SM H12 New BIOS and IPMI Released
- Thread starter AugustaLemke
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Here is an explanation from the gaming side of things but I think it should answer your question:
What is Resizable BAR?
All gaming PCs produce an on-screen image by way of the CPU processing data – textures, shaders and the like – from the graphics card’s frame buffer. Usually the CPU can only access this buffer in 256MB read blocks, which obviously isn’t very much when modern GPUs regularly have 8GB of video memory or much, much more.
Resizable BAR essentially makes the entirety of the graphics frame buffer accessible to the CPU at once; where it could once sip, it now guzzles. The idea is that once textures, shaders and geometry are loading in faster, games should run faster with higher frame rates.
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Modern GPUs can take a massive performance hit without resizeable bar. If you look at Intel's new Arc GPUs, they actually require it.
What is Resizable BAR?
All gaming PCs produce an on-screen image by way of the CPU processing data – textures, shaders and the like – from the graphics card’s frame buffer. Usually the CPU can only access this buffer in 256MB read blocks, which obviously isn’t very much when modern GPUs regularly have 8GB of video memory or much, much more.
Resizable BAR essentially makes the entirety of the graphics frame buffer accessible to the CPU at once; where it could once sip, it now guzzles. The idea is that once textures, shaders and geometry are loading in faster, games should run faster with higher frame rates.
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Modern GPUs can take a massive performance hit without resizeable bar. If you look at Intel's new Arc GPUs, they actually require it.
I can confirm new BMC firmware 1.01.25 and new BIOS v2.6 fixed the issue with the VRM sensors not reading correctly on my H12DSi-N6.
I have a M12SWA-TF with a 5975WX on it and was surprised when I realized it didn't have it since AMD advertises the 5000 series TR Pro as though it's a standard feature, and particularly since they sell this board in a system with desktop 3000 series NVidia cards (and that's more likely to be used with desktop GPUs than their servers). Workstation GPUs are a pretty terrible cost / benefit proposition unless the consumer models have been massively inflated in price by scalpers to the point that costs aren't very far apart. Otherwise the 24GB of video ram a 7900XTX offers for $1000 is still quite a lot and makes spending the something like $5000 more for 48GB on the workstation model pretty terrible value unless you desperately need it.
The annoying part is that they seem to support it on the X13 / H13 boards so it's not like they can't, and from what I've seen of AMI BIOS tools with the correct version of the toolset the change would be editing a UI menu, saving, and re-signing the firmware at the simplest and doing that + adding one of the default AGESA modules at the worst, x86 platform firmware has become really plug & play. It's not like anyone is asking them to write a new feature. I could see not wanting to make it a default firmware upgrade if they have no desire to test it against all their already-validated hardware, but they could at least add it as an unsupported beta build or something.
Anyway, I asked and they have no plans to add it on that BIOS either although I put in a feature request. I doubt Supermicro expects people to be using stuff that requires resizable BAR vs. cards that either flat out require or use the more normal "large BAR support" (All AMD and NVidia workstation cards made recently, Instinct MI210, Mellanox cards with their corresponding BIOS option enabled, some RAID controllers with the bios option enabled) that comes automatically with >4GB decoding on and is requested / configured by the card BIOS at boot rather than the OS. I was less interested in it for my video card and more for a future mellanox ethernet / IB link to my old workstation turned storage server, but it turned out that those use large BAR when it's enabled and it doesn't necessarily help. I'm was also thinking it would be needed in case CDNA3 displaces a bunch of MI210s and I can pick one up for relatively cheap on ebay down the line, but those use large bar too.
I'd been confused about the two since every source on google talking about resizable makes it sound like there was no way to do this before, but I remembered x99 and prior era NVidia compute cards that required above 64G decoding and started digging around. Their decision not to add it made more sense once I figured that out but it's still kinda silly. The garbage TR Pro board Asus made supports it but I wouldn't use their hardware again if you paid me after x99.
Yeah it is disappointing. I really came to SM because I thought they had good support, but when Asus has better support/features something is wrong. I'd love to pick up an Intel Arc card for plex transcoding when it's supported, but no re-bar support really holds them back.
Slightly off topic: supermicro released a new bios for the m12swa and the rebar setting is accessible there under pcie configurations
Thanks for posting this, I'd actually checked a couple weeks ago but their site doesn't get updated with new BIOS builds immediately. I can confirm it's working correctly on the 7900xtx, which now has a BAR 0 of 32GB (available values are power of two) mapped and 24GB of Device-Local / Host-Visible / Host-Coherent showing in vulkaninfo.
Hopefully they get it added for you H12-XYZ owners soon. It's likely already in the BIOS on most of them but the option is hidden... I'd suggest writing their support with a feature request on it. I don't know how much my request mattered to them but it's here now and that's all I care about.
Supermicro advertises it in the x|h13 paltforms.Hopefully they get it added for you H12-XYZ owners soon. It's likely already in the BIOS on most of them but the option is hidden... I'd suggest writing their support with a feature request on it. I don't know how much my request mattered to them but it's here now and that's all I care about.
I think they will add it in a future update for the x12|h12 platforms as these are still actively supported
Supermicro was very quick to tell me to pound sand when I requested this be added to the bios. Makes sense because I'm just an end user, but I won't be purchasing from them again. I also am friends with the IT support for a couple of the hospitals that I work in and will suggest they do the same.
Its very strange but I just updated my BIOS to 2.7 and I no longer see VRM temps, nor any power usage or fan readings, in the BMC. I was on 2.4 before. Anyone know what's going on here?
I have also run into the missing rebar functionality issue with this board (H12SSL-i) and have also contacted SuperMicro to see if it can be resolved. I explained my usage of the system and the open source work I contribute to that this feature directly impacts and the response seemed positive. They requested more details of the issue to pass onto the software team, but did state it was a long shot to ask.
The rationale for the missing support seems to be that the platform is not validated for GPU usage at all, however I have explained that rebar is not a GPU specific feature and many devices on the market can and will take advantage of a rebar if it's made available (ie, Intel NIC XXV710-DA2, Samsung PM9A3 NVMe, Mellanox ConnectX-6 NICs).
Hopefully this will not fall on deaf ears.
The rationale for the missing support seems to be that the platform is not validated for GPU usage at all, however I have explained that rebar is not a GPU specific feature and many devices on the market can and will take advantage of a rebar if it's made available (ie, Intel NIC XXV710-DA2, Samsung PM9A3 NVMe, Mellanox ConnectX-6 NICs).
Hopefully this will not fall on deaf ears.
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Yep Ive done a full power cycle etc etc and cleared browsing data. The BMC seems to be screwed up because it becomes very very slow to the point where it is almost inaccessible after being up for a day or so. The machine itself is running fine.
So I have an update, today SuperMicro sent me a BIOS with REBAR support to test for the H12SSL-i. Right now I am upgrading to it to verify it works for them, but I can confirm that REBAR support for this motherboard will be available soon!
Glad they are trying to help you out, they told me to pound sand when I asked if it was something they could do.
Contacting SM support is like a box of chocolates, you never know what you're gonna get. Sometimes you'll get a response from someone who'll bend over to help and other times you'll get a butthole who basically tells you to get lost and little else. Now contact the sales dept. and that's another story.