Re: What dose 'general protection fault: 0000' mean?

From: Wang Hui (
Date: Tue Jun 11 2002 - 00:36:25 EST

Thanks to Ganda.

In fact, I am implementing RFC3095 to linux kernel. I want to make it
a kernel module.

The basic function of this module could be described as the following 2

1. The module will modify the outgoing packet(ipv6 or IPv6 ) and compress
   the IP header.(we will do flow recognition and update some context
   for further compress stuff here.)

2. The other part of this module will de-compress this compressed
   IP header. And then passes the de-compressed packet up to IP(v4 or v6)
   module to do the normal recieving processes.

To realize the function 1, I use this tricks: I modified all the kernel's
active network device's dev->hard_start_xmit function pointer to be my own
function named as 'my_output_handler', and backuped the original
'dev->hard_start_xmit' funtion pointer witch will be called inside
'my_output_handler' as to send out the modified data.

As to realize function 2, I would like to omitted here. For it has
nothing to do with this current panic.

All the above funtions are implemented and I tested the codes via my
loopback network device(lo) using the address of '::1' or ''.
The codes run OK in the lo device. But when I put my codes to the real
ethernet device which is a realtek 8139 network card, I got kernel panic.
I dont know what to do with it? I guess this panic is due to something
difference between loopback network device and the real network device
drivers. But I dont know exactly what is wrong, or say, that what should I
do to avoid this panic? Any rules to write safe code here?

Many thanks again.

Best regards,

On Tue, 11 Jun 2002, ganda utama wrote:

> it seems that you remove the process that handles this
> interupt (perhaps by using kfree). or remove the module,
> while the kernel still think that the handler is still there...
> ganz
> wrote:
> >Hi, all,
> >
> >I am coding a linux kernel module, but when I run my testing code I got
> >a kernel panic. And the panic screen said:
> >
> >general protection fault:0000
> >CPU: 0
> >EIP: 0010:[<d289a213>] Tainted: P
> >EFLAGS: 00010297
> >............
> >............
> >Code: 8b 02 8b 55 08 89 02 8b 55 0c 8b 42 04 8b 55 08 89 42 04 8b
> ><0> Kernel panic: Aiee, killing interrupt handler!
> >In interrupt handler - not syncing
> >
> >==================================================
> >
> >I am a newbie to linux kernel hacking. I dont know how to find out
> >where is the fault code. :( Could anyone give me some hints???
> >
> >Thanks a lot in advance!!
> >
> >Regards,
> >Wang Hui.
> >
> >-
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