bug#29662: 'guix gc' as user makes system unbootable

[ludo@gnu.org (Ludovic Courtès)]

Hi Martin,

Martin Castillo <castilma@uni-bremen.de> skribis:

> I had a similar situation today. guix gc removed the grub background png
> from the store. the one, that was used by /boot/grub/grub.cfg. the boot
> menu then had a black and blue background. rebuilding the configuration
> refetched the background image, but guix gc removed it again.

Normally the current ‘grub.cfg’ is a GC root, which prevents the
background image and other items from being deleted:

--8<---------------cut here---------------start------------->8---
$ ls -l /var/guix/gcroots/bootcfg 
lrwxrwxrwx 1 root root 52 Dec  7 23:21 /var/guix/gcroots/bootcfg -> /gnu/store/2bnr3z8q0rpvdc9zrshhyq4znx7jpzq6-grub.cfg
$ guix gc --references /var/guix/gcroots/bootcfg 
/gnu/store/i3l4cv1mz30l4jafbghmbgmafc0xb38h-grub-image.png
/gnu/store/j5x3dfappv9fdp7h46kgm8wxjbcqv5r6-system
/gnu/store/qkhhqqkr0lkczwqwbp95gx4s8v0pjj41-raw-initrd
/gnu/store/xqfpwxbghvi3h85pfji6kdzw7db2sgxz-grub-2.02
/gnu/store/zi4awdcvrlj0fp74yb0y4ngah4qmcri0-linux-libre-4.14.4
$ sudo diff /var/guix/gcroots/bootcfg /boot/grub/grub.cfg 
$ echo $?
0
--8<---------------cut here---------------end--------------->8---

Could you check if this is the case on your machine?

Thanks,
Ludo’.