On Wed, Aug 27, 2014 at 07:10:20PM +0100, Stefan Hajnoczi wrote: > On Wed, Aug 27, 2014 at 6:27 PM, Konrad Rzeszutek Wilk > <konrad.wilk@xxxxxxxxxx> wrote: > > On Wed, Aug 27, 2014 at 07:46:46AM +0100, Stefan Hajnoczi wrote: > >> On Tue, Aug 26, 2014 at 10:16 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: > >> > There are two outstanding issues. virtio_net warns if DMA debugging > >> > is on because it does DMA from the stack. (The warning is correct.) > >> > This also is likely to do something unpleasant to s390. > >> > (Maintainers are cc'd -- I don't know what to do about it.) > >> > >> This changes the semantics of vring and breaks existing guests when > >> bus address != physical address. > > > > Isn't that what this is suppose to fix? Right now the semantics of the > > vring is that bus address == physical address. > > Today the assumption is that the device emulation code has access to > guest physical memory (no translation necessary). Right. > > Changing the semantics breaks today's guests. You need to make this > change in a way so that existing guests don't break. Well, the DMA API will preserve that semantic as under KVM it will return phys == bus. But that is a side-effect of the DMA API implementation preserving this semantic so I understand your point. > > Stefan -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
