On Thu, Apr 30, 2020 at 12:50:40PM -0700, Linus Torvalds wrote: I see your point about the namimg being important. I think Dan's case is indeed "copy from pmem to user" where only options for faulting are #MC on the source addresses, and #PF on the destination. > The only *fundamental* access would likely be a single read/write > operation, not a copy operation. Think "get_user()" instead of > "copy_from_user()". Even there you get combinatorial explosions with > access sizes, but you can often generate those automatically or with > simple patterns, and then you can build up the copy functions from > that if you really need to. That's maybe very clean. But it looks like it would be hard to build a high performance interface on top of that primitive. Remember that for Dan's copy 99.999999999367673%[1] of copies will not hit a machine check on the read from pmem. Dan wants (whatever the function name) to get to a "REP MOVS" with an exception table entry to handle the cases where there is a fault. -Tony [1] Likely several more '9's in there
