Index: oea_machdep.c
===================================================================
RCS file: /cvsroot/src/sys/arch/powerpc/oea/oea_machdep.c,v
retrieving revision 1.73
diff -p -u -r1.73 oea_machdep.c
--- oea_machdep.c	30 May 2016 13:04:24 -0000	1.73
+++ oea_machdep.c	10 Feb 2018 11:08:02 -0000
@@ -144,7 +144,11 @@ oea_init(void (*handler)(void))
 #ifdef PPC_HIGH_VEC
 	exc_base = EXC_HIGHVEC;
 #else
-	exc_base = 0;
+	/*
+	 * Load "pointer" with 0 behind GCC's back, otherwise it will
+	 * emit a "trap" instead.
+	 */
+	__asm volatile ("li %0, 0" : "=r"(exc_base) :);
 #endif
 	KASSERT(mfspr(SPR_SPRG0) == (uintptr_t)ci);
 
@@ -289,8 +293,15 @@ oea_init(void (*handler)(void))
 	 * Install a branch absolute to trap0 to force a panic.
 	 */
 	if ((uintptr_t)trap0 < 0x2000000) {
-		*(volatile uint32_t *) 0 = 0x7c6802a6;
-		*(volatile uint32_t *) 4 = 0x48000002 | (uintptr_t) trap0;
+		uint32_t *p;
+
+		/*
+		 * Load "pointer" with 0 behind GCC's back, otherwise it will
+		 * emit a "trap" instead.
+		 */
+		__asm volatile ("li %0, 0" : "=r"(p) :);
+		p[0] = 0x7c6802a6;
+		p[1] = 0x48000002 | (uintptr_t) trap0;
 	}
 
 	/*