On Thu, Sep 17, 2020 at 3:56 PM Rasmus Villemoes <li...@rasmusvillemoes.dk> wrote: > > 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: Rasmus Villemoes <li...@rasmusvillemoes.dk> > --- > v2: use 12 instead of 15, and ensure that the result does have exactly > 12 hex chars. > > scripts/setlocalversion | 21 ++++++++++++++++----- > 1 file changed, 16 insertions(+), 5 deletions(-)
Applied to linux-kbuild. Thanks. -- Best Regards Masahiro Yamada
