On Thu, Mar 11, 2010 at 12:58:30PM -0800, Matt Thomas wrote:
>
> On Mar 11, 2010, at 12:31 PM, David Young wrote:
>
> > On Thu, Mar 11, 2010 at 12:20:41PM -0800, Matt Thomas wrote:
> >> On Mar 11, 2010, at 11:40 AM, David Young wrote:
> >>> Resource management:
> >>>
> >>> PCI-* bridges can override bus_space_alloc(9)/bus_space_free(9)
> >>> in order to (1) allocate space from the upstream bus, (2)
> >>> widen/narrow its I/O- or memory-space window. Then we can
> >>> provide a reliable rbus-like facility to detachable buses
> >>> through bus_space(9).
> >>
> >> bus_dma_subregion can be used for that. So bus_space_subregion.
> >
> > Matt,
> >
> > How do we open the windows?
>
> I don't see a reason to do that but you could allocate new larger
> subregions from the parent.
Let's say that we have this PCI setup:
Host-PCI bridge: forwards MMIO 0xff000000-0xffffffff to PCI bus
|
pci0
|
+-------- - - -
|
PCI-PCI bridge: forwards MMIO in [0xffff0000-0xffffffff] to secondary
|
pci1
|
+------------------------+-----------------------+
| | |
PCI-CardBus bridge IDE controller video adapter
|
+--------+
| |
cardbus0 cardbus1
| |
| |
| |
NIC NIC
The BIOS has exclusively assigned MMIO regions to each PCI adapter. It
may or may not have assigned a range to the CardBus bridge itself. It
has probably not reserved space for the CardBus NICs, especially not if
they were attached after boot-up.
We have to exclusively assign MMIO space to each CardBus NIC's
registers. If the PCI-PCI bridge does not forward an address range that
is big enough to fit the NICs' registers, then we have to reprogram the
bridge to forward a wider range.
Dave
--
David Young OJC Technologies
dyo...@ojctech.com Urbana, IL * (217) 278-3933
