linux-kernel - Re: [PATCH] INITRAMFS: Add option to preserve mtime from INITRAMFS cpio images

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Date:	Thu, 04 Sep 2008 00:13:04 -0700
From:	nyet <nyet@....com>
To:	Frans Meulenbroeks <fransmeulenbroeks@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>, Nye Liu <nyet@...t.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] INITRAMFS: Add option to preserve mtime from INITRAMFS
 cpio images

Frans Meulenbroeks wrote:
> 2008/9/4 Nye Liu <nyet@....com>:
>   
>> On Wed, Sep 03, 2008 at 03:22:31PM -0700, Andrew Morton wrote:
>>     
>>>> From: Nye Liu <nyet@...t.org>
>>>>
>>>> When unpacking the cpio into the initramfs, mtimes are not preserved by
>>>> default. This patch adds an INITRAMFS_PRESERVE_MTIME option that allows mtimes
>>>> stored in the cpio image to be used when constructing the initramfs. For
>>>> embedded applications that run exclusively out of the initramfs, this is
>>>> invaluable.
>>>>         
>>> Why is it "invlauable".  Please explain this value in full detail -
>>> it's the whole reason for merging the patch!
>>>       
>> When building embedded application initramfs images, its nice to know
>> when the files were actually created during the build process - that
>> makes it easier to see what files were modified when so we can compare
>> the files that are being used on the image with the files used during
>> the build process. This might help (for example) to determine if the
>> target system has all the updated files you expect to see w/o having to
>> check MD5s etc.
>>     
>
> Hm.
>
> "Invaluable" != "nice to know".
>
> What worries me is that this code is executed at boot time (when
> populating the ramfs).
> For embedded systems a fast boot time is often important.
> I admit that the net effect of this on boot time is marginal (but some
> might consider having mtime a marginal benefit), and 100 cents also
> make a dollar, so my suggestion would be to either reject this patch
> or make it optional (e.g. depending on some debug config flag).
>
> Best regards, Frans.
>   
An earlier rev patch made it optional. I can resubmit of course.
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