Re: SCSI breakage on non-cache coherent architectures

Roland Dreier
2007-11-19T21:44:20Z

> I've been debugging various issues on the PowerPC 44x embedded
> architecture which happens to have non-coherent PCI DMA.
>
> One of the problem I'm hitting is that one really need to enforce
> kmalloc alignement to cache lines or bad things will happen (among
> others with USB), for some reasons, powerpc failed to do so, I fixed it.

Heh... I hit the same problem literally 5 years ago:
http://lwn.net/Articles/1783/

I implemented the __dma_buffer annotation:
http://lwn.net/Articles/2269/

But DaveM said we should just use the PCI pool code instead:
http://lwn.net/Articles/2270/

- R.