pool: command info prompts are not friendly

[kelvin-qin]

ISSUE: pmempool info prompts are not friendly

Environment Information

• PMDK package version(s): 1.7
• OS(es) version(s): CentOS7.7
• ndctl version(s): 64.1
• kernel version(s): 5.4.6

Reproduction of the bug:

1. Disable and destroy all of devdax's namespace in the environment
2. then,Create a namespace with devdax mode
3. and,This creates a mount point /dev/dax1.1 (or other like dax0.0)
4. Execute the command：pmempool info /dev/dax1.1
5. Get an output of error

How often bug is revealed: (always, often, rare):

• Always

Details

# pmempool info /dev/dax1.1 error: /dev/dax1.1 :unknown pool type – ‘’

But the NameSpace I created is ready and there are no exceptions. so,this content is confusing, You might think there's something wrong with the NS that you created. The user should be told to create a specific pool, or to initialize a pool file, rather than saying it is of unknown type.