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

[BALATON Zoltan]

On Tue, 3 Jun 2014, Segher Boessenkool wrote:
> 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.

I don't know if PCI bridges are supported by OpenBIOS yet (probably not as 
an XXX comment says in qemu/hw/pci-host/uninorth.c) but if not then it 
would not work on real hardware anyway, would it?

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

I could enclose the enabling bus mastering part in a check for CONFIG_QEMU 
if that would make it safer. What do you think?

Regards,
BALATON Zoltan