Author: andrew
Date: Tue Sep 13 16:33:33 2016
New Revision: 305775
URL: https://svnweb.freebsd.org/changeset/base/305775

Log:
  Merge from stable/11 305768:
  Add a warning about a known erratum we have observed on ThunderX pass 1.1.
  As this is evaluation hardware with only a few users, and there is a lack
  of information add a warning when booting on this hardware.
  
  Approved by:  re (gjb)

Modified:
  releng/11.0/sys/arm64/arm64/identcpu.c
Directory Properties:
  releng/11.0/   (props changed)

Modified: releng/11.0/sys/arm64/arm64/identcpu.c
==============================================================================
--- releng/11.0/sys/arm64/arm64/identcpu.c      Tue Sep 13 16:31:20 2016        
(r305774)
+++ releng/11.0/sys/arm64/arm64/identcpu.c      Tue Sep 13 16:33:33 2016        
(r305775)
@@ -179,6 +179,28 @@ print_cpu_features(u_int cpu)
        }
        printf("\n");
 
+       /*
+        * There is a hardware errata where, if one CPU is performing a TLB
+        * invalidation while another is performing a store-exclusive the
+        * store-exclusive may return the wrong status. A workaround seems
+        * to be to use an IPI to invalidate on each CPU, however given the
+        * limited number of affected units (pass 1.1 is the evaluation
+        * hardware revision), and the lack of information from Cavium
+        * this has not been implemented.
+        *
+        * At the time of writing this the only information is from:
+        * https://lkml.org/lkml/2016/8/4/722
+        */
+       /*
+        * XXX: CPU_MATCH_ERRATA_CAVIUM_THUNDER_1_1 on it's own also
+        * triggers on pass 2.0+.
+        */
+       if (cpu == 0 && CPU_VAR(PCPU_GET(midr)) == 0 &&
+           CPU_MATCH_ERRATA_CAVIUM_THUNDER_1_1)
+               printf("WARNING: ThunderX Pass 1.1 detected.\nThis has known "
+                   "hardware bugs that may cause the incorrect operation of "
+                   "atomic operations.\n");
+
        if (cpu != 0 && cpu_print_regs == 0)
                return;
 
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