Re: [PATCH 09/26] cxl/region: Add Dynamic Capacity CXL region support

[Jonathan Cameron]

On Sun, 24 Mar 2024 16:18:12 -0700
ira.weiny@xxxxxxxxx wrote:

> From: Navneet Singh <navneet.singh@xxxxxxxxx>
> 
> CXL devices optionally support dynamic capacity.  CXL Regions must be
> configured correctly to access this capacity.  Similar to ram and pmem
> partitions, DC Regions, as they are called in CXL 3.1, represent
> different partitions of the DPA space.
> 
> Introduce the concept of a sparse DAX region.  Add the create_dc_region
> sysfs entry to create sparse DC DAX regions.  Special case DC capable
> regions to create a 0 sized seed DAX device to maintain backwards
> compatibility with older software which needs a default DAX device to
> hold the region reference.
> 
> Flag sparse DAX regions to indicate 0 capacity available until such time
> as DC capacity is added.
> 
> Interleaving is deferred in this series.  Add an early check.
> 
> Signed-off-by: Navneet Singh <navneet.singh@xxxxxxxxx>
> Co-developed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
With the -EBUSY others addressed LGTM.  Fan's duplication comment
might be something to tidy up later.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>