ASUS releases beta bios beta versions with SAM - Resizable BAR function for Intel Z490 motherboards

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#5860391
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i wonder if i m gonna see resizabler bar support for x470 and ryzen 2700x, or 3700x
#5860399
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Any 6800 or XT users on Intel systems? Does it work?!
#5860400
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I was wondering why the beta bios for my Formula had no changelog. Will wait to update this once i can get a use out of it.
#5860406
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God damn it ... I have Gigabyte mobo :-/
#5860429
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I have "Above 4G decoding" on my Z370 ASRock, if that's the same thing talked about here... edit: obviously not, that's not BAR...
#5860619
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gx-x:

I have "Above 4G decoding" on my Z370 ASRock, if that's the same thing talked about here... edit: obviously not, that's not BAR...
"Above 4G decoding" is one of the names for Resizable Bar, or RBAR.
#5860636
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Thanks.
#5860647
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Yep, it needs to be two options, above 4G enabling is not enough.
#5860650
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I haven't noticed any difference with it ON/OFF to be honest...
#5860652
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gx-x:

I haven't noticed any difference with it ON/OFF to be honest...
You need to wait until Nvidia and Intel support via drivers if you have an Intel MB w Nvidia GPU. If you have a AMD GPU then you need to wait for AMD & Intel driver support.
#5860655
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SpajdrEX:

Yep, it needs to be two options, above 4G enabling is not enough.
Do you have a link? It may be true for AMD motherboards. For Intel MB's "Above 4G decoding" one of 4 different names motherboard manufacturers use for Resizable RBAR. It is enough besides driver support. Edit: Just saw the image above. Perhaps you do need both for AMD cards.
#5860665
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Why they always talk about "exclusive" z490 features? This bios is available for other 400 series chipset. Like when most webs talk about rocket lake only compatible with z490 boards. It will be probably compatible with the entire 400 series.
#5860681
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pharma:

"Above 4G decoding" is one of the names for Resizable Bar, or RBAR.
no it isn't.
#5860772
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Astyanax:

no it isn't.
yes it is. Already went over this with you. Google is your friend. Reddit post detailing resizable BAR usage for years on Linux enabled via 4G Decoding. Smart Access Memory already works on Linux and is not exclusive to Zen 3 or Navi 2x : Amd (reddit.com)
Some hardware vendors name component differently. For example, 64-bit MMIO, Memory Hole for PCI MMIO, and Above 4G Decoding in PCI handling options.
How to Resolve GPU Memory Mapping Issues in XenServer (citrix.com)
#5860796
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Whatever AMD's doing on their boards appear dependent on two separate options one of which is SAM and the other being Above 4G Decoding. Not sure how this is implemented on Intel boards though or what the separate SAM option on AMD's boards does if 4G Decoding achieves a similar purpose. EDIT: Guess the naming varies a bit on AMD systems too but it's still two separate toggles in the bios and if I understand it correctly also a reliance on UEFI without the compatibility support module. 🙂 https://www.amd.com/en/technologies/smart-access-memory https://www.amd.com/system/files/2020-11/677259-SAM-enabled-screen-1260x500.jpg
#5860813
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JonasBeckman:

Whatever AMD's doing on their boards appear dependent on two separate options one of which is SAM and the other being Above 4G Decoding. Not sure how this is implemented on Intel boards though or what the separate SAM option on AMD's boards does if 4G Decoding achieves a similar purpose. EDIT: Guess the naming varies a bit on AMD systems too but it's still two separate toggles in the bios and if I understand it correctly also a reliance on UEFI without the compatibility support module. 🙂 https://www.amd.com/en/technologies/smart-access-memory https://www.amd.com/system/files/2020-11/677259-SAM-enabled-screen-1260x500.jpg
I'm not sure exactly about the function of the second toggle. It might be related to specific AMD-specific instructions to access gpummu features, but this is speculation from the reddit link above.
This has nothing to do with AMD CPU or GPU; it's just that the AMD graphics team didn't want to implement Intel-specific instructions to access gpummu features, and implemented access only via the AMD instruction set extensions. It's no different from what Intel has been doing with their optimization in math libraries for years. If NVidia wants the same feature, they can re-use the same AMD-specific instructions to access gpummu on AMD processors, and work with Intel to use intel-specific instructions to access their gpummu features.
#5860828
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So ... anyone with mentioned Asus Z490 motherboard + 6800(XT)? I wan't to know the results 🙂
#5861106
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from @RED.Misfit: "This is a PCI express feature, everyone with a PCI 3.0 and a compatible motherboard (bios option "resizable BAR" required) should be able to use it. Windows is compatible since WDDM v2, so Windows 10 only." -> https://docs.microsoft.com/en-us/windows-hardware/drivers/display/resizable-bar-support I really don´t know, why AMD is hyping it´s so called SAM feature that much, because it is not an AMD feature, it simply belongs to PCIe3.0 specification and therefore it should be available on all mainboards with enabled in BIOS, no matter if AMD, nvidia or Intel. Your OS must support it as well e.g. see posting and link above from @RED.Misfit AMD says approx. 10% performance gain with SAM on, in my eyes with games already over 100fps this is almost nothing (most games only show 5 or maybe 10fps more in reviews with SAM enabled). Much more significant is the fact, that "resizable bar" or SAM will work only in UEFI with CSM mode switched OFF, as far as I know. That means, your boot disk must be formatted in a GPT partition scheme. This will cause much more trouble for users, because many systems are still booting with CSM mode ON. So, if you want to use your MBR boot disk (and your DATA) with "SAM" or "resizable bar", you have to repartion it to GPT scheme first.
#5862891
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For AMD I believe you currently are required to have a 6800(or 6800XT) GPU and 20.11.2 or newer. NVIDIA I think is coming in with the 460 branch or newer but I have no idea what GPU's will be supported beyond Ampere as the likeliest to get initial support when their drivers add this functionality. (Turing probably is highly likely possibly Pascal too.) Intel I am also unsure what CPU's will be supported and how many motherboards other than the latest will see bios updates provided even if they'd technically be compatible hardware wise.

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