Index: sys/conf/Makefile.riscv
===================================================================
--- sys/conf/Makefile.riscv
+++ sys/conf/Makefile.riscv
@@ -46,6 +46,8 @@
 CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
 .endif
 
+CFLAGS += -DMACHINE_ARCH=\"${TARGET_ARCH}\"
+
 # hack because genassym.c includes sys/bus.h which includes these.
 genassym.o: bus_if.h device_if.h