a979522a1a
To avoid unnecessary recompilations, mkcompile_h does not regenerate compile.h if just the timestamp changed. Though, if KBUILD_BUILD_TIMESTAMP is set, an explicit timestamp for the build was requested, in which case we should not ignore it. If a user follows the documentation for reproducible builds [1] and defines KBUILD_BUILD_TIMESTAMP as the git commit timestamp, a clean build will have the correct timestamp. A subsequent cherry-pick (or amend) changes the commit timestamp and if an incremental build is done with a different KBUILD_BUILD_TIMESTAMP now, that new value is not taken into consideration. But it should for reproducibility. Hence, whenever KBUILD_BUILD_TIMESTAMP is explicitly set, do not ignore UTS_VERSION when making a decision about whether the regenerated version of compile.h should be moved into place. [1] https://www.kernel.org/doc/html/latest/kbuild/reproducible-builds.html Signed-off-by: Matthias Maennich <maennich@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.