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Re: [RFC] Change PCH "checksum"
On Tue, 26 Feb 2019, Michael Matz wrote:
> Hi,
>
> On Tue, 26 Feb 2019, Richard Biener wrote:
>
> > get_build_id_1 (struct dl_phdr_info *info, size_t, void *data)
> > {
>
> Isn't this all a bit silly? We could simply encode the svn revision, or
> maybe even just some random bytes generated once in stage1 at build time
> as "checksum" and be done with. In the latter case PCHs will then not
> work across different compiler builds, but so what?
Yes, a random number would work for PCH purposes but of course not
for reproducible builds. Somehow even compile-options are relevant
though so I'm not really sure how volatile the PCH format is.
That is, whether for example checksumming sources would work.
But yeah, I considered a --with-pch-checksum=XYZ to make this
configurable (where we could for example checksum the rpm
changes - iff PCHs of two different builds - say, one with checking
enabled and one with checking disabled - really interoperate).
Still, using the build-id looks so "obvious" ...
Richard.