Re: [ndctl PATCH 06/15] cxl/list: Skip emitting pmem_size when it is zero

[Alison Schofield <alison.schofield@intel.com>]

On Sun, Nov 06, 2022 at 03:47:20PM -0800, Dan Williams wrote:
> The typical case is that CXL devices are pure ram devices. Only emit
> capacity sizes when they are non-zero to avoid confusion around whether
> pmem is available via partitioning or not.
> 
> Do the same for ram_size on the odd case that someone builds a pure pmem
> device.

Maybe a few more words around what confusion this seeks to avoid.
The confusion being that a user may assign more meaning to the zero
size value than it actually deserves. A zero value for either 
pmem or ram, doesn't indicate the devices capability for either mode.
Use the -I option to cxl list to include paritition info in the
memdev listing. That will explicitly show the ram and pmem capabilities
of the device.


> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  cxl/json.c |   20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/cxl/json.c b/cxl/json.c
> index 63c17519aba1..1b1669ab021d 100644
> --- a/cxl/json.c
> +++ b/cxl/json.c
> @@ -305,7 +305,7 @@ struct json_object *util_cxl_memdev_to_json(struct cxl_memdev *memdev,
>  {
>  	const char *devname = cxl_memdev_get_devname(memdev);
>  	struct json_object *jdev, *jobj;
> -	unsigned long long serial;
> +	unsigned long long serial, size;
>  	int numa_node;
>  
>  	jdev = json_object_new_object();
> @@ -316,13 +316,19 @@ struct json_object *util_cxl_memdev_to_json(struct cxl_memdev *memdev,
>  	if (jobj)
>  		json_object_object_add(jdev, "memdev", jobj);
>  
> -	jobj = util_json_object_size(cxl_memdev_get_pmem_size(memdev), flags);
> -	if (jobj)
> -		json_object_object_add(jdev, "pmem_size", jobj);
> +	size = cxl_memdev_get_pmem_size(memdev);
> +	if (size) {
> +		jobj = util_json_object_size(size, flags);
> +		if (jobj)
> +			json_object_object_add(jdev, "pmem_size", jobj);
> +	}
>  
> -	jobj = util_json_object_size(cxl_memdev_get_ram_size(memdev), flags);
> -	if (jobj)
> -		json_object_object_add(jdev, "ram_size", jobj);
> +	size = cxl_memdev_get_ram_size(memdev);
> +	if (size) {
> +		jobj = util_json_object_size(size, flags);
> +		if (jobj)
> +			json_object_object_add(jdev, "ram_size", jobj);
> +	}
>  
>  	if (flags & UTIL_JSON_HEALTH) {
>  		jobj = util_cxl_memdev_health_to_json(memdev, flags);
>