mp.isextra = true
	// mark we are in C by default.
	mp.isExtraInC = true
	mp.lockedInt++
	mp.lockedg.set(gp)
	gp.lockedm.set(mp)
	gp.goid = sched.goidgen.Add(1)
	if raceenabled {
		gp.racectx = racegostart(abi.FuncPCABIInternal(newextram) + sys.PCQuantum)
	}
	// put on allg for garbage collector
	allgadd(gp)

	// gp is now on the allg list, but we don't want it to be