I posted
this on Xen Mailing List. Got some useful replies, mainly
this and
this.
The resumen:
* In order to do passthrough, you need to have that Hardware part virtualized. So virtualization and passthrough are not two different methods, but one is a prerequisite for the other to work. And that continues to the next point:
* VT-d was introduced on Wolfdale supporting Chipsets. It seems to be a Chipset feature on that platform, unrelated to the Processor, as even on an older Conroe based Core 2 Duo that doesn't officialy includes VT-d support (On some Wolfdales is mentioned as a feature on Intel Ark), VGA passthrough worked. I originally though that on the VGA passthrough video with the Core 2 Duo, the GPU wasn't virtualized because I didn't know that it was actually using VT-d.
* There was
another Thread asking about IOMMU virtualization with a Trinity. Got pretty much no replies. So it seems that its REALLY unknow how widespread AMD-Vi support is on that platform, or the actual Chipsets requeriments (I know some guys here said that it was an A85X feature, but I didn't found anything else that claims that only it supports it and the other Chipsets do not).
* Motherboard/BIOS is still the most important piece of the puzzle. One of the guys that replied me said that some extra chips on a Motherboard, like the PCI Bridges used to split PCIe lanes, doesn't seem to work with IOMMU virtualization and can render unusable for this purpose any PCIe slot connected to it. This means that you're more likely to get all your Motherboard components working properly virtualized the more simple it is, so maybe you want to avoid high end Motherboards that got an extra SATA Controller, another USB Controller, etc. Basically, you need to get the most out of the existing Northbridge and Southbridge chips. This means that many high end Motherboards could be discarded on sight due to them being filled with all those extra features that you will not be able to virtualize on the first place.
I have yet to resend AMD the ticket asking about AMD-Vi support on Fusion platforms, and also pay a visit to Coreboot Mailing List. I don't have idea about how much Coreboot progressed on the virtualization area, but
they claim that its possible for it to support features that the shipping Motherboard's BIOS doesn't have. I don't know if they already managed to get working VT-d or AMD-Vi. Assuming they do, you have at least a minor hope of somehow getting those features working on your Motherboard in case your Motherboard manufacturer doesn't provides the proper support.
Now, making Coreboot to work on your Motherboard is yet another nightmare, worse that finding one that works properly out of the box, because you need a lot of tools and knowledge to get it running. Failure means high chances of bricking your Motherboard, unless you have a spare Flash chip with the original BIOS or a Flash reprogrammer at hand. It seems to be a mammoth task, maybe of moderate difficulty for someone with programming experience, but don't expect any type of Joe Average to succed here. Assuming I could manage to get a hand with that matter, the idea would be to purchase a simple Socket FM2 Motherboard (High quality construction with no extra controllers or fancy features, like the old Biostar TForce style) expecting that I could make Coreboot work on it and thus the missing virtualization features.
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