[SeaBIOS] [PATCH 0/8] seabios: pci: multi pci bus support

[Isaku Yamahata]

On Thu, Jun 17, 2010 at 02:17:20PM +0300, Michael S. Tsirkin wrote:
> On Thu, Jun 17, 2010 at 08:03:08PM +0900, Isaku Yamahata wrote:
> > This patch set allows seabios to initialize multi pci bus and 64bit BAR.
> > 
> > Currently seabios is able to initialize only pci root bus.
> > However multi pci bus support is wanted because
> >   - more pci bus is wanted in qemu for many slots
> >   - pci express support is commin in qemu which requires multi pci bus.
> > those patches on Qemu part are under way, though.
> 
> Not that I object, but - does it really require multi bus? Why?

I should have explained about pci express a bit more.
Express defines root/upstream/upstream port. They are shown
to software as pci-to-pci bride.
Express slot to which express device is inserted is
under a root or downstream port. That means multi bus.
Native hot plug is implemented in root or downstream port.
Again that means multi bus.

I heard that some windows device driver checks pci-to-pci
bridge existence. Perhaps others may know this better.
-- 
yamahata