coreboot

coreboot™: fast, flexible and reproducible Open Source firmware!

Reproducible Coreboot

Reproducible builds enable anyone to reproduce bit by bit identical binary packages from a given source, so that anyone can verify that a given binary derived from the source it was said to be derived. There is more information about reproducible builds on the Debian wiki and on https://reproducible-builds.org. These pages explain in more depth why this is useful, what common issues exist and which workarounds and solutions are known.

Reproducible Coreboot is an effort to apply this to coreboot. Thus each coreboot.rom is build twice (without payloads), with a few variations added and then those two ROMs are compared using diffoscope. Please note that the toolchain is not varied at all as the rebuild happens on exactly the same system. More variations are expected to be seen in the wild.

There is a weekly run jenkins job to test the master branch of coreboot.git. The jenkins job is running reproducible_coreboot.sh in a Debian environment and this script is solely responsible for creating this page. Feel invited to join #reproducible-builds (on irc.oftc.net) to request job runs whenever sensible. Patches and other feedback are very much appreciated - if you want to help, please start by looking at the ToDo list for coreboot, you might find something easy to contribute.
Thanks to IONOS for donating the virtual machines this is running on!

167 (100.0%) out of 167 built coreboot images were reproducible in our test setup ! These tests were last run on 2026-02-11 for version 25.12-434-gb4b9e87669 using diffoscope 312.

variationfirst buildsecond build
hostname osuosl1-amd64 or osuosl2-amd64the other one
domainname is not yet varied between rebuilds of coreboot.
env CAPTURE_ENVIRONMENTnot setCAPTURE_ENVIRONMENT="I capture the environment"
env TZTZ="/usr/share/zoneinfo/Etc/GMT+12"TZ="/usr/share/zoneinfo/Etc/GMT-14"
env LANGLANG="en_GB.UTF-8"LANG="et_EE.UTF-8"
env LC_ALLnot setLC_ALL="et_EE.UTF-8"
env PATHPATH="/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:"PATH="/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/i/capture/the/path"
env USER is not yet varied between rebuilds of coreboot.
uid is not yet varied between rebuilds of coreboot.
gid is not yet varied between rebuilds of coreboot.
UTS namespace is not yet varied between rebuilds of coreboot.
kernel version, modified using /usr/bin/linux64 --uname-2.6Linux 6.12.63+deb13-amd64Linux 2.6.72+deb13-amd64
umask00220002
CPU type Intel Xeon Processor (Cascadelake)same for both builds
/bin/sh is not yet varied between rebuilds of coreboot.
year, month, datetoday (2026-02-11)same for both builds (currently, work in progress)
hour, minutehour and minute will probably vary between two builds...the future system actually runs 398 days, 6 hours and 23 minutes ahead...
Filesystemtmpfssame for both builds (currently, this could be varied using disorderfs)
everything else...is likely the same. There will be more variations in the wild.

commit b4b9e87669383fd49a3be74aae15d7ab3fa8ad38
Author: Patrick Rudolph 
Date:   Sat Jan 24 09:58:59 2026 +0100

    cpu/intel/model_206xx: Load microcode in pre_mp_init()
    
    Ensure that BSP has latest microcode loaded before MPinit starts.
    This aligns the code with other platforms ensuring that the microcode
    on the BSP is up to date.
    
    It likely has updated microcode before enabling NEM, so this is a
    nop, but it also ensures that the microcode is located in CBFS
    before the MTRRs are setup using x86_setup_mtrrs_with_detect() which
    removes caching the SPI flash MMIO area.
    
    Since intel_microcode_find() caches the microcode location
    get_microcode_info() will be faster since it doesn't need to access
    the CBFS.
    
    TEST=Lenovo X220 still boots.
    
    Change-Id: Ic4c5d1a06ce314b38b92e8a9c089ed901716ff27
    Signed-off-by: Patrick Rudolph 
    Reviewed-on: https://review.coreboot.org/c/coreboot/+/90893
    Reviewed-by: Naresh 
    Tested-by: build bot (Jenkins)

cross toolchain sourcesha256sum
acpica-unix-20250807.tar.gz eaca4c0248db872a055ab38b0deab4f5f577d1a0cada0fcbc0d80955e2a98e33
binutils-2.45.tar.xz c50c0e7f9cb188980e2cc97e4537626b1672441815587f1eab69d2a1bfbef5d2
gcc-14.2.0.tar.xz a7b39bc69cbf9e25826c5a60ab26477001f7c08d85cec04bc0e29cabed6f3cc9
gmp-6.3.0.tar.xz a3c2b80201b89e68616f4ad30bc66aee4927c3ce50e33929ca819d5c43538898
mpc-1.3.1.tar.gz ab642492f5cf882b74aa0cb730cd410a81edcdbec895183ce930e706c1c759b8
mpfr-4.2.2.tar.xz b67ba0383ef7e8a8563734e2e889ef5ec3c3b898a01d00fa0a6869ad81c6ce01
Debian 13.3 package on amd64installed version
gcc 4:14.2.0-1
g++ 4:14.2.0-1
make 4.4.1-2
cmake 3.31.6-2
flex 2.6.4-8.2+b4
bison 2:3.8.2+dfsg-1+b2
pkg-config 1.8.1-4

There is more information about jenkins.debian.net and about reproducible builds of Debian available elsewhere.
Please send technical feedback about this setup to the Debian jenkins development list, or as a bug report against the jenkins.debian.org package. Feedback about specific job results should go to their respective lists and/or the BTS.
The code of jenkins.debian.net is mostly GPL-2 licensed. The weather icons are public domain and were taken from the Tango Icon Library. Copyright 2014-2024 Holger Levsen and many others.
Last update: 2026-02-11 15:50 UTC