On Monday, 8 January 2001 at 10:04:44 +0200, Roman Shterenzon wrote:
> * Roman Shterenzon <[EMAIL PROTECTED]> [010107 10:24] wrote:
>> Hi,
>>
>> Could you please take a look at :
>> http://www.freebsd.org/cgi/query-pr.cgi?pr=24019
>> It's my friend's PR. Can you give me some hints on how can I debug this
>> issue. I'm completely puzzled here.
>> It panics on "goto out" with page fault. What I understand from it is that
>> the block at the address it tries to jmp to isn't present. But it's kernel
>> code which is never swapped out. Does it mean that the address was
>> rewritten? If it's so, what can rewrite this address? Ideas?
My first suspicion here is that the sources are out of sync with the
kernel you're debugging. It's very important to ensure that they are
absolutely in sync. Here are a couple of incantations to throw at
this dump (you may recognize the second one from an earlier mail
exchange):
(kgdb) x/10i epread
(kgdb) x/10i 0xc012a038
The first one should show the beginning of the function; if it's in
sync it will look like (modulo addresses):
(kgdb) x/10i epread
0xc0165f8c <epread>: push %ebp
0xc0165f8d <epread+1>: mov %esp,%ebp
0xc0165f8f <epread+3>: sub $0x1c,%esp
0xc0165f92 <epread+6>: push %edi
0xc0165f93 <epread+7>: push %esi
0xc0165f94 <epread+8>: push %ebx
0xc0165f95 <epread+9>: mov 0x8(%ebp),%eax
0xc0165f98 <epread+12>: mov %eax,0xfffffff4(%ebp)
0xc0165f9b <epread+15>: mov 0x118(%eax),%edx
0xc0165fa1 <epread+21>: add $0x8,%edx
In particular, those first two instructions are at the beginning of
just about every function, so if you don't find them, you should check
whether your code is in sync.
>> P.S. Can it be due to faulty hardware?
Or faulty Italian cuisine? In each case, not if it's repeatable.
Greg
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