Ira Weiny wrote: [..] > > The distinction is "can this DPA capacity be allocated to a region" the > > new holes introduced by DCD are cases where the partition size is > > greater than the allocatable size. Contrast to ram and pmem the > > allocatable size is always identical to the partition size. > > I still don't quite get what you are saying. The user can always allocate > a region of the full DCD partition size. It is just that the memory Quick note: "region of the full DCD partition size" means something to me immediately where "region of full DC region size" would tempt a clarifying question. > within that region may not be backed yet (no extents). A partition is a boundary between DPA capacity ranges of different operation modes / performance characteristics. A region is constructed of decoders that reference decode length. The usable capacity of that decode range, even when fully populated with extents, may be less than the decode range of the decoder / partition. That is similar in concept to the low-memory-hole where the decoders map more in their range than the usable capacity seen by the region. [..] > > > > Linux is not obligated to follow the questionable naming decisions of > > > > specifications. > > > > > > We are not. But as Alejandro says it can be confusing if we don't make > > > some association to the spec. > > > > > > What do you think about the HW/SW line I propose above? > > > > Rename to cxl_dc_partition_info and drop the region_ prefixes, sure. > > > > Otherwise, for this init-time only concern I would much rather deal with > > the confusion of: > > > > "why does Linux call this partition when the spec calls it region?": > > But this is not the question I will get. The question will be. > > "Where is DCD region processed in the code? I grepped for region and > found nothing." Make grep find that definition: $ git grep -n -C2 -i "dc region" Documentation/driver-api/cxl/memory-devices.rst-387- Documentation/driver-api/cxl/memory-devices.rst-388-partition: a span of DPA capacity delineated by "Get Partition Info", or Documentation/driver-api/cxl/memory-devices.rst:389:"Get Dynamic Capacity Configuration". A "DC Region" is equivalent to a > Or > > "I'm searching the spec PDF for DCD partition and can't find that. Where > is DCD partition specified?" If they are coming from the code first that's why we have spec reference comments in the code.
