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OPTIONS(4)		 BSD Kernel Interfaces Manual		    OPTIONS(4)

NAME
     options --	Miscellaneous kernel configuration options

SYNOPSIS
     cinclude ...
     config ...
     [no] file-system ...
     ident ...
     include ...
     [no] makeoptions ...
     maxusers ...
     [no] options ...
     [no] pseudo-device	...

DESCRIPTION
     This manual page describes	a number of miscellaneous kernel configuration
     options that may be specified in a	kernel config file.  See config(1) and
     config(5) for information on how to configure and build kernels.

     The no form removes a previously specified	option.

   Keywords
     The following keywords are	recognized in a	kernel configuration file:

     cinclude "filename"
     Conditionally includes another kernel configuration file whose name is
     filename, which may be double-quoted and may be an	explicit path or rela-
     tive to the kernel	source directory.  Failure to open the named file is
     ignored.

     config exec_name root on rootdev [type fstype] [dumps on dumpdev]
     Defines a configuration whose kernel executable is	named exec_name, nor-
     mally "netbsd", with its root file	system of type fstype on the device
     rootdev, and optionally specifying	the location of	kernel core dumps on
     the device	dumpdev.  dev or dumpdev and fstype may	be specified as	"?",
     which is a	wild card.  The	root fstype and	dumpdev	are optional and as-
     sumed to be wild carded if	they are not specified.

     device_instance at	attachment [locators value [...]] [flags value]
     Define an instance	of the device driver device_instance that attaches to
     the bus or	device named attachment.  An attachment	may require additional
     information on where the device can be found, such	as an address, chan-
     nel, function, offset, and/or slot, referred to as	locators, whose	value
     often may be a wild card, "?".  Some device drivers have one or more
     flags that	can be adjusted	to affect the way they operate.

     file-system fs_name [, fs_name [...]]
     Include support for the file-system fs_name.

     ident "string"
     Sets the kernel identification string to string.

     include "filename"
     Functions the same	as cinclude, except failure to open filename produces
     a fatal error.

     options option_name [, option_name=value [...]]
     Specifies (or sets) the option, or	comma-separated	list of	options,
     option_name.  Some	options	expect to be assigned a	value, which may be an
     integer, a	double-quoted word, a bare word, or an empty string ("").
     Note that those are eventually handled by the C compiler, so the rules of
     that language apply.

     Note: Options that	are not	defined	by device definition files are passed
     to	the compile process as -D flags	to the C compiler.

     makeoptions name=value
     Defines a make(1) macro name with the value value in the kernel Makefile.

     maxusers integer
     Set the maxusers variable in the kernel.

     no	keyword	name [arguments	[...]]
     For the config(1) keywords	file-system, makeoptions, options, and pseudo-
     device, no	removes	the file-system, makeoption, options, or pseudo-de-
     vice, name.  This is useful when a	kernel configuration file includes an-
     other which has undesired options.

     For example, a local configuration	file that wanted the kitchen sink, but
     not COMPAT_09 or bridging,	might be:

	   include "arch/i386/conf/GENERIC"
	   no options COMPAT_09
	   no pseudo-device bridge

     pseudo-device name	[N]
     Includes support for the pseudo-device name.  Some	pseudo-devices can
     have multiple or N	instances.

   Compatibility Options
     options COMPAT_09
     Enable binary compatibility with NetBSD 0.9.  This	enables	support	for
     16-bit user, group, and process IDs (following revisions support 32-bit
     identifiers).  It also allows the use of the deprecated getdomainname(3),
     setdomainname(3), and uname(3) syscalls.  This option also	allows using
     numeric file system identifiers rather than strings.  Post	NetBSD 0.9
     versions use string identifiers.

     options COMPAT_10
     Enable binary compatibility with NetBSD 1.0.  This	option allows the use
     of	the file system	name of	"ufs" as an alias for "ffs".  The name "ffs"
     should be used post 1.0 in	/etc/fstab and other files.  It	also adds old
     syscalls for the AT&T System V UNIX shared	memory interface.  This	was
     changed post 1.0 to work on 64-bit	architectures.	This option also en-
     ables "sgtty" compatibility, without which	programs using the old inter-
     face produce an "inappropriate ioctl" error, and /dev/io only works when
     this option is set	in the kernel, see io(4) on ports that support it.

     options COMPAT_11
     Enable binary compatibility with NetBSD 1.1.  This	allows binaries	run-
     ning on the i386 port to gain direct access to the	io ports by opening
     /dev/io read/write.  This functionality was replaced by i386_iopl(2) post
     1.1.  On the Atari	port, the location of the disk label was moved after
     1.1.  When	the COMPAT_11 option is	set, the kernel	will read (pre)	1.1
     style disk	labels as a last resort.  When a disk label is re-written, the
     old style label will be replaced with a post 1.1 style label.  This also
     enables the EXEC_ELF_NOTELESS option.

     options COMPAT_12
     Enable binary compatibility with NetBSD 1.2.  This	allows the use of old
     syscalls for reboot() and swapon().  The syscall numbers were changed
     post 1.2 to add functionality to the reboot(2) syscall, and the new
     swapctl(2)	interface was introduced.  This	also enables the
     EXEC_ELF_NOTELESS option.

     options COMPAT_13
     Enable binary compatibility with NetBSD 1.3.  This	allows the use of old
     syscalls for sigaltstack(), and also enables the old swapctl(2) command
     SWAP_STATS	(now called SWAP_OSTATS), which	does not include the se_path
     member of struct swapent.

     options COMPAT_14
     Enable binary compatibility with NetBSD 1.4.  This	allows some old
     ioctl(2) on wscons(4) to be performed, and	allows the NFSSVC_BIOD mode of
     the nfssvc(2) system call to be used for compatibility with the depre-
     cated nfsiod program.

     options COMPAT_15
     Enable binary compatibility with NetBSD 1.5.  Since there were no API
     changes from NetBSD 1.5 and NetBSD	1.6, this option does nothing.

     options COMPAT_16
     Enable binary compatibility with NetBSD 1.6.  This	allows the use of old
     signal trampoline code which has been deprecated with the addition	of
     siginfo(2).

     options COMPAT_20
     Enable binary compatibility with NetBSD 2.0.  This	allows the use of old
     syscalls for statfs(), fstatfs(), getfsstat() and fhstatfs(), which have
     been deprecated with the addition of the statvfs(2), fstatvfs(2),
     getvfsstat(2) and fhstatvfs(2) system calls.

     options COMPAT_30
     Enable binary compatibility with NetBSD 3.0.  See compat_30(8) for	de-
     tails about the changes made after	the NetBSD 3.0 release.

     options COMPAT_43
     Enables compatibility with	4.3BSD.	 This adds an old syscall for
     lseek(2).	It also	adds the ioctls	for TIOCGETP and TIOCSETP.  The	return
     values for	getpid(2), getgid(2), and getuid(2) syscalls 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 disci-
     pline.  It	also provides backwards	compatibility with "old"
     SIOC[GS]IF{ADDR,DSTADDR,BRDADDR,NETMASK} interface	ioctls,	including bi-
     nary compatibility	with code written before the introduction of the
     sa_len field in sockaddrs.	 It also enables support for some older	pre
     4.4BSD socket calls.

     options COMPAT_BSDPTY
     This option is currently on by default and	enables	the pty	multiplexer
     ptm(4) and	ptmx(4)	to find	and use	ptys named /dev/ptyXX (master) and
     /dev/ttyXX	(slave).  Eventually this option will become optional as ptyfs
     based pseudo-ttys become the default, see mount_ptyfs(8).

     options COMPAT_SVR4
     On	those architectures that support it, this enables binary compatibility
     with AT&T System V	Release	4 UNIX applications built for the same archi-
     tecture.  This currently includes the i386, m68k, and sparc ports.

     options COMPAT_LINUX
     On	those architectures that support it, this enables binary compatibility
     with Linux	ELF and	a.out(5) applications built for	the same architecture.
     This currently includes the alpha,	arm, i386, m68k, mips, powerpc and
     x86_64 ports.

     options COMPAT_LINUX32
     On	those 64 bit architectures that	support	it, this enables binary	com-
     patibility	with 32	bit Linux binaries.  For now this is limited to	run-
     ning i386 ELF Linux binaries on amd64.

     options COMPAT_SUNOS
     On	those architectures that support it, this enables binary compatibility
     with SunOS	4.1 applications built for the same architecture.  This	cur-
     rently includes the sparc,	sparc64	and most or all	m68k ports.  Note that
     the sparc64 requires the COMPAT_NETBSD32 option for 64-bit	kernels, in
     addition to this option.

     options COMPAT_ULTRIX
     On	those architectures that support it, this enables binary compatibility
     with ULTRIX applications built for	the same architecture.	This currently
     is	limited	to the pmax.  The functionality	of this	option is unknown.

     options COMPAT_FREEBSD
     On	those architectures that support it, this enables binary compatibility
     with FreeBSD applications built for the same architecture.	 At the	moment
     this is limited to	the i386 port.

     options COMPAT_IBCS2
     On	those architectures that support it, this enables binary compatibility
     with iBCS2	or SVR3	applications built for the same	architecture.  This is
     currently limited to the i386 and vax ports.

     options COMPAT_OSF1
     On	those architectures that support it, this enables binary compatibility
     with Digital UNIX (formerly OSF/1)	applications built for the same	archi-
     tecture.  This is currently limited to the	alpha port.

     options COMPAT_NOMID
     Enable compatibility with a.out(5)	executables that lack a	machine	ID.
     This includes NetBSD 0.8's	ZMAGIC format, and 386BSD and BSDI's QMAGIC,
     NMAGIC, and OMAGIC	a.out(5) formats.

     options COMPAT_NETBSD32
     On	those architectures that support it, this enables binary compatibility
     with 32-bit applications built for	the same architecture.	This is	cur-
     rently limited to the amd64 and sparc64 ports, and	only applicable	for
     64-bit kernels.

     options COMPAT_SVR4_32
     On	those architectures that support it, this enables binary compatibility
     with 32-bit SVR4 applications built for the same architecture.  This is
     currently limited to the sparc64 port, and	only applicable	for 64-bit
     kernels.

     options COMPAT_AOUT_M68K
     On	m68k architectures which have switched to ELF, this enables binary
     compatibility with	NetBSD/m68k a.out(5) executables on NetBSD/m68k	ELF
     kernels.  This handles alignment incompatibility of m68k ABI between
     a.out and ELF which causes	the structure padding differences.  Currently
     only some system calls which use struct stat are adjusted and some	bina-
     ries which	use sysctl(3) to retrieve network details would	not work prop-
     erly.

     options EXEC_ELF_NOTELESS
     Run unidentified ELF binaries as NetBSD binaries.	This might be needed
     for very old NetBSD ELF binaries on some archs.  These old	binaries
     didn't contain an appropriate .note.netbsd.ident section, and thus	can't
     be	identified by the kernel as NetBSD binaries otherwise.	Beware - if
     this option is on,	the kernel would run any unknown ELF binaries as if
     they were NetBSD binaries.

     options P1003_1B_SEMAPHORE
     Includes kernel support for the standard C	library	(libc) functions that
     implement semaphores as specified in ISO/IEC 9945-1:1996 ("POSIX.1").

   Debugging Options
     options DDB
     Compiles in a kernel debugger for diagnosing kernel problems.  See	ddb(4)
     for details.  NOTE: not available on all architectures.

     options DDB_FROMCONSOLE=integer
     If	set to non-zero, DDB may be entered by sending a break on a serial
     console or	by a special key sequence on a graphics	console.  A value of
     "0" ignores console breaks	or key sequences.  If not explicitly speci-
     fied, the default value is	"1".  Note that	this sets the value of the
     ddb.fromconsole sysctl(3) variable	which may be changed at	run time --
     see sysctl(8) for details.

     options DDB_HISTORY_SIZE=integer
     If	this is	non-zero, enable history editing in the	kernel debugger	and
     set the size of the history to this value.

     options DDB_ONPANIC
     The default if not	specified is "1" - just	enter into DDB.	 If set	to "2"
     the kernel	will attempt to	print out a stack trace	before entering	into
     DDB.  If set to "0" the kernel will attempt to print out a	stack trace
     and reboot	the system.  If	set to "-1" then neither a stack trace is
     printed or	DDB entered - it is as if DDB were not compiled	into the ker-
     nel.  Note	that this sets the value of the	ddb.onpanic sysctl(3) variable
     which may be changed at run time -- see sysctl(8) for details.

     options DDB_COMMANDONENTER=string
     This option specify commands which	will be	executed on each entry to DDB.
     This sets the default value of the	ddb.commandonenter sysctl(3) variable
     which may be changed at run time.

     options DDB_BREAK_CHAR=integer
     This option overrides using break to enter	the kernel debugger on the se-
     rial console.  The	value given is the ASCII value to be used instead.
     This is currently only supported by the com driver.

     options DDB_VERBOSE_HELP
     This option adds more verbose descriptions	to the help command.

     options KGDB
     Compiles in a remote kernel debugger stub for diagnosing kernel problems
     using the "remote target" feature of gdb.	See gdb(1) for details.	 NOTE:
     not available on all architectures.

     options KGDB_DEV
     Device number (as a dev_t)	of kgdb	device.

     options KGDB_DEVADDR
     Memory address of kgdb device.

     options KGDB_DEVMODE
     Permissions of kgdb device.

     options KGDB_DEVNAME
     Device name of kgdb device.

     options KGDB_DEVRATE
     Baud rate of kgdb device.

     makeoptions DEBUG="-g"
     The -g flag causes	netbsd.gdb to be built in addition to netbsd.
     netbsd.gdb	is useful for debugging	kernel crash dumps with	gdb.  See
     gdb(1) for	details.  This also turns on options DEBUG (which see).

     options DEBUG
     Turns on miscellaneous kernel debugging.  Since options are turned	into
     preprocessor defines (see above), options DEBUG is	equivalent to doing a
     #define DEBUG throughout the kernel.  Much	of the kernel has #ifdef DEBUG
     conditionalized debugging code.  Note that	many parts of the kernel (typ-
     ically device drivers) include their own #ifdef XXX_DEBUG conditionals
     instead.  This option also	turns on certain other options,	which may de-
     crease system performance.

     options 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.  These checks	can decrease performance up to 15%.

     options LOCKDEBUG
     Adds code to the kernel to	detect incorrect use of	locking	primitives
     (mutex, rwlock, simplelock).  This	code will cause	the kernel to check
     for dead lock conditions.	It will	also check for memory being freed to
     not contain initialised lock primitives.  Functions for use in ddb(4) to
     check lock	chains etc. are	also enabled.  These checks are	very expensive
     and can decrease performance on multi-processor machines by a factor of
     three.

     options KSTACK_CHECK_MAGIC
     Check kernel stack	usage and panic	if stack overflow is detected.	This
     check is performance sensitive because it scans stack on each context
     switch.

     options KTRACE
     Add hooks for the system call tracing facility, which allows users	to
     watch the system call invocation behavior of processes.  See ktrace(1)
     for details.

     options MSGBUFSIZE=integer
     This option sets the size of the kernel message buffer.  This buffer
     holds the kernel output of	printf() when not (yet)	read by	syslogd(8).
     This is particularly useful when the system has crashed and you wish to
     lookup the	kernel output from just	before the crash.  Also, since the au-
     toconfig output becomes more and more verbose, it sometimes happens that
     the message buffer	overflows before syslogd(8) was	able to	read it.  Note
     that not all systems are capable of obtaining a variable sized message
     buffer.  There are	also some systems on which memory contents are not
     preserved across reboots.

     options MALLOCLOG
     Enables an	event log for malloc(9).  Useful for tracking down "Data
     modified on freelist" and "multiple free" problems.

     options MALLOCLOGSIZE=integer
     Defines the number	of entries in the malloc log.  Default is 100000 en-
     tries.

     options UVMHIST
     Enables the UVM history logs, which create	in-memory traces of various
     UVM activities.  These logs can be	displayed be calling uvmhist_dump() or
     uvm_hist()	with appropriate arguments from	DDB.  See the kernel source
     file sys/uvm/uvm_stat.c for details.

     options UVMHIST_PRINT
     Prints the	UVM history logs on the	system console as entries are added.
     Note that the output is extremely voluminous, so this option is really
     only useful for debugging the very	earliest parts of kernel initializa-
     tion.

   File	Systems
     file-system FFS
     Includes code implementing	the Berkeley Fast File System (FFS).  Most ma-
     chines need this if they are not running diskless.

     file-system EXT2FS
     Includes code implementing	the Second Extended File System	(ext2),	revi-
     sion 0 and	revision 1 with	the filetype, sparse_super and large_file op-
     tions.  This is the most commonly used file system	on the Linux operating
     system, and is provided here for compatibility.  Some of the specific
     features of ext2 like the "behavior on errors" are	not implemented.  See
     mount_ext2fs(8) for details.

     file-system LFS
     [EXPERIMENTAL] Include the	Log-structured File System (LFS).  See
     mount_lfs(8) and newfs_lfs(8) for details.

     file-system 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	and similar file systems.  See
     mount_mfs(8) for details.

     file-system NFS
     Include the client	side of	the Network File System	(NFS) remote file
     sharing protocol.	Although the bulk of the code implementing NFS is ker-
     nel based,	several	user level daemons are needed for it to	work.  See
     mount_nfs(8) for details.

     file-system CD9660
     Includes code for the ISO 9660 + Rock Ridge file system, which is the
     standard file system on many CD-ROM discs.	 Useful	primarily if you have
     a CD-ROM drive.  See mount_cd9660(8) for details.

     file-system MSDOSFS
     Includes the MS-DOS FAT file system, which	is reportedly still used by
     unfortunate people	who have not heard about NetBSD.  Also implements the
     Windows 95	extensions to the same,	which permit the use of	longer,	mixed
     case file names.  See mount_msdos(8) and fsck_msdos(8) for	details.

     file-system NTFS
     [EXPERIMENTAL] Includes code for the Microsoft Windows NT file system.
     See mount_ntfs(8) for details.

     file-system FDESC
     Includes code for a file system, conventionally mounted on	/dev/fd, which
     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 fa-
     cility is redundant, and thus unneeded on most NetBSD systems, since the
     fd(4) pseudo-device driver	already	provides identical functionality.  On
     most NetBSD systems, instances of fd(4) are mknoded under /dev/fd/	and on
     /dev/stdin, /dev/stdout, and /dev/stderr.

     file-system KERNFS
     Includes code which permits the mounting of a special file	system (nor-
     mally mounted on /kern) in	which files representing various kernel	vari-
     ables and parameters may be found.	 See mount_kernfs(8) for details.

     file-system 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.

     file-system OVERLAY
     Includes code for a file system filter.  This permits the overlay file
     system to intercept all access to an underlying file system.  This	file
     system is intended	to serve as an example of a stacking file system which
     has a need	to interpose itself between an underlying file system and all
     other access.  See	mount_overlay(8) for details.

     file-system 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.

     file-system UDF
     [EXPERIMENTAL] Includes code for the UDF file system commonly found on CD
     and DVD media but also on USB sticks.  Currently supports read and	write
     access upto UDF 2.01 and somewhat limited write support for UDF 2.50.  It
     is	marked experimental since there	is no fsck_udf(8).  See	mount_udf(8)
     for details.

     file-system 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 dif-
     ferent UIDs and GIDs than the local system.  See mount_umap(8) for	de-
     tails.

     file-system UNION
     [EXPERIMENTAL] Includes code for the union	file system, which permits di-
     rectories 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	mount-
     ing a local writable file system on top of	the read-only file system.
     See mount_union(8)	for details.

     file-system CODA
     [EXPERIMENTAL] Includes code for the Coda file system.  Coda is a dis-
     tributed file system like NFS and AFS.  It	is freely available, like NFS,
     but it functions much like	AFS in being a "stateful" file system.	Both
     Coda and AFS cache	files on your local machine to improve performance.
     Then Coda goes a step further than	AFS by letting you access the cached
     files when	there is no available network, viz. disconnected laptops and
     network outages.  In Coda,	both the client	and server are outside the
     kernel which makes	them easier to experiment with.	 Coda is available for
     several UNIX and non-UNIX platforms.  See http://www.coda.cs.cmu.edu for
     more details.  NOTE: You also need	to enable the pseudo-device, vcoda,
     for the Coda file system to work.

     file-system SMBFS
     [EXPERIMENTAL] Includes code for the SMB/CIFS file	system.	 See
     mount_smbfs(8) for	details.  NOTE:	You also need to enable	the pseudo-de-
     vice, nsmb, for the SMB file system to work.

     file-system PTYFS
     [EXPERIMENTAL] Includes code for a	special	file system (normally mounted
     on	/dev/pts) in which pseudo-terminal slave devices become	visible	in the
     file system.  See mount_ptyfs(8) for details.

     file-system TMPFS
     Includes code for the efficient memory file system, normally used over
     /tmp.  See	mount_tmpfs(8) for details.

     file-system PUFFS
     Includes kernel support for the pass-to-userspace framework file system.
     It	can be used to implement file system functionality in userspace.  See
     puffs(3) for more details.	 This enables for example sshfs:
     mount_psshfs(8).

   File	System Options
     options MAGICLINKS
     Enables the expansion of special strings (beginning with "@") when
     traversing	symbolic links.	 See symlink(7)	for a list of supported
     strings.  Note that this option only controls the enabling	of this	fea-
     ture by the kernel	at boot-up.  This feature can still be manipulated
     with the sysctl(8)	command	regardless of the setting of this option.

     options NFSSERVER
     Include the server	side of	the NFS	(Network File System) remote file
     sharing protocol.	Although the bulk of the code implementing NFS is ker-
     nel based,	several	user level daemons are needed for it to	work.  See
     mountd(8) and nfsd(8) for details.

     options QUOTA
     Enables kernel support for	file system quotas.  See quotaon(8),
     edquota(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.

     options QUOTA2
     Enables kernel support for	the new	file system quotas format.  See
     tunefs(8),	newfs(8), mount_mfs(8),	edquota(8), and	quota(1) for details.
     Note that quota2 is only supported	by "ffs" and "mfs" file	systems	at
     this time.

     options FFS_EI
     Enable ``Endian-Independent'' FFS support.	 This allows a system to mount
     an	FFS file system	created	for another architecture, at a small perfor-
     mance cost	for all	FFS file systems.  See also newfs(8), fsck_ffs(8),
     dumpfs(8) for file	system byte order status and manipulation.

     options FFS_NO_SNAPSHOT
     Disable the "file system snapshot"	support	in FFS file systems.  Maybe
     useful for	install	media kernels, small memory systems and	embedded sys-
     tems which	don't require the snapshot support.

     options UFS_EXTATTR
     Enable extended attribute support for UFS1	filesystems.

     options WAPBL
     Enable "Write Ahead Physical Block	Logging	file system journaling".  This
     provides rapid file system	consistency checking after a system outage.
     It	also provides better general use performance over regular FFS.	See
     also wapbl(4).

     options NVNODE=integer
     This option sets the size of the cache used by the	name-to-inode transla-
     tion routines, (a.k.a. the	namei()	cache, though called by	many other
     names in the kernel source).  By default, this cache has NPROC (set as 20
     + 16 * MAXUSERS) *	(80 + NPROC / 8) entries.  A reasonable	way to derive
     a value of	NVNODE,	should you notice a large number of namei cache	misses
     with a tool such as systat(1), is to examine your system's	current	com-
     puted value with sysctl(8), (which	calls this parameter "kern.maxvnodes")
     and to increase this value	until either the namei cache hit rate improves
     or	it is determined that your system does not benefit substantially from
     an	increase in the	size of	the namei cache.

     options NAMECACHE_ENTER_REVERSE
     Causes the	namei cache to always enter a reverse mapping (vnode ->	name)
     as	well as	a normal one.  Normally, this is already done for directory
     vnodes, to	speed up the getcwd operation.	This option will cause longer
     hash chains in the	reverse	cache, and thus	slow down getcwd somewhat.
     However, it does make vnode -> path translations possible in some cases.
     For now, only useful if strict /proc/#/maps emulation for Linux binaries
     is	required.

     options EXT2FS_SYSTEM_FLAGS
     This option changes the behavior of the APPEND and	IMMUTABLE flags	for a
     file on an	ext2 file system.  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) and secmodel_securelevel(9).

     options NFS_BOOT_BOOTP
     Enable use	of the BOOTP protocol (RFCs 951	and 1048) to get configuration
     information if NFS	is used	to mount the root file system.	See
     diskless(8) for details.

     options NFS_BOOT_DHCP
     Same as "NFS_BOOT_BOOTP", but use the DHCP	extensions to the BOOTP	proto-
     col (RFC 1541).

     options NFS_BOOT_BOOTP_REQFILE
     Specifies the string sent in the bp_file field of the BOOTP / DHCP	re-
     quest packet.

     options NFS_BOOT_BOOTPARAM
     Enable use	of the BOOTPARAM protocol, consisting of RARP and BOOTPARAM
     RPC, to get configuration information if NFS is used to mount the root
     file system.  See diskless(8) for details.

     options NFS_BOOT_RWSIZE=value
     Set the initial NFS read and write	sizes for diskless-boot	requests.  The
     normal default is 8Kbytes.	 This option provides a	way to lower the value
     (e.g., to 1024 bytes) as a	workaround for buggy network interface cards
     or	boot PROMs.  Once booted, the read and write request sizes can be in-
     creased by	remounting the file system.  See mount_nfs(8) for details.

     options NFS_V2_ONLY
     Reduce the	size of	the NFS	client code by omitting	code that's only re-
     quired for	NFSv3 and NQNFS	support, leaving only that code	required to
     use NFSv2 servers.

     options UFS_DIRHASH
     Increase lookup performance by maintaining	in-core	hash tables for	large
     directories.

   Buffer queue	strategy options
     The following options enable alternative buffer queue strategies.

     options BUFQ_READPRIO
     Enable experimental buffer	queue strategy for disk	I/O.  In the default
     strategy, outstanding disk	requests are ordered by	sector number and sent
     to	the disk, regardless of	whether	the operation is a read	or write; this
     option gives priority to issuing read requests over write requests.  Al-
     though requests may therefore be issued out of sector-order, causing more
     seeks and thus lower overall throughput, interactive system responsive-
     ness under	heavy disk I/O load may	be improved, as	processes blocking on
     disk reads	are serviced sooner (file writes typically don't cause appli-
     cations to	block).	 The performance effect	varies greatly depending on
     the hardware, drive firmware, file	system configuration, workload,	and
     desired performance trade-off.  Systems using drive write-cache (most
     modern IDE	disks, by default) are unlikely	to benefit and may well	suf-
     fer; such disks acknowledge writes	very quickly, and optimize them	inter-
     nally according to	physical layout.  Giving these disks as	many requests
     to	work with as possible (the standard strategy) will typically produce
     the best results, especially if the drive has a large cache; the drive
     will silently complete writes from	cache as it seeks for reads.  Disks
     that support a large number of concurrent tagged requests (SCSI disks and
     many hardware RAID	controllers) expose this internal scheduling with
     tagged responses, and don't block for reads; such disks may not see a no-
     ticeable difference with either strategy.	However, if IDE	disks are run
     with write-cache disabled for safety, writes are not acknowledged until
     actually completed, and only one request can be outstanding; a large num-
     ber of small writes in one	locality can keep the disk busy, starving
     reads elsewhere on	the disk.  Such	systems	are likely to see the most
     benefit from this option.	Finally, the performance interaction of	this
     option with ffs soft dependencies can be subtle, as that mechanism	can
     drastically alter the workload for	file system metadata writes.

     options BUFQ_PRIOCSCAN
     Enable another buffer queue strategy for disk I/O,	per-priority cyclical
     scan.

     options NEW_BUFQ_STRATEGY
     Synonym of	BUFQ_READPRIO.

   Miscellaneous Options
     options CPU_UCODE
     Support cpu microcode loading via cpuctl(8).

     options MEMORY_DISK_DYNAMIC
     This option makes the md(4) RAM disk size dynamically sized.  It is in-
     compatible	with mdsetimage(8).

     options MEMORY_DISK_HOOKS
     This option allows	for some machine dependent functions to	be called when
     the md(4) RAM disk	driver is configured.  This can	result in automati-
     cally loading a RAM disk from floppy on open (among other things).

     options MEMORY_DISK_IS_ROOT
     Forces the	md(4) RAM disk to be the root device.  This can	only be	over-
     ridden when the kernel is booted in the 'ask-for-root' mode.

     options MEMORY_DISK_ROOT_SIZE=integer
     Allocates the given number	of 512 byte blocks as memory for the md(4) RAM
     disk, to be populated with	mdsetimage(8).

     options MEMORY_DISK_SERVER=0
     Do	not include the	interface to a userland	memory disk server process.
     Per default, this option is set to	1, including the support code.	Useful
     for install media kernels.

     options MEMORY_DISK_RBFLAGS=value
     This option sets the reboot(2) flags used when booting with a memory disk
     as	root file system.  Possible values include RB_AUTOBOOT (boot in	the
     usual fashion - default value), and RB_SINGLE (boot in single-user	mode).

     options MODULAR
     Enables the framework for kernel modules (see module(7)).

     options VND_COMPRESSION
     Enables the vnd(4)	driver to also handle compressed images.  See
     vndcompress(1), vnd(4) and	vnconfig(8) for	more information.

     options SPLDEBUG
     Help the kernel programmer	find bugs related to the interrupt priority
     level.  When spllower() or	splraise() changes the current CPU's interrupt
     priority level to or from IPL_HIGH, record	a backtrace.  Read
     return_address(9) for caveats about collecting backtraces.	 This feature
     is	experimental, and it is	only available on i386.	 See
     sys/kern/subr_spldebug.c.

     options TFTPROOT
     Download the root memory disk through TFTP	at root	mount time.  This en-
     ables the use of a	root RAM disk without requiring	it to be embedded in
     the kernel	using mdsetimage(8).  The RAM disk name	is obtained using
     DHCP's filename parameter.	 This option requires MEMORY_DISK_HOOKS,
     MEMORY_DISK_DYNAMIC, and MEMORY_DISK_IS_ROOT.  It is incompatible with
     MEMORY_DISK_ROOT_SIZE.

     options MALLOC_NOINLINE
     Time critical fixed size memory allocation	is performed with MALLOC() and
     FREE().  Normally these expand to inline code, but	with MALLOC_NOINLINE
     these call	the normal malloc() and	free() functions.  Useful for install
     media kernels, small memory systems and embedded systems.

     options HZ=integer
     On	ports that support it, set the system clock frequency (see hz(9)) to
     the supplied value.  Handle with care.

     options NTP
     Turns on in-kernel	precision timekeeping support used by software imple-
     menting NTP (Network Time Protocol, RFC 1305).  The NTP option adds an
     in-kernel Phase-Locked Loop (PLL) for normal NTP operation, and a Fre-
     quency-Locked Loop	(FLL) for intermittently-connected operation.  ntpd(8)
     will employ a user-level PLL when kernel support is unavailable, but the
     in-kernel version has lower latency and more precision, and so typically
     keeps much	better time.

     The interface to the kernel NTP support is	provided by the	ntp_adjtime(2)
     and ntp_gettime(2)	system calls, which are	intended for use by ntpd(8)
     and are enabled by	the option.  On	systems	with sub-microsecond resolu-
     tion timers, or where (HZ / 100000) is not	an integer, the	NTP option
     also enables extended-precision arithmetic	to keep	track of fractional
     clock ticks at NTP	time-format precision.

     options PPS_SYNC
     This option enables a kernel serial line discipline for receiving time
     phase signals from	an external reference clock such as a radio clock.
     (The NTP option (which see) must be on if the PPS_SYNC option is used).
     Some reference clocks generate a Pulse Per	Second (PPS) signal in phase
     with their	time source.  The PPS line discipline receives this signal on
     either the	data leads or the DCD control lead of a	serial port.

     NTP uses the PPS signal to	discipline the local clock oscillator to a
     high degree of precision (typically less than 50 microseconds in time and
     0.1 ppm in	accuracy).  PPS	can also generate a serial output pulse	when
     the system	receives a PPS interrupt.  This	can be used to measure the
     system interrupt latency and thus calibrate NTP to	account	for it.	 Using
     PPS usually requires a gadget box to convert from TTL to RS-232 signal
     levels.  The gadget box and PPS are described in more detail in the HTML
     documentation for ntpd(8) in /usr/share/doc/html/ntp.

     NetBSD currently supports this option in com(4) and zsc(4).

     options SETUIDSCRIPTS
     Allows scripts with the setuid bit	set to execute as the effective	user
     rather than the real user,	just like binary executables.

     NOTE: Using this option will also enable options FDSCRIPTS

     options FDSCRIPTS
     Allows execution of scripts with the execute bit set, but not the read
     bit, by opening the file and passing the file descriptor to the shell,
     rather than the filename.

     NOTE: Execute only	(non-readable) scripts will have argv[0] set to
     /dev/fd/*.	 What this option allows as far	as security is concerned, is
     the ability to safely ensure that the correct script is run by the	inter-
     preter, as	it is passed as	an already open	file.

     options PUCCN
     Enables treating serial ports found on PCI	boards puc(4) as potential
     console devices.  The method for choosing such a console device is	port
     dependent.

     options RTC_OFFSET=integer
     The kernel	(and typically the hardware battery backed-up clock on those
     machines that have	one) keeps time	in UTC (Universal Coordinated Time,
     once known	as GMT,	or Greenwich Mean Time)	and not	in the time of the lo-
     cal time zone.  The RTC_OFFSET option is used on some ports (such as the
     i386) to tell the kernel that the hardware	clock is offset	from UTC by
     the specified number of minutes.  This is typically used when a machine
     boots several operating systems and one of	them wants the hardware	clock
     to	run in the local time zone and not in UTC, e.g.	 RTC_OFFSET=300	means
     the hardware clock	is set to US Eastern Time (300 minutes behind UTC),
     and not UTC.  (Note: RTC_OFFSET is	used to	initialize a kernel variable
     named rtc_offset which is the source actually used	to determine the clock
     offset, and which may be accessed via the kern.rtc_offset sysctl vari-
     able.  See	sysctl(8) and sysctl(3)	for details.  Since the	kernel clock
     is	initialized from the hardware clock very early in the boot process, it
     is	not possible to	meaningfully change rtc_offset in system initializa-
     tion scripts.  Changing this value	currently may only be done at kernel
     compile time or by	patching the kernel and	rebooting).

     NOTE: Unfortunately, in many cases	where the hardware clock is kept in
     local time, it is adjusted	for Daylight Savings Time; this	means that at-
     tempting to use RTC_OFFSET	to let NetBSD coexist with such	an operating
     system, like Windows, would necessitate changing RTC_OFFSET twice a year.
     As	such, this solution is imperfect.

     options KMEMSTATS
     The kernel	memory allocator, malloc(9), will keep statistics on its per-
     formance if this option is	enabled.  Unfortunately, this option therefore
     essentially disables the MALLOC() and FREE() forms	of the memory alloca-
     tor, which	are used to enhance the	performance of certain critical	sec-
     tions of code in the kernel.  This	option therefore can lead to a signif-
     icant decrease in the performance of certain code in the kernel if	en-
     abled.  Examples of such code include the namei() routine,	the ccd(4)
     driver, and much of the networking	code.

     options MAXUPRC=integer
     Sets the soft RLIMIT_NPROC	resource limit,	which specifies	the maximum
     number of simultaneous processes a	user is	permitted to run, for process
     0;	this value is inherited	by its child processes.	 It defaults to
     CHILD_MAX,	which is currently defined to be 160.  Setting MAXUPRC to a
     value less	than CHILD_MAX is not permitted, as this would result in a vi-
     olation of	the semantics of ISO/IEC 9945-1:1990 ("POSIX.1").

     options NOFILE=integer
     Sets the soft RLIMIT_NOFILE resource limit, which specifies the maximum
     number of open file descriptors for each process; this value is inherited
     by	its child processes.  It defaults to OPEN_MAX, which is	currently de-
     fined to be 64.

     options MAXFILES=integer
     Sets the default value of the kern.maxfiles sysctl	variable, which	indi-
     cates the maximum number of files that may	be open	in the system.

     options DEFCORENAME=string
     Sets the default value of the kern.defcorename sysctl variable, otherwise
     it	is set to %n.core.  See	sysctl(8) and sysctl(3)	for details.

     options RASOPS_CLIPPING
     Enables clipping within the rasops	raster-console output system.  NOTE:
     only available on architectures that use rasops for console output.

     options RASOPS_SMALL
     Removes optimized character writing code from the rasops raster-console
     output system.  NOTE: only	available on architectures that	use rasops for
     console output.

     options INCLUDE_CONFIG_FILE
     Embeds the	kernel config file used	to define the kernel in	the kernel bi-
     nary itself.  The embedded	data also includes any files directly included
     by	the config file	itself,	e.g.  GENERIC.local or std.$MACHINE.  The em-
     bedded config file	can be extracted from the resulting kernel with
     config(1) -x, or by the following command:

	   strings netbsd | sed	-n 's/^_CFG_//p' | unvis

     options INCLUDE_JUST_CONFIG
     Similar to	the above option, but includes just the	actual config file,
     not any included files.

     options PIPE_SOCKETPAIR
     Use slower, but smaller socketpair(2)-based pipe implementation instead
     of	default	faster,	but bigger one.	 Primarily useful for installation
     kernels.

     options USERCONF
     Compiles in the in-kernel device configuration manager.  See userconf(4)
     for details.

     options PERFCTRS
     Compiles in kernel	support	for CPU	performance-monitoring counters.  See
     pmc(1) for	details.  NOTE:	not available on all architectures.

     options SYSCALL_STATS
     Count the number of times each system call	number is called.  The values
     can be read through the sysctl interface and displayed using systat(1).
     NOTE: not yet available on	all architectures.

     options SYSCALL_TIMES
     Count the time spent (using cpu_counter32()) in each system call.	NOTE:
     Using this	option will also enable	options	SYSCALL_STATS.

     options SYSCALL_TIMES_HASCOUNTER
     Force use of cpu_counter32() even if cpu_hascounter() reports false.
     Useful for	systems	where the cycle	counter	doesn't	run at a constant rate
     (e.g. Soekris boxes).

     options XSERVER_DDB
     A supplement to XSERVER that adds support for entering ddb(4) while in
     X11.

     options FILEASSOC
     Support for fileassoc(9).

     options FILEASSOC_NHOOKS=integer
     Number of storage slots per file for fileassoc(9).	 Default is 4.

   Networking Options
     options GATEWAY
     Enables IPFORWARDING (which see) and (on most ports) increases the	size
     of	NMBCLUSTERS (which see).  In general, GATEWAY is used to indicate that
     a system should act as a router, and IPFORWARDING is not invoked di-
     rectly.  (Note that GATEWAY has no	impact on protocols other than IP,
     such as CLNP).  GATEWAY option also compiles IPv4 and IPv6	fast forward-
     ing code into the kernel.

     options ICMPPRINTFS
     The ICMPPRINTFS option will enable	debugging information to be printed
     about the icmp(4) protocol.

     options IPFORWARDING=value
     If	value is 1 this	enables	IP routing behavior.  If value is 0 (the de-
     fault), it	disables it.  The GATEWAY option sets this to 1	automatically.
     With this option enabled, the machine will	forward	IP datagrams destined
     for other machines	between	its interfaces.	 Note that even	without	this
     option, the kernel	will still forward some	packets	(such as source	routed
     packets) -- removing GATEWAY and IPFORWARDING is insufficient to stop all
     routing through a bastion host on a firewall -- source routing is con-
     trolled independently.  To	turn off source	routing, use options
     IPFORWSRCRT=0 (which see).	 Note that IP forwarding may be	turned on and
     off independently of the setting of the IPFORWARDING option through the
     use of the	net.inet.ip.forwarding sysctl variable.	 If
     net.inet.ip.forwarding is 1, IP forwarding	is on.	See sysctl(8) and
     sysctl(3) for details.

     options IPFORWSRCRT=value
     If	value is set to	zero, source routing of	IP datagrams is	turned off.
     If	value is set to	one (the default) or the option	is absent, source
     routed IP datagrams are forwarded by the machine.	Note that source rout-
     ing of IP packets may be turned on	and off	independently of the setting
     of	the IPFORWSRCRT	option through the use of the net.inet.ip.forwsrcrt
     sysctl variable.  If net.inet.ip.forwsrcrt	is 1, forwarding of source
     routed IP datagrams is on.	 See sysctl(8) and sysctl(3) for details.

     options IFA_STATS
     Tells the kernel to maintain per-address statistics on bytes sent and re-
     ceived over (currently) Internet and AppleTalk addresses.	The option is
     not recommended as	it degrades system stability.

     options IFQ_MAXLEN=value
     Increases the allowed size	of the network interface packet	queues.	 The
     default queue size	is 50 packets, and you do not normally need to in-
     crease it.

     options IPSELSRC
     Includes support for source-address selection policies.  See
     in_getifa(9).

     options MROUTING
     Includes support for IP multicast routers.	 You certainly want INET with
     this.  Multicast routing is controlled by the mrouted(8) daemon.  See
     also option PIM.

     options PIM
     Includes support for Protocol Independent Multicast (PIM) routing.	 You
     need MROUTING and INET with this.	Software using this can	be found e.g.
     in	pkgsrc/net/xorp.

     options INET
     Includes support for the TCP/IP protocol stack.  You almost certainly
     want this.	 See inet(4) for details.

     options 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.

     options 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.

     options IPSEC
     Includes support for the IPsec protocol, using the	FAST_IPSEC implementa-
     tion.  See	fast_ipsec(4) for details.  (This option is an alias for the
     FAST_IPSEC	option described below.)

     options KAME_IPSEC
     Includes support for the IPsec protocol, using the	KAME implementation.
     See kame_ipsec(4) for details.

     options IPSEC_DEBUG
     Enables debugging code in IPsec stack.  See ipsec(4) for details.

     options IPSEC_ESP
     Includes support for IPsec	ESP protocol, using the	KAME implementation.
     See kame_ipsec(4) for details.

     options FAST_IPSEC
     Includes support for the IPsec protocol, using the	implementation derived
     from OpenBSD, relaying on opencrypto(9) to	carry out cryptographic	opera-
     tions.  See fast_ipsec(4) for details.

     options IPSEC_NAT_T
     Includes support for IPsec	Network	Address	Translator traversal (NAT-T),
     as	described in RFCs 3947 and 3948.  This feature might be	patent-encum-
     bered in some countries.

     options ALTQ
     Enabled ALTQ (Alternate Queueing).	 For simple rate-limiting, use
     tbrconfig(8) to set up the	interface transmission rate.  To use queueing
     disciplines, their	appropriate kernel options should also be defined
     (documented below).  Queueing disciplines are managed by altqd(8).	 See
     altq(9) for details.

     options ALTQ_HFSC
     Include support for ALTQ-implemented HFSC (Hierarchical Fair Service
     Curve) module.  HFSC supports both	link-sharing and guaranteed real-time
     services.	HFSC employs a service curve based QoS model, and its unique
     feature is	an ability to decouple delay and bandwidth allocation.	Re-
     quires ALTQ_RED to	use the	RED queueing discipline	on HFSC	classes, or
     ALTQ_RIO to use the RIO queueing discipline on HFSC classes.  This	option
     assumes ALTQ.

     options ALTQ_PRIQ
     Include support for ALTQ-implemented PRIQ (Priority Queueing).  PRIQ im-
     plements a	simple priority-based queueing discipline.  A higher priority
     class is always served first.  Requires ALTQ_RED to use the RED queueing
     discipline	on HFSC	classes, or ALTQ_RIO to	use the	RIO queueing disci-
     pline on HFSC classes.  This option assumes ALTQ.

     options ALTQ_WFQ
     Include support for ALTQ-implemented WFQ (Weighted	Fair Queueing).	 WFQ
     implements	a weighted-round robin scheduler for a set of queues.  A
     weight can	be assigned to each queue to give a different proportion of
     the link capacity.	 A hash	function is used to map	a flow to one of a set
     of	queues.	 This option assumes ALTQ.

     options ALTQ_FIFOQ
     Include support for ALTQ-implemented FIFO queueing.  FIFOQ	is a simple
     drop-tail FIFO (First In, First Out) queueing discipline.	This option
     assumes ALTQ.

     options ALTQ_RIO
     Include support for ALTQ-implemented RIO (RED with	In/Out).  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 cus-
     tomers.  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).  This option assumes ALTQ.

     options ALTQ_BLUE
     Include support for ALTQ-implemented Blue buffer management.  Blue	is an-
     other active buffer management mechanism.	This option assumes ALTQ.

     options ALTQ_FLOWVALVE
     Include support for ALTQ-implemented Flowvalve.  Flowvalve	is a simple
     implementation of a RED penalty box that identifies and punishes misbe-
     having flows.  This option	requires ALTQ_RED and assumes ALTQ.

     options ALTQ_CDNR
     Include support for ALTQ-implemented CDNR (diffserv traffic conditioner)
     packet marking/manipulation.  Traffic conditioners	are components to me-
     ter, mark,	or drop	incoming packets according to some rules.  As opposed
     to	queueing disciplines, traffic conditioners handle incoming packets at
     an	input interface.  This option assumes ALTQ.

     options ALTQ_NOPCC
     Disables use of processor cycle counter 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.  This option assumes ALTQ.

     options ALTQ_IPSEC
     Include support for IPsec in IPv4 ALTQ.  This option assumes ALTQ.

     options ALTQ_JOBS
     Include support for ALTQ-implemented JoBS (Joint Buffer Management	and
     Scheduling).  This	option assumes ALTQ.

     options ALTQ_AFMAP
     Include support for an undocumented ALTQ feature that is used to map an
     IP	flow to	an ATM VC (Virtual Circuit).  This option assumes ALTQ.

     options ALTQ_LOCALQ
     Include support for ALTQ-implemented local	queues.	 Its practical use is
     undefined.	 Assumes ALTQ.

     options SUBNETSARELOCAL
     Sets default value	for net.inet.ip.subnetsarelocal	variable, which	con-
     trols whether non-directly-connected subnets of connected networks	are
     considered	"local"	for purposes of	choosing the MSS for a TCP connection.
     This is mostly present for	historic reasons and completely	irrelevant if
     you enable	Path MTU discovery.

     options HOSTZEROBROADCAST
     Sets default value	for net.inet.ip.hostzerobroadcast variable, which con-
     trols whether the zeroth host address of each connected subnet is also
     considered	a broadcast address.  Default value is "1", for	compatibility
     with old systems; if this is set to zero on all hosts on a	subnet,	you
     should be able to fit an extra host per subnet on the ".0"	address.

     options MCLSHIFT=value
     This option is the	base-2 logarithm of the	size of	mbuf clusters.	The
     BSD networking stack keeps	network	packets	in a linked list, or chain, of
     kernel buffer objects called mbufs.  The system provides larger mbuf
     clusters as an optimization for large packets, instead of using long
     chains for	large packets.	The mbuf cluster size, or MCLBYTES, must be a
     power of two, and is computed as two raised to the	power MCLSHIFT.	 On
     systems with Ethernet network adapters, MCLSHIFT is often set to 11, giv-
     ing 2048-byte mbuf	clusters, large	enough to hold a 1500-byte Ethernet
     frame in a	single cluster.	 Systems with network interfaces supporting
     larger frame sizes	like ATM, FDDI,	or HIPPI may perform better with
     MCLSHIFT set to 12	or 13, giving mbuf cluster sizes of 4096 and 8192
     bytes, respectively.

     options ISO,TPIP
     Include support for the ubiquitous	OSI protocol stack.  See iso(4)	for
     details.  This option assumes INET.

     options EON
     Include support for tunneling OSI protocols over IP.  Known to be broken,
     or	at least very fragile, and undocumented.

     options NETATALK
     Include support for the AppleTalk protocol	stack.	The kernel provides
     provision for the Datagram	Delivery Protocol (DDP), providing SOCK_DGRAM
     support and AppleTalk routing.  This stack	is used	by the NETATALK	pack-
     age, which	adds support for AppleTalk server services via user libraries
     and applications.

     options BLUETOOTH
     Include support for the Bluetooth protocol	stack.	See bluetooth(4) for
     details.

     options IPNOPRIVPORTS
     Normally, only root can bind a socket descriptor to a so-called
     "privileged" TCP port, that is, a port number in the range	0-1023.	 This
     option eliminates those checks from the kernel.  This can be useful if
     there is a	desire to allow	daemons	without	privileges to bind those
     ports, e.g., on firewalls.	 The security tradeoffs	in doing this are sub-
     tle.  This	option should only be used by experts.

     options TCP_COMPAT_42
     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
     would not respond.

     options TCP_DEBUG
     Record the	last TCP_NDEBUG	TCP packets with SO_DEBUG set, and decode to
     the console if tcpconsdebug is set.

     options TCP_NDEBUG
     Number of packets to record for TCP_DEBUG.	 Defaults to 100.

     options TCP_SENDSPACE=value

     options TCP_RECVSPACE=value
     These options set the max TCP window size to other	sizes than the de-
     fault.  The TCP window sizes can be altered via sysctl(8) as well.

     options TCP_INIT_WIN=value
     This option sets the initial TCP window size for non-local	connections,
     which is used when	the transmission starts.  The default size is 1, but
     if	the machine should act more aggressively, the initial size can be set
     to	some other value.  The initial TCP window size can be set via
     sysctl(8) as well.

     options PFIL_HOOKS
     This option turns on the packet filter interface hooks.  See pfil(9) for
     details.  This option assumes INET.

     options IPFILTER_LOG
     This option, in conjunction with pseudo-device ipfilter, enables logging
     of	IP packets using IP-Filter.

     options IPFILTER_LOOKUP
     This option enables the IP-Filter ippool(8) functionality to be enabled.

     options IPFILTER_COMPAT
     This option enables older IP-Filter binaries to work.

     options IPFILTER_DEFAULT_BLOCK
     This option sets the default policy of IP-Filter.	If it is set, IP-Fil-
     ter will block packets by default.

     options BRIDGE_IPF
     This option causes	bridge devices to use the IP and/or IPv6 filtering
     hooks, forming a link-layer filter	that uses protocol-layer rules.	 This
     option assumes the	presence of pseudo-device ipfilter.

     options MBUFTRACE
     This option can help track	down mbuf leaks.  When enabled,	mbufs are
     tagged with the devices and protocols using them, which slightly de-
     creases network performance.  This	additional information can be viewed
     with netstat(1):
	   netstat -mssv
     Not all devices or	protocols support this option.

   Sysctl Related Options
     options SYSCTL_DISALLOW_CREATE
     Disallows the creation or deletion	of nodes from the sysctl tree, as well
     as	the assigning of descriptions to nodes that lack them, by any process.
     These operations are still	available to kernel sub-systems, including
     loadable kernel modules.

     options SYSCTL_DISALLOW_KWRITE
     Prevents processes	from adding nodes to the sysctl	tree that make exist-
     ing kernel	memory areas writable.	Sections of kernel memory can still be
     read and new nodes	that own their own data	may still be writable.

     options SYSCTL_DEBUG_SETUP
     Causes the	SYSCTL_SETUP routines to print a brief message when they are
     invoked.  This is merely meant as an aid in determining the order in
     which sections of the tree	are created.

     options SYSCTL_DEBUG_CREATE
     Prints a message each time	sysctl_create(), the function that adds	nodes
     to	the tree, is called.

     options SYSCTL_INCLUDE_DESCR
     Causes the	kernel to include short, human readable	descriptions for nodes
     in	the sysctl tree.  The descriptions can be retrieved programmatically
     (see sysctl(3)), or by the	sysctl binary itself (see sysctl(8)).  The de-
     scriptions	are meant to give an indication	of the purpose and/or effects
     of	a given	node's value, not replace the documentation for	the given sub-
     system as a whole.

   System V IPC	Options
     options SYSVMSG
     Includes support for AT&T System V	UNIX style message queues.  See
     msgctl(2),	msgget(2), msgrcv(2), msgsnd(2).

     options SYSVSEM
     Includes support for AT&T System V	UNIX style semaphores.	See semctl(2),
     semget(2),	semop(2).

     options SEMMNI=value
     Sets the number of	AT&T System V UNIX style semaphore identifiers.	 The
     GENERIC config file for your port will have the default.

     options SEMMNS=value
     Sets the number of	AT&T System V UNIX style semaphores in the system.
     The GENERIC config	file for your port will	have the default.

     options SEMUME=value
     Sets the maximum number of	undo entries per process for AT&T System V
     UNIX style	semaphores.  The GENERIC config	file for your port will	have
     the default.

     options SEMMNU=value
     Sets the number of	undo structures	in the system for AT&T System V	UNIX
     style semaphores.	The GENERIC config file	for your port will have	the
     default.

     options SYSVSHM
     Includes support for AT&T System V	UNIX style shared memory.  See
     shmat(2), shmctl(2), shmdt(2), shmget(2).

     options 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 ports.  See /usr/include/machine/vmparam.h for the default.

   VM Related Options
     options NMBCLUSTERS=value
     The number	of mbuf	clusters the kernel supports.  Mbuf clusters are
     MCLBYTES in size (usually 2k).  This is used to compute the size of the
     kernel VM map mb_map, which maps mbuf clusters.  Default on most ports is
     1024 (2048	with "options GATEWAY" ).  See /usr/include/machine/param.h
     for exact default information.  Increase this value if you	get "mclpool
     limit reached" messages.

     options NKMEMPAGES=value

     options NKMEMPAGES_MIN=value

     options NKMEMPAGES_MAX=value
     Size of kernel VM map kmem_map, in	PAGE_SIZE-sized	chunks (the VM page
     size; this	value may be read from the sysctl(8) variable hw.pagesize ).
     This VM map is used to map	the kernel malloc arena.  The kernel attempts
     to	auto-size this map based on the	amount of physical memory in the sys-
     tem.  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	pro-
     vided in the event	the computed value is insufficient resulting in	an
     "out of space in kmem_map"	panic.

     options SB_MAX=value
     Sets the max size in bytes	that a socket buffer is	allowed	to occupy.
     The default is 256k, but sometimes	it needs to be increased, for example
     when using	large TCP windows.  This option	can be changed via sysctl(8)
     as	well.

     options SOMAXKVA=value
     Sets the maximum size of kernel virtual memory that the socket buffers
     are allowed to use.  The default is 16MB, but in situations where for ex-
     ample large TCP windows are used this value must also be increased.  This
     option can	be changed via sysctl(8) as well.

     options BUFCACHE=value
     Size of the buffer	cache as a percentage of total available RAM.  Ignored
     if	BUFPAGES is also specified.

     options NBUF=value
     Sets the number of	buffer headers available, i.e.,	the number of open
     files that	may have a buffer cache	entry.	Each buffer header requires
     MAXBSIZE (machine dependent, but usually 65536) bytes.  The default value
     is	machine	dependent, but is usually equal	to the value of	BUFPAGES.  If
     an	architecture dependent VM_MAX_KERNEL_BUF constant is defined then NBUF
     may be reduced at run time	so that	the storage allocated for buffer head-
     ers doesn't exceed	that limit.

     options 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 be-
     tween 5% and 10% of total available RAM.

     options MAXTSIZ=bytes
     Sets the maximum size limit of a process' text segment.  See
     /usr/include/machine/vmparam.h for	the port-specific default.

     options DFLDSIZ=bytes
     Sets the default size limit of a process' data segment, the value that
     will be returned as the soft limit	for RLIMIT_DATA	(as returned by
     getrlimit(2)).  See /usr/include/machine/vmparam.h	for the	port-specific
     default.

     options MAXDSIZ=bytes
     Sets the maximum size limit of a process' data segment, the value that
     will be returned as the hard limit	for RLIMIT_DATA	(as returned by
     getrlimit(2)).  See /usr/include/machine/vmparam.h	for the	port-specific
     default.

     options DFLSSIZ=bytes
     Sets the default size limit of a process' stack segment, the value	that
     will be returned as the soft limit	for RLIMIT_STACK (as returned by
     getrlimit(2)).  See /usr/include/machine/vmparam.h	for the	port-specific
     default.

     options MAXSSIZ=bytes
     Sets the maximum size limit of a process' stack segment, the value	that
     will be returned as the hard limit	for RLIMIT_STACK (as returned by
     getrlimit(2)).  See /usr/include/machine/vmparam.h	for the	port-specific
     default.

     options DUMP_ON_PANIC=integer
     Defaults to one.  If set to zero, the kernel will not dump	to the dump
     device when it panics, though dumps can still be forced via ddb(4)	with
     the "sync"	command.  Note that this sets the value	of the
     kern.dump_on_panic	sysctl(3) variable which may be	changed	at run time --
     see sysctl(8) for details.

     options USE_TOPDOWN_VM
     User space	memory allocations (as made by mmap(2))	will be	arranged in a
     "top down"	fashion	instead	of the traditional "upwards from MAXDSIZ +
     vm_daddr" method.	This includes the placement of ld.so(1).  Arranging
     memory in this manner allows either (or both of) the heap or mmap(2) al-
     located space to grow larger than traditionally possible.	This option is
     not available on all ports, but is	instead	expected to be offered on a
     port-by-port basis, after which some ports	will commit to using it	by de-
     fault.  See the files /usr/include/uvm/uvm_param.h	for some implementa-
     tion details, and /usr/include/machine/vmparam.h for port specific	de-
     tails including availability.

     options VMSWAP
     Enable paging device/file support.	 This option is	on by default.

     options PDPOLICY_CLOCKPRO
     Use CLOCK-Pro, an alternative page	replace	policy.

   Security Options
     options INSECURE
     Hardwires the kernel security level at -1.	 This means that the system
     always runs in secure level -1 mode, even when running multiuser.	See
     the manual	page for init(8) for details on	the implications of this.  The
     kernel secure level may manipulated by the	superuser by altering the
     kern.securelevel sysctl(3)	variable (the secure level may only be lowered
     by	a call from process ID 1, i.e.,	init(8)).  See also
     secmodel_securelevel(9), sysctl(8)	and sysctl(3).

     options VERIFIED_EXEC_FP_MD5
     Enables support for MD5 hashes in Veriexec.

     options VERIFIED_EXEC_FP_SHA1
     Enables support for SHA1 hashes in	Veriexec.

     options VERIFIED_EXEC_FP_RMD160
     Enables support for RMD160	hashes in Veriexec.

     options VERIFIED_EXEC_FP_SHA256
     Enables support for SHA256	hashes in Veriexec.

     options VERIFIED_EXEC_FP_SHA384
     Enables support for SHA384	hashes in Veriexec.

     options VERIFIED_EXEC_FP_SHA512
     Enables support for SHA512	hashes in Veriexec.

     options PAX_MPROTECT=value
     Enables PaX MPROTECT, mprotect(2) restrictions from the PaX project.

     The value is the default value for	the global knob, see sysctl(3).	 If 0,
     PaX MPROTECT will be enabled only if explicitly set on programs using
     paxctl(8).	 If 1, PaX MPROTECT will be enabled for	all programs.  Pro-
     grams can be exempted using paxctl(8).

     See security(7) for more details.

     options PAX_SEGVGUARD=value
     Enables PaX Segvguard.

     The value is the default value for	the global knob, see sysctl(3).	 If 0,
     PaX Segvguard will	be enabled only	if explicitly set on programs using
     paxctl(8).	 If 1, PaX Segvguard will be enabled to	all programs, and ex-
     emption can be done using paxctl(8).

     See security(7) for more details.

     options PAX_ASLR=value
     Enables PaX ASLR.

     The value is the default value for	the global knob, see sysctl(3).	 If 0,
     PaX ASLR will be enabled only if explicitly set on	programs using
     paxctl(8).	 If 1, PaX ASLR	will be	enabled	to all programs, and exemption
     can be done using paxctl(8).

     See security(7) for more details.

     options USER_VA0_DISABLE_DEFAULT=value
     Sets the initial value of the flag	which controls whether user programs
     can map virtual address 0.	 The flag can be changed at runtime by
     sysctl(3).

   amiga-specific Options
     options BB060STUPIDROM
     When the bootloader (which	passes AmigaOS ROM information)	claims we have
     a 68060 CPU without FPU, go look into the Processor Configuration Regis-
     ter (PCR) to find out.  You need this with	Amiga ROMs up to (at least)
     V40.xxx (OS3.1), when you boot via	the bootblocks and don't have a	DraCo.

     options IOBZCLOCK=frequency
     The IOBlix	boards come with two different serial master clocks: older
     ones use 24 MHz, newer ones use 22.1184 MHz.  The driver normally assumes
     the latter.  If your board	uses 24	MHz, you can recompile your kernel
     with options IOBZCLOCK=24000000 or	patch the kernel variable iobzclock to
     the same value.

     options LIMITMEM=value
     If	there, limit the part of the first memory bank used by NetBSD to value
     megabytes.	 Default is unlimited.

     options NKPTADD=addvalue

     options NKPTADDSHIFT=shiftvalue
     The CPU specific MMU table	for the	kernel is pre-allocated	at kernel
     startup time.  Part of it is scaled with maxproc, to have enough room to
     hold the user program MMU tables; the second part is a fixed amount for
     the kernel	itself.

     The third part accounts for the size of the file buffer cache.  Its size
     is	either NKPTADD pages (if defined) or memory size in bytes divided by
     two to the	power of NKPTADDSHIFT.	The default is undefined NKPTADD and
     NKPTADDSHIFT=24, allowing for 16 buffers per megabyte of main memory
     (while a GENERIC kernel allocates about half of that).  When you get
     "can't get	KPT page" panics, you should increase NKPTADD (if defined), or
     decrease NKPTADDSHIFT by one.

     options P5PPC68KBOARD
     Add special support for Phase5 mixed 68k+PPC boards.  Currently, this
     only affects rebooting from NetBSD	and is only needed on 68040+PPC, not
     on	68060+PPC; without this, affected machines will	hang after NetBSD has
     shut down and will	only restart after a keyboard reset or a power cycle.

   arm32-specific Options
     options FRENCH_KBD
     Include translation for French keyboards when using pccons	on a Shark.

     options FINNISH_KBD
     Include translation for Finnish keyboards when using pccons on a Shark.

     options GERMAN_KBD
     Include translation for German keyboards when using pccons	on a Shark.

     options NORWEGIAN_KBD
     Include translation for French keyboards when using pccons	on a Shark.

   atari-specific Options
     options DISKLABEL_AHDI
     Include support for AHDI (native Atari) disklabels.

     options DISKLABEL_NBDA
     Include support for NetBSD/atari labels.  If you don't set	this option,
     it	will be	set automatically.  NetBSD/atari will not work without it.

     options FALCON_SCSI
     Include support for the 5380-SCSI configuration as	found on the Falcon.

     options RELOC_KERNEL
     If	set, the kernel	will relocate itself to	TT-RAM,	if possible.  This
     will give you a slightly faster system.  Beware that on some TT030	sys-
     tems, the system will frequently dump with	MMU-faults with	this option
     enabled.

     options SERCONSOLE
     Allow the modem1-port to act as the system-console.  A carrier should be
     active on modem1 during system boot to active the console functionality.

     options TT_SCSI
     Include support for the 5380-SCSI configuration as	found on the TT030 and
     Hades.

   i386-specific Options
     options CPURESET_DELAY=value
     Specifies the time	(in millisecond) to wait before	doing a	hardware reset
     in	the last phase of a reboot.  This gives	the user a chance to see error
     messages from the shutdown	operations (like NFS unmounts, buffer cache
     flush, etc	...).  Setting this to 0 will disable the delay.  Default is 2
     seconds.

     options VM86
     Include support for virtual 8086 mode, used by DOS	emulators and X
     servers to	run BIOS code, e.g., for some VESA routines.

     options USER_LDT
     Include i386-specific system calls	for modifying the local	descriptor ta-
     ble, used by Windows emulators.

     options PAE
     Enable PAE	(Physical Address Extension) mode.  PAE	permits	up to 36 bits
     physical addressing (64GB of physical memory), and	turns physical ad-
     dresses to	64 bits	entities in the	memory management subsystem.  Userland
     virtual address space remains at 32 bits (4GB).  PAE mode is required to
     enable the	NX/XD (No-eXecute/eXecute Disable) bit for pages, which	allows
     marking certain ones as not being executable.  Any	attempt	to execute
     code from such a page will	raise an exception.

     options REALBASEMEM=integer
     Overrides the base	memory size passed in from the boot block.  (Value
     given in kilobytes.)  Use this option only	if the boot block reports the
     size incorrectly.	(Note that some	BIOSes put the extended	BIOS data area
     at	the top	of base	memory,	and therefore report a smaller base memory
     size to prevent programs overwriting it.  This is correct behavior, and
     you should	not use	the REALBASEMEM	option to access this memory).

     options REALEXTMEM=integer
     Overrides the extended memory size	passed in from the boot	block.	(Value
     given in kilobytes.  Extended memory does not include the first
     megabyte.)	 Use this option only if the boot block	reports	the size in-
     correctly.

     options FRENCH_KBD,FINNISH_KBD,GERMAN_KBD,NORWEGIAN_KBD
     Select a non-US keyboard layout for the pccons console driver.

     options CYRIX_CACHE_WORKS
     Relevant only to the Cyrix	486DLC CPU.  This option is used to turn on
     the cache in hold-flush mode.  It is not turned on	by default because it
     is	known to have problems in certain motherboard implementations.

     options CYRIX_CACHE_REALLY_WORKS
     Relevant only to the Cyrix	486DLC CPU.  This option is used to turn on
     the cache in write-back mode.  It is not turned on	by default because it
     is	known to have problems in certain motherboard implementations.	In or-
     der for this option to take effect, option	CYRIX_CACHE_WORKS must also be
     specified.

     options PCIBIOS
     Enable support for	initializing the PCI bus using information from	the
     BIOS.  See	pcibios(4) for details.

     options KSTACK_CHECK_DR0
     Detect kernel stack overflow using	DR0 register.  This option uses	DR0
     register exclusively so you can't use DR0 register	for other purpose
     (e.g., hardware breakpoint) if you	turn this on.

     options MTRR
     Include support for accessing MTRR	registers from user-space.  See
     i386_get_mtrr(2).

     options BEEP_ONHALT
     Make the system speaker emit several beeps	when it	is completely safe to
     power down	the computer after a halt(8) command.  Requires	sysbeep(4)
     support.

     options BEEP_ONHALT_COUNT=times
     Number of times to	beep the speaker when options BEEP_ONHALT is enabled.
     Defaults to 3.

     options BEEP_ONHALT_PITCH=hz
     The tone frequency	used when options BEEP_ONHALT option, in hertz.	 De-
     faults to 1500.

     options BEEP_ONHALT_PERIOD=msecs
     The duration of each beep when options BEEP_ONHALT	is enabled, in mil-
     liseconds.	 Defaults to 250.

     options MULTIBOOT
     Makes the kernel Multiboot-compliant, allowing it to be booted through a
     Multiboot-compliant boot manager such as GRUB.  See multiboot(8) for more
     information.

     options SPLASHSCREEN
     Display a splash screen during boot.

     options SPLASHSCREEN_PROGRESS
     Display a progress	bar at the splash screen during	boot.  This option re-
     quires SPLASHSCREEN.

   isa-specific	Options
     Options specific to isa(4)	busses.

     options PCIC_ISA_ALLOC_IOBASE=address, PCIC_ISA_ALLOC_IOSIZE=size
     Control the section of IO bus space used for PCMCIA bus space mapping.
     Ideally the probed	defaults are satisfactory, however in practice that is
     not always	the case.  See pcmcia(4) for details.

     options PCIC_ISA_INTR_ALLOC_MASK=mask
     Controls the allowable interrupts that may	be used	for PCMCIA devices.
     This mask is a logical-or of power-of-2s of allowable interrupts:

	 IRQ Val      IRQ Val	   IRQ Val	 IRQ Val
	  0  0x0001    4  0x0010    8  0x0100	 12  0x1000
	  1  0x0002    5  0x0020    9  0x0200	 13  0x2000
	  2  0x0004    6  0x0040   10  0x0400	 14  0x4000
	  3  0x0008    7  0x0080   11  0x0800	 15  0x8000

     options PCKBC_CNATTACH_SELFTEST
     Perform a self test of the	keyboard controller before attaching it	as a
     console.  This might be necessary on machines where we boot on cold iron,
     and pckbc refuses to talk until we	request	a self test.  Currently	only
     the netwinder port	uses it.

     options PCKBD_CNATTACH_MAY_FAIL
     If	this option is set the PS/2 keyboard will not be used as the console
     if	it cannot be found during boot.	 This allows other keyboards, like
     USB, to be	the console keyboard.

     options PCKBD_LAYOUT=layout
     Sets the default keyboard layout, see pckbd(4).

   m68k-specific Options
     options FPU_EMULATE
     Include support for MC68881/MC68882 emulator.

     options FPSP
     Include support for 68040 floating	point.

     options M68020,M68030,M68040,M68060
     Include support for a specific CPU, at least one (the one you are using)
     should be specified.

     options M060SP
     Include software support for 68060.  This provides	emulation of unimple-
     mented integer instructions as well as emulation of unimplemented float-
     ing point instructions and	data types and software	support	for floating
     point traps.

   powerpc-specific Options (OEA Only)
     options PMAP_MEMLIMIT=value
     Limit the amount of memory	seen by	the kernel to value bytes.

     options PTEGCOUNT=value
     Specify the size of the page table	as value PTE groups.  Normally,	one
     PTEG is allocated per physical page frame.

   sparc-specific Options
     options AUDIO_DEBUG
     Enable simple event debugging of the logging of the audio(4) device.

     options BLINK
     Enable blinking of	LED.  Blink rate is full cycle every N seconds for N <
     then current load average.	 See getloadavg(3).

     options COUNT_SW_LEFTOVERS
     Count how many times the sw SCSI device has left 3, 2, 1 and 0 in the
     sw_3_leftover, sw_2_leftover, sw_1_leftover, and sw_0_leftover variables
     accessible	from ddb(4).  See sw(4).

     options DEBUG_ALIGN
     Adds debugging messages calls when	user-requested alignment fault han-
     dling happens.

     options DEBUG_EMUL
     Adds debugging messages calls for emulated	floating point and alignment
     fixing operations.

     options DEBUG_SVR4
     Prints registers messages calls for emulated SVR4 getcontext and setcon-
     text operations.  See options COMPAT_SVR4.

     options EXTREME_DEBUG
     Adds debugging functions callable from ddb(4).  The debug_pagetables,
     test_region and print_fe_map functions print information about page ta-
     bles for the SUN4M	platforms only.

     options EXTREME_EXTREME_DEBUG
     Adds extra	info to	options	EXTREME_DEBUG.

     options FPU_CONTEXT
     Make options COMPAT_SVR4 getcontext and setcontext	include	floating point
     registers.

     options MAGMA_DEBUG
     Adds debugging messages to	the magma(4) device.

     options RASTERCONS_FULLSCREEN
     Use the entire screen for the console.

     options RASTERCONS_SMALLFONT
     Use the Fixed font	on the console,	instead	of the normal font.

     options SUN4
     Support sun4 class	machines.

     options SUN4C
     Support sun4c class machines.

     options SUN4M
     Support sun4m class machines.

     options SUN4_MMU3L
     Enable support for	sun4 3-level MMU machines.

     options V9
     Enable SPARC V9 assembler in ddb(4).

   sparc64-specific Options
     options AUDIO_DEBUG
     Enable simple event debugging of the logging of the audio(4) device.

     options BLINK
     Enable blinking of	LED.  Blink rate is full cycle every N seconds for N <
     then current load average.	 See getloadavg(3).

   x68k-specific Options
     options EXTENDED_MEMORY
     Include support for extended memory, e.g.,	TS-6BE16 and 060turbo on-
     board.

     options JUPITER
     Include support for Jupiter-X MPU accelerator

     options ZSCONSOLE,ZSCN_SPEED=value
     Use the built-in serial port as the system-console.  Speed	is specified
     in	bps, defaults to 9600.

     options ITE_KERNEL_ATTR=value
     Set the kernel message attribute for ITE.	Value, an integer, is a	logi-
     cal or of the following values:
	   1	 color inversed
	   2	 underlined
	   4	 bolded

SEE ALSO
     config(1),	gdb(1),	ktrace(1), pmc(1), quota(1), vndcompress(1),
     gettimeofday(2), i386_get_mtrr(2),	i386_iopl(2), msgctl(2), msgget(2),
     msgrcv(2),	msgsnd(2), ntp_adjtime(2), ntp_gettime(2), reboot(2),
     semctl(2),	semget(2), semop(2), shmat(2), shmctl(2), shmdt(2), shmget(2),
     sysctl(3),	apm(4),	ddb(4),	inet(4), iso(4), md(4),	pcibios(4), pcmcia(4),
     ppp(4), userconf(4), vnd(4), wscons(4), config(5),	edquota(8), init(8),
     mdsetimage(8), mount_cd9660(8), mount_fdesc(8), mount_kernfs(8),
     mount_lfs(8), mount_mfs(8), mount_msdos(8), mount_nfs(8), mount_ntfs(8),
     mount_null(8), mount_portal(8), mount_procfs(8), mount_udf(8),
     mount_umap(8), mount_union(8), mrouted(8),	newfs_lfs(8), ntpd(8),
     quotaon(8), rpc.rquotad(8), sysctl(8), in_getifa(9)

HISTORY
     The options man page first	appeared in NetBSD 1.3.

BUGS
     The EON option should be a	pseudo-device, and is also very	fragile.

BSD			       January 13, 2012				   BSD

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY | BUGS

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