Re: dual head r128

[Michel Lanners <mlan@cpu.lu>]

On  17 Oct, this message from Paul Mackerras echoed through cyberspace:
> I think iobase should be a constant, and we should set up our virt ->
> phys mapping to do anything fancy that we might need.

The discussion about IO seems to always concentrate on kernel access of
IO space. How would you address user space access? Does the syscall
that's been discussed address this to an acceptable degree?

>> > Unfortunately, there's no simple way to allow two busses to have the
>> > legacy IOs. That means on UniN machines that they'll be available either
>> > on the AGP bus, or the external PCI bus, but not both.
>>
>> Indeed, this is too awkward (is tere no way to redirect only the VGA
>> part of the legacy I/O space ? That's what the PCI-PCI bridges do, but
>> I've not yet used a single machine with AGP so I'm ignorant).
>
> Could someone fill me in on why we need legacy I/O to the AGP bus?

Legacy VGA?

Michel

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