On Mon, Feb 6, 2012 at 10:48 AM, Bjorn Helgaas [off-list ref] wrote:

quoted

+struct resource iobusn_resource = {
+       .name   = "PCI busn",
+       .start  = 0,
+       .end    = 0xffffff,
+       .flags  = IORESOURCE_BUS,
+};

I'm not sure this should be global.  iomem_resource and
ioport_resource *are* really global, because they refer to processor
address space that is the same for everybody.  But PCI bus numbers are
specific to PCI.  Some machines don't have PCI at all, and there are
different bus architectures to which this doesn't apply.

that does not hurt them.

The 0-0xffffff range is misleading because it includes both the domain
and the bus number, and it's meaningless to allocate ranges that cross
domain boundaries.  For example, [bus 0x0000f0-0x000120] includes bus
numbers from domain 0000 and domain 0001, which doesn't make any sense
because a bus can only be in one domain.

allocation code will make sure it will be cross the boundary for domain.

I think it would make more sense to keep this bus number resource in a
per-host bridge structure.  Then we wouldn't need to include the
domain number at all because the host bridge determines the domain.

not sure. insert the all busn_res of all peer root buses into one
global iobusn_resource
looks more simple.

Yinghai