Arvid Brodin wrote:
> 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
To reply to my own email, the problem probably has to do with the fact that the
kernel is built with optimization. Modifying KBUILD_CFLAGS in the Makefile to
specify -O1 made things a lot better (although you still cannot rely completely
on the line number reported). Unfortunately, the kernel won't build with -O0.
--
Arvid Brodin
Enea Services Stockholm AB
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