On Sat, Sep 19, 2020 at 04:22:35PM -0300, Jason Gunthorpe wrote: > On Sat, Sep 19, 2020 at 07:27:30PM +0200, Greg Kroah-Hartman wrote: > > > It's probably heresy, but why do I need to integrate into the RDMA subsystem ? > > > I understand your reasoning about networking (Ethernet) as the driver > > > connects to the kernel networking stack (netdev), but with RDMA the > > > driver doesn't use or connect to anything in that stack. If I were to > > > support IBverbs and declare that I support it, then of course I would > > > need to integrate to the RDMA subsystem and add my backend to > > > rdma-core. > > > > IBverbs are horrid and I would not wish them on anyone. Seriously. > > I'm curious what drives this opinion? Did you have it since you > reviewed the initial submission all those years ago? As I learned more about that interface, yes, I like it less and less :) But that's the userspace api you all are stuck with, for various reasons, my opinion doesn't matter here. > > I think the general rdma apis are the key here, not the userspace api. > > Are you proposing that habana should have uAPI in drivers/misc and > present a standard rdma-core userspace for it? This is the only > userspace programming interface for RoCE HW. I think that would be > much more work. > > If not, what open source userspace are you going to ask them to > present to merge the kernel side into misc? I don't think that they have a userspace api to their rdma feature from what I understand, but I could be totally wrong as I do not know their hardware at all, so I'll let them answer this question. > > Note, I do not know exactly what they are, but no, IBverbs are not ok. > > Should we stop merging new drivers and abandon the RDMA subsystem? Is > there something you'd like to see fixed? > > Don't really understand your position, sorry. For anything that _has_ to have a userspace RMDA interface, sure ibverbs are the one we are stuck with, but I didn't think that was the issue here at all, which is why I wrote the above comments. thanks, greg k-h
