Re: IA64: copying /proc/vmcore caused kernel MCA'ed

[Jay Lan <jlan@sgi.com>]

Bernhard Walle wrote:
> * Jay Lan <jlan@sgi.com> [2008-09-08]: 
> 
>> Any input helping me speed up debugging is appreciated.
> 
> I would start with comparing the ELF program headers of /proc/vmcore
> which you get with "readelf -l /proc/vmcore" in kdump environment and
> the /proc/iomem which kexec uses to set up the ELF core headers.
> 
> If both does contain the memory regions which should not be accessed,
> then it's a bug in the ressource assignment of the kernel, and
> if /proc/iomem does not, the kexec tool has a bug.

Hi Bernhard,

I talked to Jack Steiner about this problem. He said:
  The memory at 0xe000006000100000 is part of Altix "fetchop" space
  (AKA mspec). The memory supports only uncached attributes. A normal
  "cached" access may cause MCAs.

  The kernel should not be using this memory for anything. Only the
  fetchop driver is suppose to access this area.

  Note: /proc/iomem shows the memory as "System RAM" but that does NOT
  mean that is can be accessed w/o special code. See efi.c for the code
  that prints the iomem info. Maybe efi.c needs to be changed to show
  a different name for the fetchop memory so that kdump will work.

I still need to understand why it did not cause a problem before.

Thanks,
jay

> 
> 
> Bernhard
> 
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