Re: [PATCH v6 0/7] ndctl: Dynamic Capacity additions for cxl-cli

[Alison Schofield]

On Sat, May 23, 2026 at 02:50:35AM -0700, Anisa Su wrote:
> CXL Dynamic Capacity Device (DCD) support has continued to evolve in the
> upstream kernel since Ira's v5 posting [1].  The kernel side has settled
> on a uuid-driven claim model for sparse DAX devices: dax_resources carry
> the tag delivered with each extent, and userspace selects which ones to
> claim by writing a UUID to the dax device's sysfs 'uuid' attribute (or
> "0" to claim a single untagged resource).  Size on a sparse region is
> determined by the claim, not requested up-front.
> 
> This series brings cxl-cli and daxctl in line with that model and
> extends cxl_test to exercise the new paths end-to-end.

Hi Anisa,

I just now picked this up with the kernel side and took it for a quick
test drive. Based on what's been touched, first meaningful finding is
all the DAX unit tests pass, and then for CXL unit tests, all but these
2 pass: cxl-security.sh and cxl-dcd.sh

Please let me know if there are known problems with either of those
before I explore further.

Question below about dependency....

> 
> The corresponding kernel patchset is here:
> https://lore.kernel.org/linux-cxl/cover.1779528761.git.anisa.su@xxxxxxxxxxx/T/#t
> 
> Picked up unchanged from v5 (Ira):
> 
>   libcxl: Add Dynamic RAM A partition mode support
>   cxl/region: Add cxl-cli support for dynamic RAM A
>   libcxl: Add extent functionality to DC regions
>   cxl/region: Add extent output to region query
> 
> New in v6:
> 
>   daxctl: Add --uuid option to create-device for DC DAX regions
>     - Plumbs writes to the new dax 'uuid' sysfs attribute through a new
>       daxctl_dev_set_uuid() helper (LIBDAXCTL_11).
>     - --uuid is mutually exclusive with --size; pass "0" to claim a
>       single untagged dax_resource.  An unmatched UUID surfaces ENOENT
>       from the kernel and leaves the device at size 0.
>     - Documents the option in the man page.
> 
>   cxl/test: Add Dynamic Capacity tests (rewritten on top of Ira's
>   original patch to track the post-redesign kernel)
>     - Routes untagged claims via --uuid "0" so daxctl exercises the
>       kernel uuid_store path; tagged claims use real UUID strings.
>     - Asserts that for DC regions, size-grow returns -EOPNOTSUPP (real grow is
>       --uuid only) and that tag reuse across More-chains is rejected
>       by the cross-More uniqueness gate.
>     - Adds coverage for the new validators: test_uuid_no_match,
>       test_uuid_no_match_seed_intact, test_uuid_show,
>       test_cross_more_uniqueness, test_alignment_rejection.
>     - Sharable-partition coverage (test_shared_extent_inject,
>       test_seq_integrity_gap) is routed at runtime to a dedicated mock
>       memdev that tools/testing/cxl stamps with serial 0xDCDC, so a
>       single cxl_test module load exercises both regimes.
>     - Localizes positional-arg assignments in every helper so functions
>       no longer clobber caller globals (the previous behavior leaked
>       the sharable memdev into later tests).
>     - test_reject_overlapping arithmetic now lands an actual overlap
>       inside the DC region (the prior math landed past the end).
> 
> Depends on the kernel DCD/sparse-DAX series; without it the new tests
> will skip and 'cxl list -r N -Nu' will simply report no extents.

What is this dependency- DCD/sparse-DAX series ?

> 
> The branch is also available at:
> 
>   https://github.com/anisa-su993/anisa-ndctl/tree/dcd-2026-05-21
> 
> Based on pmem/pending commit:
> 
>   bbd403a test/cxl-sanitize: avoid sanitize submit/wait race
> 
> [1] https://lore.kernel.org/nvdimm/20250413-dcd-region2-v5-0-fbd753a2e0e8@xxxxxxxxx/
> 
> ---
> Changes in v6:
> - anisa: New patch — daxctl --uuid option + daxctl_dev_set_uuid() helper
> - anisa: Rewrite cxl/test DCD tests against the post-redesign kernel
>          (uuid sysfs claim, tag-group atomic release, cross-More
>          uniqueness, alignment rejection, DC size-grow refusal)
> - anisa: Rebase onto bbd403a (pmem/pending)
> - Link to v5: https://lore.kernel.org/nvdimm/20250413-dcd-region2-v5-0-fbd753a2e0e8@xxxxxxxxx/
> 
> Changes in v5:
> - iweiny: Adjust all code to view only the dynamic RAM A partition
> - Alison: s/tag/uuid/ in region query extent output
> - Link to v4: https://patch.msgid.link/20241214-dcd-region2-v4-0-36550a97f8e2@xxxxxxxxx
> 
> Anisa Su (1):
>   daxctl: Add --uuid option to create-device for DC regions
> 
> Ira Weiny (6):
>   ndctl: Dynamic Capacity additions for cxl-cli
>   libcxl: Add Dynamic RAM A partition mode support
>   cxl/region: Add cxl-cli support for dynamic RAM A
>   libcxl: Add extent functionality to DC regions
>   cxl/region: Add extent output to region query
>   cxl/test: Add Dynamic Capacity tests
> 
>  Documentation/cxl/cxl-list.txt                |   29 +
>  Documentation/cxl/lib/libcxl.txt              |   33 +-
>  Documentation/daxctl/daxctl-create-device.txt |   12 +
>  cxl/filter.h                                  |    3 +
>  cxl/json.c                                    |   67 +
>  cxl/json.h                                    |    3 +
>  cxl/lib/libcxl.c                              |  181 +++
>  cxl/lib/libcxl.sym                            |    9 +
>  cxl/lib/private.h                             |   14 +
>  cxl/libcxl.h                                  |   21 +-
>  cxl/list.c                                    |    3 +
>  cxl/memdev.c                                  |    4 +-
>  cxl/region.c                                  |   27 +-
>  daxctl/device.c                               |   72 +-
>  daxctl/lib/libdaxctl.c                        |   44 +
>  daxctl/lib/libdaxctl.sym                      |    5 +
>  daxctl/libdaxctl.h                            |    1 +
>  test/cxl-dcd.sh                               | 1267 +++++++++++++++++
>  test/meson.build                              |    2 +
>  util/json.h                                   |    1 +
>  20 files changed, 1771 insertions(+), 27 deletions(-)
>  create mode 100644 test/cxl-dcd.sh
> 
> 
> base-commit: bbd403a03fa2a1551c1a10bbf78f32027c718758
> -- 
> 2.43.0
>