Changeset 48695 in vbox for trunk/include/iprt

Timestamp:

Sep 26, 2013 12:20:56 AM (12 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

89320

Message:

CPUM: MSR_CORE_THREAD_COUNT and MSR_FLEX_RATIO for snow leopard.

File:

• trunk/include/iprt/x86.h (modified) (2 diffs)

trunk/include/iprt/x86.h

@@ -947 +947 @@
 #endif
 
+/** Undocumented intel MSR for reporting thread and core counts.
+ * Judging from the XNU sources, it seems to be introduced in Nehalem. The
+ * first 16 bits is the thread count. The next 16 bits the core count, except
+ * on westmer where it seems it's only the next 4 bits for some reason. */
+#define MSR_CORE_THREAD_COUNT               0x35
+
 /** CPU Feature control. */
 #define MSR_IA32_FEATURE_CONTROL            0x3A
@@ -1014 +1020 @@
 #define MSR_IA32_PERFEVTSEL0                0x186
 #define MSR_IA32_PERFEVTSEL1                0x187
-#define MSR_IA32_FLEX_RATIO                 0x194
+/** Flexible ratio, seems to be undocumented, used by XNU (tsc.c).
+ * The 16th bit whether flex ratio is being used, in which case bits 15:8
+ * holds a ratio that Apple takes for TSC granularity.
+ *
+ * @note This MSR conflics the P4 MSR_MCG_R12 register. */
+#define MSR_FLEX_RATIO                      0x194
+/** Performance state value and starting with Intel core more.
+ * Apple uses the >=core features to determine TSC granularity on older CPUs. */
 #define MSR_IA32_PERF_STATUS                0x198
 #define MSR_IA32_PERF_CTL                   0x199