[okl4-developer] unhandled page fault - please help

[Nelson Tam]

Hi Gabi,

On 06/03/2008, at 12:23 PM, Gabi Voiculescu wrote:

> Hello again and sorry for being so pushy.
>
> I have made a stub driver for LCD under PXA in two ways: with my own  
> h file and with a dx file. My current goal is to trigger the LCD to  
> appear in Skyeye.

I'd be very careful here - we don't know how much of an LCD peripheral  
Skyeye supports, if at all, and the answer is not apparent from their  
SourceForge wiki.  If anything, I'd be inclined to say that skyeye  
doesn't support LCD on the pxa platforms:

http://skyeye.wiki.sourceforge.net/Linux

Notice how the lcd: config line is commented out.

> I have edited device_core.c for platform/pxa/iguana/devicecore/src/  
> in the scan_devices function to include the following:
>
> <snip>
>
> Unhandled page fault:
>   addr=0x4/??? priv=R
>   ip=0x8040317c, sp=80048ea0
>   pd=0x800271d8 thread=0x1e8001
>
> I can't figure out what I did wrong. Where could this page fault be  
> generated from?

Hit ESC to enter KDB, 't' to show TCBs, and enter 1e8001 as the tid.   
It will show you which thread faulted, and sometimes the name is  
descriptive enough to help you pinpoint the problem.

Then you want to find out where the faulting IP (0x8040317c) is.

  # readelf -a build/images/image.elf

will tell you which ELF binary the faulting IP comes from.  Let's just  
say it's "ig_server".

  # find build -name "ig_server"
  build/iguana_server/include/ig_server
  build/iguana_server/ig_server
  build/iguana_server/bin/ig_server <- this is the one you want

  # arm-linux-objdump -dx ./build/iguana_server/bin/ig_server

will help you pinpoint the exact instruction that causes the fault.

--
(nt)

Nelson Tam
nelson at ok-labs.com