cannot boot with linux-libre>=5.7, amdgpu and cryptsetup

[Denis 'GNUtoo' Carikli]

On Mon, 13 Jul 2020 02:31:03 +0000
edgar at openmail.cc wrote:

> Hello.
Hi,

> My computer has an AMD Ryzen 2500 with a Raven Ridge GPU (Vega 8).
> Since linux-libre version 5.7.2, I have not been able to boot. I am
> still able to do it with 5.6.12.
> 
> In the past (including 5.6.12), the screen would go blank (completely 
> dark) and I would be able to type-in my password (without seeing 
> anything on the screen) to unlock the hard-drive (LVM on cryptsetup). 
> Now, the keyboard is unresponsive, and I never get to see my
> operating system (Parabola GNU/Linux).
I can help a bit with the GPU part as I'm the one who added support for
many radeon GPUs in linux-libre.

For the black screen, I fear that the problem is the same than usual:
linux-libre probably doesn't support your GPU (yet) and while it's
super easy to add support for it, nobody did it (yet).

I've already added support in linux-libre for all the AMD/ATI GPUs that
I had access too, but despite writing in depth documentation for both
Trisquel and Parabola on how to do that, I fear that only the GPU I had
access to were added.

Here's the GPU status with links to documentation:
https://libreplanet.org/wiki?title=Group:Hardware/research/gpu/radeon

I didn't add any GPUs supported by the amdgpu driver yet.

As changes like that need to be tested, and that I don't know what GPU
you have exactly I would need:
- The output of the lspci command
- The output of the dmesg command after loading the amdgpu driver

In addition I will need you to test a patched linux-libre kernel. In the
worst case I can temporarily add a new kernel for that in Paraobla to
make it easy for you to test the result.

But first you need to boot with a recent Parabola.

As I don't know OpenRC you'll either have to use systemd for that, or
use OpenRC and find equivalent to the systemd specific part.

To boot and not mess up with your current system, you could try to
install Parabola on an external storage device, like an USB key, and
make sure that:
- The radeon and amdgpu drivers are not loaded. With systemd, adding
  'modprobe.blacklist=radeon' and 'modprobe.blacklist=amdgpu' to
  the kernel command line should be sufficient for that.
- You don't have Xorg or any desktop manager, as desktop managers like
  gdm, lightdm, etc do load the GPU drivers if they are not already
  loaded.

When you managed to boot, you could try to paste the output of the
'lspci -nn' command as root.

The next thing would be to try to load the amdgpu driver and get the
kernel logs.

If you use systemd for that, you could try to make journald store logs
in a persistant way. To do that, make sure that
/etc/systemd/journald.conf has 'Storage=persistent', so for instance it
could look like that:
> [Journal]
> Storage=persistent
> [...]

Then you need to restart journald:
> systemctl restart systemd-journald.service

Then, to be sure it works, you could restart your computer and try to
get the previous kernel log:
> journalctl -k  -b -1

I'm unsure if you need to restart it once or twice though.

Then, as root, try to load the amdgpu driver and get back logs with the
following commands:
> dmesg -c
> modprobe amdgpu
> dmesg > amdgpu.log
> sync
> poweroff

Normally after the modprobe amdgpu, you should have a black screen, but
you will need to continue typing the commands blindly.

If everything goes well, it should turn off your computer and it would
have created a file named amdgpu.log in the current directory (most
probably /root/ if you logged in as root).

Denis.
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