to be no ill effects, and so far as Iknow none of the variables in
question depend on 16-bit wraparound behavior. (The sizes are in
many cases relics from when a PCB had to fit inside a 128-byte mbuf. PCBs
are no longer stored in that way, and the old structure would not have
fit, either.)
it was referenced from.. stops a rather annoying panic, but
introduces a rather interesting but "I can live with it" bug
`ln a b ; mv a b; echo ?`
returns a rather than b..
I know why but I need to think of the 'correct' answer. at least this is 'safe'
Obtained from: other people on the net ?
1. stepping over syscalls (gdb ni) sends you to DDB, and returned
to the wrong address afterwards, with or without DDB. patch in
i386/i386/trap.c below.
2. the linux emulator (modload'ed) still causes panics with DIAGNOSTIC,
re-applied a patch posted to one of the lists...
for testing.. (for cdevsw_add and bdevsw_add)
make the lkm code use the new generic devsw add routines (if so required)
define these routines in conf.h so we can use them
This is really just a token gesture at this point. We can't really turn
on swapping here anymore because (I think) we need to do a namei() lookup
in order to get a vnode which we can pass to swaponvp(). But to do a
namei(), we need a properly initialized proc structure, and we don't
have one. (I was hopping to toss it proc0, but that isn't initialized
until later.) We could conceiveably fabricate a dummy proc structure
to make namei() happy, but that's too much work for too little payoff.
For now, swapgeneric's only remaining saving grace is that it lets
you set the root device with -a.
This is a place for all things to do with conf.c and conf.h
that are not machine specific.
Other things that are at present in i386/isa/conf.c might
migrate into here..
It's the first small step in cleaning up the device interface
to make it more dynamic and to assist in more modular drivers
(i.e. both loadable via LKMs and linked in..
e.g able to add a device without having to edit conf.c)
this code is not yet used and the whole thing will be conditionally
compiled in for a while till proven useful :)
matching IP options..Check and test this - i made only a couple
of rough tests and this could be buggy.. Ipaccounting can't use
IP Options (and i don't see any need to cound packets with specific
options either..)
More to come...
1542 revs work by assuming the next few sequential ID codes are
new Adaptec boards and enabling them after printing a warning.
Conditionalize the informational boot messages with "if (bootverbose)".
1) "obj" was't initialized properly, resulting in an important vm_page_lookup
always failing (resulting in a panic).
2) busy pages could be put on the cache queue or freed (resulting in a panic).
were making and were no-brainers. However, the xcdplayer
eject button didn't work because xcdplayer gave up and didn't bother
to try the EJECT ioctl anyway when CDIOCALLOW was not available.
This all works now.
o A change so that xcdplayer gets TOC entry data for the lead-out area
on the disc. Xcdplayer can now play the last track on a CD, which
it would not do in earlier versions (but no one reported).
Cdplayer gets the TOC data differently and it works in old and new
versions.
o Eliminated a race condition that caused the driver to sleep forever
on very slow and heavily loaded systems on rare occasions when
the system was doing lots of audio-related ioctls to the drive.
o Fixed a problem where a locked drive could be unlocked by accessing
one of the non-locking devs. Door locking now follows the documented
rules.
o Made all wait channel strings unique to matcd.
Submitted by: Frank Durda IV <uhclem%nemesis@fw.ast.com>
scheduled for demolition. This is a first step: get rid of if_zereg.h,
by adding the five extra definitions to if_edreg.h.
Also add some definitions which will become needed when if_ze.c gets
replaced entirely by pccard and if_ed.c. (this is a 2.1.0 candidate)
is swapped in. Also, remove unnecessary map locking/unlocking during
selection of processes to be swapped out.
This code might afford proper panics as opposed to spontaneous reboots
on certain systems. This should allow us to debug these problems better.
David Greenman, it has been determined that the more sophisticated code
only made a very minor difference in fault performance. Therefore, this
code eliminates some of the complication of the fault code, decreasing
the amount of CPU used to scan shadow chains.
support for EXT2FS. Note that the Sig-11 problems appear to be caused by
this, but there is still probably an underlying VM problem that let this
clustering bug cause vnode objects to appear to be corrupted.
The direct manifestation of this bug would have been severely mis-read
files. It is possible that processes would Sig-11 on very damaged
input files and might explain the mysterious differences in system
behaviour when phk's malloc is being used.
with the driver's stability now. I've not had a single problem with it for
weeks.. All that remains is a bit of performance tuning, and finishing
the manpages.
Fix loopback and discard interfaces to understand BPF writes.
(These two from Bill Fenner to fix PR 512.)
Move ifpromisc() from bpf.c to if.c as suggested by comment in BPF.
Send a notice to the log when promiscuous mode is enabled.
time ago. I left in Garrett's one, because his was in the 4.4-Lite-2
location, making any diffs just that little bit smaller.
I presume this choice means that netstat needs to be recompiled before
"netstat -s" will give a meaningful answer on tcp stats.
and for the 53c810ap, the improved version of the 53c810.
The driver should work with all those controllers, but doesn't know
about any of their advanced features.
and gated on `options MTUDISC' in the source. It is also practically
untested becausse (sniff!) I don't have easy access to a network with
an MTU of less than an Ethernet. If you have a small MTU network,
please try it and tell me if it works!
Now comes up in the old line-oriented interface by default for serial
and pcvt folk with a `visual' command for going to the visual interface.
Best of both worlds, no?
Submitted by: Michael Smith <msmith@atrad.adelaide.edu.au>
<sys/sysproto.h> and use them (so far only) in kern/init_sysent.c.
Don't put $Id in generated files.
kern/syscalls.master:
I had to add some new fields to describe some non-orthogonal names.
E.g., the args struct for the syscall-implementing function foo()
is usually named `foo_args', but for getpid() it is named `args'.
sys/sysent.h:
sy_call_t is still incomplete to hide a couple of warnings.
Changes relative to 1.12:
- Put extra instruction between outl()/inl() sequence to prevent the
old value being read back because of the bus capacitance.
- Additional check for existence of register at CONF2_ENABLE_PORT.
UPAGES and associated page table page. Panic on error. This is less than
optimial and will be fixed in the future, but is better than the old
behavior of panicing with a "kernel page directory invalid" in pmap_enter.
setting the control register. Make the read and write operations two
completely separate steps.
While we're at it, pull in the whole set of Cyrix cache control options
from NetBSD-current, since a few motherboards do the right thing with
the Cyrix chip.
There is no option to disable the internal cache completely (yet).
Reviewed by: pst
Obtained from: NetBSD
ignore and set it to 18 sectors/track. This allows FreeBSD to boot with
2.88MB floppies which are used in older ThinkPads.
Submitted by: Random Net person whose name I lost
EFAULT if it is not resident. This prevents the system from manufacturing
a zero-fill page for unused but allocated areas of the kernel's VM. This
should fix the "CMAP busy" panic that some people saw during system
startup.
there is a PCI bus at all) ...
- Do not expect the chip sets to follow even very clearly expressed
requirements of the PCI 2.0 spec.
- Do not read back the value just written to an I/O port without making
sure that some other data have crossed the bus in between ...
2) Killed i386pagesperpage as it is not used by anything.
3) Fixed benign miscalculations in pmap_bootstrap().
4) Moved allocation of ISA DMA memory to machdep.c.
5) Removed bogus vm_map_find()'s in pmap_init() - the entire range was
already allocated kmem_init().
6) Added some comments.
virual_avail is still miscalculated NKPT*NBPG too large, but in order to
fix this properly requires moving the variable initialization into locore.s.
Some other day.
used and went a long way toward confusing the code.
2) Fix proc0's initial stack to not be 48 bytes smaller than it needs to
be.
3) Correct comment about 'first' arg to init386().
bugs that the type-checking would otherwise have found. (This has no
effect on anything that I noticed in the current system other than finding
the bug in some code that I am writing.)
to be sent, just clean up and return ENOBUFS rather than silently
proceeding without sending any of the data. This makes it consistent
with the `#ifdef notyet' case immediately above.
Reviewed by: Andras Olah <olah@freebsd.org>
Obtained from: Lite-2
Add prototypes. Use static for function definitions to match existing
prototypes. Otherwise leave functions that should be static as extern.
TODO: declare everthing except sidriver and siintr as static. I use
some new cdevs registration functions to do this for syscons and pcvt.
Fix siintr() to match its prototype in ioconf.c (don't return anything).
This may break the eisa support, but Julian says that eisa interrupts
never worked anyway.
(EISA support was never tested anyway - Peter)
Submitted by: bde
any reasonably busy machine, and by any measure is a lousy "max" value.
32 was chosen after a careful analysis of typical listen queue depths
on several busy Internet servers (both web and ftp). I also intend to
add a statistics counter for dropped connection requests due to the limit
being exceeded.
of NCR script labels and of command control block structure components.
This allows for easy modification of the actual virtual to physical
mapping operator used ...
Make all applicable references to physical address values use the above
macros instead of calls to vtophys().
definitions even though the functions are inline. If vnode_if.h was
compiled by a non-ANSI compiler, then `inline' would be defined away,
so vnode_if.h might compile correctly.
the first one in the config has priority. They can be switched using
userconfig().
i386/i386/conf.c:
Initialize the shared syscons/pcvt cdevsw entry to `nx'.
Add cdevsw registration functions.
Use devsw functions of the correct type if they exist.
i386/i386/cons.c:
Add renamed syscons entry points to constab.
i386/i386/cons.h:
Declare the renamed syscons entry points.
i386/i386/machdep.c:
Repeat console initialization after userconfig() in case the current
console has become wrong. This depends on cn functions not wiring down
anything important.
sys/conf.h:
Declare new functions.
i386/isa/isa.[ch]:
Add a function to decide which display driver has priority. Should be
done better.
i386/isa/syscons.c:
Rename pccn* -> sccn*.
Initialize CRTC start address in case the previous driver has moved it.
i386/isa/syscons.c, i386/isa/pcvt/*
Initialize the bogusly shared variable Crtat dynamically in case the
stored value was changed by the previous driver.
Initialize cdevsw table from a template.
Don't grab the console if another display driver has priority.
i386/isa/syscons.h, i386/isa/pcvt/pcvt_hdr.h:
Don't externally declare now-static cdevsw functions.
i386/isa/pcvt/pcvt_hdr.h:
Set the sensitive hardware flag so that pcvt doesn't always have lower
priority than syscons. This also fixes the "stupid" detection of the
display after filling the display with text.
i386/isa/pcvt/pcvt_out.c:
Don't be confused the off-screen cursor offset 0xffff set by syscons.
kern/subr_xxx.c:
Add enough nxio/nodev/null devsw functions of the correct type for syscons
and pcvt.
Split off cdevsw initialization in cninit() into a new function
cninit_finish() that isn't called until all hardware device drivers
have been attached. The bdevsw entry of the driver for the physical
console needs to be hooked after the physical driver has been
attached in case the attachment modified the entry.
Rearrange cninit() to avoid changing cn_tab until the driver for the
physical console has been initialized, so that the previous driver
(if any) can be used for debugging.
Start removing half-baked lint support. bdevsw functions usually have
unused args but /*ARGSUSED*/ was used for only about 5% of them.
cons.h:
Declare cn_init_finish().
autoconf.c:
Call cn_init_finish().
Start adding prototypes. Functions with bogus linkage (extern where
static is probably should be static) are explicitly declared as extern
so that the can be found easily (extern in a non-header is usually
wrong).
All:
Continue cleaning up init stuff: init functions shall be static;
INITs should be at the start of files...
in pppstart(), the output process may be overloaded to handle hardware
flow control and hardware output completions.
Don't wait for output to drain in slclose(). Discard output immediately.
New output is not prevented while processes are waiting for output to
drain (this is a bug), so the wait was sometimes forever. Infinite
waits are also possible when CCTS_OFLOW is enabled and CTS is down.
Infinite waits were also caused by the above bug in slstart().
Start changing new init stuff yet again: rename unused arg `dummy'.
Reviewed by: davidg
I can now do an mv on devices and directories in devfs
This was the hardest part.. link, delete and symlink will follow in
short order.
This code works but has definitly got vnode locking problems
I am electing to get the structure of it working before
spending too much time on the vnode confusion
so it's probably not reliable at the moment..
never-the less it looks good.
:)
by me...
Original message:
This patch upgrades the ATAPI CD-ROM driver to version 1.3.
It has three bugs fixed:
1) The `controller not ready' message at startup and later.
It was caused by staled media change bit.
2) Incorrect shuffling of model string for some drives (NEC, Mitsumi).
3) Handling of drives which report itself as been of direct-access type,
instead of CD-ROM type.
There is one known bug which is not fixed yet -- probing
in absense of IDE disks. A work-around exists though (thanks Steve!).
If you have no IDE disks attached, then remove them from the kernel
config file to make the CD-ROM attach correctly.
Unfortunately, there is no way to disable them from the kernel
interactive config mode.
Reviewed by: sos (Soren Schmidt)
Submitted by: vak@gw.cronyx.msk.su (Serge V.Vakulenko)
fix a change where a shortcut resulted in teh wrong answer..
e.g.
touch a
touch b
mv a b
resulted in b being removed and a being moved to b
in the shortcut..
touch a
ln a b
mv a b
the wrong link was removed..
leaving a instead of b, giving a different result to when
both files were separate.
They shouldn't affect FreeBSD, since they are within #ifdef NETBSD
directives.
Changed the HAD_ERROR return code into COMPLETE according to a comment
in "/sys/scsi/scsiconf.h"
Submitted by: Andreas Wrede <andreas@planix.com>
2) Output K bytes instead of pages as this means something to more people.
3) Moved printf of avail memory to after vm_bounce_init() call so that
bounce buffers are included in the figure.
4) Killed initcpu(); it's an unused vestige from the VAX.
This seems to work fine on my 53c810, but really should be tested on
a 53c825 with at least one target set to an ID >= 8.
The script is now copied to memory mapped using vm_page_alloc_contig(),
since it has to be physically contigous. This must be changed, if the
driver is converted into a loadable module !
Two of the probe messages are suppressed, unless "bootverbose" is set.
added prototypes for every function and
put (void *) as the args to the vop array definitions.
can now compile with:
CWARNFLAGS?= -W -Wreturn-type -Wcomment -Wredundant-decls -Wimplicit \
-Wnested-externs -Wstrict-prototypes -Wmissing-prototypes \
-Winline -Wstrict-prototypes
and only get errors for files external to this module:
namely
./vnode_if.h
../../sys/vnode.h
../../sys/buf.h
../../miscfs/specfs/specdev.h
1) Make the driver "quiet" by sticking most boot messages behind
bootverbose conditionals. This means that you won't see the
sync and wide negotiation, but you will find out if they fail.
2) Add support to the 93cx6 serial eeprom code to read at an abitrary
offset. This is needed so that we can access the second half
of the eeprom on 3940 cards where the second channel's config
is stored.
3) Add flags argument to ahcprobe(). This is used by the pci probe code
to tell the generic driver that an adapter should be treated
as a channel B device as well as notify it of the presence of
external SCB SRAM. These are needed for some motherboard
implementations of the aic7870 and for the 3940 controllers.
4) Print "Channel A"/"Channel B" instead of "Single Channel" for the
two busses of the 3940. I received many reports of confusion
about how the 3940 was probed since most people belived that
only one ahc entry was needed. This will hopefully make it
clearer.
5) Walk the SCBs to determine just how many their are if external SCB
ram is detected.
6) Hard code that external SCB ram is present for the 3940 since it doesn't
use the documented reporting facility for reporting the SRAM. :(
255 commands per channel are supported on the 3940.
7) Read the seeprom starting at addres 32 for the second channel of the
3940 so we get the right info for that channel.
8) Clean up printing of the "Disabling tagged queuing message".
9) Queue timeouts if they occur while we are handling a timeout. The code
was totally unprotected in this scenario.
Reviewed by: Timeout code reviewed by David Greenman <davidg>
contiguous memory in virtual space, but doesn't guarantee any particular
physical layout of pages, the script may be not contguous in physical
memory. This made the first write command fail in very rare cases.
This has been fixed by checking the region returned by malloc() for
being contiguous, but there should be a physical memory allocate
and later mapping to virtual memory instead.
A few assertions and error messages are improved.
/*
+ * Code for MTERASE added by John Lind (john@starfire.mn.org) 95/09/02.
+ * This was very easy due to the excellent structure and clear coding
+ * of the original driver.
+ */
Better performance -- more aggressive read-ahead
under certain circumstanses.
Mods to support clustering on small
( < PAGE_SIZE) block size filesystems (e.g. ext2fs,
msdosfs.)
changes to allow devices that don't probe (e.g. /dev/mem)
to create devfs entries
this required giving 'configure' its own SYSINIT entry
so we could duck in just before it with a DEVFS init
and some device inits..
my devfs now looks like:
./misc
./misc/speaker
./misc/mem
./misc/kmem
./misc/null
./misc/zero
./misc/io
./misc/console
./misc/pcaudio
./misc/pcaudioctl
./disks
./disks/rfloppy
./disks/rfloppy/fd0.1440
./disks/rfloppy/fd1.1200
./disks/floppy
./disks/floppy/fd0.1440
./disks/floppy/fd1.1200
also some sligt cleanups.. DEVFS needs a lot of work
but I'm getting back to it..
had a 2.1 tag, thus sending these two changes into the 2.1 branch instead
of -current. Argh. I may bring these changes into the 2.1 anyway (they're
benign there) so I'm not going to admin them out of 2.1 for the time
being.
4k to 8k. This has a significant effect on the pipe performance. In
the future it might be good to increase this to 16k. PIPSIZ is now
tunable for experimentation.
external linkage.
Remove useless comments saying that SYSINIT() does system initialization.
shm.c:
Remove nearly useless comment that gave wrong pseudo-prototypes.
bp->b_flags has been broken for many years:
a) they didn't set B_BUSY for doing i/o. This has been fatal since
1995/07/25 when biodone() started checking that B_BUSY is set.
b) they didn't set B_INVAL for releasing the buffer. This at best
just put a useless buffer in the LRU queue for a little while.
Fix a couple of spelling errors and complete a couple of function
pointer declarations.
Submitted by: terry (terry lambert)
This is a composite of 3 patch sets submitted by terry.
they are:
New low-level init code that supports loadbal modules better
some cleanups in the namei code to help terry in 16-bit character support
some changes to the mount-root code to make it a little more
modular..
NOTE: mounting root off cdrom or NFS MIGHT be broken as I haven't been able
to test those cases..
certainly mounting root of disk still works just fine..
mfs should work but is untested. (tomorrows task)
The low level init stuff includes a total rewrite of init_main.c
to make it possible for new modules to have an init phase by simply
adding an entry to a TEXT_SET (or is it DATA_SET) list. thus a new module can
be added to the kernel without editing any other files other than the
'files' file.
calls with a byte size of 1. This special case was not
correctly emulated. Now programs such as a simple 'ls' to a commercial
Macintosh emulator called 'executor' will work correctly.
instead of with none. The first (struct proc *) arg is used if lkmnosys()
if is actually called.
Implement lkmnosys() with the correct number and type of args so that
the first of them can be used and the others won't need to be fixed
lated.
nfsm_rpchead() has been called with the wrong number of args and misplaced
args since someone added new args in the middle for nfsv3.
Here's another one that would be important on 64-bit systems. VOP_READDIR
takes a `u_int **cookies' arg.
Submitted by: Bruce Evans <bde@zeta.org.au>
This is still very green, but I have managed to get my modem working.
Lots of work still to do, but now at least we can commit it. /phk
Reviewed by: phk
Submitted by: Andrew McRae <andrew@mega.com.au>
This change forces the controller drivers to allocate a scsibus_data struct
via a call to scsi_alloc_bus(), fill in the adapter_link field, and optionally
modify any other fields of the struct. Scsi_alloc_bus() initializes all fields
to the default, so the changes in most drivers are very minimal. For drivers
that support Wide controllers, the maxtarg field will have to be updated to
allow probing of all targets (for an example, look at the aic7xxx driver).
Scsi_attachdevs() now takes a scsibus_data* as its argument instead of an
sc_link*. This allows us to expand the role of the scsibus_data struct for
other bus level configuration setings (max number of transactions, current
transaction opennings, etc for better tagged queuing support).
Reviewed by: Rodney Grimes <rgrimes>, Peter Dufault <dufault>, Julian Elischer <julian>
Change some leading spaces to tabs.
This change forces the controller drivers to allocate a scsibus_data struct
via a call to scsi_alloc_bus(), fill in the adapter_link field, and optionally
modify any other fields of the struct. Scsi_alloc_bus() initializes all fields
to the default, so the changes in most drivers are very minimal. For drivers
that support Wide controllers, the maxtarg field will have to be updated to
allow probing of all targets (for an example, look at the aic7xxx driver).
Scsi_attachdevs() now takes a scsibus_data* as its argument instead of an
sc_link*. This allows us to expand the role of the scsibus_data struct for
other bus level configuration setings (max number of transactions, current
transaction opennings, etc for better tagged queuing support).
Reviewed by: Rodney Grimes <rgrimes>, Peter Dufault <dufault>, Julian Elischer <julian>
Garrett,
Here are some patches for the rate limiting code. It should be faster,
and in particular it doesn't leak malloc'd memory any more when rate_limit'ing
a phyint.
It now uses an mbuf chain at each vif, instead of the static queue array.
This means that the MAXQSIZE is now variable per vif (although there is no
interface to change it other than a debugger); this is an area for more
experimentation.
Bill
Submitted by: Bill Fenner <fenner@parc.xerox.com>
Implement the slip/ppp "hotchar" detection to improve latency
Debug the L_RINT bypass code..
Fix an interesting feature that caused 8-bit chars to loose their top bit
in some circumstances..
This finishes the remaining outstanding problems that I'm aware of, with
the exception of efficiency... Optimizing can come later after it's fully
debugged.
Claim the major numbers (before sombedoy else jumps in again and
claims the slots for his foocd driver :-), install all the hooks that
are required.
While i've been at this, i've cleaned up some of the routines at the
end of i386/conf.c; all the importers of the latest CDROM drivers
forgot to fill in the appropriate information. The `ata' driver
(vapourware?) does only occupy a slot in the bdevsw[] array, btw.
The actual import of the code does require a minor change in the SCSI
subsystem, and i want to have this reviewed by Peter first, so it will
be deferred for some days. The driver is already working for me
though.
Submitted by: akiyama@kme.mei.co.jp (Shunsuke Akiyama)
calls.
Found by: gcc -Wstrict-prototypes after I supplied some of the 5000+
missing prototypes. Now I have 9000+ lines of warnings and errors
about bogus conversions of function pointers.
Note, I tested this on a NEC Versa, IBM 750C, and a IBM 755CX w/out
problems. The card still works fine in TP mode.
Submitted by: schwarz@alpharel.com (Steve Schwarz)
Reviewed by: jleppek@suw2k.ess.harris.com (James Leppek)
actually a timeout only. The existing behaviour caused a
mcd0: timeout getreply
at halt/reboot time.
Submitted by: graichen@sirius.physik.fu-berlin.de (Thomas Graichen)
traps occurred. This also helps ddb backtrace through trap frames.
Backtracing through syscall and interrupt frames still doesn't work
but it is relatively unimportant and more expensive to fix.
ISA GAT mode and hidden refresh seem to cause reliability problems
on Saturn based systems and are now reported when booting with '-v'.
Submitted by: Danny J. Zerkel <dzerkel@feephi.phofarm.com>
moved to the driver proper, so that <machine/si.h> can be #included by user
programs without needing to include stuff from /sys/i386/isa..
Various (now) redundant features removed, eg: the locks on IXANY and HWFLOW
as these are now done with the "initial" and "lock" termios devices.
Note that it still (for reasons unknown) appears to be masking data to
7-bit with ppp - hence the cleanup to support the debugging via 'sicontrol'
This was originally ported to BSDI by Andy Rutter <andy@acronym.co.uk>.
At the end of the day, this code has very little in common with Andy's
version, or the Specialix SYSV version. Essentially it has been gradually
and almost completely rewritten, with LOTS of advice and inspiration from
Bruce Evans. There are a couple of missing bits still, but they are minor.
The user-mode "sicontrol" program is in sad shape and will come in soon.
Transparent printing died a timely death.. Maybe later..
Jeremy Rolls @ Specialix (Development directory) has confirmed this is OK
to distribute, and Andy personally sent me his version that I started from.
Although this driver stood up to a nasty stress-test in this form, I am not
confident that there are no nasty bugs lurking.
People are welcome to try it, but dont go out and buy one just yet.. :-)
And *DONT* use it on a mission-critical machine... This is ALPHA QUALITY!
of "__volatile". Note also that the original mods that were submitted
by me were as a result of a discussion between various FreeBSD contributors.
Submitted by: peter@haywire.dialix.com (Peter Wemm)
for return values. It just so happens that in the cases where it is likely
to fail, it is okay to change the M_NOWAIT to M_WAITOK -- and all will
be well. This problem was manfest as a panic very regularly on a 4MB
system right after bootup.
disksort is called at non-interrupt time and can be actively traversing
the list when that happens, there is a very small window of vulnerability.
Close it by protecting disksort with splbio().
