Re: pci_dma64_available() and Xen

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sun, Oct 12, 2008 at 12:31:15AM +0200, Joerg Sonnenberger wrote:
> On Sun, Oct 12, 2008 at 12:17:06AM +0200, Manuel Bouyer wrote:
> > What overhead are we talking about ?
> 
> Drivers and bus. But looking at the code it seems drivers don't care
> right now, so I guess it doesn't matter. E.g. twa could have been a good
> example where it can make a difference as the driver can program both a
> 32bit and 64bit interface to the firmware, but it doesn't do so
> conditionally.

It does, but at compile time. I guess doing it at runtime cost more
than what we gain by saving a few 32bit writes ...

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--