Questions about debugging kernel panics
Questions about debugging kernel panics
- Subject: Questions about debugging kernel panics
- From: James Reynolds <email@hidden>
- Date: Tue, 17 Jan 2006 13:21:37 -0700
I have several questions on debugging kernel panics. I hope this
isn't asking too much. Because of my work debugging a previous panic,
my boss is having me do a presentation tomorrow and webpage on
panics, and I thought I understood things well enough to do one,
until I got into it, then I realized how much I don't know...
Is "unresolved kernel trap" different from "panic(cpu ... caller
...)" because the trap was initiated by the CPU but the panic was
initiated by the kernel code? Or is it that certain traps (0x100 to
0x900) are initiated by the CPU and the others are code?
Does the "PC" in the following line refer to a line number in code?
Unresolved kernel trap(cpu 0): 0x600 - Alignment
DAR=0x0000000001BB5DEE PC=0x00000000000A4F20
So if I have a bunch of panic logs from different computers and they
all have the same PC numbers, but different DAR numbers, what does
that mean?
If I understand correctly, the trap number (0x100-0xF00) refers to
the type of error that caused the crash, but doesn't really help
figure out what caused the crash. Is that right?
How is moving to Intel going to change CPU panics? Will trap numbers
stay the same?
There is a bit of documentation about debugging the FreeBSD kernel on
the web and I'm wondering how similar it is to Darwin. (for example:
http://www.onlamp.com/pub/a/bsd/2002/04/04/Big_Scary_Daemons.html
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig-trouble.html)
In particular, I read that a core dump is the size of your physical
RAM. Does Darwin do the same?
I also read that core dumps may contain passwords that were stored in
RAM. Is that true of Darwin?
I also read that it is possible to setup FreeBSD to save core dumps
to the swap partition. Because Darwin doesn't have a swap partition
but uses the main partition for swap, is that why Darwin supports
kdumpd for remote core dump storing? Does Darwin support saving core
dumps to the local hard disk at all (not that I want it, just
curious)?
--
Thanks,
James Reynolds
University of Utah
Student Computing Labs
email@hidden
801-585-9811
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