.\" $OpenBSD: options.4,v 1.191 2008/09/06 14:04:48 jmc Exp $ .\" $NetBSD: options.4,v 1.21 1997/06/25 03:13:00 thorpej Exp $ .\" .\" Copyright (c) 1998 Theo de Raadt .\" Copyright (c) 1998 Todd Miller .\" Copyright (c) 1998 Gene Skonicki .\" Copyright (c) 1996 .\" Perry E. Metzger. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgment: .\" This product includes software developed for the NetBSD Project .\" by Perry E. Metzger. .\" 4. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .\" .Dd $Mdocdate: September 6 2008 $ .Dt OPTIONS 4 .Os .Sh NAME .Nm options .Nd kernel configuration options .Sh SYNOPSIS .Cd option ... .Sh DESCRIPTION This manual page describes a number of miscellaneous kernel configuration options that may be specified in a kernel config file. See .Xr config 8 for information on how to configure and build kernels. .Em Note: options are passed to the compile process as .Fl D flags to the C compiler. .Sh COMPATIBILITY OPTIONS .Bl -ohang .It Cd option COMPAT_43 Use of this option is discouraged. It enables compatibility with .Bx 4.3 . It adds an old syscall for .Fn lseek as well as ioctls for .Dv TIOCGETP and .Dv TIOCSETP . The return values for the .Xr getpid 2 , .Xr getgid 2 , and .Xr getuid 2 system calls are modified as well, to return the parent's PID and UID as well as the current process's. It also enables the deprecated .Dv NTTYDISC terminal line discipline. It provides backwards compatibility with the .Dq old SIOC[GS]IF{ADDR,DSTADDR,BRDADDR,NETMASK} interface ioctls, including binary compatibility for code written before the introduction of the .Li sa_len field in sockaddrs. It also enables support for some older pre .Bx 4.4 socket calls. .It Cd option COMPAT_AOUT On those ELF architectures that require it, this enables full compatibility with old a.out binaries, by allowing the a.out dynamic linking system to reside under .Pa /emul/a.out . This option is available on the i386 architecture. See .Xr compat_aout 8 . .It Cd option COMPAT_BSDOS On those architectures that support it, this enables binary compatibility with .Em BSD/OS applications. This option is supported on the i386 architecture. See .Xr compat_bsdos 8 . It also requires the use of .Cm option COMPAT_43 for proper operation. .It Cd option COMPAT_FREEBSD On those architectures that support it, this enables binary compatibility with .Em FreeBSD applications built for the same architecture. This option is available on the i386 architecture. See .Xr compat_freebsd 8 . .It Cd option COMPAT_HPUX On those architectures that support it, this enables binary compatibility with .Em HP-UX applications built for the same architecture. This option is available on some m68k and hppa architectures. See .Xr compat_hpux 8 . .It Cd option COMPAT_IBCS2 On those architectures that support it, this enables binary compatibility with .Em iBCS2 applications built for the same architecture. This option is available on the i386 architecture. See .Xr compat_ibcs2 8 . .It Cd option COMPAT_LINUX On those architectures that support it, this enables binary compatibility with .Em Linux ELF and a.out applications built for the same architecture. This option is supported on the i386 architecture. See .Xr compat_linux 8 . .It Cd option COMPAT_O43 Enables compatibility with .Ox 4.3 . This makes it possible to run binaries that use old versions of the .Xr statfs 2 , .Xr fstatfs 2 , and .Xr getfsstat 2 system calls which were replaced in .Ox 4.4 when struct stat was expanded. .It Cd option COMPAT_OSF1 On those architectures that support it, this enables binary compatibility with .Em Digital UNIX (formerly .Em OSF/1 ) applications built for the same architecture. This option is available on the alpha architecture. See .Xr compat_osf1 8 . .It Cd option COMPAT_SUNOS On those architectures that support it, this enables binary compatibility with .Em SunOS 4.x applications built for the same architecture. This option is supported on sparc and all m68k architectures. See .Xr compat_sunos 8 . .It Cd option COMPAT_SVR4 On those architectures that support it, this enables binary compatibility with .At V.4 binaries built for the same architecture. This currently includes the sparc and i386. Possibly the most widely known operating system based on this binary architecture is Sun's Solaris 2.x. See .Xr compat_svr4 8 . .It Cd option COMPAT_ULTRIX On those architectures that support it, this enables binary compatibility with Ultrix applications built for the same architecture. This option is available on the vax architecture. See .Xr compat_ultrix 8 . .El .Sh DEBUGGING OPTIONS .Bl -ohang .It Cd makeoptions DEBUG="-g" The .Fl g flag causes .Pa bsd.gdb to be built in addition to .Pa bsd . .Pa bsd.gdb is useful for debugging kernels and their crash dumps with gdb. A crash dump can be debugged by starting .Xr gdb 1 with the kernel name .Pf ( Pa bsd.gdb ) as an argument (no core file) and then use the .Xr gdb 1 command .Dq target kvm COREFILE . .It Cd makeoptions PROF="-pg" The .Fl pg flag causes the kernel to be compiled with support for profiling. The .Cm option GPROF is required for the kernel compile to succeed. .It Cd option ACCOUNTING Adds support for the .Xr acct 2 system call. .It Cd option DDB Compiles in a kernel debugger for diagnosing kernel problems. See .Xr ddb 4 for details. .Em Note: not available on all architectures. .It Cd option DDB_SAFE_CONSOLE Allows a break into the kernel debugger during boot. Useful when debugging problems that can cause init(8) to fail. .It Cd option DEBUG Turns on miscellaneous kernel debugging. Since options are turned into preprocessor defines (see above), .Cm option DEBUG is equivalent to doing a .Em #define DEBUG throughout the kernel. Much of the kernel has .Em #ifdef DEBUG conditional debugging code. Note that many parts of the kernel (typically device drivers) include their own .Em #ifdef XXX_DEBUG conditionals instead. This option also turns on certain other options, notably .Cm option KMEMSTATS . .It Cd option DIAGNOSTIC Adds code to the kernel that does internal consistency checks. This code will cause the kernel to panic if corruption of internal data structures is detected. .It Cd option GPROF Adds code to the kernel for kernel profiling with .Xr kgmon 8 . .It Cd option KGDB Compiles in a remote kernel debugger stub for diagnosing kernel problems using the .Dq remote target feature of gdb. See .Xr kgdb 7 for details. .Em Note: not available on all architectures. .It Cd option KTRACE Adds hooks for the system call tracing facility, which allows users to watch the system call invocation behavior of processes. See .Xr ktrace 1 for details. .It Cd option NO_PROPOLICE Do not compile the kernel with the ProPolice stack protection. See .Xr gcc-local 1 for more information about ProPolice. .It Cd option PTRACE Adds hooks for the process tracing facility, allowing a process to control and observe another process. See .Xr ptrace 2 for details. .It Cd option RAIDDEBUG Be verbose on what RAIDframe does. See .Xr raid 4 for details. .It Cd option SMALL_KERNEL Removes some features and some optimizations from the kernel to reduce the size of the resulting kernel binary. This option is used on some installation media and should not be used for general purpose kernels. .It Cd option VFSDEBUG Turns on debugging for the Virtual File System interface. See .Xr vfs 9 for details. .El .Sh FILE SYSTEMS .Bl -ohang .It Cd option CD9660 Includes code for the ISO 9660 + Rock Ridge file system, which is the standard file system used on many CD-ROMs. It also supports Joliet extensions. See .Xr mount_cd9660 8 for details. .It Cd option EXT2FS Includes code implementing the Second Extended File System .Em ( EXT2FS ) . This is the most commonly used file system on the Linux operating system, and is provided here for compatibility. Some specific features of .Em EXT2FS like the "behavior on errors" are not implemented. This file system can't be used with .Li uid_t or .Li gid_t values greater than 65535. Also, the filesystem will not function correctly on architectures with differing byte-orders. That is, a big-endian machine will not be able to read an ext2fs filesystem created on an i386 or other little-endian machine. See .Xr mount_ext2fs 8 for details. .It Cd option FFS Includes code implementing the Berkeley Fast File System .Em ( FFS ) . Most machines need this if they are not running diskless. .It Cd option FFS2 Includes code implementing the enhanced Fast File System .Em ( FFS2 ) . .It Cd option MFS Include the memory file system .Em ( MFS ) . This file system stores files in swappable memory, and produces notable performance improvements when it is used as the file store for .Pa /tmp or similar mount points. See .Xr mount_mfs 8 for details. .It Cd option MSDOSFS Includes support for the MS-DOS FAT file system. The kernel also implements the Windows 95 extensions which permit the use of longer, mixed-case file names. See .Xr mount_msdos 8 and .Xr fsck_msdos 8 for details. .It Cd option NFSCLIENT Include the client side of the .Em NFS (Network File System) remote file sharing protocol. Although the bulk of the code implementing .Em NFS is kernel based, several user level daemons are needed for it to work. See .Xr mount_nfs 8 for details on NFS. .It Cd option NTFS Includes support for reading NTFS file systems. Experimental and read only. See .Xr mount_ntfs 8 for details. .It Cd option PORTAL Includes the (experimental) portal filesystem. This permits interesting tricks like opening TCP sockets by opening files in the file system. The portal file system is conventionally mounted on .Pa /p and is partially implemented by a special daemon. See .Xr mount_portal 8 for details. .It Cd option PROCFS Includes code for a special file system (conventionally mounted on .Pa /proc ) in which the process space becomes visible in the file system. Among other things, the memory spaces of processes running on the system are visible as files, and signals may be sent to processes by writing to .Pa ctl files in the procfs namespace. See .Xr mount_procfs 8 for details. .It Cd option UDF Includes code for the UDF file systems typically found on DVD discs. See .Xr mount_udf 8 for details. .It Cd option XFS Includes the kernel support for the AFS-compatible Arla filesystem. Since the xfs interface is simple and generic it can be used for other filesystems as well. See .Xr mount_xfs 8 for details. .El .Sh FILE SYSTEM OPTIONS .Bl -ohang .It Cd option BUFCACHEPERCENT= Ns Ar integer Percentage of RAM to use as a file system buffer. It defaults to 5. .It Cd option EXT2FS_SYSTEM_FLAGS This option changes the behavior of the APPEND and IMMUTABLE flags for a file on an .Em EXT2FS filesystem. Without this option, the superuser or owner of the file can set and clear them. With this option, only the superuser can set them, and they can't be cleared if the securelevel is greater than 0. See also .Xr chflags 1 . .It Cd option FFS_SOFTUPDATES Enables a scheme that uses partial ordering of buffer cache operations to allow metadata updates in FFS to happen asynchronously, increasing write performance significantly. Normally, the FFS filesystem writes metadata updates synchronously which exacts a performance penalty in favor of filesystem integrity. With soft updates, the performance of asynchronous writes is gained while retaining the safety of synchronous metadata updates. .Pp Soft updates must be enabled on a per-filesystem basis. See .Xr mount 8 for details. .Pp Processors with a small kernel address space, such as the sun4 and sun4c, do not have enough kernel memory to support soft updates. Attempts to use this option with these CPUs will cause a kernel hang or panic after a short period of use as the kernel will quickly run out of memory. This is not related to the amount of physical memory present in the machine -- it is a limitation of the CPU architecture itself. .It Cd option FIFO Adds support for .At V style FIFOs (i.e., .Dq named pipes ) . This option is recommended in almost all cases as many programs use these. .It Cd option NFSSERVER Include the server side of the .Em NFS (Network File System) remote file sharing protocol. Although the bulk of the code implementing .Em NFS is kernel based, several user level daemons are needed for it to work. See .Xr mountd 8 and .Xr nfsd 8 for details. .It Cd option QUOTA Enables kernel support for file system quotas. See .Xr quotaon 8 , .Xr edquota 8 , .Xr repquota 8 , and .Xr quota 1 for details. Note that quotas only work on .Dq ffs file systems, although .Xr rpc.rquotad 8 permits them to be accessed over .Em NFS . .It Cd option UFS_DIRHASH This option enables using an in memory hash table to speed lookups in large directories. .El .Sh MISCELLANEOUS OPTIONS .Bl -ohang .It Cd option APERTURE Provide in-kernel support for controlling VGA framebuffer mapping and PCI configuration registers by user-processes (such as an X Window System server). This option is supported on the .Va alpha , .Va amd64 , .Va i386 , .Va macppc , and .Va sparc64 architectures. .It Cd option BOOT_CONFIG Adds support for the .Fl c boot option (User Kernel Config). Allows modification of kernel settings (e.g., device parameters) before booting the system. .It Cd option CCDNBUF= Ns Ar integer The .Xr ccd 4 device driver uses .Dq component buffers to distribute I/O requests to the components of a concatenated disk. It keeps a freelist of buffer headers in order to reduce use of the kernel memory allocator. .Em CCDNBUF is the number of buffer headers allocated on the freelist for each component buffer. It defaults to 8. .It Cd option CRYPTO Enables support for the kernel cryptographic framework. See .Xr crypto 9 for details. While not IP specific, this option is usually used in conjunction with option .Em IPSEC . .It Cd option EISAVERBOSE Makes the boot process more verbose for EISA peripherals. .It Cd option INSECURE Hardwires the kernel security level at \-1. This means that the system always runs in securelevel 0 mode, even when running multiuser. See .Xr init 8 for details on the implications of this. The kernel secure level may be manipulated by the superuser by altering the .Em kern.securelevel sysctl variable. (It should be noted that the securelevel may only be lowered by a call from process ID 1, i.e., .Xr init 8 . ) See also .Xr sysctl 8 and .Xr sysctl 3 . .It Cd option KMEMSTATS The kernel memory allocator, .Xr malloc 9 , will keep statistics on its performance if this option is enabled. Note that this option is silently turned on by the .Cm DEBUG option. .It Cd option LKM Enables support for loadable kernel modules. See .Xr lkm 4 for details. .Em Note: This option is not yet available on all architectures. .It Cd option MACOBIOVERBOSE Makes the boot process more verbose for OBIO peripherals on the .Va macppc architecture. .It Cd option MULTIPROCESSOR On those architectures that have it, this enables multiprocessor support. .It Cd option PCIVERBOSE Makes the boot process more verbose for PCI peripherals (vendor names and other information is printed, etc.). .It Cd option PCMCIAVERBOSE Makes the boot process more verbose for PCMCIA peripherals. .It Cd option RAID_AUTOCONFIG Adds support for auto-configuring the RAIDframe devices during the kernel initialization. See .Xr raid 4 and .Xr raidctl 8 for details. .It Cd option USER_LDT Enable userland manipulation of per-process Local Descriptor Table (LDT) entries; see .Xr i386_set_ldt 2 and the .Va machdep.userldt .Xr sysctl 8 . This option is supported on the .Va i386 architecture. .It Cd option USER_PCICONF Enables the user level access to the PCI bus configuration space through ioctls on the .Pa /dev/pci device. It's used by the .Xr Xorg 1 server on some architectures. See .Xr pci 4 for details. .It Cd option UVM_SWAP_ENCRYPT Enables kernel support for encrypting pages that are written out to swap storage. Swap encryption prevents sensitive data from remaining on the disk even after the operating system has been shut down. This option should be turned on if cryptographic filesystems are used. The sysctl variable .Em vm.swapencrypt.enable controls its behaviour. See .Xr sysctl 8 and .Xr sysctl 3 for details. .El .Sh NETWORKING OPTIONS .Bl -ohang .It Cd option ALTQ Enables ALTQ (Alternate Queuing). See .Xr pfctl 8 and .Xr pf.conf 5 to set up the interface transmission rate and queueing disciplines. .Em ALTQ_CBQ , .Em ALTQ_RED , .Em ALTQ_PRIQ and .Em ALTQ_HFSC are enabled by default with option .Em ALTQ in .Ox . See .Xr altq 9 for details on ALTQ. .It Cd option ALTQ_NOPCC Disables use of processor cycle counter (e.g., Pentium TSC on i386 and PCC on alpha) to measure time in ALTQ. This option should be defined for a non-Pentium i386 CPU which does not have TSC, SMP (per-CPU counters are not in sync), or power management which affects processor cycle counter. .It Cd option ALTQ_RIO Enables ALTQ's RIO (RED with In/Out) module. The original RIO has 2 sets of RED parameters; one for in-profile packets and the other for out-of-profile packets. At the ingress of the network, profile meters tag packets as IN or OUT based on contracted profiles for customers. Inside the network, IN packets receive preferential treatment by the RIO dropper. ALTQ/RIO has 3 drop precedence levels defined for the Assured Forwarding PHB of DiffServ (RFC 2597). .It Cd option ENCDEBUG This option enables debugging information to be conditionally logged in case IPSEC encounters errors. The option .Em IPSEC is required along with this option. Debug logging can be turned on/off through the use of the .Em net.inet.ip.encdebug sysctl variable. If .Em net.ipsec.encap.encdebug is 1, debug logging is on. See .Xr sysctl 8 and .Xr sysctl 3 for details. .It Cd option INET Includes support for the TCP/IP protocol stack. This option is currently required. See .Xr inet 4 for details. .It Cd option INET6 Includes support for the IPv6 protocol stack. See .Xr inet6 4 for details. Unlike .Em INET , .Em INET6 enables multicast routing code as well. This option requires .Em INET at this moment, but it should not. .It Cd option IPSEC This option enables IP security protocol support. See .Xr ipsec 4 for more details. .It Cd option KEY Enables PFKEYv2 (RFC 2367) support. While not IP specific, this option is usually used in conjunction with option .Em IPSEC . .It Cd option MROUTING Includes support for IP multicast routers. .Em INET should be set along with this. Multicast routing is controlled by the .Xr mrouted 8 daemon. .It Cd option ND6_DEBUG The option sets the default value of .Em net.inet6.icmp6.nd6_debug to 1, for debugging IPv6 neighbor discovery protocol handling. See .Xr sysctl 3 for details. .It Cd option NETATALK Include kernel support for the AppleTalk family of protocols. This suite of supporting code is sometimes called .Em netatalk support. .It Cd option PPP_BSDCOMP Enables BSD compressor for PPP connections. .It Cd option PPP_DEFLATE For use in conjunction with PPP_BSDCOMP; provides an interface to zlib for PPP for deflate compression/decompression. .It Cd option TCP_ECN Turns on Explicit Congestion Notification (RFC 3168). .Em ECN allows intermediate routers to use the Congestion Experienced codepoint in the IP header as an indication of congestion, and allows TCP to adjust the transmission rate using this signal. Both communication endpoints negotiate enabling .Em ECN functionality at the TCP connection establishment. .It Cd option TCP_FACK Turns on forward acknowledgements allowing a more precise estimate of outstanding data during the fast recovery phase by using .Em SACK information. This option can only be used together with .Em TCP_SACK . .It Cd option TCP_SACK Turns on selective acknowledgements. Additional information about segments already received can be transmitted back to the sender, thus indicating segments that have been lost and allowing for a swifter recovery. Both communication endpoints need to support .Em SACK . The fallback behaviour is NewReno fast recovery phase, which allows one lost segment to be recovered per round trip time. When more than one segment has been dropped per window, the transmission can continue without waiting for a retransmission timeout. .It Cd option TCP_SIGNATURE Turns on support for the TCP MD5 Signature option (RFC 2385). This is used by Internet backbone routers to provide per-packet authentication for the TCP packets used to communicate BGP routing information. You will also need a routing daemon that supports this option in order to actually use it. .El .Sh OPERATION RELATED OPTIONS .Bl -ohang -compact .It Cd option APM_NOPRINT This option is supported on the i386 architecture. When enabled, kernel messages regarding the status of the automatic power management system (APM) are suppressed. APM status can still be obtained using .Xr apm 8 and/or .Xr apmd 8 . .Pp .It Cd option BUFPAGES= Ns Ar value .It Cd option NBUF= Ns Ar value These options set the number of pages available for the buffer cache. Their default value is a machine dependent value, often calculated as between 5% and 10% of total available RAM. .Pp .It Cd option DST= Ns Ar value If .Ar value is non-zero, indicates that the hardware realtime clock device is one hour ahead of the offset given in .Sq TIMEZONE , due to Daylight Saving Time (DST). If .Ar value is zero, the hardware realtime clock device is not in Daylight Saving Time. .Pp .It Cd option NKMEMPAGES= Ns Ar value .It Cd option NKMEMPAGES_MAX= Ns Ar value .It Cd option NKMEMPAGES_MIN= Ns Ar value Size of kernel malloc area in PAGE_SIZE-sized logical pages. This area is covered by the kernel submap .Em kmem_map . The kernel attempts to auto-size this map based on the amount of physical memory in the system. Platform-specific code may place bounds on this computed size, which may be viewed with the .Xr sysctl 8 variable .Em vm.nkmempages . See .Pa /usr/include/machine/param.h for the default upper and lower bounds. The related options .Sq NKMEMPAGES_MIN and .Sq NKMEMPAGES_MAX allow the bounds to be overridden in the kernel configuration file. These options are provided in the event the computed value is insufficient resulting in an .Dq out of space in kmem_map panic. .Pp .It Cd option \&"TIMEZONE= Ns Ar value Ns Cm \&" .Ar value indicates the time zone offset of the hardware realtime clock device, in minutes, from UTC. It is useful when the hardware realtime clock device is configured with local time, when dual-booting .Ox with other operating systems on a single machine. For instance, if the hardware realtime clock is set to Tokyo time, .Ar value should be .Li \&-540 as Tokyo local time is 9 hours ahead of UTC. Double quotes are needed when specifying a negative .Ar value . .El .Sh SCSI SUBSYSTEM OPTIONS .Bl -ohang .It Cd option SCSI_DELAY= Ns Ar value Delay for .Ar value seconds before starting to probe the first SCSI bus. This can be used if a SCSI device needs extra time to get ready. .It Cd option SCSIDEBUG Enable printing of SCSI subsystem debugging info to the console. Each of .Em SCSIDEBUG_LEVEL , .Em SCSIDEBUG_BUSES , .Em SCSIDEBUG_TARGETS and .Em SCSIDEBUG_LUNS must have non-zero values for any debugging info to be printed. Only .Em SCSIDEBUG_LEVEL .It Cd option SCSIDEBUG_BUSES= Ns Ar value Define which SCSI buses will print debug info. Each bit enables debugging info for the corresponding bus. e.g. a value of 0x1 enables debug info for bus 0. has a default value that is non-zero. .It Cd option SCSIDEBUG_LEVEL= Ns Ar value Define which of the four levels of debugging info are printed. Each bit enables a level, and multiple levels are specified by setting multiple bits. .Bd -literal -offset indent 0x0010 (SDEV_DB1) SCSI commands, errors, and data 0x0020 (SDEV_DB2) routine flow 0x0040 (SDEV_DB3) routine internals 0x0080 (SDEV_DB4) miscellaneous addition debugging .Ed .Pp If .Em SCSIDEBUG_LEVEL is undefined, a value of 0x0030 (SDEV_DB1|SDEV_DB2) is used. .It Cd option SCSIDEBUG_LUNS= Ns Ar value Define which SCSI luns will print debug info. Each bit enables debugging info for the corresponding lun. .It Cd option SCSIDEBUG_TARGETS= Ns Ar value Define which SCSI targets will print debug info. Each bit enables debugging info for the corresponding target. .It Cd option SCSITERSE Terser SCSI error messages. This omits the table for decoding ASC/ASCQ info, saving about 30KB. .El .Sh SYSTEM V IPC OPTIONS .Bl -ohang .It Cd option SEMMNI= Ns Ar value Number of semaphore identifiers (also called semaphore handles and semaphore sets) available in the system. Default value is 10. The kernel allocates memory for the control structures at startup, so arbitrarily large values should be avoided. .It Cd option SEMMNS= Ns Ar value Maximum number of semaphores in all sets in the system. Default value is 60. .It Cd option SEMMNU= Ns Ar value Maximum number of semaphore undo structures in the system. Default value is 30. .It Cd option SEMUME= Ns Ar value Maximum number of per-process undo operation entries in the system. Semaphore undo operations are invoked by the kernel when .Xr semop 2 is called with the SEM_UNDO flag and the process holding the semaphores terminates unexpectedly. Default value is 10. .It Cd option SHMMAXPGS= Ns Ar value Sets the maximum number of .At V style shared memory pages that are available through the .Xr shmget 2 system call. Default value is 1024 on most architectures. See .Pa /usr/include/machine/vmparam.h for the default. .It Cd option SYSVMSG Includes support for .At V style message queues. See .Xr msgctl 2 , .Xr msgget 2 , .Xr msgrcv 2 , .Xr msgsnd 2 . .It Cd option SYSVSEM Includes support for .At V style semaphores. See .Xr semctl 2 , .Xr semget 2 , .Xr semop 2 . .It Cd option SYSVSHM Includes support for .At V style shared memory. See .Xr shmat 2 , .Xr shmctl 2 , .Xr shmdt 2 , .Xr shmget 2 . .El .Sh SEE ALSO .Xr intro 4 , .Xr files.conf 5 , .Xr config 8 , .Xr sysctl 8 .Sh HISTORY The .Nm man page first appeared in .Ox 2.3 . .Sh BUGS The .Em INET option should not be required.