it seems to me that if some driver depends upon altq, then altq should simply always refuse to unload if a driver is loaded that depends upon it. this should be an explicit dependency, and probably implicit via symbols.
if, say there's a fully modular system with two NICs, and only one of them supports altq. only one of the NIC drivers will declare a dep on altq, blocking the unload of altq while the driver remains loaded. if this isn't already the case, can we arrange it to be? .mrg.
