Index: kernel/arch/ppc64/src/asm.S
===================================================================
--- kernel/arch/ppc64/src/asm.S	(revision e32e092d6f8bed442ecc81b18af9ef323bc4e650)
+++ kernel/arch/ppc64/src/asm.S	(revision 4e4052b81a9a4f4f15b01ef935279bd8084d750d)
@@ -67,4 +67,8 @@
 	mr sp, r4
 	
+	# %r3 is defined to hold pcb_ptr - set it to 0
+
+	xor r3, r3, r3
+
 	# jump to userspace