Date: Wed, 4 Nov 2009 01:32:59 +0000 (UTC) From: Attilio Rao <attilio@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r198868 - in head/sys: amd64/amd64 i386/i386 Message-ID: <200911040132.nA41WxtQ012750@svn.freebsd.org>
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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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