Author: attilio
Date: Wed Nov 4 01:32:59 2009
New Revision: 198868
URL: http://svn.freebsd.org/changeset/base/198868
Log:
Opteron rev E family of processor expose a bug where, in very rare
ocassions, memory barriers semantic is not honoured by the hardware
itself. As a result, some random breakage can happen in uninvestigable
ways (for further explanation see at the content of the commit itself).
As long as just a specific familly is bugged of an entire architecture
is broken, a complete fix-up is impratical without harming to some
extents the other correct cases.
Considering that (and considering the frequency of the bug exposure)
just print out a warning message if the affected machine is identified.
Pointed out by: Samy Al Bahra <sbahra at repnop dot org>
Help on wordings by: jeff
MFC: 3 days
Modified:
head/sys/amd64/amd64/identcpu.c
head/sys/i386/i386/identcpu.c
Modified: head/sys/amd64/amd64/identcpu.c
==============================================================================
--- head/sys/amd64/amd64/identcpu.c Wed Nov 4 01:00:28 2009
(r198867)
+++ head/sys/amd64/amd64/identcpu.c Wed Nov 4 01:32:59 2009
(r198868)
@@ -607,6 +607,24 @@ 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");
+ printf("WARNING: For details see: "
+ "http://bugzilla.kernel.org/show_bug.cgi?id=11305\n";);
+ }
}
static void
Modified: head/sys/i386/i386/identcpu.c
==============================================================================
--- head/sys/i386/i386/identcpu.c Wed Nov 4 01:00:28 2009
(r198867)
+++ head/sys/i386/i386/identcpu.c Wed Nov 4 01:32:59 2009
(r198868)
@@ -1303,6 +1303,24 @@ 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");
+ printf("WARNING: For details see: "
+ "http://bugzilla.kernel.org/show_bug.cgi?id=11305\n";);
+ }
}
static void
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