Debug kernel panic with gdb?

[Arvid Brodin]

Hi,

I'm trying to debug a kernel panic (something like this):

Unable to handle kernel NULL pointer dereference at virtual address 00000014
ptbr = 93959000 pgd = 93a0a000
Oops: Kernel access of bad area, sig: 11 [#1]
FRAME_POINTER chip: 0x01f:0x1e82 rev 2
Modules linked in: ftdi_sio usbserial
PC is at isp1760_irq+0xda/0x7f0
LR is at isp1760_irq+0x492/0x7f0
pc : [<901408be>]    lr : [<90140c76>]    Not tainted
sp : 93aa399c  r12: fffffffe  r11: 00000000
r10: 00000000  r9 : fffffffe  r8 : 00000000
r7 : 93aa3a08  r6 : 93406400  r5 : 00820004  r4 : 00000003
r3 : 00000008  r2 : 00000002  r1 : fffffffd  r0 : 93837000

Call trace:
 [<90134abc>] usb_hcd_irq+0x50/0x54
 [<900383da>] handle_IRQ_event+0x1e/0x40
 [<90039098>] handle_level_irq+0x78/0x8c
...

This is on an AVR32 platform, and I'm building the kernel myself (cross
compiling). The image is then converted to a uImage before being loaded
to the target. Is there a way to get the following to work in this context?

$ gdb arch/avr32/boot/images/vmlinux.elf 
...
Reading symbols from /home/.../linux-2.6.37/arch/avr32/boot/images/vmlinux.elf...done.
(gdb) list *isp1760_irq+0xda
0x9017ac36 is in isp1760_irq (include/linux/spinlock.h:285).
280		raw_spin_lock_init(&(_lock)->rlock);		\
281	} while (0)
282	
283	static inline void spin_lock(spinlock_t *lock)
284	{
285		raw_spin_lock(&lock->rlock);
286	}
287	
288	static inline void spin_lock_bh(spinlock_t *lock)
289	{


The problem is that the line reported is totally wrong (this being very unhelpful
and confusing indeed - it tool me awhile to realise this!). I've also tried to
use gdb from the avr32 toolchain with the same result.

Is there a way to get this to work?

Thanks,
Arvid Brodin
Enea Services Stockholm AB