[parisc-linux] Card-mode Dino
Sat, 04 Sep 1999 13:18:10 -0700
LaMont Jones wrote:
> > > And does the dino-on-a-card have it's own IODC on the card?
> > No. Dino implements the PA I/O architected registers but no IODC.
> > I suspect the problem is it's really a bus converter and that
> > needs PDC support - IODC entry points don't apply to this.
> > Can anyone confirm this?
> Can't confirm or deny, but it is possible (we've done it at least once)
> to build a bus converter that does not require PDC help, just architecture
Let me add some depth to my suspicion.
Platform IO space (which Dino "translates" 1:1 to PCI MMIO space) is
assigned exclusively by PDC on platforms with GSC busses. The OS can't
assign I/O space addresses to devices unless (a) knows where I/O space
is (could make assumptions about this), (b) exactly which parts
have been used by other bus converters or devices, and (c) which
parts are reserved for "special" devices (eg graphics)?
I suspect IODC can't provide this sort of functionality. Let me
rephrase my question: does anyone know if architected PDC interfaces
provide enough information to satisfy a/b/c above?
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