[Buildroot] Reproducible toolchain

[Romain Naour]

Hello,

Le 06/03/2020 à 15:47, lpdev at cordier.org a écrit :
> Bump for this thread
> 
> Thanks,
> 
> Louis-Paul CORDIER
> 
> ------
> 
> Hi,
> 
> I'm currently experimenting toolchain building following the section "6.1.3.
> Build an external toolchain with Buildroot" of the documentation.
> 
> My goal is to generate a reproducible sdk with the toolchain in it, and to store
> in my repo as a git lfs object. This would allow to rebuild the toolchain only
> when needed. Unfortunately, cleaning and rebuilding the toolchain with "make
> sdk" produces different hashes. It seems that only static libraries are affected.
> 
> Is there any flag I can add to my toolchain build in order to generate the same
> binaries?

At the date of the 2020.02-rc3 version, the reproducible build option is
experimental [1]. There is not guaranties that a generated sdk will be reproducible.

[1] https://git.buildroot.net/buildroot/tree/Config.in?h=2020.02-rc3#n679

> 
> This is my defconfig:
> 
> BR2_x86_64=y
> BR2_x86_core_avx2=y
> BR2_REPRODUCIBLE=y
> BR2_TOOLCHAIN_BUILDROOT_VENDOR="t est" ;
> BR2_TOOLCHAIN_BUILDROOT_GLIBC=y
> BR2_GCC_VERSION_7_X=y
> BR2_TOOLCHAIN_BUILDROOT_CXX=y
> BR2_GCC_ENABLE_OPENMP=y
> BR2_INIT_NONE=y
> BR2_SYSTEM_BIN_SH_NONE=y
> # BR2_PACKAGE_BUSYBOX is not set
> # BR2_TARGET_ROOTFS_TAR is not set
> 
> List of files that are changing at each builds:
> 
> ./x86_64-test-linux-gnu/lib64/libasan.a
> ./x86_64-test-linux-gnu/lib64/libtsan.a
> ./x86_64-test-linux-gnu/lib64/libmpxwrappers.a
> ./x86_64-test-linux-gnu/lib64/libatomic.a
> ./x86_64-test-linux-gnu/lib64/libstdc++fs.a
> ./x86_64-test-linux-gnu/lib64/libstdc++.a
> ./x86_64-test-linux-gnu/lib64/libquadmath.a
> ./x86_64-test-linux-gnu/lib64/libubsan.a
> ./x86_64-test-linux-gnu/lib64/libsupc++.a
> ./x86_64-test-linux-gnu/lib64/liblsan.a
> ./x86_64-test-linux-gnu/lib64/libmpx.a
> ./x86_64-test-linux-gnu/lib64/libitm.a
> ./x86_64-test-linux-gnu/lib64/libgomp.a
> ./x86_64-test-linux-gnu/lib64/libcilkrts.a
> ./x86_64-test-linux -gnu/sys root/usr/lib/libdl.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libmvec_nonshared.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libg.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libc.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libcrypt.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libanl.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libutil.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/librpcsvc.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libresolv.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/librt.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libgomp.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libm-2.30.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libBrokenLocale.a
> ./x86_64-test-linux-gnu/sysroot/usr/lib/libc_nonshared.a
> ./x86_64-test-linux-gnu/sysroot/lib/libatomic.a
> ./lib/gcc/x86_64-test-linux-gnu/7.4.0/libgcov.a
> ./lib/gcc/x86_64-test-linux-gnu/7.4.0/libgcc_eh.a
> ./lib/gcc/x86_64-test-linux-gnu/7.4.0/libgcc.a

You may be interested by the reproducible-builds project [2].

Note that gcc and binutils are listed as non producible packages [3], so some
work needs to be done by upstream projects.

[2] https://reproducible-builds.org
[3] https://tests.reproducible-builds.org/debian/unstable/amd64/index_FTBR.html

Best regards,
Romain

> 
> Thank you for your time,
> 
> Louis-Paul CORDIER
> 
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