I've had success making a USB3.0( FL1100 chipset) bootable on my MP3,1.
I've also been able to boot from USB2.0 flash drives connected to the USB3.0 card, but I still have some issues to sort out there, as some 2.0 Flashdrives are only bootable with the USB3 to SATA drive I have connected to the USB3 bus.
I don't have any USB3.x flash drives, so I'm not sure if it will effect them or not.
I'm using GOP enabled rEFInd as my boot loader, so I just added the XHCI EFI drivers to rEFInd rather than flash them to the somewhat fragile firmware of the 3,1.
The 5,1 has an issue with the UsbBus.efi driver in it's firmware not being compatible with XHCI, so someone with a 5,1 and a MATT card will have to try and replace that driver, in firmware, if they want bootable XHCI PCI-E cards.
All that is required for rEFInd on the 3,1 is to add the XHCI.efi and the UsbBus.efi from the MP6,1 firmware.
I think the 6,1 uses the FL1100 USB3 chipset, but these drivers don't seem to be specific to the chip, they appear to be generic XHCI drivers and should work with any XHCI PCI-E card that conforms to the Usb 3.x specification.
I'll be testing other XHCI cards and drives as time and money allow.
I've also been able to boot from USB2.0 flash drives connected to the USB3.0 card, but I still have some issues to sort out there, as some 2.0 Flashdrives are only bootable with the USB3 to SATA drive I have connected to the USB3 bus.
I don't have any USB3.x flash drives, so I'm not sure if it will effect them or not.
I'm using GOP enabled rEFInd as my boot loader, so I just added the XHCI EFI drivers to rEFInd rather than flash them to the somewhat fragile firmware of the 3,1.
The 5,1 has an issue with the UsbBus.efi driver in it's firmware not being compatible with XHCI, so someone with a 5,1 and a MATT card will have to try and replace that driver, in firmware, if they want bootable XHCI PCI-E cards.
All that is required for rEFInd on the 3,1 is to add the XHCI.efi and the UsbBus.efi from the MP6,1 firmware.
I think the 6,1 uses the FL1100 USB3 chipset, but these drivers don't seem to be specific to the chip, they appear to be generic XHCI drivers and should work with any XHCI PCI-E card that conforms to the Usb 3.x specification.
I'll be testing other XHCI cards and drives as time and money allow.
