bug#33639: ISO installer image is broken on i686

[Ludovic Courtès]

Hello,

The ISO installer image as produced on commit
4a0b87f0ec5b6c2dcf82b372dd20ca7ea6acdd9c by

  guix system disk-image --file-system-type=iso9660 \
    -s i686-linux gnu/system/install.scm

contains unreadable file(s), at least /var/guix/db/db.sqlite.

The build at <https://hydra.gnu.org/build/3151513> (2018-11-12,
64461ba20a07a0cf3197de3e97cb44e0f66cebdc) seems is the only occurrence
of the problem I could find on the build farms: while running the
installation off the ISO image, it fails like this:

--8<---------------cut here---------------start------------->8---
+ guix --version
guix (GNU Guix) 0.15.0-6.f9a8fce
Copyright (C) 2018 the Guix authors
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
+ export GUIX_BUILD_OPTIONS=--no-grafts
+ GUIX_BUILD_OPTIONS=--no-grafts
+ guix build isc-dhcp
[   95.076694] attempt to access beyond end of device
[   95.080672] sr0: rw=524288, want=2118580, limit=2115840
[   95.082317] attempt to access beyond end of device
[   95.083730] sr0: rw=0, want=2118332, limit=2115840
[   95.097050] attempt to access beyond end of device
[   95.098175] sr0: rw=0, want=2118332, limit=2115840
guix build: error: build failed: cannot open Nix database 
`/var/guix/db/db.sqlite'
--8<---------------cut here---------------end--------------->8---

Indeed, if you spawn the image and run “cat /var/guix/db/db.sqlite”, it
fails with EIO and “attempt to access beyond end of device.”  I suspect
the bugs Mark reported at <https://issues.guix.info/issue/33362> and
<https://issues.guix.info/issue/33555> are related.

My guess is that the bug has always existed on ‘core-updates’ since
<https://berlin.guixsd.org/build/662745> (‘master’, 2018-11-30, i.e.,
just before ‘core-updates’ was merged) shows a successful installation.

I tried running the ISO image in qemu-system-{x86_64,i386}, with and
without KVM, and the I/O errors are always there, including with a
pre-core-updates QEMU.

I tried reverting xorriso to 1.4.8 to no avail (which is not surprising
since xorriso was upgraded on 2018-09-18 and the successful installation
above which 2018-11-30.)

At this point I can only suspect a toolchain issue, probably binutils or
libc since gcc didn’t change.

Thoughts?

This is holding the 0.16.0 release and I’m unavailable to do it next
week and with little time over the next few days.  Thus I’m considering
exceptionally releasing without the i686 GuixSD install image; thoughts?
The rest is all fine and ready to ship.

Thanks,
Ludo’.