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Date: Wed, 12 Aug 2009 10:15:55 +0800
From: Amerigo Wang <amwang@redhat.com>
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To: "Eric W. Biederman" <ebiederm@xmission.com>
CC: linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org,
       Neil Horman <nhorman@redhat.com>, Andi Kleen <andi@firstfloor.org>,
       akpm@linux-foundation.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [RFC Patch 1/2] kexec: show memory info in /proc/iomem
References: <20090811104144.5154.77871.sendpatchset@localhost.localdomain>	<m163cub067.fsf@fess.ebiederm.org> <4A82182C.1080501@redhat.com> <m1eirhlryf.fsf@fess.ebiederm.org>
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Eric W. Biederman wrote:
> Amerigo Wang <amwang@redhat.com> writes:
>
>   
>>> Nacked-by: "Eric W. Biederman" <ebiederm@xmission.com>
>>>
>>> We can inspect the image we are going to load to get this information.
>>> In fact /sbin/kexec already inspects the image we are going to load
>>> to get this information.  Putting this in the kernel adds kernel
>>> complexity for no gain.
>>>   
>>>       
>> /sbin/kexec is supported to know this, of course. But this is not for
>> /sbin/kexec, this is for user (or other programs) to observe the memory
>> information, so that he can know the memory he reserved is too much or not.
>>     
>
>   
>> Without this, it is a little hard to use patch 2/2.
>>     
>
> So add on option to /sbin/kexec.
>   

This can be another choice.
> Furthermore none of this does a good job of predicting how much
> memory /sbin/fsck will require to check the filesystem before we
> write a crash dump.
>   

No one actually knows this without testing... But if 128M on x86 is 
still not enough, that is probably a bug of fsck, not our fault.