AMD Navi 14 problem

Hi,
I can not make work last stable or test Manjaro with KDE. I have a new graphics card AMD RX 5500 XT (Navi 14, released few weeks ago, it should be supported from kernel 5.4 and Mesa 19.3 - https://www.phoronix.com/scan.php?page=article&item=amd-rx5500xt-linux&num=2) and I think it is the problem. If I was trying to install Manjaro from flash disc (I've try more tools for making bootflash), eachtime I got this screen: https://ibb.co/XSRw7Jq loading stopped (I was waiting 30 minutes and nothing happens) and I can't do anything. My BIOS is updated.
I've try Manjaro Architect and it works (because it is CLI installation). I can install Manjaro KDE (through Manjaro Architect) but after reboot Manjaro stop during booting (black screen).
I've found some tips: iommu=pt, amdgpu.dpm=0 and iommu=soft. Nothing make it works.
Do you have any ideas how to make it works?
My HW:
Ryzen 2600
AMD RX 5500 XT
MSI B450 Tomahawk
Thank you.

you should read more carefully. You need Kernel 5.5 for the 5500 to get a working GUI:

support is there so as long as you are using the latest bits of Linux 5.5 and Mesa 19.3/20.0-devel. When I received the review sample, I was still running Linux 5.4 stable but unfortunately that is not new enough

You should be able to install 5.5 in architect or from TTY on your existing installation.

I was facing similar issues with my setup (AMD Ryzen 5 3600, AMD Radeon RX 5500 XT) and I was able to boot Manjaro successfully with Kernel 5.5 installed via Manjaro Architect and the following Kernel Boot Parameters:

amd_iommu=off iommu=off amdgpu.noretry=0

The issue apparently being, that IOMMU groups could not be assigned successfully so the Kernel wasn't able to talk to the GPU anymore, hence apparent "hangups" and black-screens. So I disabled IOMMU completely and the machine booted up successfully.

Give it a try

with 5.5rc6, all those parameters should not be necessary anymore.

You say "should" but I still needed those to boot my machine. Removing just one parameter would cause the machine to freeze. Kernel 5.5 is still in development, tho, so things can change on a weekly basis until the final gets released late January to early February. Also, I'm on an X570 chipset, so maybe things are slightly different with those.

rc6 is not in the repo's yet - I just thought that it already is ... Check again when it is here.

Thank you. It works.

Do you have idea when 5.5rc6+ could be in official Manjaro KDE release? I'd like to have official Manjaro KDE and not KDE installed via Manjaro Architect. Thanks.

up until the 18.1 ISO's, the iso's in general had only LTS kernels, which means the current 19.X series should use Kernel 5.4 and the next LTS kernels is not coming out for several months at least.

With 18.1.X, for hardware enablement, non-LTS kernels were used on ISO's.

I am not sure if the general approach will now go towards non-LTS kernels, but I doubt it will.

You might need to spin your own ISO with Kernel 5.5:
https://wiki.manjaro.org/Build_Manjaro_ISOs_with_buildiso

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