I'm not entirely convinced that the BAR size isn't the same setting as the aperture size with a interchangeable name changing to describe the same concept a bit more adequately. Think about aperture is a bit of a fuzzier term really more associated with camera's and fairly applicable, but not the best means to describe what the setting really represents as neatly as BAR size.
Also take a gander at this and notice the CSM disabled part and 4G decoding the latter also being kind of fuzzy and interchangeable with MMIO 4GB.
https://www.techarp.com/computer/smart-access-memory-guide/
Lastly you've got this which describes the VRAM aperture as BAR1 also rather coincidental in turn. I'm pretty self convinced it's the same unless someone can definitively in a strong way prove otherwise at least for the time being. I think we could know more for certain perhaps when Nvidia enables support to be fair. If it's supported at the driver level by Nvidia on GPU's it should work if the MB supports it and I think Nvidia knows as much or wouldn't be coming out so quickly quite so guns blazing on the matter.
https://envytools.readthedocs.io/en/latest/hw/bus/bars.html
I also found this by Nvidia that talks about the BAR and the MMIO so yeah I'm fairly convinced.
https://docs.nvidia.com/cuda/gpudirect-rdma/index.html
It wasn't showing up in bios like I thought initially, but it's also a previous bios version so idk if the naming changed. There defiantly isn't a "accessible" option with the same naming structure in P7.30 bios it could be something a bios mod needs to enable I think you change something extended user I don't recall there is a way to temper with some stuff and enable/disable some bios options though by modding them with the AMI tool. There is something called TOLUD MMIO with a 2.5GB/3.5GB/Dynamic option in the version of the bios I have though that could possibly be the same option with slightly different naming in the older bios used. The CSM option was present though and already disabled by default and from what I read AsRock does that along with most other MB makers though Gigabyte seems to enable it by default apparently.
Also take a gander at this and notice the CSM disabled part and 4G decoding the latter also being kind of fuzzy and interchangeable with MMIO 4GB.
https://www.techarp.com/computer/smart-access-memory-guide/
Lastly you've got this which describes the VRAM aperture as BAR1 also rather coincidental in turn. I'm pretty self convinced it's the same unless someone can definitively in a strong way prove otherwise at least for the time being. I think we could know more for certain perhaps when Nvidia enables support to be fair. If it's supported at the driver level by Nvidia on GPU's it should work if the MB supports it and I think Nvidia knows as much or wouldn't be coming out so quickly quite so guns blazing on the matter.
https://envytools.readthedocs.io/en/latest/hw/bus/bars.html
I also found this by Nvidia that talks about the BAR and the MMIO so yeah I'm fairly convinced.
https://docs.nvidia.com/cuda/gpudirect-rdma/index.html
It wasn't showing up in bios like I thought initially, but it's also a previous bios version so idk if the naming changed. There defiantly isn't a "accessible" option with the same naming structure in P7.30 bios it could be something a bios mod needs to enable I think you change something extended user I don't recall there is a way to temper with some stuff and enable/disable some bios options though by modding them with the AMI tool. There is something called TOLUD MMIO with a 2.5GB/3.5GB/Dynamic option in the version of the bios I have though that could possibly be the same option with slightly different naming in the older bios used. The CSM option was present though and already disabled by default and from what I read AsRock does that along with most other MB makers though Gigabyte seems to enable it by default apparently.
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