DSDT Patching on Opensuse Slowroll

English Install/Boot/Login
1

Hey!

I have an older PC. Biostar H81MHV3 motherboard, i7 4790 (Haswell), 16Gb DDR3 and an RX 6600 XT.

I’ve ran into a problem with the game Wreckfest that it runs on very low FPS. The solution seems to be to turn on Resizable BAR, but the problem is that my motherboard doesn’t support it, so I’ve searched more and found that in linux you can use a DSDT patch.

I’ve tried asking AI for help, but it doesn’t seem really that knows what it is doing, so I didn’t modify anything before I f… up anything.

Is this can be used on my system? If so can someone please guide me through how to apply this patch?

Thank You!

2

Hi
I think you may be on a downward spiral to try this out with that old hardware?

Did you check the output from journalctl -b | grep drm to see if it shows something mentioning “‘Resizable BAR’ or similar”?

Did you check the output from journalctl -b | grep "root bus resource"

ReBarState needs patching, then just a cmake then make should produce a binary for you to run as root user.

diff -Naur a/ReBarState/ReBarState.cpp b/ReBarState/ReBarState.cpp
--- a/ReBarState/ReBarState.cpp	2023-02-25 23:37:56.000000000 -0600
+++ b/ReBarState/ReBarState.cpp	2026-08-17 22:04:45.781360822 -0500
@@ -9,6 +9,7 @@
 #ifdef _MSC_VER
 #include <Windows.h>
 #else
+#include <cstdint>
 #include <unistd.h>
 #include <linux/fs.h>
 #include <sys/ioctl.h>
@@ -203,4 +204,4 @@
 exit:
 	#endif
 	return ret;
-}
\ No newline at end of file
+}
3

I see that Motherboard is only PCIe 2.0 as well… Might be time to look around for some replacement hardware?

4

Hey!

To be honest I don’t know what all this means:

https://paste.opensuse.org/pastes/f2236ad8c0ee

5

Yeah slowly maybe, but with todays hardware prices, even used stuff is getting expensive :frowning:

6

So this doesn’t end at all f’s according to the documents…

root bus resource [mem 0xe0000000-0xfeafffff window]

I have Intel boards here if I change the CPU it will give PCIe 3.0 support, those have the same CPU the image shows on the website i5-3470 from memory (they only support PCIe 2.0)…

Honestly, your better off to look for something newer to support the GPU.

I’d investigate recovery of the BIOS and test that before looking at anything else.

7

Looking at your CPU, it has onboard graphics, so look at using the Intel 4600 GPU as the primary device, then use switcherooctl to use the AMD GPU for your games, as in offload, you should get better performace.

8

If you have a above 4G Decoding option in your BIOS or something like that, enabling that is generally sufficient to enable rebar on Linux. No dstd or bios hacking needed. Linux will sidestep BIOS/UEFI if it can and enable it itself.

To verify state, just grep your dmesg for BAR and look for a line that lists your GPU memory and if the BAR value is the same as RAM, rebar is enabled:

[ 13.670233] [ T605] amdgpu 0000:03:00.0: [drm] Detected VRAM RAM=8176M, BAR=8192M

If BAR=256M rebar is not enabled. That’s how I did it on my X99 platform (haswell-e / broadwell)