/proc/vmcore mmap() failure issue

H. Peter Anvin hpa at zytor.com
Wed Nov 13 18:08:22 EST 2013

On 11/13/2013 03:00 PM, Vivek Goyal wrote:
> I think it should be easy to truncate ELF headers in kexec-tools too when
> we are preparing elf headers. I am not sure if it is right thing to do or
> not. If some entry is showing up in /proc/iomem as RAM, then kexec-tools
> need to believe that it is a possibility that kernel is using that pfn and
> that pfn needs to be dumped out in vmcore. IMHO, kernel should fix this
> issue.

The kernel will never use a fractional page, so that is not an issue.

> Secondly, I am writing in-kernel kexec support too and I prepare ELF
> headers there too. And I am facing the same problem there too. So if
> we truncate partial pages in e820 both kexec-tools and in kernel kexec
> implementation don't have to do anything.

I'm mostly worried about truncation upon truncation causing problems.
As long as the trimming is done once and with proper consideration for
abutting regions, I guess I'm okay with it, although it feels wrong to me.


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