[PATCH] [2/2] POWERPC: Lower threshold for DART enablement to 1GB, V2

[Olof Johansson]

On Thu, Apr 13, 2006 at 08:45:49PM +1000, Benjamin Herrenschmidt wrote:
> On Thu, 2006-04-13 at 09:40 +0300, Muli Ben-Yehuda wrote:
> > On Wed, Apr 12, 2006 at 09:52:33PM -0500, Olof Johansson wrote:
> > 
> > > iommu=off can still be used for those who don't want to deal with the
> > > overhead (and don't need it for any devices).
> > 
> > I've been pondering walking the PCI bus before deciding to enable an
> > IOMMU and checking each device's DMA mask. Is this something that you
> > considered and rejected, or just something no one got around to doing?
> 
> It would do the trick for airport cards in G5s.. a little bit of OF
> walking to find the card.

Walking the DT means we need to hardcode it on PCI IDs, since the Apple
OF doesn't give the Airport device a logical name. It's probably easier
to implement than walking PCI, but we'd need to maintain a table. My
vote is for PCI walking, I'll give that a shot over the weekend.

> It won't help with cardbus broadcom's but then, there is currently no G5
> with a cardbus adaptor that I know of :) It's possible I suppose to get
> a pci<->cardbus adapter but I suppose in that case, we can ignore it ...

Yep, that should be rare enough.

-Olof