Unverified Commit bfb046f6 authored by Gang Yan's avatar Gang Yan Committed by Nicolas Schier
Browse files

kbuild: doc: improve KBUILD_BUILD_TIMESTAMP documentation 



This patch adds an example of how to set KBUILD_BUILD_TIMESTAMP to a
specific date. Also, note that the provided timestamp is used for
initramfs mtime fields, which are 32-bit and thus limited to dates
between the Unix epoch and 2106-02-07 06:28:15 UTC. Dates outside this
range will cause errors.

Suggested-by: default avatarDavid Disseldorp <ddiss@suse.de>
Signed-off-by: default avatarGang Yan <yangang@kylinos.cn>
Reviewed-by: default avatarDavid Disseldorp <ddiss@suse.de>
Reviewed-by: default avatarNicolas Schier <nsc@kernel.org>
Link: https://patch.msgid.link/20251017021209.6586-1-gang.yan@linux.dev


Signed-off-by: default avatarNicolas Schier <nsc@kernel.org>
parent af61da28

Documentation/kbuild/kbuild.rst

+8 −2
Original line number Diff line number Diff line
@@ -328,8 +328,14 @@ KBUILD_BUILD_TIMESTAMP 
----------------------

Setting this to a date string overrides the timestamp used in the

UTS_VERSION definition (uname -v in the running kernel). The value has to

be a string that can be passed to date -d. The default value

is the output of the date command at one point during build.

be a string that can be passed to date -d. E.g.::



    $ KBUILD_BUILD_TIMESTAMP="Mon Oct 13 00:00:00 UTC 2025" make



The default value is the output of the date command at one point during

build. If provided, this timestamp will also be used for mtime fields

within any initramfs archive. Initramfs mtimes are 32-bit, so dates before

the 1970 Unix epoch, or after 2106-02-07 06:28:15 UTC will fail.



KBUILD_BUILD_USER, KBUILD_BUILD_HOST

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