--- ./src/promemul/yamon.c.orig	Sat May  5 14:02:45 2007
+++ ./src/promemul/yamon.c	Sat May  5 16:43:21 2007
@@ -188,17 +188,47 @@
 		    CACHE_DATA | NO_EXCEPTIONS);
 		break;
 
-	case YAMON_SYSCON_READ_OFS:
+	case YAMON_SYSCON_READ_OFS: {
 		/*
-		 *  syscon
+		 *  syscon_read(oid [a0], addr [a1], size [a2])
 		 */
-		fatal("[ yamon_emul(): syscon: TODO ]\n");
+		uint32_t	 oid;
+		void		*paddr;
+		uint32_t	 psize;
 
-		/*  TODO. For now, return some kind of "failure":  */
-		cpu->cd.mips.gpr[MIPS_GPR_V0] = 1;
+		oid = cpu->cd.mips.gpr[MIPS_GPR_A0];
+		paddr = (void *)(intptr_t)cpu->cd.mips.gpr[MIPS_GPR_A1];
+		psize = cpu->cd.mips.gpr[MIPS_GPR_A2];
+
+		switch (oid) {
+		case SYSCON_BOARD_CPU_CLOCK_FREQ_ID:
+			if (psize == sizeof(uint32_t)) {
+				uint32_t freq = cpu->machine->emulated_hz;
+
+				debug("[ yamon_emul(): reporting CPU "
+				      "frequency of %u ]\n", freq);
+
+				cpu->memory_rw(cpu, cpu->mem, (int32_t)paddr,
+				    (void *)&freq, sizeof(freq),
+				    MEM_WRITE, CACHE_DATA | NO_EXCEPTIONS);
+
+				cpu->cd.mips.gpr[MIPS_GPR_V0] = 0;
+				break;
+			} else {
+				cpu->cd.mips.gpr[MIPS_GPR_V0] = 1;
+			}
+			break;
+		default:
+			fatal("[ yamon_emul(): unimplemented object id 0x%"
+			    PRIx32" ]\n", oid);
+			cpu->cd.mips.gpr[MIPS_GPR_V0] = 1;
+			break;
+		} /* oid */
+	} /* read ofs */
 		break;
 
-	default:cpu_register_dump(cpu->machine, cpu, 1, 0);
+	default:
+		cpu_register_dump(cpu->machine, cpu, 1, 0);
 		printf("\n");
 		fatal("[ yamon_emul(): unimplemented yamon function 0x%"
 		    PRIx32" ]\n", ofs);