…hit me again (in a positive way). i was experimenting in my lab and wanted to define a lot of queues (and i mean a lot of them) in ALTQ. unfortunately, very quickly during parsing of pf.conf pfctl barked out following information:

pfctl: DIOCADDALTQ: Cannot allocate memory

to overcome the problem, you only need to modify those three files:

/usr/include/altq/altq_hfsc.h
/usr/src/sbin/pfctl/missing/altq/altq_hfsc.h
/usr/src/sys/contrib/altq/altq/altq_hfsc.h

where #define HFSC_MAX_CLASSES 64 is defined - to requested value. then rebuild the kernel and everything should work as expected.