Re: [PATCH v3 01/21] vmcore: reference e_phoff member explicitly to get position of program header table

HATAYAMA Daisuke
2013-03-21T02:50:54Z

From: "Eric W. Biederman" <ebiederm@xmission.com>
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@jp.fujitsu.com> 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?

Thanks.
HATAYAMA, Daisuke