On 10/01/2015 12:42 PM, Vincent JARDIN wrote: > On 01/10/2015 11:22, Avi Kivity wrote: >>> As far as I could see, without this kind of motivation, people do not >>> even want to try. >> >> You are mistaken. The problem is a lot harder than you think. >> >> People didn't go and write userspace drivers because they were lazy. >> They wrote them because there was no other way. > > I disagree, it is possible to write a 'partial' userspace driver. > > Here it is an example: > http://dpdk.org/browse/dpdk/tree/drivers/net/mlx4 > > It benefits of the kernel's capabilities while the userland manages > only the IOs. >
That is because the device itself contains an iommu. > There were some tentative to get it for other (older) drivers, named > 'bifurcated drivers', but it is stalled. IIRC they still exposed the ring to userspace.
