diff options
authorThomas Gleixner <>2016-05-10 09:20:33 +0200
committerThomas Gleixner <>2016-05-10 09:28:31 +0200
commit8d415ee225a3d15d3e3029524350e8237a4de7b8 (patch)
parent4abac0d0bbc628df5f26845fe05ffc6b3a6533dd (diff)
x86/topology: Set x86_max_cores to 1 for CONFIG_SMP=n
Josef reported that the uncore driver trips over with CONFIG_SMP=n because x86_max_cores is 16 instead of 12. The reason is, that for SMP=n the extended topology detection is a NOOP and the cache leaf is used to determine the number of cores. That's wrong in two aspects: 1) The cache leaf enumerates the maximum addressable number of cores in the package, which is obviously not correct 2) UP has no business with topology bits at all. Make intel_num_cpu_cores() return 1 for CONFIG_SMP=n Reported-by: Josef Bacik <> Signed-off-by: Thomas Gleixner <> Cc: Peter Zijlstra <> Cc: kernel-team <> Cc: Kan Liang <> Link:
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 1f7fdb91a818..e4393bfc7f0d 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -336,7 +336,7 @@ static int intel_num_cpu_cores(struct cpuinfo_x86 *c)
unsigned int eax, ebx, ecx, edx;
- if (c->cpuid_level < 4)
+ if (!IS_ENABLED(CONFIG_SMP) || c->cpuid_level < 4)
return 1;
/* Intel has a non-standard dependency on %ecx for this CPUID level. */