Hi, On 4/16/21 4:05 PM, Jason Gunthorpe wrote: > On Fri, Apr 16, 2021 at 03:38:02PM +0200, Auger Eric wrote: > >> The redesign requirement came pretty late in the development process. >> The iommu user API is upstream for a while, the VFIO interfaces have >> been submitted a long time ago and under review for a bunch of time. >> Redesigning everything with a different API, undefined at this point, is >> a major setback for our work and will have a large impact on the >> introduction of features companies are looking forward, hence our >> frustration. > > I will answer both you and Jacob at once. > > This is uAPI, once it is set it can never be changed. > > The kernel process and philosophy is to invest heavily in uAPI > development and review to converge on the best uAPI possible. > > Many past submissions have take a long time to get this right, there > are several high profile uAPI examples. > > Do you think this case is so special, or the concerns so minor, that it > should get to bypass all of the normal process? That's not my intent to bypass any process. I am just trying to understand what needs to be re-designed and for what use case. > > Ask yourself, is anyone advocating for the current direction on > technical merits alone? > > Certainly the patches I last saw where completely disgusting from a > uAPI design perspective. > > It was against the development process to organize this work the way > it was done. Merging a wack of dead code to the kernel to support a > uAPI vision that was never clearly articulated was a big mistake. > > Start from the beginning. Invest heavily in defining a high quality > uAPI. Clearly describe the uAPI to all stake holders. This was largely done during several confs including plumber, KVM forum, for several years. Also API docs were shared on the ML. I don't remember any voice was raised at those moments. Break up the > implementation into patch series without dead code. Make the > patches. Remove the dead code this group has already added. > > None of this should be a surprise. The VDPA discussion and related > "what is a mdev" over a year ago made it pretty clear VFIO is not the > exclusive user of "IOMMU in userspace" and that places limits on what > kind of uAPIs expansion it should experience going forward. Maybe clear for you but most probably not for many other stakeholders. Anyway I do not intend to further argue and I will be happy to learn from you and work with you, Jacob, Liu and all other stakeholders to define a better integration. Thanks Eric > > Jason >
