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Enrico Jörns 2d2d17e136 kernel-yocto: make kernel commits reproducible
The git commit hashes for the kernel checkout are not reproducible under
certain conditions:

- If the git repository is initialized on an archive (rather than a
  git), the initial git commit not only has the current user name set,
  it also uses the current system time as committer and author date.
  This will affect the initial git hash and thus all subsequent ones.

- The patches applied by the kern-tools have a valid author and date.
  However, their committer again depends on the user building the BSP.

This is an issue, for example, if one compiles a kernel with
CONFIG_LOCALVERSION_AUTO enabled where the commit hash lands into the
kernel and thus the package version. This not only makes the package
version non-reproducible, but also leads to version mismatches between
kernel modules built against a fresh kernel checkout and the kernel
retrieved from the sstate cache.

The class uses 'check_git_config' from utils.bbclass, but this only sets
the git user and only if none existed before. Thus it doesn't really
help here.

Since in Git the committer information can be set only from the
environment variables GIT_COMMITTER_NAME, GIT_COMMITTER_EMAIL, and
GIT_COMMITTER_DATE, we introduce a helper function to set those and
apply the author settings in the same way.
As values simply use PATCH_GIT_USER_NAME, PATCH_GIT_USER_EMAIL (from
patch.bbclass) and SOURCE_DATE_EPOCH.
For convenience, put the new helper 'reproducible_git_committer_author'
into utils.bbclass next to 'check_git_config' so others can use it, too.

Using this helper in kernel-yocto.bbclass makes the committer and author
date/name/email for the initial commit reproducible, as well as the
committer name/email for the patches applied with kern-tools.

For debugging purpose, allow disabling the reproducibility features by
setting KERNEL_DEBUG_TIMESTAMPS to "1".

Suggested-by: Felix Klöckner <F.Kloeckner@weinmann-emt.de>
(From OE-Core rev: aab4517b4649917abd519ea85a20fd9d51bf3d99)

Signed-off-by: Enrico Jörns <ejo@pengutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
2025-01-21 13:26:07 +00:00
bitbake bitbake: data_smart: fix ??= operator for variable flags 2025-01-14 09:51:45 +00:00
contrib contrib/git-hooks: add a sendemail-validate example hook that adds FROM: lines to outgoing patch emails 2020-12-30 14:01:07 +00:00
documentation test-manual/reproducible-builds: fix reproducible links 2025-01-20 13:45:06 +00:00
meta kernel-yocto: make kernel commits reproducible 2025-01-21 13:26:07 +00:00
meta-poky poky/poky-tiny: update default to v6.12 2024-12-12 12:32:44 +00:00
meta-selftest bbconfigbuild/configfragments.py: set BBPATH in standalone datastore 2025-01-09 16:59:23 +00:00
meta-skeleton multilib-example.conf: explicitly overwrite the BASELIB 2025-01-11 18:37:14 +00:00
meta-yocto-bsp yocto-bsp: drop genericarm64 SRCREV 2025-01-11 18:34:30 +00:00
scripts devtool: ide-sdk remove the plugin from eSDK installer 2025-01-20 13:38:59 +00:00
.gitignore vscode: drop .vscode folder 2024-02-19 11:34:33 +00:00
.templateconf meta-poky/conf: move default templates to conf/templates/default/ 2022-09-01 10:07:02 +01:00
LICENSE meta/lib+scripts: Convert to SPDX license headers 2019-05-09 16:31:55 +01:00
LICENSE.GPL-2.0-only meta/lib+scripts: Convert to SPDX license headers 2019-05-09 16:31:55 +01:00
LICENSE.MIT meta/lib+scripts: Convert to SPDX license headers 2019-05-09 16:31:55 +01:00
MAINTAINERS.md MAINTAINERS.md: fix patchtest entry 2024-06-25 11:50:58 +01:00
MEMORIAM MEMORIAM: Add recognition for contributors no longer with us 2020-01-30 15:22:35 +00:00
oe-init-build-env oe-init-build-env: generate .vscode from template 2024-02-19 11:34:33 +00:00
README.hardware.md README: Move to using markdown as the format 2021-06-16 16:33:18 +01:00
README.md Add README link to README.poky 2021-07-19 18:07:21 +01:00
README.OE-Core.md README: fix mail address in git example command 2023-09-04 10:27:46 +01:00
README.poky.md README: Move to using markdown as the format 2021-06-16 16:33:18 +01:00
README.qemu.md README.OE-Core/README.qemu: Move to markdown format 2021-07-20 08:51:06 +01:00
SECURITY.md SECURITY.md: add file 2023-10-19 11:31:13 +01:00

Poky

Poky is an integration of various components to form a pre-packaged build system and development environment which is used as a development and validation tool by the Yocto Project. It features support for building customised embedded style device images and custom containers. There are reference demo images ranging from X11/GTK+ to Weston, commandline and more. The system supports cross-architecture application development using QEMU emulation and a standalone toolchain and SDK suitable for IDE integration.

Additional information on the specifics of hardware that Poky supports is available in README.hardware. Further hardware support can easily be added in the form of BSP layers which extend the systems capabilities in a modular way. Many layers are available and can be found through the layer index.

As an integration layer Poky consists of several upstream projects such as BitBake, OpenEmbedded-Core, Yocto documentation, the 'meta-yocto' layer which has configuration and hardware support components. These components are all part of the Yocto Project and OpenEmbedded ecosystems.

The Yocto Project has extensive documentation about the system including a reference manual which can be found at https://docs.yoctoproject.org/

OpenEmbedded is the build architecture used by Poky and the Yocto project. For information about OpenEmbedded, see the OpenEmbedded website.

Contribution Guidelines

Please refer to our contributor guide here: https://docs.yoctoproject.org/dev/contributor-guide/ for full details on how to submit changes.

Where to Send Patches

As Poky is an integration repository (built using a tool called combo-layer), patches against the various components should be sent to their respective upstreams:

OpenEmbedded-Core (files in meta/, meta-selftest/, meta-skeleton/, scripts/):

BitBake (files in bitbake/):

Documentation (files in documentation/):

meta-yocto (files in meta-poky/, meta-yocto-bsp/):

If in doubt, check the openembedded-core git repository for the content you intend to modify as most files are from there unless clearly one of the above categories. Before sending, be sure the patches apply cleanly to the current git repository branch in question.

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