Re: Debugging double page fault

[Bill Kish]

Hi Terry,

 Nothing's changed hardware or configuration wise. Since this system handles alot
of network traffic, I was thinking it might be some kind of martian packet causing
the crash. I'd seen that happen before with RR pings from Linux systems, but at
least had a reasonable dump to work with.

 I'll try swapping out the hardware and see what happens. But I'm still curious
about a methodology for analyzing such dumps.

-=BK

Terry Lambert wrote:

 Bill Kish wrote:
   I've recently started seeing double fault panics on a formerly FreeBSD
  2.2.8 based system (It's running 2.2.8 as a somewhat embedded OS, so please
  don't flame me about being back rev!)
 [ ... ]
   My rough understanding is that double faults are usually the result of
  running out of stack, and that the underlying cause of the panic can probably
  be uncovered if I can find the previous stack .
 
   Can anyone point me towards some hints for debugging this sort of crash. Any
  advice greatly appreciated.

 It's very old.

 This makes me think that it used to work, and now it
 doesn't.

 What did you change just before it stopped working?

 If nothing, then it's likely a hardware problem.

 -- Terry

--
---
Bill Kish  Ph: 650.969.6000
Chief Engineer,12 S. First Street, Suite 616
Coyote Point Systems Inc.   San Jose, CA 95113
Email: [EMAIL PROTECTED]   http://www.coyotepoint.com/
---
For support call: 1-888-891-8150  Email: [EMAIL PROTECTED]
---



To Unsubscribe: send mail to [EMAIL PROTECTED]
with unsubscribe freebsd-hackers in the body of the message

Debugging double page fault

[Bill Kish]

Hi All,

 I've recently started seeing double fault panics on a formerly FreeBSD
2.2.8 based system (It's running 2.2.8 as a somewhat embedded OS, so please
don't flame me about being back rev!)

 The stack trace looks like:

$ gdb -k  kernel.0 vmcore.0
GDB is free software and you are welcome to distribute copies of it
 under certain conditions; type show copying to see the conditions.
There is absolutely no warranty for GDB; type show warranty for details.
GDB 4.16 (i386-unknown-freebsd),
Copyright 1996 Free Software Foundation, Inc...(no debugging symbols
found)...
IdlePTD 1aa000
current pcb at 1967a0
panic: double fault
#0  0xf010cf63 in boot ()
(kgdb) bt
#0  0xf010cf63 in boot ()
#1  0xf010d232 in panic ()
#2  0xf0176f5a in trap_fatal ()
#3  0xf0176a1c in trap_pfault ()
#4  0xf01766df in trap ()
#5  0xf012baae in vget ()
#6  0xf01558dc in ffs_sync ()
#7  0xf012cf7b in sync ()
#8  0xf010ce2d in boot ()
#9  0xf010d232 in panic ()
#10 0xf0176ff0 in trapwrite ()
(kgdb)

 My rough understanding is that double faults are usually the result of
running out of stack, and that the underlying cause of the panic can probably
be uncovered if I can find the previous stack .

 Can anyone point me towards some hints for debugging this sort of crash. Any
advice greatly appreciated.

-=BK

To Unsubscribe: send mail to [EMAIL PROTECTED]
with unsubscribe freebsd-hackers in the body of the message