+
+#define AST_NONE 0x04000000 /* ast level */
+#define AST_USER 0x03000000 /* ast for user mode */
+
+#define ASTLVL_NONE 4
+#define ASTLVL_USER 3
+
+#define AST_CLR 0x07000000
+
+#define aston() \
+ { \
+ u.u_pcb.pcb_p0lr = (u.u_pcb.pcb_p0lr &~ AST_CLR) | AST_USER; \
+ mtpr(ASTLVL, ASTLVL_USER); \
+ }
+
+#define astoff() \
+ { \
+ u.u_pcb.pcb_p0lr = (u.u_pcb.pcb_p0lr &~ AST_CLR) | AST_NONE; \
+ mtpr(ASTLVL, ASTLVL_NONE); \
+ }