Radeon 9070 XT not being utilized for 2D rendering [SOLVED]

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motig · Post by **motig** » Thu Sep 18, 2025 1:42 pm

Greetings,
I have upgraded the graphics card in my desktop PC from a Radeon 6800 to a 9070 XT. I have a problem - 2D rendering in X11 seems to be done in software since even when I move the mouse cursor quickly, I can see CPU utilization by X get to 100%. However, when I run shadertoy for example which purely utilizes the GPU, it runs well and I can see the GPU utilization in amdgpu_top. There are no errors in Xorg log nor in the kernel log. It used to work fine with the 6800. I have upgraded the kernel to 6.16.7, mesa to 25.1.7, linux-firmware to 20250808 and xf86-video-amdgpu to 25.0.0

I have tried switching to modesetting driver and it works in the same way as amdgpu. There are no firmware loading errors in the kernel log and no errors in Xorg log. amdgpu/modesetting is loaded and used and glamor is also used. I am running this with the WindowMaker window manager which is old and has no compositing.

glxinfo: OpenGL renderer string: AMD Radeon RX 9070 XT (radeonsi, gfx1201, LLVM 20.1.7, DRM 3.64, 6.16.7-gr)

My current kernel config: https://paste.k3a.me/view/b20ceec7

Thank you for any pointers!

Post by **NeddySeagoon** » Thu Sep 18, 2025 3:41 pm

motig,

Unless you use BiOS booting, you should set FB_EFI in your kernel.
That will get you kernel messages before amdgpu loads.

Please share dmesg and your Xorg.0.log file.
if you use a display manager (graphical login) you will have two log files.
One for root, and another for the user youelog in as.
Please share both.

I'm not looking for errors. Rather warnings and things that should be there that are missing, so don't be temped to filter and logs.

motig · Post by **motig** » Thu Sep 18, 2025 4:51 pm

I have enabled FB_EFI in the configuration, the next kernel will be built with it.

Here's the Xorg.0 log: https://paste.k3a.me/view/6edbd12f
Lightdm Xorg log: https://paste.k3a.me/view/d82c6d7a
Kernel log: https://paste.k3a.me/view/2d1a058c

Never mind the errors from /dev/sdb - that is some integrated flash in the monitor connected via USB.

Post by **NeddySeagoon** » Thu Sep 18, 2025 6:40 pm

motig,

There is nothing there that says anything about acceleration being disabled.

Other than keyboard errors about your system being too slow, there is nothing unusual in the logs.
The too slow warnings are worthy of investigation as fixing them maytfix other things too.

motig · Post by **motig** » Fri Sep 19, 2025 11:31 am

In the end it looks like everything was caused by the mouse cursor, including moving windows being slow and the overall sluggishness.

Surprisingly, disabling HW cursor helped. There must be something wrong with the implementation.

In the device section of xorg.conf:

Code: Select all

Option "SWCursor" "True"

q3cpma · Post by **q3cpma** » Tue Feb 03, 2026 5:14 pm

I had the exact same problem with X pummeling a CPU core and lagging when dragging windows or simply moving the pointer but only when the GPU was in a low power state (e.g. running a small glxgears temporarily made it disappear, probably by clocking the GPU higher). Applying the aforementioned fix (also to be found in the wiki but without mention to performance) fixed the problem for me too.

NB: I have a 120 Hz monitor, might have something to do with it.