Resizeable BAR support issues

For what it's worth, I used the method in this documentation and I can say it worked.

I took my time, though, to fully read and understand the commands, and to save my data beforehand, just in case.

If I recall, I used a 8GBytes USB-key with a Windows 10 install on it (https://www.microsoft.com/fr-fr/d/w...f77x4d43rkt?rtc=1&activetab=pivot:overviewtab).

 

With Windows "11" 21966 and UWP V30 driver, AMD's UWP control panel now reports SAM status. It shows as Not Available for me though, but I'm not certain if it's actually not available (hardware/driver), or if the setting just isn't implemented to read the status yet. If anyone has a GPU and configuration that has advertised support for SAM, I wonder if the SAM option reports anything?

 

@Espionage724 windows 11 is alpha.

 

And your gpu does not support sam.

 

I'm well aware of this. The SAM option also appears on the branch 30 drivers even when installed on 19041 (stable W10), so this doesn't seem specific to 21996.

I'd like to see a report from anyone with a GPU that's "officially" supported by AMD to advertise SAM support. If the option shows something different than Not Available, then it'll appear the option does something.

For anyone interested in testing this, you need the latest UWP driver (30.0.13000.17006 currently), and check under Performance -> Tuning. The latest UWP driver works fine on 19041 W10.

 

With the latest official AMD driver (21.6.1), along with the V30 branch UWP drivers, SAM status is reported. This is the case with both stable W10 (19043) and W11 builds currently (leaked 21996 and the official 22000 insider preview released today).

There's inconsistencies as to how Resizable BAR and/or SAM are reported, but it's possible it's a misunderstanding on my part. What are the clear and detailed differences (if any) between Resizeable BAR and AMD Smart Access Memory/SAM?

In my case (RX 580), Radeon control panel says its still using 256MB of memory and SAM is not available, and shows the Smart Tool (cloud) as grayed-out (I have a 2700X and RX 580, two AMD devices). GPU-Z and Windows Device Manager both report the increased memory range after enabling Resizable BAR.

I'm not convinced this is just a simple "unsupported GPU" ordeal, or that there's more to it than that. I'm leaning towards Radeon control panel not reporting the information correctly since:

• GPU-Z and Device Manager show changes in the memory range when toggling the Resizable BAR option
• Older unsupported AMD device drivers break VRAM reporting when toggling the Resizble BAR option, proving that the option does something in-relation to the driver
• Linux reports clear BAR memory sizing adjustments when toggling the Resizable BAR option
• HWInfo reports Resizable BAR being enabled and supported

Images:

• GPU-Z -> PCIe Resizeable BAR Tab
• GPU-Z -> Vulkan Tab
  
• Device Manager -> RX 580 Large Memory Range
• Device Manager -> AMD Pci Bus Large Memory Range
• Device Manager -> PCI-to-PCI Bridge Large Memory Range
• Radeon Software -> Smart Access Memory Setting

Specs:

• RX 580 (21.6.1)
• 2700X
• ASUS PRIME X470-PRO (latest 5851 bios)
• Windows 10 (19043)
• Firmware settings: CSM off, W10 UEFI, above 4G decode enabled, Resizeable BAR enabled
• Above is all also true on W11 (22000), 30.0.13000.17006 driver, and 10.21.30011.0 Radeon control panel

 

I have exact the same issues with my drives. Whene i enabled rBAR in the Bios and i install GPU Driver this kicked my drives out, also USB and LAN. Installations hang on 99% for 1 minutes and whene finish my drives, usb and lan is working again. I dont have this issues wehen rBAR is disables in the Bios. But whene i enabled again the issues is back.

 

Apparently the solution is to either convert the drive to GPT using a tool or reinstall Windows in GPT mode. I'm too lazy to do either of these solutions as the converter could potentially damage files and I don't like reinstalling everything.

 

I use UEFI and gpt.

 

Hi!

My gpu is RX 5500 XT not supported by AMD SAM.
For me SAM is now working after some changes.


BIOS:
CMS= Disabled
4G Above= Enabled
Resizable Bar= Enabled

Install Win 11.
Install "AMD Radeon Software - UWP - v30.0.13000.17006"
Install Radeon control panel from Windows Store.

All done.


GPU-Z show unsupported gpu after enabling it on radeon software.

 

how can it work when its clearly say unsupported gpu? Only thing you did is enabled in bios that does not mean it works.

 

If you see radeon software screenshot, sam is enabled.
Also check for large memory.

When i get some free time i will try some games enabled/disabled.

 

Hello, I have a Ryzen 2700x, MSI X470 Mb, and a RX 5700 XT, I already did some tests a couple of months ago, with Resize Bar enabled/disabled:
https://forums.guru3d.com/threads/resizeable-bar-support-issues.435389/page-3#post-5874736
I found there was no difference in performance in both cases, so even if it can be enabled in UEFI, and GPU-Z says it's enabled, it doesn't mean that it's working. Also the AMD driver reports SAM status as beeing "not available". As i understand only CPU's starting with Ryzen 3000/ Zen 2 support this feature in hardware.
Anyway since then I just left it enabled and moved on. In my opinion if you want a real, "tangible" solution, just enable Radeon Anti-Lag in the driver settings, it works wonders for me!

 

Your CPU us not supported.
Already tested anti-lag, it work very well.

I already post a screenshot with SAM enabled in the AMD Radeon control panel.

This is not enabled:


This is my panel (sorry, is in spanish) with sam enabled:

 

2700X can do SAM; support is advertised as-expected on Linux, and on Windows the latest 22.5.1 driver shows it with a 6600 XT:

 

It does shows it but actually its not working. Even 3000 series are not supported properly only 5000.

 

How are they going to present an option in their own GPU control panel if it doesn't even do anything? It may as well go back to being grayed-out if the CPU doesn't support it; they have no issue with doing that for "unsupported" GPUs.

Outside of that video, has AMD straight up said that rBAR doesn't work on anything except 5000-series CPUs?

 

My gigabyte x570 didnt even alow me to enable resizable bar in the bios when i had 2700x and now with 3800x option is there.

 

Interesting; my board showed the rBAR option no problem with a 2700X and 3 different GPUs. Is ASUS lying about the support, or is GIGABYTE hiding the feature for some other reason?

What I'd really like to see is some kind of proven raw-data that shows whether rBAR is working or not. Framerates from games fluctuate too much and aren't 1:1 reproducible.

I'm mostly convinced at all the text evidence showing that rBAR is enabled and doing something (Large memory range, GPU-Z, AMD, dmesg), and I can't see how that could all be faked if the support wasn't there; I'd imagine games would be crashing all over the place with memory errors once they go beyond 256MB VRAM.

 

Do you have Forza Horizon 5? It has the biggest increase with sam enabled for amd gpus. If you have it maybe few runs with enabled/disabled can show us. I would like to know if it works too.