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Re: [PATCH -tip perf/probes 00/10] x86 insn decoder bugfixes
- From: Roland McGrath <roland at redhat dot com>
- To: Ingo Molnar <mingo at elte dot hu>
- Cc: Masami Hiramatsu <mhiramat at redhat dot com>, Arnaldo Carvalho de Melo <acme at redhat dot com>, Frédéric Weisbecker <fweisbec at gmail dot com>, lkml <linux-kernel at vger dot kernel dot org>, Steven Rostedt <rostedt at goodmis dot org>, Jim Keniston <jkenisto at us dot ibm dot com>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Christoph Hellwig <hch at infradead dot org>, "Frank Ch. Eigler" <fche at redhat dot com>, "H. Peter Anvin" <hpa at zytor dot com>, Jason Baron <jbaron at redhat dot com>, "K.Prasad" <prasad at linux dot vnet dot ibm dot com>, Peter Zijlstra <peterz at infradead dot org>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>
- Date: Thu, 29 Oct 2009 12:18:01 -0700 (PDT)
- Subject: Re: [PATCH -tip perf/probes 00/10] x86 insn decoder bugfixes
- References: <20091027204156.30545.96425.stgit@harusame> <20091029085348.GD26970@elte.hu>
> Thirdly, i think we should expose the build-id of the kernel and the
> path to the vmlinux (and modules) via /proc/build-id or so. That way
> tooling can find the vmlinux file and can validate that it matches the
> kernel's signature. (maybe include a file date as well - that's a faster
> check than a full build-id checksum, especially for large kernels)
You seem to be confused about what build IDs are. There is no "checksum
validation". Once the bits are stored there is no calculation ever done
again, only exact comparison with an expected build ID bitstring. The size
of an object file is immaterial.
As Frank mentioned, the kernel's and modules' allocated ELF notes (and thus
build IDs) are already exposed in /sys. Tools like "eu-unstrip -nk" use
this information today.
Thanks,
Roland