From 68e40aae5fc21f7296db7a8328b1ebb5d8683c1b Mon Sep 17 00:00:00 2001 From: attilio Date: Wed, 4 Nov 2009 01:32:59 +0000 Subject: 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 Help on wordings by: jeff MFC: 3 days --- sys/i386/i386/identcpu.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'sys/i386') diff --git a/sys/i386/i386/identcpu.c b/sys/i386/i386/identcpu.c index 66c5fed..e8210c2 100644 --- a/sys/i386/i386/identcpu.c +++ b/sys/i386/i386/identcpu.c @@ -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 -- cgit v1.1