On Mo, 2014-11-24 at 15:38 +0200, Marcel Apfelbaum wrote:
> On Mon, 2014-11-24 at 13:28 +0100, Gerd Hoffmann wrote:
> > On Mo, 2014-11-24 at 11:47 +0200, Marcel Apfelbaum wrote:
> > > Removed the assumption that the system has only one primary root bus.
> > > When mapping memory and IO regions go over all buses, skipping
> > > secondary and absent buses.
> >
> Hi Gerd,
> Thanks for the review.
>
> > I guess there are qemu patches adding support for multiple pci busses
> > somewhere?
> Yes, an RFC will be released soon on QEMU mailing list,
> is a work in progress and I am currently trying to decide
> if I wait for a fully functional series or release is sooner
> for comments.
Early rfc would be good I guess. First I have something to play with
when looking closer at this patch series ;)
Second I suspect there might be some non-trivial interactions with acpi
(pci region declaration), so early review is probably helpful to make
sure the design goes into the right direction.
> > Hmm, that assigns the io regions in bus order. I think it would be
> > better to integrate this with the packing logic we already have:
> > regions are sorted by size for best packing. Regions behind pci bridges
> > are grouped together. I think we could group regions belonging to a pci
> > bus in a simliar way.
> You are right, but only partial. Let me explain (as I understand it).
> The devices IO regions behind the bus are *already* packed (sorted by size).
> The buses themselves are indeed not sorted by their total IO space.
> The same is happening in pci_bios_init_root_regions_mem with the MMIO regions.
>
> It seems that what I have to do is simply replace the current bus enumeration:
> for (i = 0; i <= MaxPCIBus; i++) {
> with one that goes over the sorted list of buses in decreasing order of their
> total mem/IO consumed.
>
> Do you agree?
I think I would try to reuse the existing code which does the same for
bridges. Reuse "struct pci_bus" to add one more level (and maybe rename
the struct), then have the resource propagation code in
pci_bios_check_devices() do the job.
That will need some reorganization, because the simple "struct pci_bus
*busses" array indexed by bus number will not work any more. But I
think that should be done nevertheless. Your patch numbers all busses
across pci domains incrementally. Which I think is not how pci busses
are numbered, I think each pci domain has its private bus number
namespace.
cheers,
Gerd
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