Added 2nd CPU, not showing in sysctl


I have a pfsense box which is running FreeBSD 7.2-RELEASE-p5. It is virtualised and was having performance problems so I have shut it down, added a 2nd CPU and booted it back up again. I also increased the RAM to 1Gb.

If I run sysctl hw I see hw.ncpu is still 1 and looking in dmesg I can only see 1 cpu being initialised. It has picked up the RAM change no problem.

Is there anything I can do to get FreeBSD to recognise the 2nd CPU, short of a re-install?

It suppose, your post lacks some information. For example, board specification which allows installation of the second CPU.
What I can note is that your version of FreeBSD is old enough and unsupported anymore. Also, I don't remember if the SMP kernel option was default in that time. It is mandatory for the second CPU to work.
Anyway, you can get some information about board out of
/var/run/dmesg.boot and, of course, 7.2 is too old.