Re: unable to handle kernel paging request

[Jan-Benedict Glaw <jbglaw@lug-owl.de>]

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On Sun, 2004-10-31 20:16:31 +0100, Dennis Grevenstein <dennis@pcde.inka.de>
wrote in message <20041031191631.GB11681@aton.pcde.inka.de>:
> On Sun, Oct 31, 2004 at 07:48:15PM +0100, Stanislaw Skowronek wrote:
> > > <1>CPU 0 Unable to handle kernel paging request at\
> > >  virtual address 00000000, epc == 8810da1c, ra == 8810e22c
> > 
> > Look into your System.map and tell us what is there.
>  
> At 8810da1c or 8810e22c? Nothing directly.
> Closest thing is this:

System.map is a list of function start addresses. Typically, functions
don't crash at their very first instructions, this is why you don't see
"exact" matches.

> 8810d9b0 t ip22zilog_maybe_update_regs
> 8810d9fc t ip22zilog_receive_chars
This is epc (+0x20).

> 8810dd18 t ip22zilog_status_handle
> 8810def0 t ip22zilog_transmit_chars
> 8810e0e0 t ip22zilog_interrupt
...and this is ra.

> 8810e26c t ip22zilog_tx_empty

>From my fading MIPS knowledge, ip22zilog_interrupt called
ip22zilog_receive_chars and the later one crashed. Now, use objdump and
create a disassembly dump of the object file that contains the IP22
Zilog stuff. There, find the part that's 0x20 bytes away from the start
of ip22zilog_receive_chars. Now you know the cause of this oops. From
here, try to figure out the reason for it...

MfG, JBG

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