Don't panic. That's the kernel's job - Jeff
Of all the possible reasons for a system panic, a "trap
0x0000000E" is the one most often seen (see SCO's "What are Traps,
Interrupts and Exceptions?" for other reasons). Technically, an
E trap is a page fault that referenced an impossible page: the CPU
tries to access an address that does not exist and can't be
accessed. As page references are normally very carefully managed,
the usual cause for this is bad (defective) RAM; scrambled bits
point the CPU toward disaster and it blindly follows. Therefor, if
you have a Trap E panic on a machine that otherwise has been
running along for months or years, bad RAM is the most likely
suspect. (If you have ECC memory, don't bother looking at it: it's
not going to give you an E trap; see below.)
You can't expect that the so called "memory test" that
runs when your computer starts is going to catch bad ram. That
testing is very superficial, and really can only find ram that's
totally screwed up- subtle problems just will not be seen by that
test. There are tests available that can really stress memory, but
the best ones need to run a very long time, so if the suspect
machine is critical, you probably don't have the time to do
RAM is pretty cheap nowadays, so you may just want to replace
all of it, or you can pull individual sticks and swap things around
until you determine where the problem is. In taking this approach,
try booting with as little RAM as possible; the bad chips can be
found more easily that way (see Memory).
Of course, there are other possibilities. A bus card that uses
shared memory can mess up the CPU by misaddressing itself into an
area that the CPU doesn't expect it to be in. If it writes its own
patterns into some of that shared memory, your CPU can once again
be presented with an insane memory reference and it will react
accordingly. So, when you open the machine to see what you can do
about the memory, try pulling all non-essential cards that use any
shared memory (multiport cards, etc. use shared memory. Any card
that does will usually show that in "hwconfig"). If you aren't
sure, just pull anything that you don't need to boot- if the
problem goes away, one of those cards is the problem; put them back
one at a time until you know which one.
Another thing to realize is that hardware problems are often
expressed because of heat. If your machine is crashing so quickly
that you can't even get a backup, shut it off for an hour or so and
then arrange for some extra cooling: opening the case and setting
up a window fan to blow on the insides can sometimes keep you
running long enough to scrape some data off.
It's also possible that you just need patches- some of these
crashes are caused by problems in the OS- be sure to search the
TA database for symptoms
and messages that match yours, and be sure that you do have the
recommended minimum patches for your OS version.
Some people have an odd attitude toward these because sometimes
patches cause more problems than you have now. But it's really
silly to hesitate about an important patch that has been out for
months or years. If it had defects, someone has already found them
by now, so it's very unlikely to cause problems. So if you are
running an earlier version of your OS and don't have the
recommended patches, you are just being foolish. You are probably
being foolish even if the patch was just posted yesterday.
You can do a little panic analysis yourself: http://aplawrence.com/cgi-bin/ta.pl?arg=106181
explains how to determine if panics are consistent, that is, are
they happening in the same kernel routine. If they are, your
problem still could be hardware, but now you will have more info to
narrow it down. If the panics are inconsistent, it's surely
It's also possible that a bad CPU will cause the same symptoms
because it gets the info it read from RAM scrambled internally.
That's much more rare: the CPU's self-test and usually would halt
long before you'd get to boot. Of course, a bad motherboard can
cause good RAM to deliver bad bits to a good CPU also, but again
the POST (Power On Self Tests) will usually catch this sort of
thing unless it is very subtle.
A bad driver can also do this by trampling flowerbeds (stepping
on RAM that the CPU needs for its own sanity). If the system has
been running up to this point you can usually discount that, but if
you've just installed a new driver, this could be the cause. Try
booting "unix.old"; if that works, the new driver could very well
be at fault.
Finally, disk corruption can cause otherwise good code to be
read incorrectly from disk, which ends up being the same as a bad
driver: misread bits send the kernel off on a rampage where it
ultimately steps on its own tail and panics. Using "unix.old" or
other kernels you may have can sometimes get around this at least
long enough to save the data. Emergency Boot Floppies can also help
here, and if you don't have those, you can break into the original
install disks boot and get at the drive with that. The method for
doing that varies with the release of SCO. With modern SCO, just
type "tools" at the install floppy boot prompt. See SCO FAQ's for a listing
of different methods for older versions.
If it is disk corruption, and can't be gotten around with
alternate kernels or boot floppies, the disk recovery guys can suck
your data down to cdrom or other media:
It's unlikely that you'd need to go to this extent for a trap E
problem, though:if the disk isn't obviously trashed in other ways,
a local problem that happens to be in the kernel tracks should be
able to be gotten around with one of the other methods suggested
You might find this helpful too: http://www.tkrh.demon.co.uk/panic.html
A good reference on Linux panix=cs is Linux “Kernel Panic” — Prevent Cardiac Arrest
[email protected] added this:
The problem with the above article though is that it doesn't
take into account ECC protected memory as you commonly find on
Intel servers; Single bit failures are corrected by hardware and
are invisible to the operating system, when multiple bit failures
occur then a hardware NMI should be raised and subsequently caught
by the OpenServer nmi kernel driver, resulting in a PANIC message
that contains "FATAL:Parity error address unknown".
To date I have managed to get Caldera to include a second note
on this on this subject,
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