bug#24028: Linux-libre kernel does not build deterministically

[Maxim Cournoyer]

Hello,

ludo@gnu.org (Ludovic Courtès) writes:

> As of version 4.6.4, Linux-libre does not build reproducibly:
>
> $ guix challenge linux-libre
> /gnu/store/wkdnd1dcgljr0jxmd3li8j0qsr2zwrci-linux-libre-4.6.4 contents differ:
>   local hash: 1py214sd42qcq8l429m4zf4aibp8rl68kpkrzqi1nn65vnbxsx11
>   
> https://hydra.gnu.org/nar/wkdnd1dcgljr0jxmd3li8j0qsr2zwrci-linux-libre-4.6.4: 
> 19hsdsjy5i9nfc1g28s074znzimzhylgkdpwz435j301sn9pxxp9
> $ wget -q -O - 
> https://hydra.gnu.org/nar/wkdnd1dcgljr0jxmd3li8j0qsr2zwrci-linux-libre-4.6.4 
> | bunzip2 | guix archive -x t
> $ diff -ur --no-dereference 
> /gnu/store/wkdnd1dcgljr0jxmd3li8j0qsr2zwrci-linux-libre-4.6.4 /tmp/t
> Binary files 
> /gnu/store/wkdnd1dcgljr0jxmd3li8j0qsr2zwrci-linux-libre-4.6.4/bzImage and 
> /tmp/t/bzImage differ
>
> Apparently people are working on it:
> <https://wiki.debian.org/SameKernel>.
>
> Ludo’.

I just tested with linux-libre 5.8.10, and it still suffers from
reproducibility problems, but only for one file:

--8<---------------cut here---------------start------------->8---
diff -r /gnu/store/jc1dydmax5sdfljpi5mq5dhq9wdr92xy-linux-libre-5.8.10{,-check}
Binary files 
/gnu/store/jc1dydmax5sdfljpi5mq5dhq9wdr92xy-linux-libre-5.8.10/bzImage and 
/gnu/store/jc1dydmax5sdfljpi5mq5dhq9wdr92xy-linux-libre-5.8.10-check/bzImage 
differ
--8<---------------cut here---------------end--------------->8---

So, we're not far!

Maxim