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

["Baeuerle, Florian" <Florian.Baeuerle@allegion.com>]

Am Freitag, den 12.10.2018, 14:01 +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.
> > 
> > Signed-off-by: Florian Bäuerle <florian.baeuerle@allegion.com>
> > ---
> >  platforms/barebox.in | 10 ++++++++++
> >  rules/barebox.make   | 16 +++++++++++++++-
> >  2 files changed, 25 insertions(+), 1 deletion(-)
> > 
> > diff --git a/platforms/barebox.in b/platforms/barebox.in
> > index 645366e93..5bc2f08b6 100644
> > --- a/platforms/barebox.in
> > +++ b/platforms/barebox.in
> > @@ -13,6 +13,7 @@ menuconfig BAREBOX
> >  	select HOST_OPENSSL if BAREBOX_NEEDS_HOST_OPENSSL
> >  	select HOST_IMX_CST if BAREBOX_NEEDS_HOST_IMX_CST
> >  	select HOST_LZOP if BAREBOX_NEEDS_HOST_LZOP
> > +	select HOST_FAKETIME if BAREBOX_REPRODUCIBLE
> >  	prompt "barebox                       "
> >  	bool
> >  	help
> > @@ -50,6 +51,15 @@ config BAREBOX_EXTRA_ENV_PATH
> >  	  Directories and files to add to the builtin barebox environment.
> >  	  Relative paths must be relative to the platformconfigdir.
> >  
> > +config BAREBOX_REPRODUCIBLE
> > +	prompt "build reproducibly"
> > +	bool
> > +	default n
> > +	help
> > +	  With this, fake timestamps are injected to the barebox build, so the
> > +	  resulting barebox images are identical when the sources haven't been
> > +	  changed.
> > +
> >  config BAREBOX_BAREBOXENV
> >  	prompt "install 'bareboxenv'"
> >  	bool
> > diff --git a/rules/barebox.make b/rules/barebox.make
> > index a6ec3c394..ad160b3ba 100644
> > --- a/rules/barebox.make
> > +++ b/rules/barebox.make
> > @@ -45,6 +45,20 @@ BAREBOX_ENV := \
> >  	KCONFIG_NOTIMESTAMP=1 \
> >  	pkg_wrapper_blacklist="$(BAREBOX_WRAPPER_BLACKLIST)"
> >  
> > +ifdef PTXCONF_BAREBOX_REPRODUCIBLE
> > +BAREBOX_FAKE_TIMESTAMP := \
> > +	$(shell echo $(BAREBOX_VERSION) | \
> > +		sed -E "s/([0-9]{4})\.([0-9]{1,2}).*/\1-\2-01 00:00:00/")
> > +BAREBOX_FAKETIME := faketime -f "$(BAREBOX_FAKE_TIMESTAMP)"
> > +BAREBOX_ENV := $(BAREBOX_ENV) \
> > +	KBUILD_BUILD_TIMESTAMP="$(BAREBOX_FAKE_TIMESTAMP)" \
> > +	KBUILD_BUILD_VERSION="0" \
> > +	KBUILD_BUILD_USER="ptxdist" \
> > +	KBUILD_BUILD_HOST="ptxdist"

For the sake of completeness: the _USER and _HOST variables are *not yet*
incorporated into the resulting binaries by barebox (at least with my
configuration).

> 
> What is not covered by the KBUILD_BUILD_* variables? faketime is a big
> hammer that can cause other problems. I'd like to understand what happens
> here first.

It's an opt-in hammer at least. One annoyance that I observed is, that
menuconfig barebox also does build host-faketime and a bunch of other things
that are not a dependency of the host-faketime package.


- Florian

> 
> Michael
> 
> > +else
> > +BAREBOX_FAKETIME :=
> > +endif
> > +
> >  BAREBOX_MAKEVARS := \
> >  	V=$(PTXDIST_VERBOSE) \
> >  	HOSTCC=$(HOSTCC) \
> > @@ -113,7 +127,7 @@ ifdef PTXCONF_BAREBOX_EXTRA_ENV
> >  endif
> >  
> >  	@+cd $(BAREBOX_DIR) && $(BAREBOX_PATH) $(BAREBOX_ENV) \
> > -		$(MAKE) $(BAREBOX_MAKEVARS)
> > +		$(BAREBOX_FAKETIME) $(MAKE) $(BAREBOX_MAKEVARS)
> >  	@$(call touch)
> >  
> >  # -----------------------------------------------------------------------
> > -----
> > -- 
> > 2.19.0
> > 
> > _______________________________________________
> > ptxdist mailing list
> > ptxdist@pengutronix.de
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