Documentation: add hint about call traces & module symbols to BUG-HUNTING

Here's a couple of small additions to BUG-HUNTING.

1. point out that you can list code in gdb with only one command
	(gdb) l *(<symbol> + offset)

2. give a very brief hint how to decode module symbols in call traces

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Richard Kennedy 2008-02-06 01:38:01 -08:00 committed by Linus Torvalds
parent 844fcc5396
commit dcc85cb618

View file

@ -214,6 +214,23 @@ And recompile the kernel with CONFIG_DEBUG_INFO enabled:
gdb vmlinux gdb vmlinux
(gdb) p vt_ioctl (gdb) p vt_ioctl
(gdb) l *(0x<address of vt_ioctl> + 0xda8) (gdb) l *(0x<address of vt_ioctl> + 0xda8)
or, as one command
(gdb) l *(vt_ioctl + 0xda8)
If you have a call trace, such as :-
>Call Trace:
> [<ffffffff8802c8e9>] :jbd:log_wait_commit+0xa3/0xf5
> [<ffffffff810482d9>] autoremove_wake_function+0x0/0x2e
> [<ffffffff8802770b>] :jbd:journal_stop+0x1be/0x1ee
> ...
this shows the problem in the :jbd: module. You can load that module in gdb
and list the relevant code.
gdb fs/jbd/jbd.ko
(gdb) p log_wait_commit
(gdb) l *(0x<address> + 0xa3)
or
(gdb) l *(log_wait_commit + 0xa3)
Another very useful option of the Kernel Hacking section in menuconfig is Another very useful option of the Kernel Hacking section in menuconfig is
Debug memory allocations. This will help you see whether data has been Debug memory allocations. This will help you see whether data has been