAL 1793Sets default value for net.inet.ip.subnetsarelocal variable, which 1794controls whether non-directly-connected subnets of connected networks 1795are considered "local" for purposes of choosing the MSS for a TCP 1796connection. 1797This is mostly present for historic reasons and completely irrelevant if 1798you enable Path MTU discovery. 1799.It Cd options HOSTZEROBROADCAST 1800Sets default value for net.inet.ip.hostzerobroadcast variable, which 1801controls whether the zeroth host address of each connected subnet is 1802also considered a broadcast address. 1803Default value is "1", for compatibility with old systems; if this is 1804set to zero on all hosts on a subnet, you should be able to fit an extra 1805host per subnet on the 1806".0" address. 1807.It Cd options MCLSHIFT=value 1808This option is the base-2 logarithm of the size of mbuf clusters. 1809The 1810.Bx 1811networking stack keeps network packets in a linked 1812list, or chain, of kernel buffer objects called mbufs. 1813The system provides larger mbuf clusters as an optimization for 1814large packets, instead of using long chains for large packets. 1815The mbuf cluster size, 1816or 1817.Em MCLBYTES , 1818must be a power of two, and is computed as two raised to the power 1819.Em MCLSHIFT . 1820On systems with Ethernet network adapters, 1821.Em MCLSHIFT 1822is often set to 11, giving 2048-byte mbuf clusters, large enough to 1823hold a 1500-byte 1824.Tn Ethernet 1825frame in a single cluster. 1826Systems with network interfaces supporting larger frame sizes like 1827.Tn ATM , 1828.Tn FDDI , 1829or 1830.Tn HIPPI 1831may perform better with 1832.Em MCLSHIFT 1833set to 12 or 13, giving mbuf cluster sizes of 4096 and 8192 bytes, 1834respectively. 1835.It Cd options ISO,TPIP 1836Include support for the ubiquitous 1837.Tn OSI 1838protocol stack. 1839See 1840.Xr iso 4 1841for details. 1842This option assumes 1843.Em INET . 1844.It Cd options EON 1845Include support for tunneling 1846.Tn OSI 1847protocols over 1848.Tn IP . 1849Known to be broken, or at least very fragile, and undocumented. 1850.It Cd options NETATALK 1851Include support for the 1852.Tn AppleTalk 1853protocol stack. 1854The kernel provides provision for the 1855.Em Datagram Delivery Protocol 1856(DDP), providing SOCK_DGRAM support and 1857.Tn AppleTalk 1858routing. 1859This stack is used by the 1860.Em NETATALK 1861package, which adds support for 1862.Tn AppleTalk 1863server services via user libraries and applications. 1864.It Cd options BLUETOOTH 1865Include support for the 1866.Tn Bluetooth 1867protocol stack. 1868See 1869.Xr bluetooth 4 1870for details. 1871.It Cd options IPNOPRIVPORTS 1872Normally, only root can bind a socket descriptor to a so-called 1873.Dq privileged 1874.Tn TCP 1875port, that is, a port number in the range 0-1023. 1876This option eliminates those checks from the kernel. 1877This can be useful if there is a desire to allow daemons without 1878privileges to bind those ports, e.g., on firewalls. 1879The security tradeoffs in doing this are subtle. 1880This option should only be used by experts. 1881.It Cd options TCP_COMPAT_42 1882.Tn TCP 1883bug compatibility with 1884.Bx 4.2 . 1885In 1886.Bx 4.2 , 1887.Tn TCP 1888sequence numbers were 32-bit signed values. 1889Modern implementations of TCP use unsigned values. 1890This option clamps the initial sequence number to start in 1891the range 2^31 rather than the full unsigned range of 2^32. 1892Also, under 1893.Bx 4.2 , 1894keepalive packets must contain at least one byte or else 1895the remote end would not respond. 1896.It Cd options TCP_DEBUG 1897Record the last 1898.Em TCP_NDEBUG 1899TCP packets with SO_DEBUG set, and decode to the console if 1900.Em tcpconsdebug 1901is set. 1902.It Cd options TCP_NDEBUG 1903Number of packets to record for 1904.Em TCP_DEBUG . 1905Defaults to 100. 1906.It Cd options TCP_SENDSPACE=value 1907.It Cd options TCP_RECVSPACE=value 1908These options set the max TCP window size to other sizes than the default. 1909The TCP window sizes can be altered via 1910.Xr sysctl 8 1911as well. 1912.It Cd options TCP_INIT_WIN=value 1913This option sets the initial TCP window size for non-local connections, 1914which is used when the transmission starts. 1915The default size is 1, but if the machine should act more aggressively, 1916the initial size can be set to some other value. 1917The initial TCP window size can be set via 1918.Xr sysctl 8 1919as well. 1920.It Cd options PFIL_HOOKS 1921This option turns on the packet filter interface hooks. 1922See 1923.Xr pfil 9 1924for details. 1925This option assumes 1926.Em INET . 1927.It Cd options IPFILTER_LOG 1928This option, in conjunction with 1929.Em pseudo-device ipfilter , 1930enables logging of IP packets using IP-Filter. 1931.It Cd options IPFILTER_LOOKUP 1932This option enables the 1933IP-Filter 1934.Xr ippool 8 1935functionality to be enabled. 1936.It Cd options IPFILTER_COMPAT 1937This option enables older IP-Filter binaries to work. 1938.It Cd options IPFILTER_DEFAULT_BLOCK 1939This option sets the default policy of IP-Filter. 1940If it is set, IP-Filter will block packets by default. 1941.It Cd options BRIDGE_IPF 1942This option causes 1943.Em bridge 1944devices to use the IP and/or IPv6 filtering hooks, forming 1945a link-layer filter that uses protocol-layer rules. 1946This option assumes the presence of 1947.Em pseudo-device ipfilter . 1948.It Cd options MBUFTRACE 1949This option can help track down mbuf leaks. 1950When enabled, mbufs are tagged with the devices and protocols using them, 1951which slightly decreases network performance. 1952This additional information can be viewed with 1953.Xr netstat 1 : 1954.Dl Ic netstat Fl mssv 1955Not all devices or protocols support this option. 1956.El 1957.Ss Sysctl Related Options 1958.Bl -ohang 1959.It Cd options SYSCTL_DISALLOW_CREATE 1960Disallows the creation or deletion of nodes from the sysctl tree, as 1961well as the assigning of descriptions to nodes that lack them, by any 1962process. 1963These operations are still available to kernel sub-systems, including 1964loadable kernel modules. 1965.It Cd options SYSCTL_DISALLOW_KWRITE 1966Prevents processes from adding nodes to the sysctl tree that make 1967existing kernel memory areas writable. 1968Sections of kernel memory can still be read and new nodes that own 1969their own data may still be writable. 1970.It Cd options SYSCTL_DEBUG_SETUP 1971Causes the SYSCTL_SETUP routines to print a brief message when they 1972are invoked. 1973This is merely meant as an aid in determining the order in which 1974sections of the tree are created. 1975.It Cd options SYSCTL_DEBUG_CREATE 1976Prints a message each time 1977.Fn sysctl_create , 1978the function that adds nodes to the tree, is called. 1979.It Cd options SYSCTL_INCLUDE_DESCR 1980Causes the kernel to include short, human readable descriptions for 1981nodes in the sysctl tree. 1982The descriptions can be retrieved programmatically (see 1983.Xr sysctl 3 ) , 1984or by the sysctl binary itself (see 1985.Xr sysctl 8 ) . 1986The descriptions are meant to give an indication of the purpose and/or 1987effects of a given node's value, not replace the documentation for the 1988given subsystem as a whole. 1989.El 1990.Ss System V IPC Options 1991.Bl -ohang 1992.It Cd options SYSVMSG 1993Includes support for 1994.At V 1995style message queues. 1996See 1997.Xr msgctl 2 , 1998.Xr msgget 2 , 1999.Xr msgrcv 2 , 2000.Xr msgsnd 2 . 2001.It Cd options SYSVSEM 2002Includes support for 2003.At V 2004style semaphores. 2005See 2006.Xr semctl 2 , 2007.Xr semget 2 , 2008.Xr semop 2 . 2009.It Cd options SEMMNI=value 2010Sets the number of 2011.At V 2012style semaphore identifiers. 2013The GENERIC config file for your port will have the default. 2014.It Cd options SEMMNS=value 2015Sets the number of 2016.At V 2017style semaphores in the system. 2018The GENERIC config file for your port will have the default. 2019.It Cd options SEMUME=value 2020Sets the maximum number of undo entries per process for 2021.At V 2022style semaphores. 2023The GENERIC config file for your port will have the default. 2024.It Cd options SEMMNU=value 2025Sets the number of undo structures in the system for 2026.At V 2027style semaphores. 2028The GENERIC config file for your port will have the default. 2029.It Cd options SYSVSHM 2030Includes support for 2031.At V 2032style shared memory. 2033See 2034.Xr shmat 2 , 2035.Xr shmctl 2 , 2036.Xr shmdt 2 , 2037.Xr shmget 2 . 2038.It Cd options SHMMAXPGS=value 2039Sets the maximum number of 2040.At V 2041style shared memory pages that are available through the 2042.Xr shmget 2 2043system call. 2044Default value is 1024 on most ports. 2045See 2046.Pa /usr/include/machine/vmparam.h 2047for the default. 2048.El 2049.Ss VM Related Options 2050.Bl -ohang 2051.It Cd options NMBCLUSTERS=value 2052The number of mbuf clusters the kernel supports. 2053Mbuf clusters are MCLBYTES in size (usually 2k). 2054This is used to compute the size of the kernel VM map 2055.Em mb_map , 2056which maps mbuf clusters. 2057Default on most ports is 1024 (2048 with 2058.Dq options GATEWAY 2059). 2060See 2061.Pa /usr/include/machine/param.h 2062for exact default information. 2063Increase this value if you get 2064.Dq mclpool limit reached 2065messages. 2066.It Cd options NKMEMPAGES=value 2067.It Cd options NKMEMPAGES_MIN=value 2068.It Cd options NKMEMPAGES_MAX=value 2069Size of kernel VM map 2070.Em kmem_map , 2071in PAGE_SIZE-sized chunks (the VM page size; this value may be read 2072from the 2073.Xr sysctl 8 2074variable 2075.Em hw.pagesize 2076). 2077This VM map is used to map the kernel malloc arena. 2078The kernel attempts to auto-size this map based on the amount of 2079physical memory in the system. 2080Platform-specific code may place bounds on this computed size, 2081which may be viewed with the 2082.Xr sysctl 8 2083variable 2084.Em vm.nkmempages . 2085See 2086.Pa /usr/include/machine/param.h 2087for the default upper and lower bounds. 2088The related options 2089.Sq NKMEMPAGES_MIN 2090and 2091.Sq NKMEMPAGES_MAX 2092allow the bounds to be overridden in the kernel configuration file. 2093These options are provided in the event the computed value is 2094insufficient resulting in an 2095.Dq out of space in kmem_map 2096panic. 2097.It Cd options SB_MAX=value 2098Sets the max size in bytes that a socket buffer is allowed to occupy. 2099The default is 256k, but sometimes it needs to be increased, for example 2100when using large TCP windows. 2101This option can be changed via 2102.Xr sysctl 8 2103as well. 2104.It Cd options SOMAXKVA=value 2105Sets the maximum size of kernel virtual memory that the socket buffers 2106are allowed to use. 2107The default is 16MB, but in situations where for example large TCP 2108windows are used this value must also be increased. 2109This option can be changed via 2110.Xr sysctl 8 2111as well. 2112.It Cd options BUFCACHE=value 2113Size of the buffer cache as a percentage of total available 2114.Tn RAM . 2115Ignored if BUFPAGES is also specified. 2116.It Cd options NBUF=value 2117Sets the number of buffer headers available, i.e., the number of 2118open files that may have a buffer cache entry. 2119Each buffer header 2120requires MAXBSIZE (machine dependent, but usually 65536) bytes. 2121The default value is machine dependent, but is usually equal to the 2122value of BUFPAGES. 2123If an architecture dependent VM_MAX_KERNEL_BUF constant is defined 2124then NBUF may be reduced at run time so that the storage allocated 2125for buffer headers doesn't exceed that limit. 2126.It Cd options BUFPAGES=value 2127These options set the number of pages available for the buffer cache. 2128Their default value is a machine dependent value, often calculated as 2129between 5% and 10% of total available 2130.Tn RAM . 2131.It Cd options MAXTSIZ=bytes 2132Sets the maximum size limit of a process' text segment. 2133See 2134.Pa /usr/include/machine/vmparam.h 2135for the port-specific default. 2136.It Cd options DFLDSIZ=bytes 2137Sets the default size limit of a process' data segment, the value that 2138will be returned as the soft limit for 2139.Dv RLIMIT_DATA 2140(as returned by 2141.Xr getrlimit 2 ) . 2142See 2143.Pa /usr/include/machine/vmparam.h 2144for the port-specific default. 2145.It Cd options MAXDSIZ=bytes 2146Sets the maximum size limit of a process' data segment, the value that 2147will be returned as the hard limit for 2148.Dv RLIMIT_DATA 2149(as returned by 2150.Xr getrlimit 2 ) . 2151See 2152.Pa /usr/include/machine/vmparam.h 2153for the port-specific default. 2154.It Cd options DFLSSIZ=bytes 2155Sets the default size limit of a process' stack segment, the value that 2156will be returned as the soft limit for 2157.Dv RLIMIT_STACK 2158(as returned by 2159.Xr getrlimit 2 ) . 2160See 2161.Pa /usr/include/machine/vmparam.h 2162for the port-specific default. 2163.It Cd options MAXSSIZ=bytes 2164Sets the maximum size limit of a process' stack segment, the value that 2165will be returned as the hard limit for 2166.Dv RLIMIT_STACK 2167(as returned by 2168.Xr getrlimit 2 ) . 2169See 2170.Pa /usr/include/machine/vmparam.h 2171for the port-specific default. 2172.It Cd options DUMP_ON_PANIC=integer 2173Defaults to one. 2174If set to zero, the kernel will not dump to the dump device when 2175it panics, though dumps can still be forced via 2176.Xr ddb 4 2177with the 2178.Dq sync 2179command. 2180Note that this sets the value of the 2181.Em kern.dump_on_panic 2182.Xr sysctl 3 2183variable which may be changed at run time -- see 2184.Xr sysctl 8 2185for details. 2186.It Cd options USE_TOPDOWN_VM 2187User space memory allocations (as made by 2188.Xr mmap 2 ) 2189will be arranged in a 2190.Dq top down 2191fashion instead of the traditional 2192.Dq upwards from MAXDSIZ \&+ vm_daddr 2193method. 2194This includes the placement of 2195.Xr ld.so 1 . 2196Arranging memory in this manner allows either (or both of) the heap or 2197.Xr mmap 2 2198allocated space to grow larger than traditionally possible. 2199This option is not available on all ports, but is instead expected to be 2200offered on a port-by-port basis, after which some ports will commit to 2201using it by default. 2202See the files 2203.Pa /usr/include/uvm/uvm_param.h 2204for some implementation details, and 2205.Pa /usr/include/machine/vmparam.h 2206for port specific details including availability. 2207.It Cd options VMSWAP 2208Enable paging device/file support. 2209This option is on by default. 2210.It Cd options PDPOLICY_CLOCKPRO 2211Use CLOCK-Pro, an alternative page replace policy. 2212.El 2213.Ss Security Options 2214.Bl -ohang 2215.It Cd options INSECURE 2216Hardwires the kernel security level at \-1. 2217This means that the system 2218always runs in secure level \-1 mode, even when running multiuser. 2219See the manual page for 2220.Xr init 8 2221for details on the implications of this. 2222The kernel secure level may manipulated by the superuser by altering the 2223.Em kern.securelevel 2224.Xr sysctl 3 2225variable (the secure level may only be lowered by a call from process ID 1, 2226i.e., 2227.Xr init 8 ) . 2228See also 2229.Xr secmodel_securelevel 9 , 2230.Xr sysctl 8 2231and 2232.Xr sysctl 3 . 2233.It Cd options VERIFIED_EXEC_FP_MD5 2234Enables support for MD5 hashes in Veriexec. 2235.It Cd options VERIFIED_EXEC_FP_SHA1 2236Enables support for SHA1 hashes in Veriexec. 2237.It Cd options VERIFIED_EXEC_FP_RMD160 2238Enables support for RMD160 hashes in Veriexec. 2239.It Cd options VERIFIED_EXEC_FP_SHA256 2240Enables support for SHA256 hashes in Veriexec. 2241.It Cd options VERIFIED_EXEC_FP_SHA384 2242Enables support for SHA384 hashes in Veriexec. 2243.It Cd options VERIFIED_EXEC_FP_SHA512 2244Enables support for SHA512 hashes in Veriexec. 2245.It Cd options PAX_MPROTECT=value 2246Enables PaX MPROTECT, 2247.Xr mprotect 2 2248restrictions from the PaX project. 2249.Pp 2250The 2251.Ar value 2252is the default value for the 2253.Em global 2254knob, see 2255.Xr sysctl 3 . 2256If 0, PaX MPROTECT will be enabled only if explicitly set on programs 2257using 2258.Xr paxctl 8 . 2259If 1, PaX MPROTECT will be enabled for all programs. 2260Programs can be exempted using 2261.Xr paxctl 8 . 2262.Pp 2263See 2264.Xr security 7 2265for more details. 2266.It Cd options PAX_SEGVGUARD=value 2267Enables PaX Segvguard. 2268.Pp 2269The 2270.Ar value 2271is the default value for the 2272.Em global 2273knob, see 2274.Xr sysctl 3 . 2275If 0, PaX Segvguard will be enabled only if explicitly set on programs 2276using 2277.Xr paxctl 8 . 2278If 1, PaX Segvguard will be enabled to all programs, and exemption can 2279be done using 2280.Xr paxctl 8 . 2281.Pp 2282See 2283.Xr security 7 2284for more details. 2285.It Cd options PAX_ASLR=value 2286Enables PaX ASLR. 2287.Pp 2288The 2289.Ar value 2290is the default value for the 2291.Em global 2292knob, see 2293.Xr sysctl 3 . 2294If 0, PaX ASLR will be enabled only if explicitly set on programs 2295using 2296.Xr paxctl 8 . 2297If 1, PaX ASLR will be enabled to all programs, and exemption can 2298be done using 2299.Xr paxctl 8 . 2300.Pp 2301See 2302.Xr security 7 2303for more details. 2304.It Cd options USER_VA0_DISABLE_DEFAULT=value 2305Sets the initial value of the flag which controls whether user programs 2306can map virtual address 0. 2307The flag can be changed at runtime by 2308.Xr sysctl 3 . 2309.El 2310.Ss amiga-specific Options 2311.Bl -ohang 2312.It Cd options BB060STUPIDROM 2313When the bootloader (which passes 2314.Tn AmigaOS 2315.Tn ROM 2316information) claims we have a 68060 2317.Tn CPU 2318without 2319.Tn FPU , 2320go look into the Processor Configuration Register (PCR) to find out. 2321You need this with 2322.Tn Amiga 2323.Tn ROM Ns s 2324up to (at least) V40.xxx (OS3.1), 2325when you boot via the bootblocks and don't have a DraCo. 2326.It Cd options IOBZCLOCK=frequency 2327The IOBlix boards come with two different serial master clocks: older ones 2328use 24 MHz, newer ones use 22.1184 MHz. 2329The driver normally assumes the latter. 2330If your board uses 24 MHz, you can recompile your kernel with 2331options IOBZCLOCK=24000000 2332or patch the kernel variable 2333.Tn iobzclock 2334to the same value. 2335.It Cd options LIMITMEM=value 2336If there, limit the part of the first memory bank used by 2337.Nx 2338to value megabytes. 2339Default is unlimited. 2340.It Cd options NKPTADD=addvalue 2341.It Cd options NKPTADDSHIFT=shiftvalue 2342The 2343.Tn CPU 2344specific 2345.Tn MMU 2346table for the kernel is pre-allocated at kernel startup time. 2347Part of it is scaled with 2348.Va maxproc , 2349to have enough room to hold the user program 2350.Tn MMU 2351tables; the second part is a fixed amount for the kernel itself. 2352.Pp 2353The third part accounts for the size of the file buffer cache. 2354Its size is either 2355.Dv NKPTADD 2356pages (if defined) or memory size in bytes divided by two to 2357the power of 2358.Dv NKPTADDSHIFT . 2359The default is undefined 2360.Dv NKPTADD 2361and 2362.Dv NKPTADDSHIFT=24 , 2363allowing for 16 buffers per megabyte of main memory (while 2364a GENERIC kernel allocates about half of that). 2365When you get "can't get KPT page" panics, you should increase 2366.Dv NKPTADD 2367(if defined), or decrease 2368.Dv NKPTADDSHIFT 2369by one. 2370.It Cd options P5PPC68KBOARD 2371Add special support for Phase5 mixed 68k+PPC boards. 2372Currently, this only affects rebooting from 2373.Nx 2374and is only needed on 68040+PPC, not on 237568060+PPC; without this, affected machines will hang after 2376.Nx 2377has shut 2378down and will only restart after a keyboard reset or a power cycle. 2379.El 2380.Ss arm32-specific Options 2381.Bl -ohang 2382.It Cd options FRENCH_KBD 2383Include translation for French keyboards when using 2384.Em pccons 2385on a Shark. 2386.It Cd options FINNISH_KBD 2387Include translation for Finnish keyboards when using 2388.Em pccons 2389on a Shark. 2390.It Cd options GERMAN_KBD 2391Include translation for German keyboards when using 2392.Em pccons 2393on a Shark. 2394.It Cd options NORWEGIAN_KBD 2395Include translation for French keyboards when using 2396.Em pccons 2397on a Shark. 2398.El 2399.Ss atari-specific Options 2400.Bl -ohang 2401.It Cd options DISKLABEL_AHDI 2402Include support for AHDI (native Atari) disklabels. 2403.It Cd options DISKLABEL_NBDA 2404Include support for 2405.Nx Ns Tn /atari 2406labels. 2407If you don't set this option, it will be set automatically. 2408.Nx Ns Tn /atari 2409will not work without it. 2410.It Cd options FALCON_SCSI 2411Include support for the 5380-SCSI configuration as found on the Falcon. 2412.It Cd options RELOC_KERNEL 2413If set, the kernel will relocate itself to TT-RAM, if possible. 2414This will give you a slightly faster system. 2415.Em Beware 2416that on some TT030 systems, 2417the system will frequently dump with MMU-faults with this option enabled. 2418.It Cd options SERCONSOLE 2419Allow the modem1-port to act as the system-console. 2420A carrier should be active on modem1 during system boot to active 2421the console functionality. 2422.It Cd options TT_SCSI 2423Include support for the 5380-SCSI configuration as found on the TT030 2424and Hades. 2425.El 2426.Ss i386-specific Options 2427.Bl -ohang 2428.It Cd options CPURESET_DELAY=value 2429Specifies the time (in millisecond) to wait before doing a hardware reset 2430in the last phase of a reboot. 2431This gives the user a chance to see error messages from the shutdown 2432operations (like NFS unmounts, buffer cache flush, etc ...). 2433Setting this to 0 will disable the delay. 2434Default is 2 seconds. 2435.It Cd options VM86 2436Include support for virtual 8086 mode, used by 2437.Tn DOS 2438emulators and X servers to run BIOS code, e.g., for some VESA routines. 2439.It Cd options USER_LDT 2440Include i386-specific system calls for modifying the local descriptor table, 2441used by Windows emulators. 2442.It Cd options PAE 2443Enable 2444.Tn PAE (Physical Address Extension) 2445mode. 2446.Tn PAE 2447permits up to 36 bits physical addressing (64GB of physical memory), and 2448turns physical addresses to 64 bits entities in the memory management 2449subsystem. 2450Userland virtual address space remains at 32 bits (4GB). 2451.Tn PAE 2452mode is required to enable the 2453.Tn NX/XD (No-eXecute/eXecute Disable) 2454bit for pages, which allows marking certain ones as not being executable. 2455Any attempt to execute code from such a page will raise an exception. 2456.It Cd options REALBASEMEM=integer 2457Overrides the base memory size passed in from the boot block. 2458(Value given in kilobytes.) 2459Use this option only if the boot block reports the size incorrectly. 2460(Note that some 2461.Tn BIOS Ns es 2462put the extended 2463.Tn BIOS 2464data area at the top of base memory, and therefore report a smaller 2465base memory size to prevent programs overwriting it. 2466This is correct behavior, and you should not use the 2467.Em REALBASEMEM 2468option to access this memory). 2469.It Cd options REALEXTMEM=integer 2470Overrides the extended memory size passed in from the boot block. 2471(Value given in kilobytes. 2472Extended memory does not include the first megabyte.) 2473Use this option only if the boot block reports the size incorrectly. 2474.It Cd options FRENCH_KBD,FINNISH_KBD,GERMAN_KBD,NORWEGIAN_KBD 2475Select a non-US keyboard layout for the 2476.Em pccons 2477console driver. 2478.It Cd options CYRIX_CACHE_WORKS 2479Relevant only to the Cyrix 486DLC CPU. 2480This option is used to turn on the cache in hold-flush mode. 2481It is not turned on by default because it is known to have problems in 2482certain motherboard implementations. 2483.It Cd options CYRIX_CACHE_REALLY_WORKS 2484Relevant only to the Cyrix 486DLC CPU. 2485This option is used to turn on the cache in write-back mode. 2486It is not turned on by default because it is known to have problems in 2487certain motherboard implementations. 2488In order for this option to take effect, option 2489.Em CYRIX_CACHE_WORKS 2490must also be specified. 2491.It Cd options PCIBIOS 2492Enable support for initializing the 2493.Tn PCI 2494bus using information from the 2495.Tn BIOS . 2496See 2497.Xr pcibios 4 2498for details. 2499.It Cd options KSTACK_CHECK_DR0 2500Detect kernel stack overflow using DR0 register. 2501This option uses DR0 register exclusively so you can't use DR0 register for 2502other purpose (e.g., hardware breakpoint) if you turn this on. 2503.It Cd options MTRR 2504Include support for accessing MTRR registers from user-space. 2505See 2506.Xr i386_get_mtrr 2 . 2507.It Cd options BEEP_ONHALT 2508Make the system speaker emit several beeps when it is completely safe to 2509power down the computer after a 2510.Xr halt 8 2511command. 2512Requires 2513.Xr sysbeep 4 2514support. 2515.It Cd options BEEP_ONHALT_COUNT=times 2516Number of times to beep the speaker when 2517.Cd options BEEP_ONHALT 2518is enabled. 2519Defaults to 3. 2520.It Cd options BEEP_ONHALT_PITCH=hz 2521The tone frequency used when 2522.Cd options BEEP_ONHALT 2523option, in hertz. 2524Defaults to 1500. 2525.It Cd options BEEP_ONHALT_PERIOD=msecs 2526The duration of each beep when 2527.Cd options BEEP_ONHALT 2528is enabled, in milliseconds. 2529Defaults to 250. 2530.It Cd options MULTIBOOT 2531Makes the kernel Multiboot-compliant, allowing it to be booted through 2532a Multiboot-compliant boot manager such as GRUB. 2533See 2534.Xr multiboot 8 2535for more information. 2536.It Cd options SPLASHSCREEN 2537Display a splash screen during boot. 2538.It Cd options SPLASHSCREEN_PROGRESS 2539Display a progress bar at the splash screen during boot. 2540This option requires 2541.Em SPLASHSCREEN . 2542.El 2543.Ss isa-specific Options 2544Options specific to 2545.Xr isa 4 2546busses. 2547.Bl -ohang 2548.It Cd options PCIC_ISA_ALLOC_IOBASE=address, PCIC_ISA_ALLOC_IOSIZE=size 2549Control the section of IO bus space used for PCMCIA bus space mapping. 2550Ideally the probed defaults are satisfactory, however in practice 2551that is not always the case. 2552See 2553.Xr pcmcia 4 2554for details. 2555.It Cd options PCIC_ISA_INTR_ALLOC_MASK=mask 2556Controls the allowable interrupts that may be used for 2557.Tn PCMCIA 2558devices. 2559This mask is a logical-or of power-of-2s of allowable interrupts: 2560.Bd -literal -offset 04n 2561.Em "IRQ Val IRQ Val IRQ Val IRQ Val" 2562 0 0x0001 4 0x0010 8 0x0100 12 0x1000 2563 1 0x0002 5 0x0020 9 0x0200 13 0x2000 2564 2 0x0004 6 0x0040 10 0x0400 14 0x4000 2565 3 0x0008 7 0x0080 11 0x0800 15 0x8000 2566.Ed 2567.It Cd options PCKBC_CNATTACH_SELFTEST 2568Perform a self test of the keyboard controller before attaching it as a 2569console. 2570This might be necessary on machines where we boot on cold iron, and 2571pckbc refuses to talk until we request a self test. 2572Currently only the netwinder port uses it. 2573.It Cd options PCKBD_CNATTACH_MAY_FAIL 2574If this option is set the PS/2 keyboard will not be used as the console 2575if it cannot be found during boot. 2576This allows other keyboards, like USB, to be the console keyboard. 2577.It Cd options PCKBD_LAYOUT=layout 2578Sets the default keyboard layout, see 2579.Xr pckbd 4 . 2580.El 2581.Ss m68k-specific Options 2582.Bl -ohang 2583.It Cd options FPU_EMULATE 2584Include support for MC68881/MC68882 emulator. 2585.It Cd options FPSP 2586Include support for 68040 floating point. 2587.It Cd options M68020,M68030,M68040,M68060 2588Include support for a specific 2589.Tn CPU , 2590at least one (the one you are using) should be specified. 2591.It Cd options M060SP 2592Include software support for 68060. 2593This provides emulation of unimplemented 2594integer instructions as well as emulation of unimplemented floating point 2595instructions and data types and software support for floating point traps. 2596.El 2597.Ss powerpc-specific Options (OEA Only) 2598.Bl -ohang 2599.It Cd options PMAP_MEMLIMIT=value 2600Limit the amount of memory seen by the kernel to 2601.Ar value 2602bytes. 2603.It Cd options PTEGCOUNT=value 2604Specify the size of the page table as 2605.Ar value 2606PTE groups. 2607Normally, one PTEG is allocated per physical page frame. 2608.El 2609.Ss sparc-specific Options 2610.Bl -ohang 2611.It Cd options AUDIO_DEBUG 2612Enable simple event debugging of the logging of the 2613.Xr audio 4 2614device. 2615.It Cd options BLINK 2616Enable blinking of LED. 2617Blink rate is full cycle every N seconds for 2618N \*[Lt] then current load average. 2619See 2620.Xr getloadavg 3 . 2621.\" .It Cd options COLORFONT_CACHE 2622.\" What does this do? 2623.It Cd options COUNT_SW_LEFTOVERS 2624Count how many times the sw SCSI device has left 3, 2, 1 and 0 in the 2625sw_3_leftover, sw_2_leftover, sw_1_leftover, and sw_0_leftover 2626variables accessible from 2627.Xr ddb 4 . 2628See 2629.Xr sw 4 . 2630.It Cd options DEBUG_ALIGN 2631Adds debugging messages calls when user-requested alignment fault 2632handling happens. 2633.It Cd options DEBUG_EMUL 2634Adds debugging messages calls for emulated floating point and 2635alignment fixing operations. 2636.It Cd options DEBUG_SVR4 2637Prints registers messages calls for emulated SVR4 getcontext and 2638setcontext operations. 2639See 2640.Em options COMPAT_SVR4 . 2641.It Cd options EXTREME_DEBUG 2642Adds debugging functions callable from 2643.Xr ddb 4 . 2644The debug_pagetables, test_region and print_fe_map 2645functions print information about page tables for the SUN4M 2646platforms only. 2647.It Cd options EXTREME_EXTREME_DEBUG 2648Adds extra info to 2649.Em options EXTREME_DEBUG . 2650.It Cd options FPU_CONTEXT 2651Make 2652.Em options COMPAT_SVR4 2653getcontext and setcontext include floating point registers. 2654.It Cd options MAGMA_DEBUG 2655Adds debugging messages to the 2656.Xr magma 4 2657device. 2658.It Cd options RASTERCONS_FULLSCREEN 2659Use the entire screen for the console. 2660.It Cd options RASTERCONS_SMALLFONT 2661Use the Fixed font on the console, instead of the normal font. 2662.It Cd options SUN4 2663Support sun4 class machines. 2664.It Cd options SUN4C 2665Support sun4c class machines. 2666.It Cd options SUN4M 2667Support sun4m class machines. 2668.It Cd options SUN4_MMU3L 2669.\" XXX ??? 2670Enable support for sun4 3-level MMU machines. 2671.It Cd options V9 2672Enable SPARC V9 assembler in 2673.Xr ddb 4 . 2674.El 2675.Ss sparc64-specific Options 2676.Bl -ohang 2677.It Cd options AUDIO_DEBUG 2678Enable simple event debugging of the logging of the 2679.Xr audio 4 2680device. 2681.It Cd options BLINK 2682Enable blinking of LED. 2683Blink rate is full cycle every N seconds for 2684N \*[Lt] then current load average. 2685See 2686.Xr getloadavg 3 . 2687.El 2688.Ss x68k-specific Options 2689.Bl -ohang 2690.It Cd options EXTENDED_MEMORY 2691Include support for extended memory, e.g., TS-6BE16 and 060turbo on-board. 2692.It Cd options JUPITER 2693Include support for Jupiter-X MPU accelerator 2694.It Cd options ZSCONSOLE,ZSCN_SPEED=value 2695Use the built-in serial port as the system-console. 2696Speed is specified in bps, defaults to 9600. 2697.It Cd options ITE_KERNEL_ATTR=value 2698Set the kernel message attribute for ITE. 2699Value, an integer, is a logical or of the following values: 2700.Bl -tag -width 4n -compact -offset indent 2701.It 1 2702color inversed 2703.It 2 2704underlined 2705.It 4 2706bolded 2707.El 2708.El 2709.\" The following requests should be uncommented and used where appropriate. 2710.\" .Sh FILES 2711.\" .Sh EXAMPLES 2712.Sh SEE ALSO 2713.Xr config 1 , 2714.Xr gdb 1 , 2715.Xr ktrace 1 , 2716.Xr pmc 1 , 2717.Xr quota 1 , 2718.Xr vndcompress 1 , 2719.Xr gettimeofday 2 , 2720.Xr i386_get_mtrr 2 , 2721.Xr i386_iopl 2 , 2722.Xr msgctl 2 , 2723.Xr msgget 2 , 2724.Xr msgrcv 2 , 2725.Xr msgsnd 2 , 2726.Xr ntp_adjtime 2 , 2727.Xr ntp_gettime 2 , 2728.Xr reboot 2 , 2729.Xr semctl 2 , 2730.Xr semget 2 , 2731.Xr semop 2 , 2732.Xr shmat 2 , 2733.Xr shmctl 2 , 2734.Xr shmdt 2 , 2735.Xr shmget 2 , 2736.Xr sysctl 3 , 2737.Xr apm 4 , 2738.Xr ddb 4 , 2739.Xr inet 4 , 2740.Xr iso 4 , 2741.Xr md 4 , 2742.Xr pcibios 4 , 2743.Xr pcmcia 4 , 2744.Xr ppp 4 , 2745.Xr userconf 4 , 2746.Xr vnd 4 , 2747.Xr wscons 4 , 2748.Xr config 5 , 2749.Xr edquota 8 , 2750.Xr init 8 , 2751.Xr mdsetimage 8 , 2752.Xr mount_cd9660 8 , 2753.Xr mount_fdesc 8 , 2754.Xr mount_kernfs 8 , 2755.Xr mount_lfs 8 , 2756.Xr mount_mfs 8 , 2757.Xr mount_msdos 8 , 2758.Xr mount_nfs 8 , 2759.Xr mount_ntfs 8 , 2760.Xr mount_null 8 , 2761.Xr mount_portal 8 , 2762.Xr mount_procfs 8 , 2763.Xr mount_udf 8 , 2764.Xr mount_umap 8 , 2765.Xr mount_union 8 , 2766.Xr mrouted 8 , 2767.Xr newfs_lfs 8 , 2768.Xr ntpd 8 , 2769.Xr quotaon 8 , 2770.Xr rpc.rquotad 8 , 2771.Xr sysctl 8 , 2772.Xr in_getifa 9 2773.Sh HISTORY 2774The 2775.Nm 2776man page first appeared in 2777.Nx 1.3 . 2778.Sh BUGS 2779The 2780.Em EON 2781option should be a pseudo-device, and is also very fragile. 2782