Re: Reproducible build: linux-libre kernel

[Leo Famulari <leo@famulari.name>]

On Thu, Mar 31, 2016 at 10:26:09AM +0200, Ludovic Courtès wrote:
> Leo Famulari <leo@famulari.name> skribis:
> 
> > On Wed, Mar 30, 2016 at 11:25:54PM +0200, Ludovic Courtès wrote:
> >> This is time-consuming but also very valuable work, so big thanks!
> >
> > Indeed! I'm really glad for this patch!
> >
> > Building with --rounds=2 right now :)
> 
> Almost there, but not quite!  :-)
> 
> I’ve just built it on x86_64, and:
> 
> --8<---------------cut here---------------start------------->8---
> $ git describe 
> v0.10.0-36-g4827b36
> $ ./pre-inst-env guix challenge linux-libre
> updating list of substitutes from 'https://mirror.hydra.gnu.org'... 100.0%
> updating list of substitutes from 'https://hydra.gnu.org'... 100.0%
> /gnu/store/n20i0s96p29vkl07vlvxli5xql3m3hgi-linux-libre-4.5 contents differ:
>   local hash: 0sh393xb88sybf2dnk73yya02s3bflb29qswj0fn9lzbgiwk000a
>   https://mirror.hydra.gnu.org/nar/n20i0s96p29vkl07vlvxli5xql3m3hgi-linux-libre-4.5: 0l2la1l9q6qiyf4i6pmbvvmh94l70yvzx4kdvqjyl7d9irykivma
>   https://hydra.gnu.org/nar/n20i0s96p29vkl07vlvxli5xql3m3hgi-linux-libre-4.5: 0l2la1l9q6qiyf4i6pmbvvmh94l70yvzx4kdvqjyl7d9irykivma
> --8<---------------cut here---------------end--------------->8---

Would hydra have already built with the lastest patch?

Anyways, I seem to get contradictory results on different machines. For 
both machines, the desired output was
'/n20i0s96p29vkl07vlvxli5xql3m3hgi-linux-libre-4.5'.

When --rounds=x or --check fail, my workflow is to build twice, copy the
results of each build out of the store after each build, and compare
with diffoscope.

On my x86_64 workstation, the only difference seems to be that for one
of the two iterations of building linux-libre, the file
'lib/modules/4.5.0-gnu/build' is missing.

For the build that does have that file, it's a symlink that points to
'/tmp/guix-build-linux-libre-4.5.drv-0/linux-4.5'.

So, something is wrong there... and I did this "pair-wise comparison" 3
times, always with this result.

On this workstation machine, $TMPDIR is btrfs.

On my x86_64 low-power home server thing, building with --rounds=2
returned successfully, so I didn't do the rsync-and-diffoscope dance. On
this machine $TMPDIR is ext4.

I'm going to retry on the workstation with an ext4 $TMPDIR.