netboot.com is ignoring the gw= tag. it is only using the bp_giaddr
field to set the gateway, which is fine if you boot thru a bootp gatway
or off an HP box :-) the rfc sez that field is for bootp gatways but
HP fills it in anyhow (rfc doesn't say no....)
add starting at line 578 in /usr/src/sys/i386/boot/netboot/main.c
this will cause the gw= tag to overide bp_giaddr.
(especially useful when bp_giaddr = 0.0.0.0
Attempt to use a gateway before routed is started (say to mount /usr)
bootp server running on non hp box. (say freebsd)
Added suggested code. Not tested, presumed OK.