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 for kexec@lists.infradead.org; Wed, 14 Nov 2012 23:19:21 +0000
Date: Thu, 15 Nov 2012 08:19:18 +0900
From: Simon Horman <horms@verge.net.au>
Subject: Re: [PATCH][V2] vmcore-dmesg: Determine correct machine pointer size
Message-ID: <20121114231917.GI15960@verge.net.au>
References: <20121113163827.GB12529@redhat.com> <50A34A83.1030901@redhat.com>
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To: Dave Young <dyoung@redhat.com>
Cc: Kexec Mailing List <kexec@lists.infradead.org>, "Eric W. Biederman" <ebiederm@xmission.com>, Vivek Goyal <vgoyal@redhat.com>

On Wed, Nov 14, 2012 at 03:38:43PM +0800, Dave Young wrote:
> On 11/14/2012 12:38 AM, Vivek Goyal wrote:
> 
> > A 32bit arch can prepare ELF64 headers. For example for PAE case to
> > preresent file offsets 64bit but data size at the offset still remains
> > 32bit. If we just base our decision based on EI_CLASS, then we will try
> > to read 64bit data from file and can run into various issues.
> > 
> > We ran into following issue when we tried to run vmcore-dmesg on a 32bit
> > PAE system vmcore which had 64bit elf headers.
> > 
> > No program header covering vaddr 0xc0a6a688c0b89100found kexec bug?
> > 
> > Basically we try to read value of log_buf variable from address
> > log_buf_vaddr. We read in 64bit value and then pass that value again
> > to vaddr_to_offset() in an attempt to get to actual log_buf start
> > and get error message.
> > 
> > So determine the machine pointer size based on ELF class and arch and read
> > the bytes from file accordingly.
> > 
> > v2: Fixed the code as per suggestion from Eric.
> > 
> > Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> 
> 
> Ack

Thanks, applied.

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