Re: [PATCH] PCI: Clear bridge MEM_64 flag if one child does not support it

Benjamin Herrenschmidt
2014-12-08T22:56:30Z

On Mon, 2014-12-08 at 13:52 -0800, Yinghai Lu wrote:
> 2. or scan the children resource other than ROM to clear bridge MEM_64
> for mmio pref.
>
> The patch is using second way so will keep child mmio pref into bridge
> mmio pref range.

That means that having a single ROM BAR that is 32-bit and prefetchable
will downgrade the entire window to 32-bit ? That's not going to work
either.

I have GPUs with 16G BARs for example... suddenly they don't fit
anaymore because we downgraded the window to 32 bit because somewhere
there's a 32-bit pref resource ?

That will break more than it fixes...

Ben.