Re: Memory problem with bttv driver

Gerd Knorr (kraxel@bytesex.org)
Tue, 15 Jan 2002 16:16:53 +0100

On Tue, Jan 15, 2002 at 02:46:52PM +0100, Stephan von Krawczynski wrote:
> On Tue, 15 Jan 2002 14:20:17 +0100
> Gerd Knorr <kraxel@bytesex.org> wrote:
>
> > Yes. Instead of remapping vmalloced kernel memory it gives you shared
> > anonymous pages, then does zerocopy DMA using kiobufs. You may run in
> > trouble with >4GB machines.
>
> Interesting.
> What's the problem on > 4GB ?

The bt878/848 is a 32bit PCI device, it simply can't go DMA to main
memory above 4GB. At least on ia32, on architecures with a iommu
(sparc, ...) it should work without trouble.

Gerd

-- 
#define	ENOCLUE 125 /* userland programmer induced race condition */
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/