Re: x86_64: 2.6.14-rc4 swiotlb broken

From: Linus Torvalds
Date: Mon Oct 17 2005 - 11:03:28 EST




On Mon, 17 Oct 2005, Andi Kleen wrote:

> On Monday 17 October 2005 17:27, Linus Torvalds wrote:
> > On Mon, 17 Oct 2005, Andi Kleen wrote:
> > > The patch is actually not quite correct - in theory node 0 could be too
> > > small to contain the full swiotlb bounce buffers.
> >
> > Is node 0 guaranteed to be all low-memory? What if it allocates stuff at
> > the end of memory on NODE(0)?
>
> This is 64bit ... only low memory.

Ehh.. No there isn't.

PCI DMA isn't magically 64-bit, even on your Opteron.

So low memory in this case is anything < 32 bits. How many bits the CPU
has is immaterial.

That's the whole _point_ of swtlb, after all, so I don't see why you
argue.

Linus
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