"cpuset -n prefer:?" --what values for "?" are supposed to be allowed? (only 1 is, despite two numa domains)

In a context with:

# cpuset -g
pid -1 mask: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27
pid -1 domain policy: first-touch mask: 0, 1

I get:

# cpuset -l0 -n prefer:0 COMMAND
cpuset: setdomain: Invalid argument

# cpuset -l0 -n prefer:2 COMMAND
cpuset: setdomain: Invalid argument

But one prefer:? value does allow the COMMAND
to run:

# cpuset -l0 -n prefer:1 COMMAND

This seem odd to me. Am I missing something?

For reference: I'm using a ThreadRipper 1950X
with a head -r351227 based context for this
activity. The above happens to have been run
in a Windows 10 Pro HyperV session, instead
of in a native-boot of the same media. (A
native-boot would have had 32 CPUs.)


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)