[OpenBIOS] [PATCH] Add USB OHCI + HID driver

[Segher Boessenkool]

> Sorry but I'm not sure I can follow what you mean. Why setting BUS_MASTER
> in PCI config would fail on real hardware?

Enabling bus mastering on a PCI device allows the device to generate
reads and writes on the PCI bus.

It fails in exciting and mysterious ways if you haven't yet set up
bus mastering on your PCI-PCI bridges and your PHB yet.  And related
config, e.g. the windows on those bridges.

Things get a lot more interesting if you have an IOMMU, too.  DMA is
evil.  Scared yet?  You should be.


Segher