Re: [ptxdist] [PATCH 2/3] barebox: add option for building barebox reproducibly

[Michael Olbrich <m.olbrich@pengutronix.de>]

On Tue, Oct 16, 2018 at 02:27:05PM +0000, Baeuerle, Florian wrote:
> Am Dienstag, den 16.10.2018, 14:38 +0200 schrieb Michael Olbrich:
> > On Tue, Oct 16, 2018 at 10:57:20AM +0000, Baeuerle, Florian wrote:
> > > Am Dienstag, den 16.10.2018, 12:09 +0200 schrieb Michael Olbrich:
> > > > On Thu, Oct 11, 2018 at 02:19:17PM +0000, Baeuerle, Florian wrote:
> > > > > Inject fake timestamps into the build via faketime to produce the exact
> > > > > same binaries.
> > > > 
> > > > I'd like to see this patch split in two.
> > > > One to handle the KBUILD_BUILD_ stuff. That should be done like the kernel
> > > > with the symlink magic, but otherwise unconditionally (for now).
> > > > Use SOURCE_DATE_EPOCH for the timestamp. I want to change the kernel to
> > > > use
> > > > this too.
> > > 
> > > SOURCE_DATE_EPOCH uses the ptxdist release number for the timestamp, thus
> > > the
> > > timestamp changes with every ptxdist release. I'd prefer to *really* get the
> > > same binary when the source code was not changed at all. A ptxdist version
> > > bump
> > > has a high potential of not touching anything barebox related.
> > > 
> > > I also do not like mangling the barebox version into a timestamp, but I
> > > couldn't
> > > come up with any better idea.
> > 
> > You can easily overwrite that in your BSP and I'm wouldn't mind changing
> > that in general. The PTXdist release was just a convenient 'date' to use.
> > I'd like to have something that is global to the BSP. Do you have any
> > sugestions?
> 
> Also I'd prefer to use something BSP-global, but I couldn't find anything
> suitable:
> 
> PTXCONF_PROJECT_VERSION - not guaranteed to be a date
> PTXCONF_PLATFORM_VERSION - same here
> 
> Maybe ptxdist could offer using one of those as a fake timestamp, if the
> appropriate format is used.

I'd expect that these change as well.

Hmmm, maybe make it configurable
- ptxdist release: what we have now
- toolchain release: if the compiler changes, then the result will be
  different anyways.
- manual 'date' string: any use-case for this?

Michael

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