Re: [PATCH v3 01/21] vmcore: reference e_phoff member explicitlyto get position of program header table
From: HATAYAMA Daisuke
Date: Thu Mar 21 2013 - 20:26:44 EST
From: Vivek Goyal <vgoyal@xxxxxxxxxx>
Subject: Re: [PATCH v3 01/21] vmcore: reference e_phoff member explicitly to get position of program header table
Date: Thu, 21 Mar 2013 10:12:02 -0400
> On Thu, Mar 21, 2013 at 11:50:41AM +0900, HATAYAMA Daisuke wrote:
>> From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
>> Subject: Re: [PATCH v3 01/21] vmcore: reference e_phoff member explicitly to get position of program header table
>> Date: Tue, 19 Mar 2013 14:44:16 -0700
>> > HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx> writes:
>> >> Currently, the code assumes that position of program header table is
>> >> next to ELF header. But future change can break the assumption on
>> >> kexec-tools and the 1st kernel. To avoid worst case, reference e_phoff
>> >> member explicitly to get position of program header table in
>> >> file-offset.
>> > In principle this looks good. However when I read this it looks like
>> > you are going a little too far.
>> > You are changing not only the reading of the supplied headers, but
>> > you are changing the generation of the new new headers that describe
>> > the data provided by /proc/vmcore.
>> > I get lost in following this after you mangle merge_note_headers.
>> > In principle removing silly assumptions seems reasonable, but I think
>> > it is completely orthogonal to the task of maping vmcore mmapable.
>> > I think it is fine to claim that the assumptions made here in vmcore are
>> > part of the kexec on panic ABI at this point, which would generally make
>> > this change unnecessary.
>> This was suggested by Vivek. He prefers generic one.
>> Vivek, do you agree to this? Or is it better to re-post this and other
>> clean-up patches as another one separately to this patch set?
> Given the fact that current code has been working, I am fine to just
> re-post and take care of mmap() related issues. And we can take care
> of cleaning up of some assumptions about PT_NOTE headers later. Trying
> to club large cleanup with mmap() patches is making it hard to review.
I see. I'll post the clean-up series separately.
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