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

[Maxim Cournoyer]

Hello,

zimoun <zimon.toutoune@gmail.com> writes:

> Hi,
>
> On Fri, 09 Oct 2020 at 17:17, Maxim Cournoyer <maxim.cournoyer@gmail.com> 
> wrote:
>> 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>.
>>
>> I just tested with linux-libre 5.8.10, and it still suffers from
>> reproducibility problems, but only for one file:
>>
>> 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
>
> Still the same issue with 5.13.15.
>
> diff -r --no-dereference 
> /gnu/store/y9r7physjpa23znb7r6rg38wpmxrkp0s-linux-libre-5.13.15{,-check}
> Binary files 
> /gnu/store/y9r7physjpa23znb7r6rg38wpmxrkp0s-linux-libre-5.13.15/bzImage and 
> /gnu/store/y9r7physjpa23znb7r6rg38wpmxrkp0s-linux-libre-5.13.15-check/bzImage 
> differ

Fixed in 01ea70a29c on core-updates-frozen, after taking hints from
https://lwn.net/Articles/841624/.

Thanks,

Closing.

Maxim