Index: sys/powerpc/aim/mmu_radix.c
===================================================================
--- sys/powerpc/aim/mmu_radix.c
+++ sys/powerpc/aim/mmu_radix.c
@@ -2344,6 +2344,7 @@
 		printf("%s done\n", __func__);
 	pmap_bootstrapped = 1;
 	dmaplimit = roundup2(powerpc_ptob(Maxmem), L2_PAGE_SIZE);
+	PCPU_SET(flags, PCPU_GET(flags) | PC_FLAG_NOSRS);
 }
 
 static void
Index: sys/powerpc/aim/trap_subr64.S
===================================================================
--- sys/powerpc/aim/trap_subr64.S
+++ sys/powerpc/aim/trap_subr64.S
@@ -87,6 +87,9 @@
  */
 restore_kernsrs:
 	GET_CPUINFO(%r28)
+	lwz	%r29, PC_FLAGS(%r28)
+	mtcr	%r29
+	btlr	0
 	addi	%r28,%r28,PC_KERNSLB
 	ld	%r29,16(%r28)		/* One past USER_SLB_SLOT */
 	cmpdi	%r29,0
@@ -270,9 +273,13 @@
 	std	%r29,(savearea+CPUSAVE_R29)(%r3);			\
 	std	%r30,(savearea+CPUSAVE_R30)(%r3);			\
 	std	%r31,(savearea+CPUSAVE_R31)(%r3);			\
+	lwz	%r28,PC_FLAGS(%r3);					\
+	mtcr	%r28;							\
+	bt	0, 0f;	/* Check to skip restoring SRs. */		\
 	mflr	%r27;			/* preserve LR */		\
 	bl	restore_usersrs;	/* uses r28-r31 */		\
 	mtlr	%r27;							\
+0:									\
 	ld	%r31,(savearea+CPUSAVE_R31)(%r3);			\
 	ld	%r30,(savearea+CPUSAVE_R30)(%r3);			\
 	ld	%r29,(savearea+CPUSAVE_R29)(%r3);			\
Index: sys/powerpc/include/pcpu.h
===================================================================
--- sys/powerpc/include/pcpu.h
+++ sys/powerpc/include/pcpu.h
@@ -50,11 +50,12 @@
 	int		pc_bsp;						\
 	volatile int	pc_awake;					\
 	uint32_t	pc_ipimask;					\
+	uint32_t	pc_flags;		/* cpu feature flags */ \
 	register_t	pc_tempsave[CPUSAVE_LEN];			\
 	register_t	pc_disisave[CPUSAVE_LEN];			\
 	register_t	pc_dbsave[CPUSAVE_LEN];				\
 	void		*pc_restore;					\
-	vm_offset_t	pc_qmap_addr;
+	vm_offset_t	pc_qmap_addr;					\
 
 #define PCPU_MD_AIM32_FIELDS						\
 	struct pvo_entry *qmap_pvo;					\
@@ -77,6 +78,9 @@
 #define PCPU_MD_AIM_FIELDS	PCPU_MD_AIM32_FIELDS
 #endif
 
+/* CPU feature flags, can be used for cached flow control. */
+#define	PC_FLAG_NOSRS		0x00000001
+
 #define	BOOKE_CRITSAVE_LEN	(CPUSAVE_LEN + 2)
 #define	BOOKE_TLB_MAXNEST	4
 #define	BOOKE_TLB_SAVELEN	16
Index: sys/powerpc/powerpc/db_interface.c
===================================================================
--- sys/powerpc/powerpc/db_interface.c
+++ sys/powerpc/powerpc/db_interface.c
@@ -91,4 +91,5 @@
 
 	db_printf("PPC: hwref   = %#zx\n", pc->pc_hwref);
 	db_printf("PPC: ipimask = %#x\n", pc->pc_ipimask);
+	db_printf("PPC: flags   = %#x\n", pc->pc_flags);
 }
Index: sys/powerpc/powerpc/genassym.c
===================================================================
--- sys/powerpc/powerpc/genassym.c
+++ sys/powerpc/powerpc/genassym.c
@@ -64,6 +64,7 @@
 ASSYM(PC_DISISAVE, offsetof(struct pcpu, pc_disisave));
 ASSYM(PC_DBSAVE, offsetof(struct pcpu, pc_dbsave));
 ASSYM(PC_RESTORE, offsetof(struct pcpu, pc_restore));
+ASSYM(PC_FLAGS, offsetof(struct pcpu, pc_flags));
 
 #if defined(BOOKE)
 ASSYM(PC_BOOKE_CRITSAVE, offsetof(struct pcpu, pc_booke.critsave));
@@ -106,6 +107,7 @@
 
 ASSYM(MTX_LOCK, offsetof(struct mtx, mtx_lock));
 
+ASSYM(PC_FLAG_NOSRS, PC_FLAG_NOSRS);
 #if defined(AIM)
 ASSYM(USER_ADDR, USER_ADDR);
 #ifdef __powerpc64__
Index: sys/powerpc/powerpc/mp_machdep.c
===================================================================
--- sys/powerpc/powerpc/mp_machdep.c
+++ sys/powerpc/powerpc/mp_machdep.c
@@ -246,6 +246,7 @@
 				printf("Waking up CPU %d (dev=%x)\n",
 				    pc->pc_cpuid, (int)pc->pc_hwref);
 
+			pc->pc_flags = PCPU_GET(flags); /* Copy cached CPU flags */
 			ret = platform_smp_start_cpu(pc);
 			if (ret == 0) {
 				timeout = 2000;	/* wait 2sec for the AP */