• Rasmus Villemoes's avatar
    scripts/setlocalversion: make git describe output more reliable · 548b8b51
    Rasmus Villemoes authored
    When building for an embedded target using Yocto, we're sometimes
    observing that the version string that gets built into vmlinux (and
    thus what uname -a reports) differs from the path under /lib/modules/
    where modules get installed in the rootfs, but only in the length of
    the -gabc123def suffix. Hence modprobe always fails.
    
    The problem is that Yocto has the concept of "sstate" (shared state),
    which allows different developers/buildbots/etc. to share build
    artifacts, based on a hash of all the metadata that went into building
    that artifact - and that metadata includes all dependencies (e.g. the
    compiler used etc.). That normally works quite well; usually a clean
    build (without using any sstate cache) done by one developer ends up
    being binary identical to a build done on another host. However, one
    thing that can cause two developers to end up with different builds
    [and thus make one's vmlinux package incompatible with the other's
    kernel-dev package], which is not captured by the metadata hashing, is
    this `git describe`: The output of that can be affected by
    
    (1) git version: before 2.11 git defaulted to a minimum of 7, since
    2.11 (git.git commit e6c587) the default is dynamic based on the
    number of objects in the repo
    (2) hence even if both run the same git version, the output can differ
    based on how many remotes are being tracked (or just lots of local
    development branches or plain old garbage)
    (3) and of course somebody could have a core.abbrev config setting in
    ~/.gitconfig
    
    So in order to avoid `uname -a` output relying on such random details
    of the build environment which are rather hard to ensure are
    consistent between developers and buildbots, make sure the abbreviated
    sha1 always consists of exactly 12 hex characters. That is consistent
    with the current rule for -stable patches, and is almost always enough
    to identify the head commit unambigously - in the few cases where it
    does not, the v5.4.3-00021- prefix would certainly nail it down.
    Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
    Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
    548b8b51
setlocalversion 4.73 KB