Re: [PATCH 1/1] pci: xgene: Enable huge outbound bar support

Arnd Bergmann
2015-06-26T20:43:57Z

On Friday 26 June 2015 22:35:08 Arnd Bergmann wrote:
> > >
> > > Can you configure one of the two windows as prefetchable for improved performance?
> > >
> > The new huge window will be prefetchable.
>
> The DT marks it as non-prefetchable, so the kernel will now try to allocate
> space for non-prefetchable BARs from this area, which is a bug. If the second
> memory window is always prefetchable, you have to mark it accordingly in DT,
> to prevent it from being used for normal 64 bit BARs.

Forget what I wrote here, I just remembered that 64-bit BARs are by definition
prefetchable. You should still mark the range accordingly in DT for correct
operation, but it won't be used for non-prefetchable 64-bit BARs if you don't
because they do not exist.

Arnd