ipmitool and freeipmi don't see the same sensors

Solution 1:

I just found out that --bridge-sensors helps (ipmi-sensors --bridge-sensors).
From the man pages:

Some sensors may have a sensor reading or sensor event of "N/A" if the information is unavailable. This is typical of a sensor that is not enabled or not owned by a BMC. Please see --bridge-sensors option below to deal with sensors not owned by a BMC

Solution 2:

FreeIPMI maintainer here. Please try the workaround flag "-W discretereading" for ipmi-sensors. HP motherboards have a well known issue where they define a large number of sensors illegally. It's also possible other workaround flags may help as well, you can find a list in the ipmi-sensors manpage.