Re: [PATCH] sbuild: Fix low hit ratio for ccache on linux kernel rebuild

[Jan Kiszka <jan.kiszka@siemens.com>]

On 15.07.22 15:47, Baurzhan Ismagulov wrote:
> Hello Felix,
> 
> On Fri, Jul 15, 2022 at 01:27:27PM +0000, Moessbauer, Felix wrote:
>> Please also have a look at the reproducibility section of dpkg-buildflags.
>> The only reason the kernel is affected from this is, that the kbuild only uses KCFLAGS, not CFLAGS.
>> At least the flags about reproducibility should be added to all kernel builds done via ISAR.
> 
> IIUC, the non-reproducibility comes from the absolute paths in the debug info
> -- we'll have a look, maybe those could be replaced with relative ones.
> 
> I haven't deeply looked at reproducible packages, could you please elaborate on
> the KCFLAGS vs. CFLAGS distinction mattering here?
> 

https://www.kernel.org/doc/html/latest/kbuild/reproducible-builds.html
may explain more. I just learned from Ben Hutchings that following this
in our kernel recipe may not only resolve the absolute path topic but
would also allow to drop slow dh_strip_nondeterminism from our builds.

Jan

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