X/GDM fails on linux 5.0.7 AMD Radeon RX 580 after system reconfigure

[Pierre Neidhardt <mail@ambrevar.xyz>]

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Hi,

My last system reconfigure dates back to April 17th and works
flawlessly.
Yesterday I ran a new one and X / GDM don't start up properly:

- I can guess bits and pieces of the GDM interface but the screen is
  torn asunder by the most epic artifacts (green / purple flashing tiles).

- In a TTY, I see that GDM is restarting in an infinite loop.

- dmesg reports some "corruption" at the level of the video card (AMD
  Radeon RX 580).

The weird thing is that I'm still using Linux 5.0.7 like I was on April
17th and everything worked well.

I've tried both with linux-libre and a custom kernel.

Have we changed anything to the boot parameters maybe?


Side question: how do we know which Guix commit was used for a specific
system generation?  For now the only way I can think of is

--8<---------------cut here---------------start------------->8---
/var/guix/profiles/system-17-link/profile/bin/guix --version
--8<---------------cut here---------------end--------------->8---

Anything more convenient?  From Emacs Guix?


-- 
Pierre Neidhardt
https://ambrevar.xyz/

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