From: John Keeping <john@metanate.com>
To: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Romain Naour <romain.naour@gmail.com>,
Giulio Benetti <giulio.benetti@benettiengineering.com>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
buildroot@buildroot.org
Subject: Re: [Buildroot] [PATCH] package/gcc/gcc-final: map debug prefix when reproducible
Date: Tue, 7 Feb 2023 20:05:17 +0000 [thread overview]
Message-ID: <Y+Ku/Thi5kKP4P8E@donbot> (raw)
In-Reply-To: <20230207135503.GF4124@scaer>
Hi Yann,
On Tue, Feb 07, 2023 at 02:55:03PM +0100, Yann E. MORIN wrote:
> On 2023-02-06 16:26 +0000, John Keeping spake thusly:
> > When building with BR2_REPRODUCIBLE the toolchain wrapper passes
> > -fdebug-prefix-map for all packages that are built. But this doesn't
> > affect the target libraries (like libgcc) built by GCC's build system.
> >
> > GCC 4.3 added a configure option to set the debug prefix map for these
> > libraries, which is used here to avoid encoding potentially
> > non-reproducible build paths into the debug data.
>
> Thanks, this is indeed very interesting. We (briefly) discussed this at
> the developers day minutes ago, and the question that was brought up
> was: why is not needed for the first-stage compiler?
>
> Indeed, the first-stage compiler builds objects files that are then used
> by the C library, we would expect the debug symbols for those to also
> need prefix mapping.
>
> Could you look into that, and either pass the option to both the initial
> and final gcc if needed, or explain in the commit log why it is not
> needed for the initial gcc, please?
I've just sent v2 which moves this to HOST_GCC_COMMON_CONF_OPTS.
You're right that some files are affected by the initial compiler - I
missed it by focusing on executables (nearly all of which link libgcc.a)
when the initial compiler only affects some of glibc's shared objects.
I've been testing this with --enable-linker-build-id in the configure
options as well to see whether it's possible to enable build IDs for
reproducible builds and this change gets a lot closer - the differences
are now a handful of files that embed an RPATH pointing to .libs during
the build.
John
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next prev parent reply other threads:[~2023-02-07 20:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-06 16:26 [Buildroot] [PATCH] package/gcc/gcc-final: map debug prefix when reproducible John Keeping
2023-02-07 13:55 ` Yann E. MORIN
2023-02-07 20:05 ` John Keeping [this message]
2023-02-08 8:05 ` Arnout Vandecappelle
2023-02-08 9:34 ` John Keeping
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