Re: [PATCH v6 5/7] cxl/region: Add extent output to region query

[Richard Cheng <icheng@nvidia.com>]

On Mon, Jun 08, 2026 at 05:08:19PM +0800, Dave Jiang wrote:
> 
> 
> On 5/23/26 2:50 AM, Anisa Su wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> > 
> > DCD regions have 0 or more extents.  The ability to list those and their
> > properties is useful to end users.
> > 
> > Add an option for extent output to region queries.  An example of this
> > is:
> > 
> > 	$ ./build/cxl/cxl list -r 8 -Nu
> > 	{
> > 	  "region":"region8",
> > 	  ...
> > 	  "type":"dc",
> > 	  ...
> > 	  "extents":[
> > 	    {
> > 	      "offset":"0x10000000",
> > 	      "length":"64.00 MiB (67.11 MB)",
> > 	      "tag":"00000000-0000-0000-0000-000000000000"
> 
> I think the code emits "uuid". Update commit log.
> > 	    },
> > 	    {
> > 	      "offset":"0x8000000",
> > 	      "length":"64.00 MiB (67.11 MB)",
> > 	      "tag":"00000000-0000-0000-0000-000000000000"
> 
> same here
> 
> DJ
> 
> > 	    }
> > 	  ]
> > 	}
> > 
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> > 
> > ---
> > Changes:
> > [iweiny: s/tag/uuid/]
> > ---
> >  Documentation/cxl/cxl-list.txt | 29 +++++++++++++++++++++
> >  cxl/filter.h                   |  3 +++
> >  cxl/json.c                     | 47 ++++++++++++++++++++++++++++++++++
> >  cxl/json.h                     |  3 +++
> >  cxl/list.c                     |  3 +++
> >  util/json.h                    |  1 +
> >  6 files changed, 86 insertions(+)
> > 
> > diff --git a/Documentation/cxl/cxl-list.txt b/Documentation/cxl/cxl-list.txt
> > index 193860b..7512687 100644
> > --- a/Documentation/cxl/cxl-list.txt
> > +++ b/Documentation/cxl/cxl-list.txt
> > @@ -426,6 +426,35 @@ OPTIONS
> >  }
> >  ----
> >  
> > +-N::
> > +--extents::
> > +	Append Dynamic Capacity extent information.
> > +----
> > +13:34:28 > ./build/cxl/cxl list -r 8 -Nu
> > +{
> > +  "region":"region8",
> > +  "resource":"0xf030000000",
> > +  "size":"512.00 MiB (536.87 MB)",
> > +  "type":"dc",
> > +  "interleave_ways":1,
> > +  "interleave_granularity":256,
> > +  "decode_state":"commit",
> > +  "extents":[
> > +    {
> > +      "offset":"0x10000000",
> > +      "length":"64.00 MiB (67.11 MB)",
> > +      "uuid":"00000000-0000-0000-0000-000000000000"
> > +    },
> > +    {
> > +      "offset":"0x8000000",
> > +      "length":"64.00 MiB (67.11 MB)",
> > +      "uuid":"00000000-0000-0000-0000-000000000000"
> > +    }
> > +  ]
> > +}
> > +----
> > +
> > +
> >  -r::
> >  --region::
> >  	Specify CXL region device name(s), or device id(s), to filter the listing.
> > diff --git a/cxl/filter.h b/cxl/filter.h
> > index 70463c4..30e7fe2 100644
> > --- a/cxl/filter.h
> > +++ b/cxl/filter.h
> > @@ -31,6 +31,7 @@ struct cxl_filter_params {
> >  	bool alert_config;
> >  	bool dax;
> >  	bool media_errors;
> > +	bool extents;
> >  	int verbose;
> >  	struct log_ctx ctx;
> >  };
> > @@ -93,6 +94,8 @@ static inline unsigned long cxl_filter_to_flags(struct cxl_filter_params *param)
> >  		flags |= UTIL_JSON_DAX | UTIL_JSON_DAX_DEVS;
> >  	if (param->media_errors)
> >  		flags |= UTIL_JSON_MEDIA_ERRORS;
> > +	if (param->extents)
> > +		flags |= UTIL_JSON_EXTENTS;
> >  	return flags;
> >  }
> >  
> > diff --git a/cxl/json.c b/cxl/json.c
> > index e94c809..7922b32 100644
> > --- a/cxl/json.c
> > +++ b/cxl/json.c
> > @@ -1022,6 +1022,50 @@ void util_cxl_mappings_append_json(struct json_object *jregion,
> >  	json_object_object_add(jregion, "mappings", jmappings);
> >  }
> >  
> > +void util_cxl_extents_append_json(struct json_object *jregion,
> > +				  struct cxl_region *region,
> > +				  unsigned long flags)
> > +{
> > +	struct json_object *jextents;
> > +	struct cxl_region_extent *extent;
> > +
> > +	jextents = json_object_new_array();
> > +	if (!jextents)
> > +		return;
> > +
> > +	cxl_extent_foreach(region, extent) {

Every region rendered with the flag, including non-DC RAM/PMEM regions.
They all get a spurious "extents": [].
I would suggest guarding on cxl_extent_get_first(region) != NULL before
adding the key.

What do you think?

Best regards,
Richard Cheng.

> > +		struct json_object *jextent, *jobj;
> > +		unsigned long long val;
> > +		char uuid_str[40];
> > +		uuid_t uuid;
> > +
> > +		jextent = json_object_new_object();
> > +		if (!jextent)
> > +			continue;
> > +
> > +		val = cxl_extent_get_offset(extent);
> > +		jobj = util_json_object_hex(val, flags);
> > +		if (jobj)
> > +			json_object_object_add(jextent, "offset", jobj);
> > +
> > +		val = cxl_extent_get_length(extent);
> > +		jobj = util_json_object_size(val, flags);
> > +		if (jobj)
> > +			json_object_object_add(jextent, "length", jobj);
> > +
> > +		cxl_extent_get_uuid(extent, uuid);
> > +		uuid_unparse(uuid, uuid_str);
> > +		jobj = json_object_new_string(uuid_str);
> > +		if (jobj)
> > +			json_object_object_add(jextent, "uuid", jobj);
> > +
> > +		json_object_array_add(jextents, jextent);
> > +		json_object_set_userdata(jextent, extent, NULL);
> > +	}
> > +
> > +	json_object_object_add(jregion, "extents", jextents);
> > +}
> > +
> >  struct json_object *util_cxl_region_to_json(struct cxl_region *region,
> >  					     unsigned long flags)
> >  {
> > @@ -1126,6 +1170,9 @@ struct json_object *util_cxl_region_to_json(struct cxl_region *region,
> >  		}
> >  	}
> >  
> > +	if (flags & UTIL_JSON_EXTENTS)
> > +		util_cxl_extents_append_json(jregion, region, flags);
> > +
> >  	if (cxl_region_qos_class_mismatch(region)) {
> >  		jobj = json_object_new_boolean(true);
> >  		if (jobj)
> > diff --git a/cxl/json.h b/cxl/json.h
> > index eb7572b..f9c07ab 100644
> > --- a/cxl/json.h
> > +++ b/cxl/json.h
> > @@ -20,6 +20,9 @@ struct json_object *util_cxl_region_to_json(struct cxl_region *region,
> >  void util_cxl_mappings_append_json(struct json_object *jregion,
> >  				  struct cxl_region *region,
> >  				  unsigned long flags);
> > +void util_cxl_extents_append_json(struct json_object *jregion,
> > +				  struct cxl_region *region,
> > +				  unsigned long flags);
> >  void util_cxl_targets_append_json(struct json_object *jdecoder,
> >  				  struct cxl_decoder *decoder,
> >  				  const char *ident, const char *serial,
> > diff --git a/cxl/list.c b/cxl/list.c
> > index 0b25d78..47d1351 100644
> > --- a/cxl/list.c
> > +++ b/cxl/list.c
> > @@ -59,6 +59,8 @@ static const struct option options[] = {
> >  		    "include alert configuration information"),
> >  	OPT_BOOLEAN('L', "media-errors", &param.media_errors,
> >  		    "include media-error information "),
> > +	OPT_BOOLEAN('N', "extents", &param.extents,
> > +		    "include extent information (Dynamic Capacity regions only)"),
> >  	OPT_INCR('v', "verbose", &param.verbose, "increase output detail"),
> >  #ifdef ENABLE_DEBUG
> >  	OPT_BOOLEAN(0, "debug", &debug, "debug list walk"),
> > @@ -135,6 +137,7 @@ int cmd_list(int argc, const char **argv, struct cxl_ctx *ctx)
> >  		param.decoders = true;
> >  		param.targets = true;
> >  		param.regions = true;
> > +		param.extents = true;
> >  		/*fallthrough*/
> >  	case 0:
> >  		break;
> > diff --git a/util/json.h b/util/json.h
> > index 560f845..79ae324 100644
> > --- a/util/json.h
> > +++ b/util/json.h
> > @@ -21,6 +21,7 @@ enum util_json_flags {
> >  	UTIL_JSON_TARGETS	= (1 << 11),
> >  	UTIL_JSON_PARTITION	= (1 << 12),
> >  	UTIL_JSON_ALERT_CONFIG	= (1 << 13),
> > +	UTIL_JSON_EXTENTS	= (1 << 14),
> >  };
> >  
> >  void util_display_json_array(FILE *f_out, struct json_object *jarray,
> 
>