On Mon, Oct 16, 2023 at 03:17:16PM +0200, Christoph Hellwig wrote: > On Mon, Oct 16, 2023 at 01:49:41PM +0100, Conor Dooley wrote: > > Hey, > > > > On Mon, Oct 16, 2023 at 07:47:43AM +0200, Christoph Hellwig wrote: > > > RISCV_NONSTANDARD_CACHE_OPS is also used for the pmem cache maintenance > > > helpers, which are built into the kernel unconditionally. > > > > You surely have better insight than I do here, but is this actually > > required? > > This patch seems to allow creation of a kernel where the cache > > maintenance operations could be used for pmem, but would be otherwise > > unavailable, which seems counter intuitive to me. > > > > Why would someone want to provide the pmem helpers with cache > > maintenance operations, but not provide them generally? > > > > Even if all your periphals are cache coherent (very common on server > class hardware) you still need cache maintenance for pmem. No need > to force the extra text size and runtime overhead for non-coherent DMA. Ah, right. > > I also don't really understand what the unconditional nature of the pmem > > helpers has to do with anything, as this patch does not unconditionally > > provide any cache management operations, only relax the conditions under > > which the non-standard cache management operations can be provided. > > They simply were broken if a platform had non-standard cache mem but > only coherent DMA before. That's probably more a theoretical than > practial case, but still worth fixing. And this part of it makes more sense with the above use-case explained. Acked-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> Thanks, Conor.
Attachment:
signature.asc
Description: PGP signature
