initramfs: Use KBUILD_BUILD_TIMESTAMP for generated entries

gen_init_cpio gets the current time and uses it for each symlink,
special file, and directory.  Grab the current time once and make it
possible to override it with the KBUILD_BUILD_TIMESTAMP variable for
reproducible builds.

Signed-off-by: Michal Marek <mmarek@suse.cz>

1 files changed, 2 insertions, 1 deletions

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index f11ebb33e4a6..646e2c114fff 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -205,7 +205,8 @@ gcc -W... options for more extensive build-time checking.
 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 default value
+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.
 
 KBUILD_BUILD_USER, KBUILD_BUILD_HOST