Re: DMA Keyhole

>As a user, you know how much memory your video card has, and indeed the 
>kernel provides an option to specify SWIOTLB size at boot. So, if you are 
>building a nice gaming PC, you plug in a GeForce 6800 with 256MB of 
>memory, and suddenly you need to allocate half a gig for SWIOTLB. I guess 
>we won't be seeing many gaming or 3D graphics PCs with Noconas.
>
>So we have a similar scenario where an obscure keyhole nobody cared about 
>suddenly became a major keyhole, on top of the keyhole created by Intel's 
>limited implementation of DMA.

I'm having trouble seeing the keyhole here.  Intel's failure to support
IOMMU looks like a missing feature, not a keyhole.  The fixed size of the
SWIOTLB is a keyhole, but at least the size is boot-configurable.  Where is
the bad keyhole design here?

Scott