Re: Zero size /proc/vmcore on ia64

From: Magnus Damm <magnus.damm_at_gmail.com>
Date: 2007-02-14 19:27:36
Vivek, everyone,

On 2/8/07, Vivek Goyal <vgoyal@in.ibm.com> wrote:
> I think we should not remove this check because even to parse the info
> passed in ELF headers, you need to first read the ELF headers from crashed
> kernel's memory. So if some programming error has passed wrong location of
> ELF headers (elfcoreheader= invalid location) then we might try reading the
> elf header from a non-existing physical page frame.

Are you saying that the ELF header is located in the memory space of
the first kernel?

The way I read the code the ELF header is put into the reserved memory
space for the secondary kernel. At least on ia64 that is true, and I
think the same goes for i386.

And the fact that the ELF header is put in to the secondary kernel
brings me memory setup problems on ia64.

Basically the ELF header is marked as EFI_UNUSABLE_MEMORY by the EFI
mangling code in purgatory. The secondary kernel detects this while
parsing the EFI tables and refuses to use/map the other memory present
in the same 16M granule. And in my case the initramfs happens to be
located in the same granule... boom! No good. =)

So I'm wondering about the reason why we put the ELF header in the
secondary kernel. Can't we just put it in the first kernel and be done
with it? We still point it out using the kernel command line, don't
we?

Thanks,

/ magnus
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Received on Wed Feb 14 19:27:52 2007

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