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From: Joshua Lock <joshua.g.lock@linux.intel.com>
To: "Bystricky, Juro" <juro.bystricky@intel.com>, Martin Jansa
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Date: Thu, 27 Apr 2017 10:50:10 +0100
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Subject: Re: [PATCH 0/4] Reproducible binaries
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On Wed, 2017-04-26 at 19:50 +0000, Bystricky, Juro wrote:
> > I wasnted to say "passing the seed value" through some separate
> > variable
> > which is easy to override from somewhere else.
> > 
> > e.g.
> > export PRELINK_TIMESTAMP=`git log -1 --pretty=%ct `
> > 
> > in image-prelink.bbclass:prelink_image() is a bit difficult to
> > override.
> > 
> 
> I think it is best to keep all reproducible build related variables
> gathered together, 
> so bitbake.conf seems like a natural place (same place as the
> variable BUILD_REPRODUCIBLE_BINARIES),
> i.e something like:
> 
> PRELINK_TIMESTAMP ??=`git log -1 --pretty=%ct `
> 
> A single "general purpose" fallback timestamp variable (not specific
> to prelinking) would be my
> preference. Unfortunately, the timestamps may need to come in various
> different formats...

One option for a single general purpose timestamp variable is just to
use a static value. Guix[1] just set the value of SOURCE_DATE_EPOCH to
1[2].

Joshua

1. https://www.gnu.org/software/guix/
2. http://git.savannah.gnu.org/cgit/guix.git/tree/guix/build/gnu-build-
system.scm#n42