options - miscellaneous kernel configuration options
option ...
This manual page describes a number of miscellaneous kernel
configuration
options that may be specified in a kernel config file. See
config(8) for
information on how to configure and build kernels. Note:
options are
passed to the compile process as -D flags to the C compiler.
Compatibility Options [Toc] [Back]
option COMPAT_23
Enables compatibility with OpenBSD 2.3. This makes it possible to run
binaries that use old versions of the msgctl(2), shmctl(2)
and semctl(2)
system calls which changed semantics in OpenBSD 2.4.
option COMPAT_25
Enables compatibility with OpenBSD 2.5. This makes it possible to run
binaries that use old versions of the statfs(2), fstatfs(2)
and
getfsstat(2) system calls which were replaced in OpenBSD 2.6
when struct
stat was expanded.
option COMPAT_35
Enables compatibility with OpenBSD 3.5. This makes it possible to run
binaries that use old versions of the semop(2) and shmget(2)
system calls
which were replaced in OpenBSD 3.6 when their arguments were
changed to
match IEEE Std 1003.1-2003 (``POSIX''), as well as binaries
that use old
versions of the fhstat(2), fstat(2), lstat(2), msgctl(2),
semctl(2),
shmctl(2) and stat(2) system calls which were replaced in
OpenBSD 3.6
when types mode_t and nlink_t were extended to 32 bits.
option COMPAT_43
Use of this option is discouraged. It enables compatibility
with 4.3BSD.
It adds an old syscall for lseek() as well as ioctls for TIOCGETP and
TIOCSETP. The return values for the getpid(2), getgid(2),
and 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 NTTYDISC
terminal line discipline. It provides backwards compatibility with the
``old'' SIOC[GS]IF{ADDR,DSTADDR,BRDADDR,NETMASK} interface
ioctls, including
binary compatibility for code written before the introduction of
the sa_len field in sockaddrs. It also enables support for
some older
pre 4.4BSD socket calls.
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 /emul/a.out. This option is available on
the i386 architecture.
See compat_aout(8).
option COMPAT_BSDOS
On those architectures that support it, this enables binary
compatibility
with BSD/OS applications. This option is supported on the
i386 architecture.
See compat_bsdos(8). It also requires the use of
option COMPAT_43
for proper operation.
option COMPAT_FREEBSD
On those architectures that support it, this enables binary
compatibility
with FreeBSD applications built for the same architecture.
This option
is available on the i386 architecture. See compat_freebsd(8).
option COMPAT_HPUX
On those architectures that support it, this enables binary
compatibility
with HP-UX applications built for the same architecture.
This option is
available on some m68k architectures. See compat_hpux(8).
option COMPAT_IBCS2
On those architectures that support it, this enables binary
compatibility
with iBCS2 applications built for the same architecture.
This option is
available on the i386 architecture. See compat_ibcs2(8).
option COMPAT_LINUX
On those architectures that support it, this enables binary
compatibility
with Linux ELF and a.out applications built for the same architecture.
This option is supported on the i386 architecture. See compat_linux(8).
option COMPAT_NETBSD
On those architectures that support it, this enables binary
compatibility
with NetBSD applications built for the same architecture.
This option is
available on the alpha architecture.
option COMPAT_OSF1
On those architectures that support it, this enables binary
compatibility
with Digital UNIX (formerly OSF/1) applications built for
the same architecture.
This option is available on the alpha architecture. See
compat_osf1(8).
option COMPAT_SUNOS
On those architectures that support it, this enables binary
compatibility
with SunOS 4.x applications built for the same architecture.
This option
is supported on sparc and all m68k architectures. See compat_sunos(8).
option COMPAT_SVR4
On those architectures that support it, this enables binary
compatibility
with AT&T System V.4 UNIX 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 compat_svr4(8).
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 compat_ultrix(8).
Debugging Options [Toc] [Back]
option DDB
Compiles in a kernel debugger for diagnosing kernel problems. See ddb(4)
for details. Note: not available on all architectures.
option DDB_SAFE_CONSOLE
Allows a break into the kernel debugger during boot. Useful
when debugging
problems that can cause init(8) to fail.
option KGDB
Compiles in a remote kernel debugger stub for diagnosing
kernel problems
using the ``remote target'' feature of gdb. See kgdb(7) for
details.
Note: not available on all architectures.
makeoptions DEBUG="-g"
The -g flag causes bsd.gdb to be built in addition to bsd.
bsd.gdb is
useful for debugging kernels and their crash dumps with gdb.
Note that
gdb(1)'s -k flag is obsolete and should not be used. Instead, a crash
dump can be debugged by starting gdb(1) with the kernel name
as an argument
(no core file) and then use the gdb(1) command ``target
kcore
COREFILE''.
option DEBUG
Turns on miscellaneous kernel debugging. Since options are
turned into
preprocessor defines (see above), option DEBUG is equivalent
to doing a
#define DEBUG throughout the kernel. Much of the kernel has
#ifdef DEBUG
conditional debugging code. Note that many parts of the
kernel (typically
device drivers) include their own #ifdef XXX_DEBUG conditionals instead.
This option also turns on certain other options, notably option
KMEMSTATS, which may decrease system performance.
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.
option SMALL_KERNEL
Removes some optimizations from the kernel to reduce the
size of the resulting
kernel binary. This option can decrease system performance.
option NO_PROPOLICE
Do not compile the kernel with the ProPolice stack protection. See
gcc-local(1) for more information about ProPolice.
option GPROF
Adds code to the kernel for kernel profiling with kgmon(8).
makeoptions PROF="-pg"
The -pg flag causes the kernel to be compiled with support
for profiling.
The option GPROF is required for the kernel compile to succeed.
option ACCOUNTING
Adds support for the acct(2) system call.
option KTRACE
Adds hooks for the system call tracing facility, which allows users to
watch the system call invocation behavior of processes. See
ktrace(1)
for details.
option PTRACE
Adds hooks for the process tracing facility, allowing a process to control
and observe another process. See ptrace(2) for details.
option RAIDDEBUG
Be verbose on what RAIDframe does. See raid(4) for details.
File Systems [Toc] [Back]
option FFS
Includes code implementing the Berkeley Fast File System
(FFS). Most machines
need this if they are not running diskless.
option ADOSFS
Includes code implementing the AmigaDOS Fast File System
(ADOSFS). Note
that the Professional and Smart File Systems are not supported. See
mount_ados(8) for details.
option EXT2FS
Includes code implementing the Second Extended File System
(EXT2FS).
This is the most commonly used file system on the Linux operating system,
and is provided here for compatibility. Some specific features of EXT2FS
like the "behavior on errors" are not implemented. This
file system
can't be used with uid_t or 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
mount_ext2fs(8) for details.
option MFS
Include the memory file system (MFS). This file system
stores files in
swappable memory, and produces notable performance improvements when it
is used as the file store for /tmp or similar mount points.
See
mount_mfs(8) for details.
option NFSCLIENT
Include the client side of the NFS (Network File System) remote file
sharing protocol. Although the bulk of the code implementing NFS is kernel
based, several user level daemons are needed for it to
work. See
mount_nfs(8) for details on NFS.
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 mount_cd9660(8) for details.
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, mixedcase
file names. See mount_msdos(8) and fsck_msdos(8) for
details.
option NTFS
Includes support for reading NTFS file systems. Experimental and read
only. See mount_ntfs(8) for details.
option FDESC
Includes code for a file system which can be mounted on
/dev/fd. This
filesystem permits access to the per-process file descriptor
space via
special files in the file system. See mount_fdesc(8) for
details. Note
that this facility is redundant, and thus unneeded on most
OpenBSD systems,
since the fd(4) pseudo-device driver already provides
identical
functionality. On most systems, instances of fd(4) are mknoded under
/dev/fd/ and on /dev/stdin, /dev/stdout, and /dev/stderr.
option KERNFS
Includes code which permits the mounting of a special file
system (normally
mounted on /kern) in which files representing various
kernel variables
and parameters may be found. See mount_kernfs(8) for
details.
option NULLFS
Includes code for a loopback file system. This permits portions of the
file hierarchy to be re-mounted in other places. The code
really exists
to provide an example of a stackable file system layer. See
mount_null(8) for details.
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 /p and is
partially implemented
by a special daemon. See mount_portal(8) for details.
option PROCFS
Includes code for a special file system (conventionally
mounted on /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 ctl
files in the procfs namespace. See mount_procfs(8) for details.
option UMAPFS
Includes a loopback file system in which user and group IDs
may be
remapped -- this can be useful when mounting alien file systems with different
uids and gids than the local system (eg, remote NFS).
See
mount_umap(8) for details.
option UNION
Includes code for the union file system, which permits directories to be
mounted on top of each other in such a way that both file
systems remain
visible -- this permits tricks like allowing writing (and
the deleting of
files) on a read-only file system like a CD-ROM by mounting
a local
writable file system on top of the read-only file system.
This filesystem
is still experimental and is known to be somewhat unstable. See
mount_union(8) for details.
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 mount_xfs(8) for details.
File System Options [Toc] [Back]
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.
Soft updates must be enabled on a per-filesystem basis. See
mount(8) for
details.
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.
option BUFCACHEPERCENT=integer
Percentage of RAM to use as a file system buffer. It defaults to 5.
option NFSSERVER
Include the server side of the NFS (Network File System) remote file
sharing protocol. Although the bulk of the code implementing NFS is kernel
based, several user level daemons are needed for it to
work. See
mountd(8) and nfsd(8) for details.
option QUOTA
Enables kernel support for file system quotas. See quotaon(8),
edquota(8), repquota(8), and quota(1) for details. Note
that quotas only
work on ``ffs'' file systems, although rpc.rquotad(8) permits them to be
accessed over NFS.
option FIFO
Adds support for AT&T System V UNIX style FIFOs (i.e.,
``named pipes'').
This option is recommended in almost all cases as many programs use
these.
option EXT2FS_SYSTEM_FLAGS
This option changes the behavior of the APPEND and IMMUTABLE
flags for a
file on an 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 chflags(1).
option UFS_EXTATTR
This option enables Extended Attribute support for UFS
filesystems.
option UFS_EXTATTR_AUTOSTART
This option causes Extended Attributes to be started and enabled when
each UFS filesystem is mounted. The attribute storage is
expected to be
(relative to mount point)
/.attribute/{system|user}/<attrname>
option UFS_DIRHASH
This option enables using an in memory hash table to speed
lookups in
large directories.
Miscellaneous Options [Toc] [Back]
option PCIVERBOSE
Makes the boot process more verbose for PCI peripherals
(vendor names and
other information is printed, etc.).
option EISAVERBOSE
Makes the boot process more verbose for EISA peripherals.
option PCMCIAVERBOSE
Makes the boot process more verbose for PCMCIA peripherals.
option MACOBIOVERBOSE
Makes the boot process more verbose for Mac OBIO peripherals.
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 alpha, i386,
macppc, and
sparc64 architectures.
option LKM
Enables support for loadable kernel modules. See lkm(4) for
details.
Note: This option is not yet available on all architectures.
option CRYPTO
Enables support for the kernel cryptographic framework. See
crypto(9)
for details. While not IP specific, this option is usually
used in conjunction
with option IPSEC.
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
init(8) for details on the implications of this. The kernel
secure level
may be manipulated by the superuser by altering the
kern.securelevel
sysctl variable. (It should be noted that the securelevel
may only be
lowered by a call from process ID 1, i.e., init(8).) See also sysctl(8)
and sysctl(3).
option CCDNBUF=integer
The ccd(4) device driver uses ``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.
CCDNBUF is the number of buffer headers allocated on the
freelist for
each component buffer. It defaults to 8.
option KMEMSTATS
The kernel memory allocator, malloc(9), will keep statistics
on its performance
if this option is enabled. Unfortunately, this option therefore
essentially disables MALLOC() and FREE() forms of the memory
allocator,
which are used to enhance the performance of certain critical sections of
code in the kernel. This option therefore can lead to a
significant decrease
in the performance of certain code in the kernel if
enabled. Examples
of such code include the namei() routine, the ccd(4)
driver, the
ncr(4) driver, and much of the networking code. Note that
this option is
silently turned on by the DEBUG option.
option BOOT_CONFIG
Adds support for the -c boot option (User Kernel Config).
Allows modification
of kernel settings (e.g., device parameters) before
booting the
system.
option RAID_AUTOCONFIG
Adds support for auto-configuring the RAIDframe devices during the kernel
initialization. See raid(4) and raidctl(8) for details.
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 vm.swapencrypt.enable controls its behaviour. See
sysctl(8) and
sysctl(3) for details.
option USER_PCICONF
Enables the user level access to the PCI bus configuration
space through
ioctls on the /dev/pci device. It's used by the XFree86(1)
server on
some architectures. See pci(4) for details.
option PCIAGP
Enables ioctl(2) access to the AGP GART on the supported
chipsets. It's
used by the XFree86(1) server on some architectures. See
vga(4) for details.
Networking Options [Toc] [Back]
option MROUTING
Includes support for IP multicast routers. INET should be
set along with
this. Multicast routing is controlled by the mrouted(8)
daemon.
option INET
Includes support for the TCP/IP protocol stack. This option
is currently
required. See inet(4) for details.
option INET6
Includes support for the IPv6 protocol stack. See inet6(4)
for details.
Unlike INET, INET6 enables multicast routing code as well.
This option
requires INET at this moment, but it should not.
option ND6_DEBUG
The option sets the default value of
net.inet6.icmp6.nd6_debug to 1, for
debugging IPv6 neighbor discovery protocol handling. See
sysctl(3) for
details.
option NS
Include support for the Xerox XNS protocol stack. See ns(4)
for details.
option EON
Include support for OSI tunneling over IP.
option CCITT,LLC,HDLC
Include support for the X.25 protocol stack. The state of
this code is
currently unknown. It probably contains bugs.
option IPX, IPXIP
Include support for Internetwork Packet Exchange protocol
commonly in use
by Novell NetWare.
option NETATALK
Include kernel support for the AppleTalk family of protocols. This suite
of supporting code is sometimes called netatalk support.
option TCP_COMPAT_42
Use of this option is extremely discouraged, so it should
not be enabled.
If any other machines on the network require enabling this,
it's recommended
that they be disconnected from the network.
TCP bug compatibility with 4.2BSD. In 4.2BSD, TCP sequence
numbers were
32-bit signed values. Modern implementations of TCP use unsigned values.
This option clamps the initial sequence number to start in
the range 2^31
rather than the full unsigned range of 2^32. Also, under
4.2BSD,
keepalive packets must contain at least one byte or else the
remote end
will not respond.
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 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.
option TCP_FACK
Turns on forward acknowledgements allowing a more precise
estimate of
outstanding data during the fast recovery phase by using
SACK information.
This option can only be used together with TCP_SACK.
option TCP_ECN
Turns on Explicit Congestion Notification (RFC 3168). 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 ECN functionality at the TCP connection establishment.
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.
option PPP_BSDCOMP
Enables BSD compressor for PPP connections.
option PPP_DEFLATE
For use in conjunction with PPP_BSDCOMP; provides an interface to zlib
for PPP for deflate compression/decompression.
option IPSEC
This option enables IP security protocol support. See
ipsec(4) for more
details.
option ENCDEBUG
This option enables debugging information to be conditionally logged in
case IPSEC encounters errors. The option IPSEC is required
along with
this option. Debug logging can be turned on/off through the
use of the
net.inet.ip.encdebug sysctl variable. If
net.ipsec.encap.encdebug is 1,
debug logging is on. See sysctl(8) and sysctl(3) for details.
option KEY
Enables PFKEYv2 (RFC 2367) support. While not IP specific,
this option
is usually used in conjunction with option IPSEC.
option ALTQ
Enables ALTQ (Alternate Queuing). See pfctl(8) and
pf.conf(5) to set up
the interface transmission rate and queueing disciplines.
ALTQ_CBQ,
ALTQ_RED, ALTQ_PRIQ and ALTQ_HFSC are enabled by default
with option ALTQ
in OpenBSD. See altq(9) for details on ALTQ.
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-ofprofile
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).
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.
SCSI Subsystem Options [Toc] [Back]
option SCSITERSE
Terser SCSI error messages. This omits the table for decoding ASC/ASCQ
info, saving about 30KB.
option SCSIDEBUG
Enable printing of SCSI subsystem debugging info to the console. Each of
SCSIDEBUG_LEVEL, SCSIDEBUG_BUSES, SCSIDEBUG_TARGETS and
SCSIDEBUG_LUNS
must have non-zero values for any debugging info to be
printed. Only
SCSI_DEBUG_LEVEL has a default value that is non-zero.
option SCSIDEBUG_LEVEL=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.
0x0010 (SDEV_DB1) SCSI commands, errors, and data
0x0020 (SDEV_DB2) routine flow
0x0040 (SDEV_DB3) routine internals
0x0080 (SDEV_DB4) miscellaneous addition debugging
If SCSIDEBUG_LEVEL is undefined, a value of 0x0030
(SDEV_DB1|SDEV_DB2) is
used.
option SCSIDEBUG_BUSES=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.
option SCSIDEBUG_TARGETS=value
Define which SCSI targets will print debug info. Each bit
enables debugging
info for the corresponding target.
option SCSIDEBUG_LUNS=value
Define which SCSI luns will print debug info. Each bit enables debugging
info for the corresponding lun.
option SCSIFORCELUN_BUSES=value
Define which SCSI buses will do full lun scanning.
SCSIFORCELUN_TARGETS
must also be set to a non-zero value for this option to take
effect.
Each bit enables a full lun scan for the corresponding SCSI
bus. The lun
scan normally terminates if identical INQUIRY data is seen
for lun 0 and
another lun, as this usually means the target cannot distinguish between
different luns. But some devices (e.g. some external RAID
devices) can
legitimately supply identical INQUIRY data for several luns.
option SCSIFORCELUN_TARGETS=value
Define which SCSI targets will do full lun scanning.
SCSIFORCELUN_BUSES
must also be set to a non-zero value for this option to have
any effect.
Each bit enables a full lun scan for the corresponding target on the buses
specified by SCSIFORCELUN_BUSES.
System V IPC Options [Toc] [Back]
option SYSVMSG
Includes support for AT&T System V UNIX style message
queues. See
msgctl(2), msgget(2), msgrcv(2), msgsnd(2).
option SYSVSEM
Includes support for AT&T System V UNIX style semaphores.
See semctl(2),
semget(2), semop(2).
option SYSVSHM
Includes support for AT&T System V UNIX style shared memory.
See
shmat(2), shmctl(2), shmdt(2), shmget(2).
option SHMMAXPGS=value
Sets the maximum number of AT&T System V UNIX style shared
memory pages
that are available through the shmget(2) system call. Default value is
1024 on most architectures. See
/usr/include/machine/vmparam.h for the
default.
option SEMMNI=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.
option SEMMNS=value
Maximum number of semaphores in all sets in the system. Default value is
60.
option SEMMNU=value
Maximum number of semaphore undo structures in the system.
Default value
is 30.
option SEMUME=value
Maximum number of per-process undo operation entries in the
system.
Semaphore undo operations are invoked by the kernel when semop(2) is
called with the SEM_UNDO flag and the process holding the
semaphores terminates
unexpectedly. Default value is 10.
Operation Related Options [Toc] [Back]
option NKMEMPAGES=value
option NKMEMPAGES_MIN=value
option NKMEMPAGES_MAX=value
Size of kernel malloc area in PAGE_SIZE-sized logical pages.
This area
is covered by the kernel submap kmem_map. The kernel attempts to autosize
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 sysctl(8) variable vm.nkmempages. See
/usr/include/machine/param.h for the default upper and lower
bounds. The
related options `NKMEMPAGES_MIN' and `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
``out of space in kmem_map'' panic.
option NBUF=value
option BUFPAGES=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.
option DUMMY_NOPS
This option is supported on the i386 architecture. When enabled, it
speeds up interrupt processing by removing delays while accessing the interrupt
controller. Care should be taken when using this
option.
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 apm(8)
and/or apmd(8).
option "TIMEZONE=value"
value indicates the timezone 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 OpenBSD
with other operating systems on a single machine. For instance, if the
hardware realtime clock is set to Tokyo time, value should
be -540 as
Tokyo local time is 9 hours ahead of UTC. Double quotes are
needed when
specifying a negative value.
option DST=value
If value is non-zero, indicates that the hardware realtime
clock device
is one hour ahead of the offset given in `TIMEZONE', due to
Daylight Saving
Time (DST). If value is zero, the hardware realtime
clock device is
not in Daylight Saving Time.
gcc-local(1), gdb(1), ktrace(1), quota(1), gettimeofday(2),
i386_iopl(2),
msgctl(2), msgget(2), msgrcv(2), msgsnd(2), ptrace(2), semctl(2),
semget(2), semop(2), shmat(2), shmctl(2), shmdt(2),
shmget(2), sysctl(3),
ddb(4), inet(4), ipsec(4), lkm(4), ns(4), pci(4), xf86(4),
X(7), apm(8),
apmd(8), config(8), edquota(8), init(8), mount_cd9660(8),
mount_fdesc(8),
mount_kernfs(8), mount_mfs(8), mount_msdos(8), mount_nfs(8),
mount_null(8), mount_portal(8), mount_procfs(8),
mount_umap(8),
mount_union(8), mrouted(8), quotaon(8), rpc.rquotad(8),
sysctl(8),
altq(9)
The options man page first appeared in OpenBSD 2.3.
The INET option should not be required.
OpenBSD 3.6 July 15, 2004
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