ThreadContext is the external interface to all thread state for anything outside of the CPU...
Defines global host-dependent types: Counter, Tick, and (indirectly) {int,uint}{8,16,32,64}_t.
Addr mmap(ThreadContext *tc, Addr start, uint64_t length, int prot, int tgtFlags, int tgtFd, int offset)
Currently, mmap() will simply setup a mapping for the associated device's packet processor's doorbell...