1.\" $NetBSD: options.4,v 1.426 2013/07/22 13:56:46 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 July 22, 2013 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 KERNHIST 645Enables the kernel history logs, which create in-memory traces of 646various kernel activities. 647These logs can be displayed by using 648.Cm show kernhist 649from DDB. 650See the kernel source file sys/kern/kern_history.c for details. 651.It Cd options KERNHIST_PRINT 652Prints the kernel history logs on the system console as entries are added. 653Note that the output is 654.Em extremely 655voluminous, so this option is really only useful for debugging 656the very earliest parts of kernel initialization. 657.It Cd options UVMHIST 658Like 659.Em KERNHIST , 660it enables the UVM history logs. 661These logs can be displayed by using 662.Cm show kernhist 663from DDB. 664See the kernel source file sys/uvm/uvm_stat.c for details. 665.It Cd options UVMHIST_PRINT 666Like 667.Em UVMHIST , 668it prints the UVM history logs on the system console as entries are added. 669Note that the output is 670.Em extremely 671voluminous, so this option is really only useful for debugging 672the very earliest parts of kernel initialization. 673.El 674.Ss File Systems 675.Bl -ohang 676.It Cd file-system FFS 677Includes code implementing the Berkeley Fast File System 678.Po Em FFS Pc . 679Most machines need this if they are not running diskless. 680.It Cd file-system EXT2FS 681Includes code implementing the Second Extended File System 682.Po Em ext2 Pc , 683revision 0 and revision 1 with the 684.Em filetype , 685.Em sparse_super 686and 687.Em large_file 688options. 689This is the most commonly used file system on the Linux operating system, 690and is provided here for compatibility. 691Some of the specific features of 692.Em ext2 693like the "behavior on errors" are not implemented. 694See 695.Xr mount_ext2fs 8 696for details. 697.It Cd file-system LFS 698.Bq Em EXPERIMENTAL 699Include the Log-structured File System 700.Po Em LFS Pc . 701See 702.Xr mount_lfs 8 703and 704.Xr newfs_lfs 8 705for details. 706.It Cd file-system MFS 707Include the Memory File System 708.Po Em MFS Pc . 709This file system stores files in swappable memory, and produces 710notable performance improvements when it is used as the file store 711for 712.Pa /tmp 713and similar file systems. 714See 715.Xr mount_mfs 8 716for details. 717.It Cd file-system NFS 718Include the client side of the Network File System 719.Pq Tn NFS 720remote file sharing protocol. 721Although the bulk of the code implementing 722.Tn NFS 723is kernel based, several user level daemons are needed for it to work. 724See 725.Xr mount_nfs 8 726for details. 727.It Cd file-system CD9660 728Includes code for the 729.Tn ISO 7309660 + Rock Ridge file system, which is the standard file system on many 731.Tn CD-ROM 732discs. 733Useful primarily if you have a 734.Tn CD-ROM 735drive. 736See 737.Xr mount_cd9660 8 738for details. 739.It Cd file-system MSDOSFS 740Includes the 741.Tn MS-DOS 742FAT file system, which is reportedly still used 743by unfortunate people who have not heard about 744.Nx . 745Also implements the 746.Tn Windows 95 747extensions to the same, which permit the use of longer, mixed case 748file names. 749See 750.Xr mount_msdos 8 751and 752.Xr fsck_msdos 8 753for details. 754.It Cd file-system NTFS 755.Bq Em EXPERIMENTAL 756Includes code for the 757.Tn Microsoft Windows NT 758file system. 759See 760.Xr mount_ntfs 8 761for details. 762.It Cd file-system FDESC 763Includes code for a file system, conventionally mounted on 764.Pa /dev/fd , 765which permits access to the per-process file descriptor space via 766special files in the file system. 767See 768.Xr mount_fdesc 8 769for details. 770Note that this facility is redundant, and thus unneeded on most 771.Nx 772systems, since the 773.Xr fd 4 774pseudo-device driver already provides identical functionality. 775On most 776.Nx 777systems, instances of 778.Xr fd 4 779are mknoded under 780.Pa /dev/fd/ 781and on 782.Pa /dev/stdin , 783.Pa /dev/stdout , 784and 785.Pa /dev/stderr . 786.It Cd file-system KERNFS 787Includes code which permits the mounting of a special file system 788(normally mounted on 789.Pa /kern ) 790in which files representing various kernel variables and parameters 791may be found. 792See 793.Xr mount_kernfs 8 794for details. 795.It Cd file-system NULLFS 796Includes code for a loopback file system. 797This permits portions of the file hierarchy to be re-mounted in other places. 798The code really exists to provide an example of a stackable file system layer. 799See 800.Xr mount_null 8 801for details. 802.It Cd file-system OVERLAY 803Includes code for a file system filter. 804This permits the overlay file system to intercept all access to an underlying 805file system. 806This file system is intended to serve as an example of a stacking file 807system which has a need to interpose itself between an underlying file 808system and all other access. 809See 810.Xr mount_overlay 8 811for details. 812.It Cd file-system PROCFS 813Includes code for a special file system (conventionally mounted on 814.Pa /proc ) 815in which the process space becomes visible in the file system. 816Among 817other things, the memory spaces of processes running on the system are 818visible as files, and signals may be sent to processes by writing to 819.Pa ctl 820files in the procfs namespace. 821See 822.Xr mount_procfs 8 823for details. 824.It Cd file-system UDF 825.Bq Em EXPERIMENTAL 826Includes code for the UDF file system commonly found on CD and DVD 827media but also on USB sticks. 828Currently supports read and write access upto UDF 2.01 and somewhat limited 829write support for UDF 2.50. 830It is marked experimental since there is no 831.Xr fsck_udf 8 . 832See 833.Xr mount_udf 8 834for details. 835.It Cd file-system UMAPFS 836Includes a loopback file system in which user and group IDs may be 837remapped -- this can be useful when mounting alien file systems with 838different UIDs and GIDs than the local system. 839See 840.Xr mount_umap 8 841for details. 842.It Cd file-system UNION 843.Bq Em EXPERIMENTAL 844Includes code for the union file system, which permits directories to 845be mounted on top of each other in such a way that both file systems 846remain visible -- this permits tricks like allowing writing (and the 847deleting of files) on a read-only file system like a 848.Tn CD-ROM 849by mounting a local writable file system on top of the read-only file system. 850See 851.Xr mount_union 8 852for details. 853.It Cd file-system CODA 854.Bq Em EXPERIMENTAL 855Includes code for the Coda file system. 856Coda is a distributed file system like NFS and AFS. 857It is freely available, like NFS, but it functions much like AFS in being a 858.Dq stateful 859file system. 860Both Coda and AFS cache files on your local machine to improve performance. 861Then Coda goes a step further than AFS by letting you access the cached 862files when there is no available network, viz. disconnected laptops and 863network outages. 864In Coda, both the client and server are outside the kernel which makes 865them easier to experiment with. 866Coda is available for several UNIX and non-UNIX platforms. 867See 868.Lk http://www.coda.cs.cmu.edu 869for more details. 870.Em NOTE : 871You also need to enable the pseudo-device, vcoda, for the Coda 872file system to work. 873.It Cd file-system SMBFS 874.Bq Em EXPERIMENTAL 875Includes code for the SMB/CIFS file system. 876See 877.Xr mount_smbfs 8 878for details. 879.Em NOTE : 880You also need to enable the pseudo-device, nsmb, for the SMB 881file system to work. 882.It Cd file-system PTYFS 883.Bq Em EXPERIMENTAL 884Includes code for a special file system (normally mounted on 885.Pa /dev/pts ) 886in which pseudo-terminal slave devices become visible in the file system. 887See 888.Xr mount_ptyfs 8 889for details. 890.It Cd file-system TMPFS 891Includes code for the efficient memory file system, normally used over 892.Pa /tmp . 893See 894.Xr mount_tmpfs 8 895for details. 896.It Cd file-system PUFFS 897Includes kernel support for the pass-to-userspace framework file system. 898It can be used to implement file system functionality in userspace. 899See 900.Xr puffs 3 901for more details. 902This enables for example sshfs: 903.Xr mount_psshfs 8 . 904.El 905.Ss File System Options 906.Bl -ohang 907.It Cd options MAGICLINKS 908Enables the expansion of special strings 909.Po 910beginning with 911.Dq @ 912.Pc 913when traversing symbolic links. 914See 915.Xr symlink 7 916for a list of supported strings. 917Note that this option only controls the enabling of this feature 918by the kernel at boot-up. 919This feature can still be manipulated with the 920.Xr sysctl 8 921command regardless of the setting of this option. 922.It Cd options NFSSERVER 923Include the server side of the 924.Em NFS 925(Network File System) remote file sharing protocol. 926Although the bulk of the code implementing 927.Em NFS 928is kernel based, several user level daemons are needed for it to 929work. 930See 931.Xr mountd 8 932and 933.Xr nfsd 8 934for details. 935.It Cd options QUOTA 936Enables kernel support for file system quotas. 937See 938.Xr quotaon 8 , 939.Xr edquota 8 , 940and 941.Xr quota 1 942for details. 943Note that quotas only work on 944.Dq ffs 945file systems, although 946.Xr rpc.rquotad 8 947permits them to be accessed over 948.Em NFS . 949.It Cd options QUOTA2 950Enables kernel support for the new file system quotas format. 951See 952.Xr tunefs 8 , 953.Xr newfs 8 , 954.Xr mount_mfs 8 , 955.Xr edquota 8 , 956and 957.Xr quota 1 958for details. 959Note that quota2 is only supported by 960.Dq ffs 961and 962.Dq mfs 963file systems at this time. 964.It Cd options FFS_EI 965Enable ``Endian-Independent'' FFS support. 966This allows a system to mount an FFS file system created for another 967architecture, at a small performance cost for all FFS file systems. 968See also 969.Xr newfs 8 , 970.Xr fsck_ffs 8 , 971.Xr dumpfs 8 972for file system byte order status and manipulation. 973.It Cd options FFS_NO_SNAPSHOT 974Disable support for the creation of file system internal snapshot 975of FFS file systems. 976Maybe useful for install media kernels, small memory systems and 977embedded systems which don't require the snapshot support. 978.It Cd options UFS_EXTATTR 979Enable extended attribute support for UFS1 filesystems. 980.It Cd options WAPBL 981Enable 982.Dq Write Ahead Physical Block Logging file system journaling . 983This provides rapid file system consistency checking after a system outage. 984It also provides better general use performance over regular FFS. 985See also 986.Xr wapbl 4 . 987.It Cd options NVNODE=integer 988This option sets the size of the cache used by the name-to-inode translation 989routines, (a.k.a. the 990.Fn namei 991cache, though called by many other names in the kernel source). 992By default, this cache has 993.Dv NPROC 994(set as 20 + 16 * MAXUSERS) * (80 + NPROC / 8) entries. 995A reasonable way to derive a value of 996.Dv NVNODE , 997should you notice a large number of namei cache misses with a tool such as 998.Xr systat 1 , 999is to examine your system's current computed value with 1000.Xr sysctl 8 , 1001(which calls this parameter "kern.maxvnodes") and to increase this value 1002until either the namei cache hit rate improves or it is determined that 1003your system does not benefit substantially from an increase in the size of 1004the namei cache. 1005.It Cd options NAMECACHE_ENTER_REVERSE 1006Causes the namei cache to always enter a reverse mapping (vnode -\*[Gt] name) 1007as well as a normal one. 1008Normally, this is already done for directory vnodes, to speed up the getcwd 1009operation. 1010This option will cause longer hash chains in the reverse cache, and thus 1011slow down getcwd somewhat. 1012However, it does make vnode -\*[Gt] path translations possible in some cases. 1013For now, only useful if strict /proc/#/maps emulation for Linux binaries is 1014required. 1015.It Cd options EXT2FS_SYSTEM_FLAGS 1016This option changes the behavior of the APPEND and IMMUTABLE flags 1017for a file on an 1018.Em ext2 1019file system. 1020Without this option, the superuser or owner of the file can 1021set and clear them. 1022With this option, only the superuser can set them, and 1023they can't be cleared if the securelevel is greater than 0. 1024See also 1025.Xr chflags 1 1026and 1027.Xr secmodel_securelevel 9 . 1028.It Cd options NFS_BOOT_BOOTP 1029Enable use of the BOOTP protocol (RFCs 951 and 1048) to get configuration 1030information if NFS is used to mount the root file system. 1031See 1032.Xr diskless 8 1033for details. 1034.It Cd options NFS_BOOT_BOOTSTATIC 1035Enable use of static values defined as 1036.Dq NFS_BOOTSTATIC_MYIP , 1037.Dq NFS_BOOTSTATIC_GWIP , 1038.Dq NFS_BOOTSTATIC_SERVADDR , 1039and 1040.Dq NFS_BOOTSTATIC_SERVER 1041in kernel options to get configuration information 1042if NFS is used to mount the root file system. 1043.It Cd options NFS_BOOT_DHCP 1044Same as 1045.Dq NFS_BOOT_BOOTP , 1046but use the DHCP extensions to the 1047BOOTP protocol (RFC 1541). 1048.It Cd options NFS_BOOT_BOOTP_REQFILE 1049Specifies the string sent in the bp_file field of the BOOTP / DHCP 1050request packet. 1051.It Cd options NFS_BOOT_BOOTPARAM 1052Enable use of the BOOTPARAM protocol, consisting of RARP and 1053BOOTPARAM RPC, to get configuration information if NFS 1054is used to mount the root file system. 1055See 1056.Xr diskless 8 1057for details. 1058.It Cd options NFS_BOOT_RWSIZE=value 1059Set the initial NFS read and write sizes for diskless-boot requests. 1060The normal default is 8Kbytes. 1061This option provides a way to lower the value (e.g., to 1024 bytes) 1062as a workaround for buggy network interface cards or boot PROMs. 1063Once booted, the read and write request sizes can be increased by 1064remounting the file system. 1065See 1066.Xr mount_nfs 8 1067for details. 1068.It Cd options NFS_V2_ONLY 1069Reduce the size of the NFS client code by omitting code that's only required 1070for NFSv3 and NQNFS support, leaving only that code required to use NFSv2 1071servers. 1072.It Cd options UFS_DIRHASH 1073Increase lookup performance by maintaining in-core hash tables 1074for large directories. 1075.El 1076.Ss Buffer queue strategy options 1077The following options enable alternative buffer queue strategies. 1078.Bl -ohang 1079.It Cd options BUFQ_READPRIO 1080Enable experimental buffer queue strategy for disk I/O. 1081In the default strategy, outstanding disk requests are ordered by 1082sector number and sent to the disk, regardless of whether the 1083operation is a read or write; this option gives priority to issuing 1084read requests over write requests. 1085Although requests may therefore be issued out of sector-order, causing 1086more seeks and thus lower overall throughput, interactive system 1087responsiveness under heavy disk I/O load may be improved, as processes 1088blocking on disk reads are serviced sooner (file writes typically 1089don't cause applications to block). 1090The performance effect varies greatly depending on the hardware, drive 1091firmware, file system configuration, workload, and desired performance 1092trade-off. 1093Systems using drive write-cache (most modern IDE disks, by default) 1094are unlikely to benefit and may well suffer; such disks acknowledge 1095writes very quickly, and optimize them internally according to 1096physical layout. 1097Giving these disks as many requests to work with as possible (the 1098standard strategy) will typically produce the best results, especially 1099if the drive has a large cache; the drive will silently complete 1100writes from cache as it seeks for reads. 1101Disks that support a large number of concurrent tagged requests (SCSI 1102disks and many hardware RAID controllers) expose this internal 1103scheduling with tagged responses, and don't block for reads; such 1104disks may not see a noticeable difference with either strategy. 1105However, if IDE disks are run with write-cache disabled for safety, 1106writes are not acknowledged until actually completed, and only one 1107request can be outstanding; a large number of small writes in one 1108locality can keep the disk busy, starving reads elsewhere on the disk. 1109Such systems are likely to see the most benefit from this option. 1110Finally, the performance interaction of this option with ffs soft 1111dependencies can be subtle, as that mechanism can drastically alter 1112the workload for file system metadata writes. 1113.It Cd options BUFQ_PRIOCSCAN 1114Enable another buffer queue strategy for disk I/O, per-priority cyclical scan. 1115.It Cd options NEW_BUFQ_STRATEGY 1116Synonym of 1117.Em BUFQ_READPRIO . 1118.El 1119.Ss Miscellaneous Options 1120.Bl -ohang 1121.It Cd options CPU_UCODE 1122Support cpu microcode loading via 1123.Xr cpuctl 8 . 1124.It Cd options MEMORY_DISK_DYNAMIC 1125This option makes the 1126.Xr md 4 1127.Tn RAM 1128disk size dynamically sized. 1129It is incompatible with 1130.Xr mdsetimage 8 . 1131.It Cd options MEMORY_DISK_HOOKS 1132This option allows for some machine dependent functions to be called when 1133the 1134.Xr md 4 1135.Tn RAM 1136disk driver is configured. 1137This can result in automatically loading a 1138.Tn RAM 1139disk from floppy on open (among other things). 1140.It Cd options MEMORY_DISK_IS_ROOT 1141Forces the 1142.Xr md 4 1143.Tn RAM 1144disk to be the root device. 1145This can only be overridden when 1146the kernel is booted in the 'ask-for-root' mode. 1147.It Cd options MEMORY_DISK_ROOT_SIZE=integer 1148Allocates the given number of 512 byte blocks as memory for the 1149.Xr md 4 1150.Tn RAM 1151disk, to be populated with 1152.Xr mdsetimage 8 . 1153.It Cd options MEMORY_DISK_SERVER=0 1154Do not include the interface to a userland memory disk server process. 1155Per default, this option is set to 1, including the support code. 1156Useful for install media kernels. 1157.It Cd options MEMORY_DISK_RBFLAGS=value 1158This option sets the 1159.Xr reboot 2 1160flags used when booting with a memory disk as root file system. 1161Possible values include 1162.Dv RB_AUTOBOOT 1163(boot in the usual fashion - default value), and 1164.Dv RB_SINGLE 1165(boot in single-user mode). 1166.It Cd options MODULAR 1167Enables the framework for kernel modules (see 1168.Xr module 7 ) . 1169.It Cd options VND_COMPRESSION 1170Enables the 1171.Xr vnd 4 1172driver to also handle compressed images. 1173See 1174.Xr vndcompress 1 , 1175.Xr vnd 4 1176and 1177.Xr vnconfig 8 1178for more information. 1179.It Cd options SPLDEBUG 1180Help the kernel programmer find bugs related to the interrupt priority 1181level. 1182When 1183.Fn spllower 1184or 1185.Fn splraise 1186changes the current CPU's interrupt priority level to or from 1187.Dv IPL_HIGH , 1188record a backtrace. 1189Read 1190.Xr return_address 9 1191for caveats about collecting backtraces. 1192This feature is experimental, and it is only available on i386. 1193See 1194.Pa sys/kern/subr_spldebug.c . 1195.It Cd options TFTPROOT 1196Download the root memory disk through TFTP at root mount time. 1197This enables the use of a root 1198.Tn RAM 1199disk without requiring it to be embedded in the kernel using 1200.Xr mdsetimage 8 . 1201The 1202.Tn RAM 1203disk name is obtained using DHCP's filename parameter. 1204This option requires 1205.Em MEMORY_DISK_HOOKS , 1206.Em MEMORY_DISK_DYNAMIC , 1207and 1208.Em MEMORY_DISK_IS_ROOT . 1209It is incompatible with 1210.Em MEMORY_DISK_ROOT_SIZE . 1211.It Cd options MALLOC_NOINLINE 1212Time critical fixed size memory allocation is performed with 1213.Fn MALLOC 1214and 1215.Fn FREE . 1216Normally these expand to inline code, but with 1217.Em MALLOC_NOINLINE 1218these call the normal 1219.Fn malloc 1220and 1221.Fn free 1222functions. 1223Useful for install media kernels, small memory systems and embedded systems. 1224.It Cd options HZ=integer 1225On ports that support it, set the system clock frequency (see 1226.Xr hz 9 ) 1227to the supplied value. 1228Handle with care. 1229.It Cd options NTP 1230Turns on in-kernel precision timekeeping support used by software 1231implementing 1232.Em NTP 1233(Network Time Protocol, RFC 1305). 1234The 1235.Em NTP 1236option adds an in-kernel Phase-Locked Loop (PLL) for normal 1237.Em NTP 1238operation, and a Frequency-Locked Loop (FLL) for intermittently-connected 1239operation. 1240.Xr ntpd 8 1241will employ a user-level PLL when kernel support is unavailable, 1242but the in-kernel version has lower latency and more precision, and 1243so typically keeps much better time. 1244.Pp 1245The interface to the kernel 1246.Em NTP 1247support is provided by the 1248.Xr ntp_adjtime 2 1249and 1250.Xr ntp_gettime 2 1251system calls, which are intended for use by 1252.Xr ntpd 8 1253and are enabled by the option. 1254On systems with sub-microsecond resolution timers, or where (HZ / 100000) 1255is not an integer, the 1256.Em NTP 1257option also enables extended-precision arithmetic to keep track of 1258fractional clock ticks at NTP time-format precision. 1259.It Cd options PPS_SYNC 1260This option enables a kernel serial line discipline for receiving time 1261phase signals from an external reference clock such as a radio clock. 1262.Po 1263The 1264.Em NTP 1265option (which see) must be on if the 1266.Em PPS_SYNC 1267option is used 1268.Pc . 1269Some reference clocks generate a Pulse Per Second (PPS) signal in 1270phase with their time source. 1271The 1272.Em PPS 1273line discipline receives this signal on either the data leads 1274or the DCD control lead of a serial port. 1275.Pp 1276.Em NTP 1277uses the PPS signal to discipline the local clock oscillator to a high 1278degree of precision (typically less than 50 microseconds in time and 12790.1 ppm in accuracy). 1280.Em PPS 1281can also generate a serial output pulse when the system receives a PPS 1282interrupt. 1283This can be used to measure the system interrupt latency and thus calibrate 1284.Em NTP 1285to account for it. 1286Using 1287.Em PPS 1288usually requires a gadget box 1289to convert from 1290.Tn TTL 1291to 1292.Tn RS-232 1293signal levels. 1294The gadget box and PPS are described in more detail in the HTML documentation 1295for 1296.Xr ntpd 8 1297in 1298.Pa /usr/share/doc/html/ntp . 1299.Pp 1300.Nx 1301currently supports this option in 1302.Xr com 4 1303and 1304.Xr zsc 4 . 1305.It Cd options SETUIDSCRIPTS 1306Allows scripts with the setuid bit set to execute as the effective 1307user rather than the real user, just like binary executables. 1308.Pp 1309.Em NOTE : 1310Using this option will also enable 1311.Em options FDSCRIPTS 1312.It Cd options FDSCRIPTS 1313Allows execution of scripts with the execute bit set, but not the 1314read bit, by opening the file and passing the file descriptor to 1315the shell, rather than the filename. 1316.Pp 1317.Em NOTE : 1318Execute only (non-readable) scripts will have 1319.Va argv[0] 1320set to 1321.Pa /dev/fd/* . 1322What this option allows as far as security is 1323concerned, is the ability to safely ensure that the correct script 1324is run by the interpreter, as it is passed as an already open file. 1325.It Cd options RTC_OFFSET=integer 1326The kernel (and typically the hardware battery backed-up clock on 1327those machines that have one) keeps time in 1328.Em UTC 1329(Universal Coordinated Time, once known as 1330.Em GMT , 1331or Greenwich Mean Time) 1332and not in the time of the local time zone. 1333The 1334.Em RTC_OFFSET 1335option is used on some ports (such as the i386) to tell the kernel 1336that the hardware clock is offset from 1337.Em UTC 1338by the specified number of minutes. 1339This is typically used when a machine boots several operating 1340systems and one of them wants the hardware clock to run in the 1341local time zone and not in 1342.Em UTC , 1343e.g. 1344.Em RTC_OFFSET=300 1345means 1346the hardware clock is set to US Eastern Time (300 minutes behind 1347.Em UTC ) , 1348and not 1349.Em UTC . 1350(Note: 1351.Em RTC_OFFSET 1352is used to initialize a kernel variable named 1353.Va rtc_offset 1354which is the source actually used to determine the clock offset, and 1355which may be accessed via the kern.rtc_offset sysctl variable. 1356See 1357.Xr sysctl 8 1358and 1359.Xr sysctl 3 1360for details. 1361Since the kernel clock is initialized from the hardware clock very 1362early in the boot process, it is not possible to meaningfully change 1363.Va rtc_offset 1364in system initialization scripts. 1365Changing this value currently may only be done at kernel compile 1366time or by patching the kernel and rebooting). 1367.Pp 1368.Em NOTE : 1369Unfortunately, in many cases where the hardware clock 1370is kept in local time, it is adjusted for Daylight Savings 1371Time; this means that attempting to use 1372.Em RTC_OFFSET 1373to let 1374.Nx 1375coexist with such an operating system, like Windows, 1376would necessitate changing 1377.Em RTC_OFFSET 1378twice a year. 1379As such, this solution is imperfect. 1380.It Cd options KMEMSTATS 1381The kernel memory allocator, 1382.Xr malloc 9 , 1383will keep statistics on its performance if this option is enabled. 1384Unfortunately, this option therefore essentially disables the 1385.Fn MALLOC 1386and 1387.Fn FREE 1388forms of the memory allocator, which are used to enhance the performance 1389of certain critical sections of code in the kernel. 1390This option therefore can lead to a significant decrease in the 1391performance of certain code in the kernel if enabled. 1392Examples of such code include the 1393.Fn namei 1394routine, the 1395.Xr ccd 4 1396driver, 1397and much of the networking code. 1398.It Cd options MAXUPRC=integer 1399Sets the soft 1400.Dv RLIMIT_NPROC 1401resource limit, which specifies the maximum number of simultaneous 1402processes a user is permitted to run, for process 0; 1403this value is inherited by its child processes. 1404It defaults to 1405.Em CHILD_MAX , 1406which is currently defined to be 160. 1407Setting 1408.Em MAXUPRC 1409to a value less than 1410.Em CHILD_MAX 1411is not permitted, as this would result in a violation of the semantics of 1412.St -p1003.1-90 . 1413.It Cd options NOFILE=integer 1414Sets the soft 1415.Dv RLIMIT_NOFILE 1416resource limit, which specifies the maximum number of open 1417file descriptors for each process; 1418this value is inherited by its child processes. 1419It defaults to 1420.Em OPEN_MAX , 1421which is currently defined to be 64. 1422.It Cd options MAXFILES=integer 1423Sets the default value of the 1424.Em kern.maxfiles 1425sysctl variable, which indicates the maximum number of files that may 1426be open in the system. 1427.It Cd options DEFCORENAME=string 1428Sets the default value of the 1429.Em kern.defcorename 1430sysctl variable, otherwise it is set to 1431.Nm %n.core . 1432See 1433.Xr sysctl 8 1434and 1435.Xr sysctl 3 1436for details. 1437.It Cd options RASOPS_CLIPPING 1438Enables clipping within the 1439.Nm rasops 1440raster-console output system. 1441.Em NOTE : 1442only available on architectures that use 1443.Nm rasops 1444for console output. 1445.It Cd options RASOPS_SMALL 1446Removes optimized character writing code from the 1447.Nm rasops 1448raster-console output system. 1449.Em NOTE : 1450only available on architectures that use 1451.Nm rasops 1452for console output. 1453.It Cd options INCLUDE_CONFIG_FILE 1454Embeds the kernel config file used to define the kernel in the kernel 1455binary itself. 1456The embedded data also includes any files directly included by the config 1457file itself, e.g. 1458.Pa GENERIC.local 1459or 1460.Pa std.$MACHINE . 1461The embedded config file can be extracted from the resulting kernel with 1462.Xr config 1 1463.Fl x , 1464or by the following command: 1465.Bd -literal -offset indent 1466strings netbsd | sed -n 's/^_CFG_//p' | unvis 1467.Ed 1468.It Cd options INCLUDE_JUST_CONFIG 1469Similar to the above option, but includes just the actual config file, 1470not any included files. 1471.It Cd options PIPE_SOCKETPAIR 1472Use slower, but smaller socketpair(2)-based pipe implementation instead 1473of default faster, but bigger one. 1474Primarily useful for installation kernels. 1475.It Cd options USERCONF 1476Compiles in the in-kernel device configuration manager. 1477See 1478.Xr userconf 4 1479for details. 1480.It Cd options PERFCTRS 1481Compiles in kernel support for CPU performance-monitoring counters. 1482See 1483.Xr pmc 1 1484for details. 1485.Em NOTE : 1486not available on all architectures. 1487.It Cd options SYSCALL_STATS 1488Count the number of times each system call number is called. 1489The values can be read through the sysctl interface and displayed using 1490.Xr systat 1 . 1491.Em NOTE : 1492not yet available on all architectures. 1493.It Cd options SYSCALL_TIMES 1494Count the time spent (using 1495.Fn cpu_counter32 ) 1496in each system call. 1497.Em NOTE : 1498Using this option will also enable 1499.Cd options SYSCALL_STATS . 1500.It Cd options SYSCALL_TIMES_HASCOUNTER 1501Force use of 1502.Fn cpu_counter32 1503even if 1504.Fn cpu_hascounter 1505reports false. 1506Useful for systems where the cycle counter doesn't run at a constant rate 1507(e.g. Soekris boxes). 1508.It Cd options XSERVER_DDB 1509A supplement to XSERVER that adds support for entering 1510.Xr ddb 4 1511while in 1512.Tn X11 . 1513.It Cd options FILEASSOC 1514Support for 1515.Xr fileassoc 9 . 1516.It Cd options FILEASSOC_NHOOKS=integer 1517Number of storage slots per file for 1518.Xr fileassoc 9 . 1519Default is 4. 1520.El 1521.Ss Networking Options 1522.Bl -ohang 1523.It Cd options GATEWAY 1524Enables 1525.Em IPFORWARDING 1526(which see) 1527and (on most ports) increases the size of 1528.Em NMBCLUSTERS 1529(which see). 1530In general, 1531.Em GATEWAY 1532is used to indicate that a system should act as a router, and 1533.Em IPFORWARDING 1534is not invoked directly. 1535(Note that 1536.Em GATEWAY 1537has no impact on protocols other than 1538.Tn IP , 1539such as 1540.Tn CLNP ) . 1541.Em GATEWAY 1542option also compiles IPv4 and IPv6 fast forwarding code into the kernel. 1543.It Cd options ICMPPRINTFS 1544The 1545.Em ICMPPRINTFS 1546option will enable debugging information to be printed about 1547the 1548.Xr icmp 4 1549protocol. 1550.It Cd options IPFORWARDING=value 1551If 1552.Em value 1553is 1 this enables IP routing behavior. 1554If 1555.Em value 1556is 0 (the default), it disables it. 1557The 1558.Em GATEWAY 1559option sets this to 1 automatically. 1560With this option enabled, the machine will forward IP datagrams destined 1561for other machines between its interfaces. 1562Note that even without this option, the kernel will 1563still forward some packets (such as source routed packets) -- removing 1564.Em GATEWAY 1565and 1566.Em IPFORWARDING 1567is insufficient to stop all routing through a bastion host on a 1568firewall -- source routing is controlled independently. 1569To turn off source routing, use 1570.Em options IPFORWSRCRT=0 1571(which see). 1572Note that IP forwarding may be turned on and off independently of the 1573setting of the 1574.Em IPFORWARDING 1575option through the use of the 1576.Em net.inet.ip.forwarding 1577sysctl variable. 1578If 1579.Em net.inet.ip.forwarding 1580is 1, IP forwarding is on. 1581See 1582.Xr sysctl 8 1583and 1584.Xr sysctl 3 1585for details. 1586.It Cd options IPFORWSRCRT=value 1587If 1588.Em value 1589is set to zero, source routing of IP datagrams is turned off. 1590If 1591.Em value 1592is set to one (the default) or the option is absent, source routed IP 1593datagrams are forwarded by the machine. 1594Note that source routing of IP packets may be turned on and off 1595independently of the setting of the 1596.Em IPFORWSRCRT 1597option through the use of the 1598.Em net.inet.ip.forwsrcrt 1599sysctl variable. 1600If 1601.Em net.inet.ip.forwsrcrt 1602is 1, forwarding of source routed IP datagrams is on. 1603See 1604.Xr sysctl 8 1605and 1606.Xr sysctl 3 1607for details. 1608.It Cd options IFA_STATS 1609Tells the kernel to maintain per-address statistics on bytes sent 1610and received over (currently) Internet and AppleTalk addresses. 1611.\"This can be a fairly expensive operation, so you probably want to 1612.\"keep this disabled. 1613The option is not recommended as it degrades system stability. 1614.It Cd options IFQ_MAXLEN=value 1615Increases the allowed size of the network interface packet queues. 1616The default queue size is 50 packets, and you do not normally need 1617to increase it. 1618.It Cd options IPSELSRC 1619Includes support for source-address selection policies. 1620See 1621.Xr in_getifa 9 . 1622.It Cd options MROUTING 1623Includes support for IP multicast routers. 1624You certainly want 1625.Em INET 1626with this. 1627Multicast routing is controlled by the 1628.Xr mrouted 8 1629daemon. 1630See also option 1631.Cd PIM . 1632.It Cd options PIM 1633Includes support for Protocol Independent Multicast (PIM) routing. 1634You need 1635.Em MROUTING 1636and 1637.Em INET 1638with this. 1639Software using this can be found e.g. in 1640.Pa pkgsrc/net/xorp . 1641.It Cd options INET 1642Includes support for the 1643.Tn TCP/IP 1644protocol stack. 1645You almost certainly want this. 1646See 1647.Xr inet 4 1648for details. 1649.It Cd options INET6 1650Includes support for the 1651.Tn IPv6 1652protocol stack. 1653See 1654.Xr inet6 4 1655for details. 1656Unlike 1657.Em INET , 1658.Em INET6 1659enables multicast routing code as well. 1660This option requires 1661.Em INET 1662at this moment, but it should not. 1663.It Cd options ND6_DEBUG 1664The option sets the default value of net.inet6.icmp6.nd6_debug to 1, 1665for debugging IPv6 neighbor discovery protocol handling. 1666See 1667.Xr sysctl 3 1668for details. 1669.It Cd options IPSEC 1670Includes support for the 1671.Tn IPsec 1672protocol, using the implementation derived from 1673.Ox , 1674relying on 1675.Xr opencrypto 9 1676to carry out cryptographic operations. 1677See 1678.Xr fast_ipsec 4 1679for details. 1680.It Cd options IPSEC_DEBUG 1681Enables debugging code in 1682.Tn IPsec 1683stack. 1684See 1685.Xr ipsec 4 1686for details. 1687The 1688.Cd IPSEC 1689option includes support for 1690.Tn IPsec 1691Network Address Translator traversal (NAT-T), as described in RFCs 3947 1692and 3948. 1693This feature might be patent-encumbered in some countries. 1694.It Cd options ALTQ 1695Enabled ALTQ (Alternate Queueing). 1696For simple rate-limiting, use 1697.Xr tbrconfig 8 1698to set up the interface transmission rate. 1699To use queueing disciplines, their appropriate kernel options should also 1700be defined (documented below). 1701Queueing disciplines are managed by 1702.Xr altqd 8 . 1703See 1704.Xr altq 9 1705for details. 1706.It Cd options ALTQ_HFSC 1707Include support for ALTQ-implemented HFSC (Hierarchical Fair Service Curve) 1708module. 1709HFSC supports both link-sharing and guaranteed real-time services. 1710HFSC employs a service curve based QoS model, and its unique feature 1711is an ability to decouple delay and bandwidth allocation. 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_PRIQ 1720Include support for ALTQ-implemented PRIQ (Priority Queueing). 1721PRIQ implements a simple priority-based queueing discipline. 1722A higher priority class is always served first. 1723Requires 1724.Em ALTQ_RED 1725to use the RED queueing discipline on HFSC classes, or 1726.Em ALTQ_RIO 1727to use the RIO queueing discipline on HFSC classes. 1728This option assumes 1729.Em ALTQ . 1730.It Cd options ALTQ_WFQ 1731Include support for ALTQ-implemented WFQ (Weighted Fair Queueing). 1732WFQ implements a weighted-round robin scheduler for a set of queues. 1733A weight can be assigned to each queue to give a different proportion 1734of the link capacity. 1735A hash function is used to map a flow to one of a set of queues. 1736This option assumes 1737.Em ALTQ . 1738.It Cd options ALTQ_FIFOQ 1739Include support for ALTQ-implemented FIFO queueing. 1740FIFOQ is a simple drop-tail FIFO (First In, First Out) queueing discipline. 1741This option assumes 1742.Em ALTQ . 1743.It Cd options ALTQ_RIO 1744Include support for ALTQ-implemented RIO (RED with In/Out). 1745The original RIO has 2 sets of RED parameters; one for in-profile 1746packets and the other for out-of-profile packets. 1747At the ingress of the network, profile meters tag packets as IN or 1748OUT based on contracted profiles for customers. 1749Inside the network, IN packets receive preferential treatment by 1750the RIO dropper. 1751ALTQ/RIO has 3 drop precedence levels defined for the Assured Forwarding 1752PHB of DiffServ (RFC 2597). 1753This option assumes 1754.Em ALTQ . 1755.It Cd options ALTQ_BLUE 1756Include support for ALTQ-implemented Blue buffer management. 1757Blue is another active buffer management mechanism. 1758This option assumes 1759.Em ALTQ . 1760.It Cd options ALTQ_FLOWVALVE 1761Include support for ALTQ-implemented Flowvalve. 1762Flowvalve is a simple implementation of a RED penalty box that identifies 1763and punishes misbehaving flows. 1764This option requires 1765.Em ALTQ_RED 1766and assumes 1767.Em ALTQ . 1768.It Cd options ALTQ_CDNR 1769Include support for ALTQ-implemented CDNR (diffserv traffic conditioner) 1770packet marking/manipulation. 1771Traffic conditioners are components to meter, mark, or drop incoming 1772packets according to some rules. 1773As opposed to queueing disciplines, traffic conditioners handle incoming 1774packets at an input interface. 1775This option assumes 1776.Em ALTQ . 1777.It Cd options ALTQ_NOPCC 1778Disables use of processor cycle counter to measure time in ALTQ. 1779This option should be defined for a non-Pentium i386 CPU which does not 1780have TSC, SMP (per-CPU counters are not in sync), or power management 1781which affects processor cycle counter. 1782This option assumes 1783.Em ALTQ . 1784.It Cd options ALTQ_IPSEC 1785Include support for IPsec in IPv4 ALTQ. 1786This option assumes 1787.Em ALTQ . 1788.It Cd options ALTQ_JOBS 1789Include support for ALTQ-implemented JoBS (Joint Buffer Management 1790and Scheduling). 1791This option assumes 1792.Em ALTQ . 1793.It Cd options ALTQ_AFMAP 1794Include support for an undocumented ALTQ feature that is used to map an IP 1795flow to an ATM VC (Virtual Circuit). 1796This option assumes 1797.Em ALTQ . 1798.It Cd options ALTQ_LOCALQ 1799Include support for ALTQ-implemented local queues. 1800Its practical use is undefined. 1801Assumes 1802.Em ALTQ . 1803.It Cd options SUBNETSARELOCAL 1804Sets default value for net.inet.ip.subnetsarelocal variable, which 1805controls whether non-directly-connected subnets of connected networks 1806are considered "local" for purposes of choosing the MSS for a TCP 1807connection. 1808This is mostly present for historic reasons and completely irrelevant if 1809you enable Path MTU discovery. 1810.It Cd options HOSTZEROBROADCAST 1811Sets default value for net.inet.ip.hostzerobroadcast variable, which 1812controls whether the zeroth host address of each connected subnet is 1813also considered a broadcast address. 1814Default value is "1", for compatibility with old systems; if this is 1815set to zero on all hosts on a subnet, you should be able to fit an extra 1816host per subnet on the 1817".0" address. 1818.It Cd options MCLSHIFT=value 1819This option is the base-2 logarithm of the size of mbuf clusters. 1820The 1821.Bx 1822networking stack keeps network packets in a linked 1823list, or chain, of kernel buffer objects called mbufs. 1824The system provides larger mbuf clusters as an optimization for 1825large packets, instead of using long chains for large packets. 1826The mbuf cluster size, 1827or 1828.Em MCLBYTES , 1829must be a power of two, and is computed as two raised to the power 1830.Em MCLSHIFT . 1831On systems with Ethernet network adapters, 1832.Em MCLSHIFT 1833is often set to 11, giving 2048-byte mbuf clusters, large enough to 1834hold a 1500-byte 1835.Tn Ethernet 1836frame in a single cluster. 1837Systems with network interfaces supporting larger frame sizes like 1838.Tn ATM , 1839.Tn FDDI , 1840or 1841.Tn HIPPI 1842may perform better with 1843.Em MCLSHIFT 1844set to 12 or 13, giving mbuf cluster sizes of 4096 and 8192 bytes, 1845respectively. 1846.It Cd options ISO,TPIP 1847Include support for the ubiquitous 1848.Tn OSI 1849protocol stack. 1850See 1851.Xr iso 4 1852for details. 1853This option assumes 1854.Em INET . 1855.It Cd options EON 1856Include support for tunneling 1857.Tn OSI 1858protocols over 1859.Tn IP . 1860Known to be broken, or at least very fragile, and undocumented. 1861.It Cd options NETATALK 1862Include support for the 1863.Tn AppleTalk 1864protocol stack. 1865The kernel provides provision for the 1866.Em Datagram Delivery Protocol 1867(DDP), providing SOCK_DGRAM support and 1868.Tn AppleTalk 1869routing. 1870This stack is used by the 1871.Em NETATALK 1872package, which adds support for 1873.Tn AppleTalk 1874server services via user libraries and applications. 1875.It Cd options BLUETOOTH 1876Include support for the 1877.Tn Bluetooth 1878protocol stack. 1879See 1880.Xr bluetooth 4 1881for details. 1882.It Cd options IPNOPRIVPORTS 1883Normally, only root can bind a socket descriptor to a so-called 1884.Dq privileged 1885.Tn TCP 1886port, that is, a port number in the range 0-1023. 1887This option eliminates those checks from the kernel. 1888This can be useful if there is a desire to allow daemons without 1889privileges to bind those ports, e.g., on firewalls. 1890The security tradeoffs in doing this are subtle. 1891This option should only be used by experts. 1892.It Cd options TCP_COMPAT_42 1893.Tn TCP 1894bug compatibility with 1895.Bx 4.2 . 1896In 1897.Bx 4.2 , 1898.Tn TCP 1899sequence numbers were 32-bit signed values. 1900Modern implementations of TCP use unsigned values. 1901This option clamps the initial sequence number to start in 1902the range 2^31 rather than the full unsigned range of 2^32. 1903Also, under 1904.Bx 4.2 , 1905keepalive packets must contain at least one byte or else 1906the remote end would not respond. 1907.It Cd options TCP_DEBUG 1908Record the last 1909.Em TCP_NDEBUG 1910TCP packets with SO_DEBUG set, and decode to the console if 1911.Em tcpconsdebug 1912is set. 1913.It Cd options TCP_NDEBUG 1914Number of packets to record for 1915.Em TCP_DEBUG . 1916Defaults to 100. 1917.It Cd options TCP_SENDSPACE=value 1918.It Cd options TCP_RECVSPACE=value 1919These options set the max TCP window size to other sizes than the default. 1920The TCP window sizes can be altered via 1921.Xr sysctl 8 1922as well. 1923.It Cd options TCP_INIT_WIN=value 1924This option sets the initial TCP window size for non-local connections, 1925which is used when the transmission starts. 1926The default size is 1, but if the machine should act more aggressively, 1927the initial size can be set to some other value. 1928The initial TCP window size can be set via 1929.Xr sysctl 8 1930as well. 1931.It Cd options PFIL_HOOKS 1932This option turns on the packet filter interface hooks. 1933See 1934.Xr pfil 9 1935for details. 1936This option assumes 1937.Em INET . 1938.It Cd options IPFILTER_LOG 1939This option, in conjunction with 1940.Em pseudo-device ipfilter , 1941enables logging of IP packets using IP-Filter. 1942.It Cd options IPFILTER_LOOKUP 1943This option enables the 1944IP-Filter 1945.Xr ippool 8 1946functionality to be enabled. 1947.It Cd options IPFILTER_COMPAT 1948This option enables older IP-Filter binaries to work. 1949.It Cd options IPFILTER_DEFAULT_BLOCK 1950This option sets the default policy of IP-Filter. 1951If it is set, IP-Filter will block packets by default. 1952.It Cd options BRIDGE_IPF 1953This option causes 1954.Em bridge 1955devices to use the IP and/or IPv6 filtering hooks, forming 1956a link-layer filter that uses protocol-layer rules. 1957This option assumes the presence of 1958.Em pseudo-device ipfilter . 1959.It Cd options MBUFTRACE 1960This option can help track down mbuf leaks. 1961When enabled, mbufs are tagged with the devices and protocols using them, 1962which slightly decreases network performance. 1963This additional information can be viewed with 1964.Xr netstat 1 : 1965.Dl Ic netstat Fl mssv 1966Not all devices or protocols support this option. 1967.El 1968.Ss Sysctl Related Options 1969.Bl -ohang 1970.It Cd options SYSCTL_DISALLOW_CREATE 1971Disallows the creation or deletion of nodes from the sysctl tree, as 1972well as the assigning of descriptions to nodes that lack them, by any 1973process. 1974These operations are still available to kernel sub-systems, including 1975loadable kernel modules. 1976.It Cd options SYSCTL_DISALLOW_KWRITE 1977Prevents processes from adding nodes to the sysctl tree that make 1978existing kernel memory areas writable. 1979Sections of kernel memory can still be read and new nodes that own 1980their own data may still be writable. 1981.It Cd options SYSCTL_DEBUG_SETUP 1982Causes the SYSCTL_SETUP routines to print a brief message when they 1983are invoked. 1984This is merely meant as an aid in determining the order in which 1985sections of the tree are created. 1986.It Cd options SYSCTL_DEBUG_CREATE 1987Prints a message each time 1988.Fn sysctl_create , 1989the function that adds nodes to the tree, is called. 1990.It Cd options SYSCTL_INCLUDE_DESCR 1991Causes the kernel to include short, human readable descriptions for 1992nodes in the sysctl tree. 1993The descriptions can be retrieved programmatically (see 1994.Xr sysctl 3 ) , 1995or by the sysctl binary itself (see 1996.Xr sysctl 8 ) . 1997The descriptions are meant to give an indication of the purpose and/or 1998effects of a given node's value, not replace the documentation for the 1999given subsystem as a whole. 2000.El 2001.Ss System V IPC Options 2002.Bl -ohang 2003.It Cd options SYSVMSG 2004Includes support for 2005.At V 2006style message queues. 2007See 2008.Xr msgctl 2 , 2009.Xr msgget 2 , 2010.Xr msgrcv 2 , 2011.Xr msgsnd 2 . 2012.It Cd options SYSVSEM 2013Includes support for 2014.At V 2015style semaphores. 2016See 2017.Xr semctl 2 , 2018.Xr semget 2 , 2019.Xr semop 2 . 2020.It Cd options SEMMNI=value 2021Sets the number of 2022.At V 2023style semaphore identifiers. 2024The GENERIC config file for your port will have the default. 2025.It Cd options SEMMNS=value 2026Sets the number of 2027.At V 2028style semaphores in the system. 2029The GENERIC config file for your port will have the default. 2030.It Cd options SEMUME=value 2031Sets the maximum number of undo entries per process for 2032.At V 2033style semaphores. 2034The GENERIC config file for your port will have the default. 2035.It Cd options SEMMNU=value 2036Sets the number of undo structures in the system for 2037.At V 2038style semaphores. 2039The GENERIC config file for your port will have the default. 2040.It Cd options SYSVSHM 2041Includes support for 2042.At V 2043style shared memory. 2044See 2045.Xr shmat 2 , 2046.Xr shmctl 2 , 2047.Xr shmdt 2 , 2048.Xr shmget 2 . 2049.It Cd options SHMMAXPGS=value 2050Sets the maximum number of 2051.At V 2052style shared memory pages that are available through the 2053.Xr shmget 2 2054system call. 2055Default value is 1024 on most ports. 2056See 2057.Pa /usr/include/machine/vmparam.h 2058for the default. 2059.El 2060.Ss VM Related Options 2061.Bl -ohang 2062.It Cd options NMBCLUSTERS=value 2063The number of mbuf clusters the kernel supports. 2064Mbuf clusters are MCLBYTES in size (usually 2k). 2065This is used to compute the size of the kernel VM map 2066.Em mb_map , 2067which maps mbuf clusters. 2068Default on most ports is 1024 (2048 with 2069.Dq options GATEWAY 2070). 2071See 2072.Pa /usr/include/machine/param.h 2073for exact default information. 2074Increase this value if you get 2075.Dq mclpool limit reached 2076messages. 2077.It Cd options NKMEMPAGES=value 2078.It Cd options NKMEMPAGES_MIN=value 2079.It Cd options NKMEMPAGES_MAX=value 2080Size of kernel VM map 2081.Em kmem_map , 2082in PAGE_SIZE-sized chunks (the VM page size; this value may be read 2083from the 2084.Xr sysctl 8 2085variable 2086.Em hw.pagesize 2087). 2088This VM map is used to map the kernel malloc arena. 2089The kernel attempts to auto-size this map based on the amount of 2090physical memory in the system. 2091Platform-specific code may place bounds on this computed size, 2092which may be viewed with the 2093.Xr sysctl 8 2094variable 2095.Em vm.nkmempages . 2096See 2097.Pa /usr/include/machine/param.h 2098for the default upper and lower bounds. 2099The related options 2100.Sq NKMEMPAGES_MIN 2101and 2102.Sq NKMEMPAGES_MAX 2103allow the bounds to be overridden in the kernel configuration file. 2104These options are provided in the event the computed value is 2105insufficient resulting in an 2106.Dq out of space in kmem_map 2107panic. 2108.It Cd options SB_MAX=value 2109Sets the max size in bytes that a socket buffer is allowed to occupy. 2110The default is 256k, but sometimes it needs to be increased, for example 2111when using large TCP windows. 2112This option can be changed via 2113.Xr sysctl 8 2114as well. 2115.It Cd options SOMAXKVA=value 2116Sets the maximum size of kernel virtual memory that the socket buffers 2117are allowed to use. 2118The default is 16MB, but in situations where for example large TCP 2119windows are used this value must also be increased. 2120This option can be changed via 2121.Xr sysctl 8 2122as well. 2123.It Cd options BUFCACHE=value 2124Size of the buffer cache as a percentage of total available 2125.Tn RAM . 2126Ignored if BUFPAGES is also specified. 2127.It Cd options NBUF=value 2128Sets the number of buffer headers available, i.e., the number of 2129open files that may have a buffer cache entry. 2130Each buffer header 2131requires MAXBSIZE (machine dependent, but usually 65536) bytes. 2132The default value is machine dependent, but is usually equal to the 2133value of BUFPAGES. 2134If an architecture dependent VM_MAX_KERNEL_BUF constant is defined 2135then NBUF may be reduced at run time so that the storage allocated 2136for buffer headers doesn't exceed that limit. 2137.It Cd options BUFPAGES=value 2138These options set the number of pages available for the buffer cache. 2139Their default value is a machine dependent value, often calculated as 2140between 5% and 10% of total available 2141.Tn RAM . 2142.It Cd options MAXTSIZ=bytes 2143Sets the maximum size limit of a process' text segment. 2144See 2145.Pa /usr/include/machine/vmparam.h 2146for the port-specific default. 2147.It Cd options DFLDSIZ=bytes 2148Sets the default size limit of a process' data segment, the value that 2149will be returned as the soft limit for 2150.Dv RLIMIT_DATA 2151(as returned by 2152.Xr getrlimit 2 ) . 2153See 2154.Pa /usr/include/machine/vmparam.h 2155for the port-specific default. 2156.It Cd options MAXDSIZ=bytes 2157Sets the maximum size limit of a process' data segment, the value that 2158will be returned as the hard limit for 2159.Dv RLIMIT_DATA 2160(as returned by 2161.Xr getrlimit 2 ) . 2162See 2163.Pa /usr/include/machine/vmparam.h 2164for the port-specific default. 2165.It Cd options DFLSSIZ=bytes 2166Sets the default size limit of a process' stack segment, the value that 2167will be returned as the soft limit for 2168.Dv RLIMIT_STACK 2169(as returned by 2170.Xr getrlimit 2 ) . 2171See 2172.Pa /usr/include/machine/vmparam.h 2173for the port-specific default. 2174.It Cd options MAXSSIZ=bytes 2175Sets the maximum size limit of a process' stack segment, the value that 2176will be returned as the hard limit for 2177.Dv RLIMIT_STACK 2178(as returned by 2179.Xr getrlimit 2 ) . 2180See 2181.Pa /usr/include/machine/vmparam.h 2182for the port-specific default. 2183.It Cd options DUMP_ON_PANIC=integer 2184Defaults to one. 2185If set to zero, the kernel will not dump to the dump device when 2186it panics, though dumps can still be forced via 2187.Xr ddb 4 2188with the 2189.Dq sync 2190command. 2191Note that this sets the value of the 2192.Em kern.dump_on_panic 2193.Xr sysctl 3 2194variable which may be changed at run time -- see 2195.Xr sysctl 8 2196for details. 2197.It Cd options USE_TOPDOWN_VM 2198User space memory allocations (as made by 2199.Xr mmap 2 ) 2200will be arranged in a 2201.Dq top down 2202fashion instead of the traditional 2203.Dq upwards from MAXDSIZ \&+ vm_daddr 2204method. 2205This includes the placement of 2206.Xr ld.so 1 . 2207Arranging memory in this manner allows either (or both of) the heap or 2208.Xr mmap 2 2209allocated space to grow larger than traditionally possible. 2210This option is not available on all ports, but is instead expected to be 2211offered on a port-by-port basis, after which some ports will commit to 2212using it by default. 2213See the files 2214.Pa /usr/include/uvm/uvm_param.h 2215for some implementation details, and 2216.Pa /usr/include/machine/vmparam.h 2217for port specific details including availability. 2218.It Cd options VMSWAP 2219Enable paging device/file support. 2220This option is on by default. 2221.It Cd options PDPOLICY_CLOCKPRO 2222Use CLOCK-Pro, an alternative page replace policy. 2223.El 2224.Ss Security Options 2225.Bl -ohang 2226.It Cd options INSECURE 2227Initializes the kernel security level with \-1 instead of 0. 2228This means that the system always starts in secure level \-1 mode, even when 2229running multiuser, unless the securelevel variable is set to value > \-1 in 2230.Pa /etc/rc.conf . 2231In this case the kernel security level will be raised to that value when the 2232.Pa /etc/rc.d/securelevel 2233script is run during system startup. 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 atari-specific Options 2396.Bl -ohang 2397.It Cd options DISKLABEL_AHDI 2398Include support for AHDI (native Atari) disklabels. 2399.It Cd options DISKLABEL_NBDA 2400Include support for 2401.Nx Ns Tn /atari 2402labels. 2403If you don't set this option, it will be set automatically. 2404.Nx Ns Tn /atari 2405will not work without it. 2406.It Cd options FALCON_SCSI 2407Include support for the 5380-SCSI configuration as found on the Falcon. 2408.It Cd options RELOC_KERNEL 2409If set, the kernel will relocate itself to TT-RAM, if possible. 2410This will give you a slightly faster system. 2411.Em Beware 2412that on some TT030 systems, 2413the system will frequently dump with MMU-faults with this option enabled. 2414.It Cd options SERCONSOLE 2415Allow the modem1-port to act as the system-console. 2416A carrier should be active on modem1 during system boot to active 2417the console functionality. 2418.It Cd options TT_SCSI 2419Include support for the 5380-SCSI configuration as found on the TT030 2420and Hades. 2421.El 2422.Ss i386-specific Options 2423.Bl -ohang 2424.It Cd options CPURESET_DELAY=value 2425Specifies the time (in millisecond) to wait before doing a hardware reset 2426in the last phase of a reboot. 2427This gives the user a chance to see error messages from the shutdown 2428operations (like NFS unmounts, buffer cache flush, etc ...). 2429Setting this to 0 will disable the delay. 2430Default is 2 seconds. 2431.It Cd options VM86 2432Include support for virtual 8086 mode, used by 2433.Tn DOS 2434emulators and X servers to run BIOS code, e.g., for some VESA routines. 2435.It Cd options USER_LDT 2436Include i386-specific system calls for modifying the local descriptor table, 2437used by Windows emulators. 2438.It Cd options PAE 2439Enable 2440.Tn PAE (Physical Address Extension) 2441mode. 2442.Tn PAE 2443permits up to 36 bits physical addressing (64GB of physical memory), and 2444turns physical addresses to 64 bits entities in the memory management 2445subsystem. 2446Userland virtual address space remains at 32 bits (4GB). 2447.Tn PAE 2448mode is required to enable the 2449.Tn NX/XD (No-eXecute/eXecute Disable) 2450bit for pages, which allows marking certain ones as not being executable. 2451Any attempt to execute code from such a page will raise an exception. 2452.It Cd options REALBASEMEM=integer 2453Overrides the base memory size passed in from the boot block. 2454(Value given in kilobytes.) 2455Use this option only if the boot block reports the size incorrectly. 2456(Note that some 2457.Tn BIOS Ns es 2458put the extended 2459.Tn BIOS 2460data area at the top of base memory, and therefore report a smaller 2461base memory size to prevent programs overwriting it. 2462This is correct behavior, and you should not use the 2463.Em REALBASEMEM 2464option to access this memory). 2465.It Cd options REALEXTMEM=integer 2466Overrides the extended memory size passed in from the boot block. 2467(Value given in kilobytes. 2468Extended memory does not include the first megabyte.) 2469Use this option only if the boot block reports the size incorrectly. 2470.It Cd options CYRIX_CACHE_WORKS 2471Relevant only to the Cyrix 486DLC CPU. 2472This option is used to turn on the cache in hold-flush mode. 2473It is not turned on by default because it is known to have problems in 2474certain motherboard implementations. 2475.It Cd options CYRIX_CACHE_REALLY_WORKS 2476Relevant only to the Cyrix 486DLC CPU. 2477This option is used to turn on the cache in write-back mode. 2478It is not turned on by default because it is known to have problems in 2479certain motherboard implementations. 2480In order for this option to take effect, option 2481.Em CYRIX_CACHE_WORKS 2482must also be specified. 2483.It Cd options PCIBIOS 2484Enable support for initializing the 2485.Tn PCI 2486bus using information from the 2487.Tn BIOS . 2488See 2489.Xr pcibios 4 2490for details. 2491.It Cd options KSTACK_CHECK_DR0 2492Detect kernel stack overflow using DR0 register. 2493This option uses DR0 register exclusively so you can't use DR0 register for 2494other purpose (e.g., hardware breakpoint) if you turn this on. 2495.It Cd options MTRR 2496Include support for accessing MTRR registers from user-space. 2497See 2498.Xr i386_get_mtrr 2 . 2499.It Cd options BEEP_ONHALT 2500Make the system speaker emit several beeps when it is completely safe to 2501power down the computer after a 2502.Xr halt 8 2503command. 2504Requires 2505.Xr sysbeep 4 2506support. 2507.It Cd options BEEP_ONHALT_COUNT=times 2508Number of times to beep the speaker when 2509.Cd options BEEP_ONHALT 2510is enabled. 2511Defaults to 3. 2512.It Cd options BEEP_ONHALT_PITCH=hz 2513The tone frequency used when 2514.Cd options BEEP_ONHALT 2515option, in hertz. 2516Defaults to 1500. 2517.It Cd options BEEP_ONHALT_PERIOD=msecs 2518The duration of each beep when 2519.Cd options BEEP_ONHALT 2520is enabled, in milliseconds. 2521Defaults to 250. 2522.It Cd options MULTIBOOT 2523Makes the kernel Multiboot-compliant, allowing it to be booted through 2524a Multiboot-compliant boot manager such as GRUB. 2525See 2526.Xr multiboot 8 2527for more information. 2528.It Cd options SPLASHSCREEN 2529Display a splash screen during boot. 2530.It Cd options SPLASHSCREEN_PROGRESS 2531Display a progress bar at the splash screen during boot. 2532This option requires 2533.Em SPLASHSCREEN . 2534.El 2535.Ss isa-specific Options 2536Options specific to 2537.Xr isa 4 2538busses. 2539.Bl -ohang 2540.It Cd options PCIC_ISA_ALLOC_IOBASE=address, PCIC_ISA_ALLOC_IOSIZE=size 2541Control the section of IO bus space used for PCMCIA bus space mapping. 2542Ideally the probed defaults are satisfactory, however in practice 2543that is not always the case. 2544See 2545.Xr pcmcia 4 2546for details. 2547.It Cd options PCIC_ISA_INTR_ALLOC_MASK=mask 2548Controls the allowable interrupts that may be used for 2549.Tn PCMCIA 2550devices. 2551This mask is a logical-or of power-of-2s of allowable interrupts: 2552.Bd -literal -offset 04n 2553.Em "IRQ Val IRQ Val IRQ Val IRQ Val" 2554 0 0x0001 4 0x0010 8 0x0100 12 0x1000 2555 1 0x0002 5 0x0020 9 0x0200 13 0x2000 2556 2 0x0004 6 0x0040 10 0x0400 14 0x4000 2557 3 0x0008 7 0x0080 11 0x0800 15 0x8000 2558.Ed 2559.It Cd options PCKBC_CNATTACH_SELFTEST 2560Perform a self test of the keyboard controller before attaching it as a 2561console. 2562This might be necessary on machines where we boot on cold iron, and 2563pckbc refuses to talk until we request a self test. 2564Currently only the netwinder port uses it. 2565.It Cd options PCKBD_CNATTACH_MAY_FAIL 2566If this option is set the PS/2 keyboard will not be used as the console 2567if it cannot be found during boot. 2568This allows other keyboards, like USB, to be the console keyboard. 2569.It Cd options PCKBD_LAYOUT=layout 2570Sets the default keyboard layout, see 2571.Xr pckbd 4 . 2572.El 2573.Ss m68k-specific Options 2574.Bl -ohang 2575.It Cd options FPU_EMULATE 2576Include support for MC68881/MC68882 emulator. 2577.It Cd options FPSP 2578Include support for 68040 floating point. 2579.It Cd options M68020,M68030,M68040,M68060 2580Include support for a specific 2581.Tn CPU , 2582at least one (the one you are using) should be specified. 2583.It Cd options M060SP 2584Include software support for 68060. 2585This provides emulation of unimplemented 2586integer instructions as well as emulation of unimplemented floating point 2587instructions and data types and software support for floating point traps. 2588.El 2589.Ss powerpc-specific Options (OEA Only) 2590.Bl -ohang 2591.It Cd options PMAP_MEMLIMIT=value 2592Limit the amount of memory seen by the kernel to 2593.Ar value 2594bytes. 2595.It Cd options PTEGCOUNT=value 2596Specify the size of the page table as 2597.Ar value 2598PTE groups. 2599Normally, one PTEG is allocated per physical page frame. 2600.El 2601.Ss sparc-specific Options 2602.Bl -ohang 2603.It Cd options AUDIO_DEBUG 2604Enable simple event debugging of the logging of the 2605.Xr audio 4 2606device. 2607.It Cd options BLINK 2608Enable blinking of LED. 2609Blink rate is full cycle every N seconds for 2610N \*[Lt] then current load average. 2611See 2612.Xr getloadavg 3 . 2613.\" .It Cd options COLORFONT_CACHE 2614.\" What does this do? 2615.It Cd options COUNT_SW_LEFTOVERS 2616Count how many times the sw SCSI device has left 3, 2, 1 and 0 in the 2617sw_3_leftover, sw_2_leftover, sw_1_leftover, and sw_0_leftover 2618variables accessible from 2619.Xr ddb 4 . 2620See 2621.Xr sw 4 . 2622.It Cd options DEBUG_ALIGN 2623Adds debugging messages calls when user-requested alignment fault 2624handling happens. 2625.It Cd options DEBUG_EMUL 2626Adds debugging messages calls for emulated floating point and 2627alignment fixing operations. 2628.It Cd options DEBUG_SVR4 2629Prints registers messages calls for emulated SVR4 getcontext and 2630setcontext operations. 2631See 2632.Em options COMPAT_SVR4 . 2633.It Cd options EXTREME_DEBUG 2634Adds debugging functions callable from 2635.Xr ddb 4 . 2636The debug_pagetables, test_region and print_fe_map 2637functions print information about page tables for the SUN4M 2638platforms only. 2639.It Cd options EXTREME_EXTREME_DEBUG 2640Adds extra info to 2641.Em options EXTREME_DEBUG . 2642.It Cd options FPU_CONTEXT 2643Make 2644.Em options COMPAT_SVR4 2645getcontext and setcontext include floating point registers. 2646.It Cd options MAGMA_DEBUG 2647Adds debugging messages to the 2648.Xr magma 4 2649device. 2650.It Cd options RASTERCONS_FULLSCREEN 2651Use the entire screen for the console. 2652.It Cd options RASTERCONS_SMALLFONT 2653Use the Fixed font on the console, instead of the normal font. 2654.It Cd options SUN4 2655Support sun4 class machines. 2656.It Cd options SUN4C 2657Support sun4c class machines. 2658.It Cd options SUN4M 2659Support sun4m class machines. 2660.It Cd options SUN4_MMU3L 2661.\" XXX ??? 2662Enable support for sun4 3-level MMU machines. 2663.It Cd options V9 2664Enable SPARC V9 assembler in 2665.Xr ddb 4 . 2666.El 2667.Ss sparc64-specific Options 2668.Bl -ohang 2669.It Cd options AUDIO_DEBUG 2670Enable simple event debugging of the logging of the 2671.Xr audio 4 2672device. 2673.It Cd options BLINK 2674Enable blinking of LED. 2675Blink rate is full cycle every N seconds for 2676N \*[Lt] then current load average. 2677See 2678.Xr getloadavg 3 . 2679.El 2680.Ss x68k-specific Options 2681.Bl -ohang 2682.It Cd options EXTENDED_MEMORY 2683Include support for extended memory, e.g., TS-6BE16 and 060turbo on-board. 2684.It Cd options JUPITER 2685Include support for Jupiter-X MPU accelerator 2686.It Cd options ZSCONSOLE,ZSCN_SPEED=value 2687Use the built-in serial port as the system-console. 2688Speed is specified in bps, defaults to 9600. 2689.It Cd options ITE_KERNEL_ATTR=value 2690Set the kernel message attribute for ITE. 2691Value, an integer, is a logical or of the following values: 2692.Bl -tag -width 4n -compact -offset indent 2693.It 1 2694color inversed 2695.It 2 2696underlined 2697.It 4 2698bolded 2699.El 2700.El 2701.\" The following requests should be uncommented and used where appropriate. 2702.\" .Sh FILES 2703.\" .Sh EXAMPLES 2704.Sh SEE ALSO 2705.Xr config 1 , 2706.Xr gdb 1 , 2707.Xr ktrace 1 , 2708.Xr pmc 1 , 2709.Xr quota 1 , 2710.Xr vndcompress 1 , 2711.Xr gettimeofday 2 , 2712.Xr i386_get_mtrr 2 , 2713.Xr i386_iopl 2 , 2714.Xr msgctl 2 , 2715.Xr msgget 2 , 2716.Xr msgrcv 2 , 2717.Xr msgsnd 2 , 2718.Xr ntp_adjtime 2 , 2719.Xr ntp_gettime 2 , 2720.Xr reboot 2 , 2721.Xr semctl 2 , 2722.Xr semget 2 , 2723.Xr semop 2 , 2724.Xr shmat 2 , 2725.Xr shmctl 2 , 2726.Xr shmdt 2 , 2727.Xr shmget 2 , 2728.Xr sysctl 3 , 2729.Xr apm 4 , 2730.Xr ddb 4 , 2731.Xr inet 4 , 2732.Xr iso 4 , 2733.Xr md 4 , 2734.Xr pcibios 4 , 2735.Xr pcmcia 4 , 2736.Xr ppp 4 , 2737.Xr userconf 4 , 2738.Xr vnd 4 , 2739.Xr wscons 4 , 2740.Xr config 5 , 2741.Xr edquota 8 , 2742.Xr init 8 , 2743.Xr mdsetimage 8 , 2744.Xr mount_cd9660 8 , 2745.Xr mount_fdesc 8 , 2746.Xr mount_kernfs 8 , 2747.Xr mount_lfs 8 , 2748.Xr mount_mfs 8 , 2749.Xr mount_msdos 8 , 2750.Xr mount_nfs 8 , 2751.Xr mount_ntfs 8 , 2752.Xr mount_null 8 , 2753.Xr mount_portal 8 , 2754.Xr mount_procfs 8 , 2755.Xr mount_udf 8 , 2756.Xr mount_umap 8 , 2757.Xr mount_union 8 , 2758.Xr mrouted 8 , 2759.Xr newfs_lfs 8 , 2760.Xr ntpd 8 , 2761.Xr quotaon 8 , 2762.Xr rpc.rquotad 8 , 2763.Xr sysctl 8 , 2764.Xr in_getifa 9 2765.Sh HISTORY 2766The 2767.Nm 2768man page first appeared in 2769.Nx 1.3 . 2770.Sh BUGS 2771The 2772.Em EON 2773option should be a pseudo-device, and is also very fragile. 2774