From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mark H Weaver <mhw@netris.org>
Subject: Re: Timestamps in tarballs created by 'patch-and-repack'
Date: Tue, 14 Jul 2015 20:01:25 -0400
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Mark H Weaver <mhw@netris.org> writes:

> Mark H Weaver <mhw@netris.org> writes:
>
>> However, this raises a deeper problem: all of the outputs of
>> 'patch-and-repack' contain non-deterministic timestamps, and these
>> timestamps can cause problems with future builds.
>>
>> Would it be sufficient to simply zero out all of the timestamps before
>> repacking?
>
> I looked into this a bit more.  In addition to timestamps, the other
> impure bits getting into tar files are the names and numeric ids of the
> owner and groups.  Section 4.3.1 (Overriding File Metadata) of the GNU
> tar manual describes how to override these when creating an archive.
>
> My guess is that the following options would be sufficient to make the
> generated tar archives deterministic:
>
>   --mtime=@0 --owner=root:0 --group=root:0

This seems to work well, so I've added these flags when creating
tarballs in commits 2e9511dfbdb5ddd78c2f205c4ca7fc23738d79f8 and
c09e6a5f5e2a77beff89d68069f3037c1b6310e5 in core-updates.

      Mark