On Sun, Sep 11, 2016 at 11:52:35AM -0600, Jason Gunthorpe wrote: > On Sun, Sep 11, 2016 at 07:24:45PM +0200, Christoph Hellwig wrote: > > > > > I've posted some initial work toward a) a while ago, and once we > > > > > > Did it get merged? Do you have a pointer? > > > > http://www.spinics.net/lists/linux-rdma/msg31958.html > > Right, I remember that. Certainly the right direction > > > > However, everything under verbs is not straightforward. The files in > > > userspace are not copies... > > > > > > user: > > > > > > struct ibv_query_device { > > > __u32 command; > > > __u16 in_words; > > > __u16 out_words; > > > __u64 response; > > > __u64 driver_data[0]; > > > }; > > > > > > kernel: > > > > > > struct ib_uverbs_query_device { > > > __u64 response; > > > __u64 driver_data[0]; > > > }; > > > > We'll obviously need different strutures for the libibvers API > > and the kernel interface in this case, and we'll need to figure out > > how to properly translate them. I think a cast, plus compile time > > type checking ala BUILD_BUG_ON is the way to go. > > I'm not sure I follow, which would I cast? > > BUILD_BUG_ON(sizeof(ibv_query_device) == sizeof(ib_uverbs_cmd_hdr) + > sizeof(ib_uverbs_query_device)) > > ? > > > > I'm thinking the best way forward might be to use a script and > > > transform userspace into: > > > > > > struct ibv_query_device { > > > struct ib_uverbs_cmd_hdr hdr; > > > struct ib_uverbs_query_device cmd; > > > }; > > > > That would break the users of the interface. > > Sorry, I mean doing this inside rdma-plumbing. Since the change is ABI > identical the modified libibverbs would still be binary compatible > with all providers but not source compatible. Since all kernel > supported providers are in rdma-plumbing we can add the '.cmd.' at the > same time. > > The kernel uapi header would stay the same. > > > However automatically generating the user ABI from the kernel one > > might still be a good idea in the long run. > > My preference would be to try and use the kernel headers directly. I thought the same, especially after realizing that they are almost copy/paste from the vendor *-abi.h files. > > Jason
Attachment:
signature.asc
Description: PGP signature
