Giving special alignment/size constraints to the Linux PCI core?

[Jason Gunthorpe]

On Tue, Feb 12, 2013 at 04:00:08PM +0000, Arnd Bergmann wrote:

> > The window sizes are power of two sizes. I didn't realize that it was
> > also the case for PCI BARs. Then there is no problem with the size I
> > guess, and only a problem of alignment. Having the possibility to
> > get the resource and return a fixed up start address would solve the
> > problem I'd say.
> 
> I thought that only device BARs in PCI had natural alignment, while
> bridges don't.

Right

> My feeling is that an easier solution would be to keep separate
> root buses for each port, which then behaves completely PCIe
> compliant, but add a hook in the procedure above to set up the
> address translation windows between the pci_bus_size_bridges()
> and the pci_bus_assign_resources() calls.

This process is only done during driver initialization. How would you
support PCI-E device hotplug (my systems rely on this)? Hotplug works
today with the existing Marvell driver, however that relies on
pre-allocated windows.

Jason