Re: [Fastboot] Ia64 kdump patch

[Takao Indoh <indou.takao@soft.fujitsu.com>]

On 09 Jun 2006 06:47:59 +0800, Zou Nan hai wrote:

> Thanks for testing and review.
> 
> There is still a lot of work to do for ia64 Kdump to be a very useful
>and robust feature.
>
> Major issues.
> 1. Full percpu dumping on INIT. 
>    You may notices I only send an IPI to user CPUs and dump part of
>registers for crashing CPU.Just stop other CPUs, not dumping their
>status. This is only a temp hack.
> On other platforms they did this by an NMI, on IA64 we should use INIT
>to acknowledge other CPUs. And I know on some platform there is a
>trigger on panel can trigger INIT. We could use that to dump at the time
>of deadlock. But currently INIT is used by MCA, we need to find a way to
>coordinate with MAC on INIT.
>
> 2. unwind section is missing in vmcore.
>    When you do a readelf on vmcore, you may notice there is no unwind
>sections. We should add this percpu stack unwind sections to help dump
>filter tools to analize the core dump.
>
> 3. kdump path at crash time. 
>    Currently I still have to do a irq->end on each level triggered irq,
>without that the MPT fusion driver can not restart. We should fix this,
>at least do that in a way of not touching any memory in previous kernel.
>
> 4. Other than this, we need port the dump filter to IA64.
>
>There are still some minor issues.
>e.g
>  When I get a crash when X is active, the new kernel will startup in a
>blank screen(network is still working). I have indeed do a brute force
>VGA reset on in purgatory code. But that seems to only shutdown the VGA
>but not reinit it if X is running.
>
>  Current kexec can't not run on a kexec'd kernel, that is because the
>memory region of EFI memmap is not reserverd in /proc/iomem, I will sent
>a patch to reserve that region later.
>
>There should be other issues and gaps need to find out.
>
>Thanks
>Zou Nan hai
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Hi, 

I tried to use kdump on ia64, and it seemed to work, but
I was not able to execute back trace for the panic process using
crash tool.

I think the reason is that 1st kernel does not save switch stack before
2nd kernel boots.

Do you have a plan to improve kdump to save switch stack?
Or is there another method to trace panic process?

Regards,
Takao Indoh