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-rw-r--r--src/arch/x86/smbios.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/src/arch/x86/smbios.c b/src/arch/x86/smbios.c
index 7e05408242..a599addb61 100644
--- a/src/arch/x86/smbios.c
+++ b/src/arch/x86/smbios.c
@@ -647,7 +647,26 @@ static int smbios_write_type4(unsigned long *current, int handle)
t->processor_version = smbios_processor_name(t->eos);
t->processor_family = (res.eax > 0) ? 0x0c : 0x6;
t->processor_type = 3; /* System Processor */
- t->core_count = (res.ebx >> 16) & 0xff;
+ /*
+ * If CPUID leaf 11 is available, calculate "core count" by dividing
+ * SMT_ID (logical processors in a core) by Core_ID (number of cores).
+ * This seems to be the way to arrive to a number of cores mentioned on
+ * ark.intel.com.
+ */
+ if (cpu_have_cpuid() && cpuid_get_max_func() >= 0xb) {
+ uint32_t leaf_b_cores = 0, leaf_b_threads = 0;
+ res = cpuid_ext(0xb, 1);
+ leaf_b_cores = res.ebx;
+ res = cpuid_ext(0xb, 0);
+ leaf_b_threads = res.ebx;
+ /* if hyperthreading is not available, pretend this is 1 */
+ if (leaf_b_threads == 0) {
+ leaf_b_threads = 1;
+ }
+ t->core_count = leaf_b_cores / leaf_b_threads;
+ } else {
+ t->core_count = (res.ebx >> 16) & 0xff;
+ }
/* Assume we enable all the cores always, capped only by MAX_CPUS */
t->core_enabled = MIN(t->core_count, CONFIG_MAX_CPUS);
t->l1_cache_handle = 0xffff;