linux-kernel - Re: [RFC Patch 1/2] kexec: show memory info in /proc/iomem

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Message-ID: <m1d471ah6r.fsf@fess.ebiederm.org>
Date:	Tue, 11 Aug 2009 19:39:56 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Amerigo Wang <amwang@...hat.com>
Cc:	linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org,
	Neil Horman <nhorman@...hat.com>,
	Andi Kleen <andi@...stfloor.org>, akpm@...ux-foundation.org,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC Patch 1/2] kexec: show memory info in /proc/iomem

Amerigo Wang <amwang@...hat.com> writes:

2> Eric W. Biederman wrote:
>> Amerigo Wang <amwang@...hat.com> writes:
>>
>>   
>>>> Nacked-by: "Eric W. Biederman" <ebiederm@...ssion.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.

x86 covers a very large range of hardware.  Some of it nearly as large as
the big ia64 machines.  So why would ia64 require significantly more memory
than x86?

Eric
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