Commit Graph

206 Commits

Author SHA1 Message Date
Peter Wemm
c2ad65ca15 elf_machdep.c and rindex.c are now standard 1998-10-09 23:08:14 +00:00
Bruce Evans
35b47c4228 Remove vestiges of SLICE code.
Forgotten by:	sos
1998-09-20 06:04:56 +00:00
Søren Schmidt
a8445737e7 Add VESA support to syscons.
Kazu writes:

The VESA support code requires vm86 support. Make sure your kernel
configuration file has the following line.
        options "VM86"
If you want to statically link the VESA support code to the kernel,
add the following option to the kernel configuration file.
        options "VESA"

The vidcontrol command now accepts the following video mode names:
VESA_132x25, VESA_132x43, VESA_132x50, VESA_132x60, VESA_800x600

The VESA_800x600 mode is a raster display mode. The 80x25 text will
be displayed on the 800x600 screen. Useful for some laptop computers.

vidcontrol accepts the new `-i <info>' option, where <info> must be
either `adapter' or `mode'.  When the `-i adapter' option is given,
vidcontrol will print basic information (not much) on the video
adapter. When the `-i mode' option is specified, vidcontrol will
list video modes which are actually supported by the video adapter.

Submitted by:   Kazutaka YOKOTA yokota@FreeBSD.ORG
1998-09-15 18:16:39 +00:00
Justin T. Gibbs
700daf5ea0 sd->da, od is gone, no SCSI control devices.
new pass, xpt, and targ devices.

Nuke no longer used AHC options.
1998-09-15 10:01:14 +00:00
Søren Schmidt
eeded4d82e Add new atapi-cd driver that supports atapi CD-R/RW drives.
This is only a stop-gab solution to get atapi burner support into 3.0.
1998-09-08 20:57:47 +00:00
Nicolas Souchu
f25c58e005 pcf.c added, support for the Philips PCF8584 I2C bus controller
(this is part of the iicbus system)
1998-09-04 06:06:55 +00:00
Brian Somers
c35bda9472 Add driver dgm - for the Digiboard PC/Xem
Submitted by:   "IBS / Andre Oppermann" <andre@pipeline.ch>
DEVFS additions: brian

dgm gets major number 101.
1998-08-04 21:44:09 +00:00
Mike Smith
b16d163da1 Add the 'cs' driver for Crystal Semiconductor CS89x0 devices. This
supports PnP and if_media.  I've been running a slightly older version
here for several weeks now.
Submitted by:	Maxim Bolotin <max@rsu.ru>
1998-07-20 20:00:43 +00:00
Bruce Evans
2ebd0c3795 Backed out rev.1.183, which had nothing to do with its log message.
It was to support a half-baked optimization of certain long long
divisions in gcc-2.8 and/or egcs.  We now avoid these divisions.
1998-06-16 14:55:27 +00:00
Julian Elischer
3e425b968d Add changes and code to implement a functional DEVFS.
This code will be turned on with the TWO options
DEVFS and SLICE. (see LINT)
Two labels PRE_DEVFS_SLICE and POST_DEVFS_SLICE will deliniate these changes.

/dev will be automatically mounted by init (thanks phk)
on bootup. See /sys/dev/slice/slice.4 for more info.
All code should act the same without these options enabled.

Mike Smith, Poul Henning Kamp, Soeren, and a few dozen others

This code does not support the following:
bad144 handling.
Persistance. (My head is still hurting from the last time we discussed this)
ATAPI flopies are not handled by the SLICE code yet.

When this code is running, all major numbers are arbitrary and COULD
be dynamically assigned. (this is not done, for POLA only)
Minor numbers for disk slices ARE arbitray and dynamically assigned.
1998-04-19 23:32:49 +00:00
Peter Wemm
e8b4f186cd add globals.s for data that is treated differently on SMP. 1998-04-06 15:49:35 +00:00
Peter Wemm
59088db3cb si driver has changed microcode file locations. 1998-03-23 16:44:22 +00:00
Julian Elischer
fdc021ba7f Add EISA support for DPT drivers
Submitted by: Matthew Dodd
Reviewd by:	shimon@simon-shapiro.org (DPT author)
1998-03-11 00:30:16 +00:00
Poul-Henning Kamp
cb7cfa353d Add the smallest and least useful device-driver by a fair margin... 1998-02-24 22:08:05 +00:00
Poul-Henning Kamp
7ec73f6417 Replace TOD clock code with more systematic approach.
Highlights:
    * Simple model for underlying hardware.
    * Hardware basis for timekeeping can be changed on the fly.
    * Only one hardware clock responsible for TOD keeping.
    * Provides a real nanotime() function.
    * Time granularity: .232E-18 seconds.
    * Frequency granularity:  .238E-12 s/s
    * Frequency adjustment is continuous in time.
    * Less overhead for frequency adjustment.
    * Improves xntpd performance.

Reviewed by:    bde, bde, bde
1998-02-20 16:36:17 +00:00
Mike Smith
1f98b2eb0f Remove the 'qcam' driver. Development has ceased, and the driver is
nonfunctional.
Submitted by:	pst (conversation some time ago)
1998-02-18 13:43:59 +00:00
Søren Schmidt
ea38cb7ffc Add 'wst" atapi tape devicefile. 1998-02-17 11:32:33 +00:00
Peter Wemm
a397086e61 Update to support SI/XIO PCI host cards (Z280 based) and the enhanced
SXISA and SXPCI host cards (Transputer based).

PR: 4836, 5021, 5654
Submitted by:  Nick Sayer <nick@specialix.com>
1998-02-15 14:42:33 +00:00
Julian Elischer
3458e54ac1 Move DPT related options out of i386 specific files
so DPT devices can be used on other PCI (alpha?) machines.

Suggested by: several people
1998-01-26 18:31:18 +00:00
Julian Elischer
b37c91fdc7 Add Simon Shapiro's DPT driver
this shouldn't break anything existing.
Userland utilities to follow.
1998-01-26 06:11:18 +00:00
Paul Traina
aaf862068b Bring in IDE ATAPI floppy support.
This is Junichi's v1.0 driver.

NOTE: Major device numbers have been changed to avoid conflict with other
      FreeBSD 3.0 devices.  The new numbers should be considered "official."
      This driver is still considered "beta" quality, although we have been
      playing with it.  Please submit bugs to junichi and myself.

Submitted by:	junichi@astec.co.jp
1998-01-16 22:13:07 +00:00
Justin T. Gibbs
c8877437a0 Add entry for i386/i386/busdma_machdep.c 1998-01-15 07:30:54 +00:00
John-Mark Gurney
6cc3943ff0 update the AWE32 wave table driver to Iwai's 0.4.2c version. This also
includes the patches to make it work under -current from Randall Hopper.

Remove the old AWE driver.
1998-01-08 23:13:22 +00:00
John Dyson
95e5e988e0 Make our v_usecount vnode reference count work identically to the
original BSD code.  The association between the vnode and the vm_object
no longer includes reference counts.  The major difference is that
vm_object's are no longer freed gratuitiously from the vnode, and so
once an object is created for the vnode, it will last as long as the
vnode does.

When a vnode object reference count is incremented, then the underlying
vnode reference count is incremented also.  The two "objects" are now
more intimately related, and so the interactions are now much less
complex.

When vnodes are now normally placed onto the free queue with an object still
attached.  The rundown of the object happens at vnode rundown time, and
happens with exactly the same filesystem semantics of the original VFS
code.  There is absolutely no need for vnode_pager_uncache and other
travesties like that anymore.

A side-effect of these changes is that SMP locking should be much simpler,
the I/O copyin/copyout optimizations work, NFS should be more ponderable,
and further work on layered filesystems should be less frustrating, because
of the totally coherent management of the vnode objects and vnodes.

Please be careful with your system while running this code, but I would
greatly appreciate feedback as soon a reasonably possible.
1998-01-06 05:26:17 +00:00
Peter Wemm
5eaf45f67b I've been using these tweaks to enable the sound driver to talk to the
(mutant) Crystal CSS4236 chip on the Intel PR440FX SMP motherboard.

XXX this uses some rather ugly PnP bootstrap code that is *NOT* compatable
with 'controller pnp0' or *ANY* other PnP devices.  If you use some other
PnP devices, enabling css0 will burn your house down. :-]  The
"simplified" PnP init sequence directly blats your config(8) settings onto
the chip.  I'm pretty sure 'css0' will conflict with 'mss0', this whole
area desperately needs a cleanup.

I have been using the following with some success on the PR440FX:
controller   snd0
device css0  at isa? port 0x534 irq 5 drq 1 flags 0x08 vector adintr
device opl0  at isa? port 0x388
device mpu0  at isa? port 0x330 irq 10 vector mpuintr
1997-12-12 14:08:50 +00:00
Jamil J. Weatherbee
a1e9e3087e add entry in LINT for alog driver
added line to files.i386 to compile in alog.c optionally as a driver
1997-12-09 12:04:49 +00:00
Amancio Hasty
9e41c7c31e Include sound_timer.c for mss device and added
sound_timer.c, opl3.c, ad1848.c, adlib_card.c to trix device.
trix is a driver for an AudioTrix Pro.
1997-12-01 09:29:50 +00:00
Mark Murray
61ca849927 From the author:
Here are the remanding changes required to support the Ensoniq
Soundscape using FreeBSD 3.0-current.

Notes:

  1) ad1848_init already has code to detect if DMA_DUPLEX should
     be set so it is not necessary (and is in fact a mistake) to
     hard code setting it.  Not all soundcards (i.e. the current
     sscape driver) are capable of using DMA_DUPLEX.

  2) The other changes are hopefully self explanatory.  Feel free
     to let me know if you need additional information.

Submitted by:	john@feith.com (John Wehle)
1997-11-25 19:30:38 +00:00
Joerg Wunsch
ebc1f80ca7 Use the new "mandatory" keyword for the npx driver. 1997-10-28 07:28:34 +00:00
Justin T. Gibbs
168bbc9927 Move the rules for aicasm to the MI conf file. 1997-09-21 21:34:31 +00:00
John-Mark Gurney
c740608242 docment the new sound drivers in LINT and add the necessary files to
files.i386.

We aren't sure if this new code and the old sound code will co-exist in a
kernel, so the device pcm0 line is left commented out in LINT.

Submitted-by:	Luigi Rizzo
1997-09-14 21:45:05 +00:00
John-Mark Gurney
53a7a570be add pnp device entries... 1997-09-09 12:40:54 +00:00
Justin T. Gibbs
c66dbc92d4 Make the aic7xxx sequencer assembler compile in the kernel's object
directory.  Rename (via repository copy) some files so that the potential
for future conflicts is minimized.

PR: conf/4363
1997-09-03 03:44:58 +00:00
Jonathan Lemon
5f07393373 Remove the vm86 support as an LKM, and link it directly into the kernel
if 'options "VM86"' is in the config file.  The LKM was really for
development, and has probably outlived its usefulness.
1997-08-28 14:36:56 +00:00
Jordan K. Hubbard
3b577e1f2f Add entries for Comtrol Rocketport serial card.
Submitted by:	Amir Farah <amir@comtrol.com>
1997-08-28 12:18:09 +00:00
Mike Smith
ab4c624ba4 Add support for the new Parallel-Port Bus and devices thereon.
Submitted by:	Nicolas Souchu <Nicolas.Souchu@prism.uvsq.fr>
1997-08-14 14:03:27 +00:00
Mike Smith
e2c77d8580 Add new BIOS-related files. 1997-08-01 06:04:34 +00:00
Søren Schmidt
8b8a0b53b1 Add support for busmaster DMA on some PCI IDE chipsets.
I changed a few bits here and there, mainly renaming wd82371.c
to ide_pci.c now that it's supposed to handle different chipsets.

It runs on my P6 natoma board with two Maxtor drives, and also
on a Fujitsu machine I have at work with an Opti chipset and
a Quantum drive.

Submitted by:cgull@smoke.marlboro.vt.us <John Hood>

Original readme:

*** WARNING ***

This code has so far been tested on exactly one motherboard with two
identical drives known for their good DMA support.

This code, in the right circumstances, could corrupt data subtly,
silently, and invisibly, in much the same way that older PCI IDE
controllers do.  It's ALPHA-quality code; there's one or two major
gaps in my understanding of PCI IDE still.  Don't use this code on any
system with data that you care about; it's only good for hack boxes.
Expect that any data may be silently and randomly corrupted at any
moment.  It's a disk driver.  It has bugs.  Disk drivers with bugs
munch data.  It's a fact of life.

I also *STRONGLY* recommend getting a copy of your chipset's manual
and the ATA-2 or ATA-3 spec and making sure that timing modes on your
disk drives and IDE controller are being setup correctly by the BIOS--
because the driver makes only the lamest of attempts to do this just
now.

*** END WARNING ***

that said, i happen to think the code is working pretty well...

WHAT IT DOES:

this code adds support to the wd driver for bus mastering PCI IDE
controllers that follow the SFF-8038 standard.  (all the bus mastering
PCI IDE controllers i've seen so far do follow this standard.)  it
should provide busmastering on nearly any current P5 or P6 chipset,
specifically including any Intel chipset using one of the PIIX south
bridges-- this includes the '430FX, '430VX, '430HX, '430TX, '440LX,
and (i think) the Orion '450GX chipsets.  specific support is also
included for the VIA Apollo VP-1 chipset, as it appears in the
relabeled "HXPro" incarnation seen on cheap US$70 taiwanese
motherboards (that's what's in my development machine).  it works out
of the box on controllers that do DMA mode2; if my understanding is
correct, it'll probably work on Ultra-DMA33 controllers as well.
it'll probably work on busmastering IDE controllers in PCI slots, too,
but this is an area i am less sure about.

it cuts CPU usage considerably and improves drive performance
slightly.  usable numbers are difficult to come by with existing
benchmark tools, but experimentation on my K5-P90 system, with VIA
VP-1 chipset and Quantum Fireball 1080 drives, shows that disk i/o on
raw partitions imposes perhaps 5% cpu load.  cpu load during
filesystem i/o drops a lot, from near 100% to anywhere between 30% and
70%.  (the improvement may not be as large on an Intel chipset; from
what i can tell, the VIA VP-1 may not be very efficient with PCI I/O.)
disk performance improves by 5% or 10% with these drives.

real, visible, end-user performance improvement on a single user
machine is about nil. :) a kernel compile was sped up by a whole three
seconds.  it *does* feel a bit better-behaved when the system is
swapping heavily, but a better disk driver is not the fix for *that*
problem.

THE CODE:

this code is a patch to wd.c and wd82371.c, and associated header
files.  it should be considered alpha code; more work needs to be
done.

wd.c has fairly clean patches to add calls to busmaster code, as
implemented in wd82371.c and potentially elsewhere (one could imagine,
say, a Mac having a different DMA controller).

wd82371.c has been considerably reworked: the wddma interface that it
presents has been changed (expect more changes), many bugs have been
fixed, a new internal interface has been added for supporting
different chipsets, and the PCI probe has been considerably extended.

the interface between wd82371.c and wd.c is still fairly clean, but
i'm not sure it's in the right place.  there's a mess of issues around
ATA/ATAPI that need to be sorted out, including ATAPI support, CD-ROM
support, tape support, LS-120/Zip support, SFF-8038i DMA, UltraDMA,
PCI IDE controllers, bus probes, buggy controllers, controller timing
setup, drive timing setup, world peace and kitchen sinks.  whatever
happens with all this and however it gets partitioned, it is fairly
clear that wd.c needs some significant rework-- probably a complete
rewrite.

timing setup on disk controllers is something i've entirely punted on.
on my development machine, it appears that the BIOS does at least some
of the necessary timing setup.  i chose to restrict operation to
drives that are already configured for Mode4 PIO and Mode2 multiword
DMA, since the timing is essentially the same and many if not most
chipsets use the same control registers for DMA and PIO timing.

does anybody *know* whether BIOSes are required to do timing setup for
DMA modes on drives under their care?

error recovery is probably weak.  early on in development, i was
getting drive errors induced by bugs in the driver; i used these to
flush out the worst of the bugs in the driver's error handling, but
problems may remain.  i haven't got a drive with bad sectors i can
watch the driver flail on.

complaints about how wd82371.c has been reindented will be ignored
until the FreeBSD project has a real style policy, there is a
mechanism for individual authors to match it (indent flags or an emacs
c-mode or whatever), and it is enforced.  if i'm going to use a source
style i don't like, it would help if i could figure out what it *is*
(style(9) is about half of a policy), and a way to reasonably
duplicate it.  i ended up wasting a while trying to figure out what
the right thing to do was before deciding reformatting the whole thing
was the worst possible thing to do, except for all the other
possibilities.

i have maintained wd.c's indentation; that was not too hard,
fortunately.

TO INSTALL:

my dev box is freebsd 2.2.2 release.  fortunately, wd.c is a living
fossil, and has diverged very little recently.  included in this
tarball is a patch file, 'otherdiffs', for all files except wd82371.c,
my edited wd82371.c, a patch file, 'wd82371.c-diff-exact', against the
2.2.2 dist of 82371.c, and another patch file,
'wd82371.c-diff-whitespace', generated with diff -b (ignore
whitespace).  most of you not using 2.2.2 will probably have to use
this last patchfile with 'patch --ignore-whitespace'.  apply from the
kernel source tree root. as far as i can tell, this should apply
cleanly on anything from -current back to 2.2.2 and probably back to
2.2.0.  you, the kernel hacker, can figure out what to do from here.
if you need more specific directions, you probably should not be
experimenting with this code yet.

to enable DMA support, set flag 0x2000 for that drive in your config
file or in userconfig, as you would the 32-bit-PIO flag.  the driver
will then turn on DMA support if your drive and controller pass its
tests.  it's a bit picky, probably.  on discovering DMA mode failures
or disk errors or transfers that the DMA controller can't deal with,
the driver will fall back to PIO, so it is wise to setup the flags as
if PIO were still important.

'controller wdc0 at isa? port "IO_WD1" bio irq 14 flags 0xa0ffa0ff
vector wdintr' should work with nearly any PCI IDE controller.

i would *strongly* suggest booting single-user at first, and thrashing
the drive a bit while it's still mounted read-only.  this should be
fairly safe, even if the driver goes completely out to lunch.  it
might save you a reinstall.

one way to tell whether the driver is really using DMA is to check the
interrupt count during disk i/o with vmstat; DMA mode will add an
extremely low number of interrupts, as compared to even multi-sector
PIO.

boot -v will give you a copious register dump of timing-related info
on Intel and VIAtech chipsets, as well as PIO/DMA mode information on
all hard drives.  refer to your ATA and chipset documentation to
interpret these.

WHAT I'D LIKE FROM YOU and THINGS TO TEST:

reports.  success reports, failure reports, any kind of reports. :)
send them to cgull+ide@smoke.marlboro.vt.us.

i'd also like to see the kernel messages from various BIOSes (boot -v;
dmesg), along with info on the motherboard and BIOS on that machine.

i'm especially interested in reports on how this code works on the
various Intel chipsets, and whether the register dump works
correctly.  i'm also interested in hearing about other chipsets.

i'm especially interested in hearing success/failure reports for PCI
IDE controllers on cards, such as CMD's or Promise's new busmastering
IDE controllers.

UltraDMA-33 reports.

interoperation with ATAPI peripherals-- FreeBSD doesn't work with my
old Hitachi IDE CDROM, so i can't tell if I've broken anything. :)

i'd especially like to hear how the drive copes in DMA operation on
drives with bad sectors.  i haven't been able to find any such yet.

success/failure reports on older IDE drives with early support for DMA
modes-- those introduced between 1.5 and 3 years ago, typically
ranging from perhaps 400MB to 1.6GB.

failure reports on operation with more than one drive would be
appreciated.  the driver was developed with two drives on one
controller, the worst-case situation, and has been tested with one
drive on each controller, but you never know...

any reports of messages from the driver during normal operation,
especially "reverting to PIO mode", or "dmaverify odd vaddr or length"
(the DMA controller is strongly halfword oriented, and i'm curious to
know if any FreeBSD usage actually needs misaligned transfers).

performance reports.  beware that bonnie's CPU usage reporting is
useless for IDE drives; the best test i've found has been to run a
program that runs a spin loop at an idle priority and reports how many
iterations it manages, and even that sometimes produces numbers i
don't believe.  performance reports of multi-drive operation are
especially interesting; my system cannot sustain full throughput on
two drives on separate controllers, but that may just be a lame
motherboard.

THINGS I'M STILL MISSING CLUE ON:

* who's responsible for configuring DMA timing modes on IDE drives?
the BIOS or the driver?

* is there a spec for dealing with Ultra-DMA extensions?

* are there any chipsets or with bugs relating to DMA transfer that
should be blacklisted?

* are there any ATA interfaces that use some other kind of DMA
controller in conjunction with standard ATA protocol?

FINAL NOTE:

after having looked at the ATA-3 spec, all i can say is, "it's ugly".
*especially* electrically.  the IDE bus is best modeled as an
unterminated transmission line, these days.

for maximum reliability, keep your IDE cables as short as possible and
as few as possible.  from what i can tell, most current chipsets have
both IDE ports wired into a single buss, to a greater or lesser
degree.  using two cables means you double the length of this bus.

SCSI may have its warts, but at least the basic analog design of the
bus is still somewhat reasonable.  IDE passed beyond the veil two
years ago.

  --John Hood, cgull@smoke.marlboro.vt.us
1997-07-29 12:57:25 +00:00
Poul-Henning Kamp
38d8a113a9 Add option for compiling in a 8x16 font. 1997-07-25 11:53:30 +00:00
Steve Passe
64ab539460 Added a new SMP specific file: i386/i386/simplelock.s.
This code was split off from apic_ipl.s.
It contains the Lite2 lock manager primitives:
 - s_lock_init()
 - s_lock()
 - s_lock_try()
 - s_unlock()
1997-07-24 23:45:17 +00:00
Bruce Evans
1013a13daf Fixed the fix for not using -fomit-frame-pointer with -pg. The previous
fix stopped it being used in all cases, because substitution on unset
variables does not work.

When profiling, put -malign-functions=4 in CFLAGS instead of in PROF.
This fixes the histogram counts for profiling support functions.  It
gives bogus but harmless extra alignment for genassym etc.
1997-06-29 16:39:11 +00:00
Doug Rabson
683523378c Move interrupt handling code from isa.c to a new file. This should make
isa.c (slightly) more portable and will make my life developing the really
portable version much easier.

Reviewed by:	peter, fsmp
1997-06-02 08:19:06 +00:00
Bruce Evans
20c776a50b Don't use -fomit-frame-pointer for ipl_funcs.c if ${PROF} is nonempty,
is incompatible with -pg.  (We use a different version of mcount for
profiling frame-pointer-less assembler functions, but gcc doesn't know
about this.)

Added a missing dependency.

Cleaned up trailing backslashes.

Added comment about config's limitations/bugs handling dependencies and
backslashe/newlines.

Finished removing support for isdn drivers.
1997-06-01 20:25:55 +00:00
Peter Wemm
f5d66b9bb4 specify compile-with option to get -fomit-frame-pointer on ipl_funcs.c 1997-05-31 18:01:38 +00:00
Peter Wemm
49c6ff7dc2 add ipl_funcs.c (Hmm.. should probably use a "compile-with" arg rather
than a Makefile.i386 hook)
1997-05-31 09:23:44 +00:00
Mike Smith
98d46ad0c9 Add the 'wl' ISA Wavelan driver.
Obtained from:	Jim Binkley <jrb@cs.pdx.edu>
1997-05-22 08:47:40 +00:00
Peter Wemm
477a642cee Man the liferafts! Here comes the long awaited SMP -> -current merge!
There are various options documented in i386/conf/LINT, there is more to
come over the next few days.

The kernel should run pretty much "as before" without the options to
activate SMP mode.

There are a handful of known "loose ends" that need to be fixed, but
have been put off since the SMP kernel is in a moderately good condition
at the moment.

This commit is the result of the tinkering and testing over the last 14
months by many people.  A special thanks to Steve Passe for implementing
the APIC code!
1997-04-26 11:46:25 +00:00
Justin T. Gibbs
c1aa7eb5f4 GENERIC, LINT:
Add an ie entry that corresponds to the location the old ix entry used
to probe and kill the ix entry.

files.i386:
Remove entries for the ix driver.
1997-04-14 00:35:25 +00:00
Justin T. Gibbs
d98667394d make obj before building the aic7xxx assembler. This puts the object
files in the right place.

The clean rule still isn't quite right since currently config doesn't
allow the specification of arbitrary clean rules.
1997-04-03 05:57:16 +00:00
KATO Takenori
4c024bbdf8 Improved CPU identification and initialization routines. This
supports All Cyrix CPUs, IBM Blue Lightning CPU and NexGen (now AMD)
Nx586 CPU, and initialize special registers of Cyrix CPU and msr of
IBM Blue Lightning CPU.

If revision of Cyrix 6x86 CPU < 2.7, CPU cache is enabled in
write-through mode.  This can be disabled by kernel configuration
options.

Reviewed by:	Bruce Evans <bde@freebsd.org> and
            	Jordan K. Hubbard <jkh@freebsd.org>
1997-03-22 18:54:54 +00:00