Mike Banon has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/30987 )
Change subject: mb/asus: Add Asus A88XM-E FM2+ with documentation ......................................................................
Patch Set 38:
Patch Set 38:
Mike, did you find anything else to fix?
I didn't test all the functions yet, and haven't encountered anything else broken (except the bad IRQ routing, which is a common problem among fam15 boards and isn't that easy to fix).
IOMMU is still broken for me on multiple distributions. Which one did you choose for testing?
It works i.e. on Linux Mint 19.3 LiveUSB. If it doesn't work for you with the same distro - to rule out as many things as possible, here is a proven good coreboot build - https://github.com/mikebdp2/coreboot-related/commit/c0d163b0b81ed7f58f6e5d8b... . After downloading and extracting this ROM (and comparing the SHA256 of course, with those given at commit message), you'll need to add your vgabios to it, using a cbfstool, with a command like: ./coreboot/build/cbfstool ~/Downloads/coreboot.rom add -f ./coreboot/pci****,****.rom -n pci****,****.rom -t optionrom -c none
If it still doesn't work for you after all that, most likely that means either coreboot's IOMMU code is incompatible with your A8 or your A8 itself has a buggy IOMMU.
Btw I think we can really disable it, nothing uses this great APU function. Even the manufacturer bioses disable this setting.
Some features and even operating systems (i.e. QubesOS) really depend on IOMMU, so it's really preferable to preserve this feature if possible, even if you don't need it personally. Manufacturer BIOSes often have stupid defaults, they shouldn't be a compass if we can do it smarter ;)