create a linux server with 0 swap
create an item for example system.swap.size[,free]
the item will become unsupported and return
system.swap.size[,free] [m|ZBX_NOTSUPPORTED] [Cannot be calculated because swap file size is 0.]
so preprocessing cant be used
i would have expected to have seen the value of 0
as this is what linux returns to me when running free
total used free shared buff/cache available
Mem: 1998 408 509 123 1081 1283
Swap: 0 0 0
apparently agent items sending out wrong information to the zabbix server is a feature and not a bug so here is my feature request.
make the items send the value of 0 to the agent so that preprocessing can be done
or create a special value that indicates that no swap is installed on the system.