what is teh root cause -- but, sometimes, a procfs vnode in pfshead is
apparantly corrupt (or a UFS vnode instead). Without this patch, I can
get it to panic by doing (in csh)
while (1)
ps auxwww
end
and it will panic when the PID's wrap. With it, it does not panic.
Yes -- I know that this is NOT the right way to fix it. But I haven't
been able to get it to panic yet (which confuses me). I am going to
be looking into the vgone() code now, as that may be a part of it.
Wrappered and enabled by the define BETTER_CLOCK (on by default in smpyests.h)
apic_vector.s also contains a small change I (smp) made to eliminate
the double level INT problem. It seems stable, but I haven't the tools
in place to prove it fixes the problem.
Reviewed by: smp@csn.net
Submitted by: Tor Egge <Tor.Egge@idi.ntnu.no>
me; unfortunately, also makes it hard ot check for errors); second, I had
managed to forget a change to PIOCSFL (it should be _IOW, not _IOR) I had
in my local copy, and Bruce called me on it.
Submitted by: bde
Note that an unload facility should be used to call rm_at_exit() (if
procfs is being loaded as an LKM and is subsequently removed), but it
was non-obvious how to do this in the VFS framework.
Reviewed by: Julian Elischer
nfs_bio.c code worked better than the 1.44. This commit reverts
the important parts of 1.44 to 1.41, and we will fix it when we
can get a handle on the problem.
surprise, procfs actually is optional, and some people truly do generate
kernels without it. Wow. I built a kernel without 'options PROCFS' and
it compiled and linked.
MS IntelliMouse, Kensington Thinking Mouse, Genius NetScroll,
Genius NetMouse, Genius NetMouse Pro, ALPS GlidePoint, ASCII
MieMouse, Logitech MouseMan+, FirstMouse+
- The `psm' driver is made to recognize various models of PS/2 mice
and enable their extra features so that their additional buttons and
wheel/roller are recognized. The name of the detected model will be
printed at boot time.
- A set of new ioctl functions are added to the `psm', `mse' and
`sysmouse' drivers so that the userland program (such as the X server)
can query device information and change driver settings.
- The wheel/roller movement is handled as the `Z' axis movement by the
mouse drivers and the moused daemon. The Z axis movement may be mapped
to another axis movement or buttons.
- The mouse drivers support a new, standard mouse data format,
MOUSE_PROTO_SYSMOUSE format which can encode x, y, and x axis movement
and up to 10 buttons.
/sys/i386/include/mouse.h
- Added some fields to `mousestatus_t' to store Z axis movement
and flag bits.
- Added the field `model' to `mousehw_t' to store mouse model code.
Defined model codes.
- Extended `mousemode_t'.
- Added new protocols and some constants for them.
- Added new ioctl functions and structures.
- Removed obsolete ioctl definitions.
/sys/i386/include/console.h
- Added `dz' field to the structure `mouse_data' to pass Z axis movement
to `syscons/sysmouse'.
- Removed LEFT_BUTTON, MIDDLE_BUTTON and RIGHT_BUTTON. Use button bits
defined in `mouse.h' instead.
/sys/i386/isa/psm.c
- Added a set of functions to detect various mice which have additional
features (wheel and buttons) unavailable in the standard PS/2 mouse.
- Refined existing ioctl functions and added new ones. Most important
of all is MOUSE_SETLEVEL which manipulates the output level of the driver.
While the output level remains zero, the output from the `psm' driver is
in the standard PS/2 mouse format (three bytes long). When the level
is set to one, the `psm' driver will send data in the extended format.
At the level two the driver uses the format which is native to the
connected mouse is used. (Meaning that the output from the device is
passed to the caller as is, unmodified.) The `psm' driver will pass
such extended data format as is to the caller if the output level is
two, but emulates the standard format if the output level is zero.
- Added kernel configuration flags to set initial resolution
(PSM_CONFIG_RESOLUTION) and acceleration (PSM_CONFIG_ACCEL).
- Removed the compile options PSM_ACCEL, PSM_CHECKSYNC and PSM_EMULATION.
Acceleration ratio is now specified by the kernel configuration flags
stated above. Sync check logic is refined and now standard.
The sync check can be turned off by the new kernel configuration flags
PSM_CONFIG_NOCHECKSYNC (0x100). PSM_EMULATION has been of little use.
- Summer clean up :-) Removed unused code and obsolete comments.
/sys/i386/isa/mse.c
- Created mseioctl() to deal with ioctl functions MOUSE_XXXX.
Most importantly, the MOUSE_SETLEVEL ioctl will change the
output format from the 5 byte format to the new, extended format
so that the caller can take advantage of Z axis movement and additional
buttons.
- Use constants defined in `mouse.h' rather than magic numbers.
/sys/i386/isa/syscons.c
- Changed scioctl() to reflect the new `console.h' and some of the new
ioctls defined in `mouse.h'. Most importantly, the MOUSE_SETLEVEL
ioctl will change the `sysmouse' output format from the MouseSystems
5 byte format to the new, extended format so that the caller can
take advantage of Z axis movement and additional buttons.
- Added support for double/triple click actions of the left button and
single click action of the right button in the virtual console. The
left button double click will select a word under the mouse pointer.
The triple click will select a line and the single click of the right
button will extend the selected region to the current position of
the mouse pointer. This will make the cut/paste support more compatible
with xterm.
/sys/i386/isa/kbdio.h
- Added PSM_INTELLI_ID.
procfs/mem file. While this doesn't prevent an unkillable process, it
means that a broken truss prorgam won't do it accidently now (well,
there's a small window of opportunity). Note that this requires the
change to truss I am about to commit.
low level ioctl routines instead of the magic number -1 so that
callers can distinguish it from ERESTART (which happens to be -1).
-1 meant that the ioctl was not handled at the called level.
ERESTART is normal when a sleeping ioctl is interrupted. ERESTART
got converted to ENOTTY instead of restarting the ioctl. Many
(most?) ioctls can not be restarted safely, but this is apparently
supposed to be handled by drivers converting ERESTART to EINTR.
I first saw this problem for TIOCDRAIN. Justin saw if for disk
ioctls.
Added missing parentheses.
is apparently useful for large shell systems, or systems with long running
idle processes. To enable the feature:
sysctl -w vm.swap_idle_enabled=1
Please note that some of the other vm sysctl variables have been renamed
to be more accurate.
Submitted by: Much of it from Matt Dillon <dillon@best.net>
isn't actually const in vmstat.
Fixed pedantic syntax errors caused by trailing semicolons in macro
definitions.
Fixed style bugs and typos in revisions 1.26-1.33.
the maximum pageout rate:
sysctl -w vm.vm_maxlaunder=n
1 < n < inf.
If paging heavily on large systems, it is likely that a performance
improvement can be achieved by increasing the parameter. On a large
system, the parm is 32, but numbers as large as 128 can make a big
difference. If paging is expensive, you might try decreasing the
number to 1-8.
1) Fix the initialization of malloc structure that changed
due to perf opt.
2) Remove unneeded include.
3) An initialization assert added to malloc.
Submitted by: John Hood <cgull@smoke.marlboro.vt.us>
so the filenames can be displayed and selected in full beauty. If RR
is present, the match is now case-sensitive, if RR is missing, the
match is case-insensitive (as it used to be before).
sysctl -w vm.defer_swap_pageouts=1
Causes the system to resist the use of swap space. In low memory
conditions, performance will decrease.
sysctl -w vm.disable_swap_pageouts=1
Causes the system to mostly disable the use of swap space. In
low memory conditions, the system will likely start killing
processes.
the barrery time remaining is reported as a random number. Initialize
edx to 0xffff in this case, and to 0 in all other cases. This change
should be benign on other machines.
Reviewed by: jdp
workaround. Note that this currently eats up two pages extra in the system;
this could be alleviated by aligning idt correctly, and then only dealing with
that (as opposed to the current method of allocated two pages and copying the
IDT table to that, and then setting that to be the IDT table).
option PCIC_NOCLRREGS). This is now the default behavior since it's
apparently required for the CLPD6832, and doesn't negatively affect
any of my test machines.
Requested by: Ted Faber <faber@ISI.EDU>
number of tags (NCR_SCSI_DFLT_TAGS), which is 0 in the FAILSAFE case.
This should fix the incompatibility between kernel and ncrcontrol,
which is the result of FAILSAFE being defined in the kernel config
file, invisible to the build of ncrcontrol. (See kern/5133, which
should be fixed by this change.)
mode. Currently, the only supported controller is the Cirrus Logic
PD6832, but others can be supported with docs on them.
Submitted by: Ted Faber <faber@ISI.EDU>
or aio_write can return the pid of the new thread. This is due to the
way that return values from system calls being passed by side-effect in
the proc structure now. This commit fixes the problem with aio_read and
aio_write.
remove alot of overly verbose debugging statements.
ioproclist {
int aioprocflags; /* AIO proc flags */
TAILQ_ENTRY(aioproclist) list; /* List of processes */
struct proc *aioproc; /* The AIO thread */
TAILQ_HEAD (,aiocblist) jobtorun; /* suggested job to run */
};
/*
* data-structure for lio signal management
*/
struct aio_liojob {
int lioj_flags;
int lioj_buffer_count;
int lioj_buffer_finished_count;
int lioj_queue_count;
int lioj_queue_finished_count;
struct sigevent lioj_signal; /* signal on all I/O done */
TAILQ_ENTRY (aio_liojob) lioj_list;
struct kaioinfo *lioj_ki;
};
#define LIOJ_SIGNAL 0x1 /* signal on all done (lio) */
#define LIOJ_SIGNAL_POSTED 0x2 /* signal has been posted */
/*
* per process aio data structure
*/
struct kaioinfo {
int kaio_flags; /* per process kaio flags */
int kaio_maxactive_count; /* maximum number of AIOs */
int kaio_active_count; /* number of currently used AIOs */
int kaio_qallowed_count; /* maxiumu size of AIO queue */
int kaio_queue_count; /* size of AIO queue */
int kaio_ballowed_count; /* maximum number of buffers */
int kaio_queue_finished_count; /* number of daemon jobs finished */
int kaio_buffer_count; /* number of physio buffers */
int kaio_buffer_finished_count; /* count of I/O done */
struct proc *kaio_p; /* process that uses this kaio block */
TAILQ_HEAD (,aio_liojob) kaio_liojoblist; /* list of lio jobs */
TAILQ_HEAD (,aiocblist) kaio_jobqueue; /* job queue for process */
TAILQ_HEAD (,aiocblist) kaio_jobdone; /* done queue for process */
TAILQ_HEAD (,aiocblist) kaio_bufqueue; /* buffer job queue for process */
TAILQ_HEAD (,aiocblist) kaio_bufdone; /* buffer done queue for process */
};
#define KAIO_RUNDOWN 0x1 /* process is being run down */
#define KAIO_WAKEUP 0x2 /* wakeup process when there is a significant
event */
TAILQ_HEAD (,aioproclist) aio_freeproc, aio_activeproc;
TAILQ_HEAD(,aiocblist) aio_jobs; /* Async job list */
TAILQ_HEAD(,aiocblist) aio_bufjobs; /* Phys I/O job list */
TAILQ_HEAD(,aiocblist) aio_freejobs; /* Pool of free jobs */
static void aio_init_aioinfo(struct proc *p) ;
static void aio_onceonly(void *) ;
static int aio_free_entry(struct aiocblist *aiocbe);
static void aio_process(struct aiocblist *aiocbe);
static int aio_newproc(void) ;
static int aio_aqueue(struct proc *p, struct aiocb *job, int type) ;
static void aio_physwakeup(struct buf *bp);
static int aio_fphysio(struct proc *p, struct aiocblist *aiocbe, int type);
static int aio_qphysio(struct proc *p, struct aiocblist *iocb);
static void aio_daemon(void *uproc);
SYSINIT(aio, SI_SUB_VFS, SI_ORDER_ANY, aio_onceonly, NULL);
static vm_zone_t kaio_zone=0, aiop_zone=0,
aiocb_zone=0, aiol_zone=0, aiolio_zone=0;
/*
* Single AIOD vmspace shared amongst all of them
*/
static struct vmspace *aiovmspace = NULL;
/*
* Startup initialization
*/
void
aio_onceonly(void *na)
{
TAILQ_INIT(&aio_freeproc);
TAILQ_INIT(&aio_activeproc);
TAILQ_INIT(&aio_jobs);
TAILQ_INIT(&aio_bufjobs);
TAILQ_INIT(&aio_freejobs);
kaio_zone = zinit("AIO", sizeof (struct kaioinfo), 0, 0, 1);
aiop_zone = zinit("AIOP", sizeof (struct aioproclist), 0, 0, 1);
aiocb_zone = zinit("AIOCB", sizeof (struct aiocblist), 0, 0, 1);
aiol_zone = zinit("AIOL", AIO_LISTIO_MAX * sizeof (int), 0, 0, 1);
aiolio_zone = zinit("AIOLIO",
AIO_LISTIO_MAX * sizeof (struct aio_liojob), 0, 0, 1);
aiod_timeout = AIOD_TIMEOUT_DEFAULT;
aiod_lifetime = AIOD_LIFETIME_DEFAULT;
jobrefid = 1;
}
/*
* Init the per-process aioinfo structure.
* The aioinfo limits are set per-process for user limit (resource) management.
*/
void
aio_init_aioinfo(struct proc *p)
{
struct kaioinfo *ki;
if (p->p_aioinfo == NULL) {
ki = zalloc(kaio_zone);
p->p_aioinfo = ki
make isa_dmacascade, isa_dmastart, isa_dmadone, and find_isadev MUCH
easier to be found by starting them at the beginging of the line...
remove braces inside of ifdef RESOURCE_CHECK... found by % in vi...
support was missing in the previous version of the AIO code. More
tunables added, and very efficient support for VCHR files has been added.
Kernel threads are not used for VCHR files, all work for such files is
done for the requesting process directly. Some attempt has been made to
charge the requesting process for resource utilization, but more work
is needed. aio_fsync is still missing (but the original fsync system
call can be used for now.) aio_cancel is essentially a noop, but that
is okay per POSIX. More aio_cancel functionality can be added later,
if it is found to be needed.
The functions implemented include:
aio_read, aio_write, lio_listio, aio_error, aio_return,
aio_cancel, aio_suspend.
The code has been implemented to support the POSIX spec 1003.1b
(formerly known as POSIX 1003.4 spec) features of the above. The
async I/O features are truly async, with the VCHR mode of operation
being essentially the same as physio (for appropriate files) for
maximum efficiency. This code also supports the signal capability,
is highly tunable, allowing management of resource usage, and
has been written to allow a per process usage quota.
Both the O'Reilly POSIX.4 book and the actual POSIX 1003.1b document
were the reference specs used. Any filedescriptor can be used with
these new system calls. I know of no exceptions where these
system calls will not work. (TTY's will also probably work.)
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)
this results in a few functions becoming static, and
the SYSINITs being close to the code they are related to.
setting up the dump device is with dumpsys() and
kicking off the scheduler is with the scheduler.
Mounting root is with the code that does it.
Reviewed by: phk
Sorted the functions into the same order as in ufs_vnops.c so that this
can be compared with the latter without getting 2627 lines of diffs.
Now we get only 1920 lines of diffs.
"high resolution" profiling. The available clocks are:
- the i8254 clock
- on non-SMP i586's and i686's: the TSC
- on systems with I586_PMC_GUPROF configured, and PERFMON configured
and available: all the performance counters.
This is unfinshed (there are problems with locking out the PERFMON
device driver, and with losing calibration after switching the clock),
but better than static configuration or writing to kmem.
Changed ifdefs to avoid generating code for non-working option
combinations.
triple indirect blocks only worked for block sizes of 4K, since
MNINDIR(ump)**3 overflows for larger block sizes (e.g.,
(8192/4)**3 = 2**33 > INT_MAX). This fix is not the obvious one of
changing some types to 64 bits. It rearranges the code to avoid some
unnecessary 64-bit calculations.
Reviewed by: Kirk McKusick <mckusick@McKusick.COM>
a mistake (since softnet interrupts may occur if malloc() waits),
and doing it harmlessly but unnecessarily here interfered with
detection of the mistaken cases.
b_flags, and this patch removes unneeded modifications. Only the needed b_flags
bits are modified now. (Specifically, it is usually wrong to zero b_flags.)
Submitted by: bde@freebsd.org
Fixed overflow of FFLAGS() in fcntl(F_SETFL, ...). This was not
a security hole, but gave wrong results for silly flags values.
E.g., it make fcntl(F_SETFL, -1) equivalent to fcntl(F_SETFL, 0).
POSIX requires ignoring the open mode bits in fcntl() (even if
they would be invalid for open()).
break for the usual sector size. dscheck() adjusts b_bcount to
handle EOF, so we must scale it and not preserve it. i/o beyond
the end of partitions has been broken since rev.1.96.
Not fixed in: od driver
are used in the `#ifdef notyet' case :-). This case is used except in
the `#if !defined (not_yes)' case :-|. This has something to do with
the `#ifdef notyet_block_reallocation_enabled' case in vfs_cluster.c :-(.
Use OID_AUTO instead of a magic number for the debug.syncprt sysctl.
(This sysctl doesn't actually work. FreeBSD nuked it, but parts
of it were mismerged from Lite2. It is not very good, but better
than nothing.)
`mount -u'. This only matters for `mount -u' competing with unmounts.
If I understand the locking correctly: if mount() blocks, then unmount()
may run and set mp->kern_flag for the same mp. Then unmount() blocks
waiting for mount() to finish. When unmount() continues, its MNTK flags
(MNTK_UNMOUNT and MNTK_MWAIT) may have been clobbered.
Didn't fix old bugs:
- restoring mp->mnt_kern_flag is wrong for the same reasons in the error
case.
- the error case of unmount() seems to be broken too:
(a) MNTK_UNMOUNT gets clobbered, although another unmount() may have
set it. Perhaps it shouldn't be set until after the full lock is
aquired.
(b) MNTK_MWAIT isn't honoured.
Fixed a nearby style bug.
time, but was left at 0. This caused the "can't happen" case in
splz_swi to happen for panics when tsleep() calls splx(safepri)
and there is a SWI_AST pending. This was harmless because the
the error handling happens to be right. Debugging this was tricky
because debugger traps force SWI_AST_MASK on in `cpl'.
there is a natural place to initialize `safepri' in a future commit.
Spinoffs:
- spl0() gets called in the unlikely event that isa is not configured.
- configure() has better control over enabling interrupts.
- it is now less unclear that interrupts aren't actually enabled early.
Rev.1.48 of autoconf.c seems to have done the opposite of what was
intended - moving the isa_configure() call delayed the spl0() side
effect.
Added some comments about the bogons. Removed the splhigh() call since
it is a no-op.
checking the BIOS video mode paramter table. Now syscons uses the
parameter table even if some bits in the table are different from the
current VGA register settings.
Even if comp_vgaregs() finds that the BIOS video parameter table looks
totally unfamiliar to it, syscons allows the user to change the
current video mode to some modes which are based on the VGA 80x25
mode. They are VGA 80x30, VGA 80x50, VGA 80x60. In this case the user
will be warned, during boot, that video mode switching is only
paritally supported on his machine.
PR: bin/4477
this mouse can correctly operate only in the high resolution mode.
If the mouse pointer jumps to the top or left edge or the top-left
corner of the screen, try defining PSM_MSCKLUDGE in the kernel
configuration file. This option will put the mouse in the high
resolution mode during device initialization.
Disallow wait options that are not a combination of the standard POSIX
options WUNTRACED and WNOHANG, as is required by POSIX. BSD doesn't
have any extensions here, but the code was `#ifdef notyet' for some
reason.
interval [VM_MIN_KERNEL_ADDRESS, etext] was used instead of
[btext, etext). Added a comment about this being completely
wrong for LKMs. This only affects interpreting the instructions
after the return to attempt decide the number of args. The
attempt usually fails anyway.
checking was mostly wrong at the boundaries. For the lower limit,
VM_MIN_KERNEL_ADDRESS was used instead of btext and there was an
off-by-(`size' - 1) error. For the upper limit, &etext was used
instead of etext and there was an off-by-1 error. The bugs were
harmless because `size' is not too large and some memory is mapped
just beyond the ends. We still depend on the former to avoid
having to handle the case where the memory range covers the whole
text section, and on the latter to prevent problems when we map
just beyond an end to allow writing an address range that overlaps
the end.
Fixed placement of a nearby comment.
one traditionally reserved for swap devices. The restrictions
should now be the same as the ones for dumpsys(). The restriction
on the partition should be removed someday, and dumpsys() shouldn't
repeat all the checks.
it if the file system is mounted noatime). Not fixed: the access
time is marked at the start of a read() and not marked on successful
completion. I think this should be handled at the vfs level.
Print a better panic message for missing vops. Don't use printf()
before panic(), since the printf()ed part isn't shown by gdb.
This actually loses a little with the current gdb, since gdb just
prints the fmt arg to panic, so %'s aren't expanded. gdb should
fetch the full message from the message buffer if possible.
Fixed default vop function for vop_getpages_desc. It needs to
just return EOPNOTSUPP so that the vnode pager can get the pages
in using a general method. Panicing broke exec'ing of files on
ext2fs file systems. ffs works because it doesn't use the default.
Fixed nearby style bugs.
Fixed nonblocking mode. It was per-device instead of per-file. This
also fixes clobbering of bd_rtout by overloading it to hold a wrong
version of the blocking flag. I hope nothing depends on the bugs.
Fixed nonblocking mode. It was per-device instead of per-file.
Don't depend on gcc's misfeature of rewriting char args in old-style
function definitions to match wrong prototypes. Break K&R1 support
to fix this quickly.
Testing in if_ppp.c is good enough.
Added comments about bogus #includes and #defines.
Removed unused #includes.
Don't depend on gcc's misfeature of rewriting short args in old-style
function definitions to match wrong prototypes. I just changed the
function definition to match the prototype, since this is easy to
verify automatically (it causes no changes in the object code), but
it breaks K&R1 support and doesn't fix the pessimal type.
Use gettime() instead of microtime() to set if_lastchange for i/o's.
microtime() is probably too expensive. However, setting if_lastchange
for i/o's may be wrong.
volatile to use outside of splclock(). microtime() is probably too
expensive to use for every i/o. However, setting ifi_lastchange for
every i/o is just wrong according to the comment about ifi_lastchange
in <net/if.h>. It is set then for atm, fddi and the latest version
of ppp.)
and don't include <sys/fcntl.h>. (The select -> poll changes replaced
fcntl macros by poll macros.)
Use <machine/*.h> instead of <i386/include/*.h>.
Fail the probe instead of crashing in the unlikely event that malloc()
fails.
Fixed #include order. <i386/isa/isa_device.h> will soon be a prerequisite
for <i386/isa/pnp.h>. Including both in alphebetical order gets this
right naturally.
years and gives a "laugh"able number of compile-time errors (see the
comment). main() just printed the struct sizes. This can be done
better by compiling with -g and reading off the sizes from the stabs.
Sorted #includes.
Fixed an unsigned vs signed comparison.
place that depended on it. The "bazillion warnings" mentioned in the
log for rev.1.45 apparently aren't a problem any more. It is hard
to be sure because the SIMPLELOCK_DEBUG option turns off (and breaks)
things in the SMP case.
place that depended on it. The "bazillion warnings" mentioned in the
log for rev.1.45 apparently aren't a problem any more. It is hard
to be sure because the SIMPLELOCK_DEBUG option turns off (and breaks)
things in the SMP case.
Don't forward declare structs that are already implicitly forward declared.
Fixed a disordered declaration.
to fix some broken application. Application breakage is now hidden by a
recently introduced wrong #include of <sys/types.h> in <sys/time.h>.
<sys/time.h> is a prerequisite for <sys/resource.h>, so the <sys/types.h>
prereqisite is automatically supplied.
Cast RLIM_INFINITY to the correct (signed) type.
LINUX_SNDCTL_DSP_GETOPTR
LINUX_SNDCTL_DSP_GETIPTR
LINUX_SNDCTL_DSP_SETTRIGGER
LINUX_SNDCTL_DSP_GETCAPS
With this rev level the linux realaudio player 5 and xquake should work.
(update_intr_masks might not need to be done in 3.X, but the new generic
interrupt code is incomplete w/regard to support for the PCCARD code, so
to avoid any potential problems use it. It can't hurt).
- Correctly register pcic_imask with the system interrupt code.
- Call update_intr_masks() so that pcic_imask modifications that occur
when card interrupts are registered get updated in the system
interrupt code.
