On Tuesday 11 April 2006 03:46, you wrote: > > > Yes, I know they hit the message, that's from a message in some forum > > that i got interested in the issue. It probably comes from an allocation > > from: > > http://www.linux-m32r.org/lxr/http/source/arch/powerpc/kernel/pci_direct_iommu.c#L32 > > > > Either the ppc code is wrong (it doesn't enforce dma_mask) either the > > driver still works without the check. > > > > Maybe ppc should do the same thing as i386: > > > > 47 if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff)) > > 48 gfp |= GFP_DMA; > > PPC doesn't have a ZONE_DMA... PPC assumes that the whole memory is > DMA'able... What happens here is that it works by "chance" on x86 ;) > ZONE_DMA is a thing of the past that represents ISA DMA (below 16M iirc > or something like that). Thus x86 historically maintained a separate > allocation zone down there for ISA devices. What happens here is that > the x86 code sort-of detects that the DMA mask isn't the full 32 bits > and kicks everything down into ZONE_DMA. Makes things work, though the > pressure on ZONE_DMA can often be high enough that you'll have a lot of > failed allocations ... > > PPC doesn't have ZONE_DMA, thus can't provide memory guaranteed to be > below that limit. > > Now, for ppc32, it should still sort-of work because all of lowmem is > below 1Gb and people generally don't hack their lowmem size (well, I do > but heh, that doesn't count :) and I don't think you'll get skb's in > highmem. But ppc64 hits the problem and at this point, there is nothing > I can do other than either implementing a split zone allocation mecanism > in the ppc64 architecture
> for the sole sake of bcm43xx (ick !) Nope. For every broadcom device, which has this stupid DMA engine. That is b44 and bcm43xx, as far as I can tell. But likely there are more. > or doing some trick with the iommu... -- Greetings Michael. _______________________________________________ Bcm43xx-dev mailing list Bcm43xx-dev@lists.berlios.de http://lists.berlios.de/mailman/listinfo/bcm43xx-dev
