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Subject[PATCHv3 0/2] Salted build ids via linker sections

This is v3 of the series to allow unique build-ids in the kernel. As
a reminder of the context:

In Fedora, the debug information is packaged separately (foo-debuginfo) and
can be installed separately. There's been a long standing issue where only one
version of a debuginfo info package can be installed at a time. Mark Wielaard
made an effort for Fedora 27 to allow parallel installation of debuginfo (see for
more details)

Part of the requirement to allow this to work is that build ids are
unique between builds. The existing upstream rpm implementation ensures
this by re-calculating the build-id using the version and release as a
seed. This doesn't work 100% for the kernel because of the vDSO which is
its own binary and doesn't get updated. After poking holes in a few of my
ideas, there was a discussion with some people from the binutils team about
adding --build-id-salt to let ld do the calculation debugedit is doing. There
was a counter proposal made about adding some extra information via a .comment
which will affect the build id calculation but just get stripped out.

I mentioned in the previous version that there were problems with
sporadic build failures. v3 switches to generating the linker script
directly instead of a header + a linker script to avoid this problem. I
also dropped the Kconfig completely (I can add it back as a guard if
this seems not small enough to want all the time). I've also dropped the
RFC tag since it's well formed enough at this point.

Laura Abbott (2):
kbuild: Introduce build-salt linker script
x86/vdso: Add build salt to the vDSO

Makefile | 4 +++-
arch/x86/entry/vdso/Makefile | 4 +++-
scripts/.gitignore | 1 +
scripts/Makefile | 9 ++++++++-
scripts/gensalt | 22 ++++++++++++++++++++++
scripts/ | 3 ++-
6 files changed, 39 insertions(+), 4 deletions(-)
create mode 100755 scripts/gensalt


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