pci <-> device node mapping

linas at austin.ibm.com linas at austin.ibm.com
Wed Jun 18 02:39:51 EST 2003

Hi Anton,

On Tue, Jun 17, 2003 at 03:42:21PM +1000, Anton Blanchard wrote:
> Hi,
> I put together a PCI domain patch for 2.5 which removed some of the
> complexity in our pci code. Im now wondering if there is any reason for
> us to map from pci dev -> OF node -> phb:
> #define PCI_GET_PHB_PTR(dev)    (((struct device_node *)(dev)->sysdata)->phb)
> >From memory the main reason for this was for EEH, but we no longer
> need it for this.

This is an unrelated issue, but what is the story for numbering/renumbering
PCI Id's?  In kernel-2.4.19, PHB's seem to chew up 256 PCI id's (for 4 slots)
and there are some machine configurations which have nearly a hundred PHB's.

In one unhappy situation, we had a machine with a graphics card which
ended up with a PCI Id of 4097, and the default X11 couldn't find it,
and so X wouldn't run.  For some reason, X feels a need to scan the
PCI bus.  Changing X to scan up to 19,000 bus ID's (the theoretical
max for this box) caused X to take 20 seconds to come up.

Any chance this might change?  I'm not saying it has to, just pointing
out one of the unintended consequences of the current design.


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