> From: Jason Gunthorpe > Sent: Friday, August 14, 2020 9:35 PM > > On Mon, Aug 10, 2020 at 07:32:24AM +0000, Tian, Kevin wrote: > > > > I would prefer to see that the existing userspace interface have the > > > extra needed bits for virtualization (eg by having appropriate > > > internal kernel APIs to make this easy) and all the emulation to build > > > the synthetic PCI device be done in userspace. > > > > In the end what decides the direction is the amount of changes that > > we have to put in kernel, not whether we call it 'emulation'. > > No, this is not right. The decision should be based on what will end > up more maintable in the long run. > > Yes it would be more code to dis-aggregate some of the things > currently only bundled as uAPI inside VFIO (eg your vSVA argument > above) but once it is disaggregated the maintability of the whole > solution will be better overall, and more drivers will be able to use > this functionality. > Disaggregation is an orthogonal topic to the main divergence in this thread, which is passthrough vs. userspace DMA. I gave detail explanation about the difference between the two in last reply. the possibility of dis-aggregating something between passthrough frameworks (e.g. VFIO and vDPA) is not the reason for growing every userspace DMA framework to be a passthrough framework. Doing that is instead hurting maintainability in general... Thanks Kevin
