>I believe uSPARC-2 support is now in the 1.2 release branch.

That turns to not be completely the case. Partial MicroSPARC-II
support, perhaps. However, sys/arch/sparc/sparc/pmap.c:pmap_enter4m()
has the fragment






	/* Initialise pteproto with cache bit */
	pteproto = (pa & PMAP_NC) == 0 ? SRMMU_PG_C : 0;

	if (pa & PMAP_TYPE4M) {		/* this page goes in an iospace */
		if (cpumod == SUN4M_MS)
			panic("pmap_enter4m: attempt to use 36-bit iospace on"
			      " MicroSPARC");
		pteproto |= (pa & PMAP_TYPE4M) << PMAP_PTESHFT4M;
	}

which is precisely the panic i encountered. That doesn't look
like MicroSPARC support to me...