MFC r198868, r198950:

Opteron rev E family of processor expose a bug where acq memory barriers
can be broken, resulting in random breakages.
Printout a warning message if affected family and model are found.

Approved by:	re (kib)

2 files changed, 30 insertions, 0 deletions

diff --git a/sys/amd64/amd64/identcpu.c b/sys/amd64/amd64/identcpu.c
index 2c1b804affd8..19ddd96d9075 100644
--- a/sys/amd64/amd64/identcpu.c
+++ b/sys/amd64/amd64/identcpu.c
@@ -607,6 +607,21 @@ print_AMD_info(void)
 		printf(", %d lines/tag", (regs[2] >> 8) & 0x0f);
 		print_AMD_l2_assoc((regs[2] >> 12) & 0x0f);	
 	}
+
+	/*
+	 * Opteron Rev E shows a bug as in very rare occasions a read memory 
+	 * barrier is not performed as expected if it is followed by a 
+	 * non-atomic read-modify-write instruction.  
+	 * As long as that bug pops up very rarely (intensive machine usage
+	 * on other operating systems generally generates one unexplainable 
+	 * crash any 2 months) and as long as a model specific fix would be
+	 * impratical at this stage, print out a warning string if the broken
+	 * model and family are identified.
+	 */
+	if (CPUID_TO_FAMILY(cpu_id) == 0xf && CPUID_TO_MODEL(cpu_id) >= 0x20 &&
+	    CPUID_TO_MODEL(cpu_id) <= 0x3f)
+		printf("WARNING: This architecture revision has known SMP "
+		    "hardware bugs which may cause random instability\n");
 }
 
 static void
diff --git a/sys/i386/i386/identcpu.c b/sys/i386/i386/identcpu.c
index af0da5b28b98..cde12eb0ccdb 100644
--- a/sys/i386/i386/identcpu.c
+++ b/sys/i386/i386/identcpu.c
@@ -1303,6 +1303,21 @@ print_AMD_info(void)
 			    (amd_whcr & 0x0100) ? "Enable" : "Disable");
 		}
 	}
+
+	/*
+	 * Opteron Rev E shows a bug as in very rare occasions a read memory
+	 * barrier is not performed as expected if it is followed by a
+	 * non-atomic read-modify-write instruction.
+	 * As long as that bug pops up very rarely (intensive machine usage
+	 * on other operating systems generally generates one unexplainable
+	 * crash any 2 months) and as long as a model specific fix would be
+	 * impratical at this stage, print out a warning string if the broken
+	 * model and family are identified.
+	 */
+	if (CPUID_TO_FAMILY(cpu_id) == 0xf && CPUID_TO_MODEL(cpu_id) >= 0x20 &&
+	    CPUID_TO_MODEL(cpu_id) <= 0x3f)
+		printf("WARNING: This architecture revision has known SMP "
+		    "hardware bugs which may cause random instability\n");
 }
 
 static void