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Subject[RFCv2 PATCH 0/3] Salted build ids via linker sections
Date
Hi,

This is v2 of my proposal to allow unique build-ids in the kernel. from
last time:

""
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
https://fedoraproject.org/wiki/Changes/ParallelInstallableDebuginfo 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.
""

This v2 cleans up the naming to be consistent and also switches to a
config option vs. an environment variable. I've seen some sporadic
failures about missing the generated header so I think I'm still missing
a dependency somewhere. I'm still mostly looking for feedback whether
this would be acceptable for merging or if we should just persue a
--build-id-salt in binutils.

Thanks,
Laura


Laura Abbott (3):
kbuild: Introduce build-salt generated header
kbuild: Link with generated build-salt header
x86/vdso: Add build salt to the vDSO

Makefile | 13 +++++++++++--
arch/x86/entry/vdso/vdso-layout.lds.S | 3 +++
init/Kconfig | 8 ++++++++
scripts/.gitignore | 1 +
scripts/Makefile | 2 +-
scripts/build-salt.lds.S | 5 +++++
scripts/gensalt | 21 +++++++++++++++++++++
scripts/link-vmlinux.sh | 3 ++-
8 files changed, 52 insertions(+), 4 deletions(-)
create mode 100644 scripts/build-salt.lds.S
create mode 100755 scripts/gensalt

--
2.16.2

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