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Diffstat (limited to 'src/cpu/intel/common/hyperthreading.c')
-rw-r--r--src/cpu/intel/common/hyperthreading.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/src/cpu/intel/common/hyperthreading.c b/src/cpu/intel/common/hyperthreading.c
new file mode 100644
index 0000000000..4caf49e5b6
--- /dev/null
+++ b/src/cpu/intel/common/hyperthreading.c
@@ -0,0 +1,45 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <cpu/x86/lapic.h>
+#include <cpu/intel/common/common.h>
+#include <arch/cpu.h>
+
+/*
+ * Return true if running thread does not have the smallest lapic ID
+ * within a CPU core.
+ */
+bool intel_ht_sibling(void)
+{
+ struct cpuid_result result;
+ unsigned int core_ids, apic_ids, threads;
+
+ /* Is Hyper-Threading supported */
+ if (!(cpuid_edx(1) & CPUID_FEAURE_HTT))
+ return false;
+
+ apic_ids = 1;
+ if (cpuid_eax(0) >= 1)
+ apic_ids = (cpuid_ebx(1) >> 16) & 0xff;
+ if (apic_ids == 0)
+ apic_ids = 1;
+
+ core_ids = 1;
+ if (cpuid_eax(0) >= 4) {
+ result = cpuid_ext(4, 0);
+ core_ids += (result.eax >> 26) & 0x3f;
+ }
+
+ threads = (apic_ids / core_ids);
+ return !!(lapicid() & (threads - 1));
+}