--- /sys/src/9k/port/fault.c
+++ /sys/src/9k/port/fault.c
@@ -177,7 +177,11 @@ fixfault(Segment *s, uintptr addr, int read, int dommuput)
 
 		if (checkaddr && addr == addr2check)
 			(*checkaddr)(addr, s, *pg);
-		mmuphys = PPN((*pg)->pa) |PTEWRITE|PTEUNCACHED|PTEVALID;
+		mmuphys = PPN((*pg)->pa) | PTEVALID;
+		if((s->pseg->attr & SG_RONLY) == 0)
+			mmuphys |= PTEWRITE;
+		if((s->pseg->attr & SG_CACHED) == 0)
+			mmuphys |= PTEUNCACHED;
 		(*pg)->modref = PG_MOD|PG_REF;
 		break;
 	}
--- /sys/src/9k/port/portdat.h
+++ /sys/src/9k/port/portdat.h
@@ -360,6 +360,7 @@ enum
 	SG_SHARED	= 04,
 	SG_PHYSICAL	= 05,
 
+	SG_CACHED	= 0020,		/* Physseg can be cached */
 	SG_RONLY	= 0040,		/* Segment is read only */
 	SG_CEXEC	= 0100,		/* Detach at exec */
 };