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-rw-r--r--src/cpu/x86/mtrr/earlymtrr.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/src/cpu/x86/mtrr/earlymtrr.c b/src/cpu/x86/mtrr/earlymtrr.c
index a84ecf8f72..eae6ba67b2 100644
--- a/src/cpu/x86/mtrr/earlymtrr.c
+++ b/src/cpu/x86/mtrr/earlymtrr.c
@@ -2,6 +2,30 @@
#include <cpu/x86/mtrr.h>
#include <cpu/x86/msr.h>
+/* Get first available variable MTRR.
+ * Returns var# if available, else returns -1.
+ */
+int get_free_var_mtrr(void)
+{
+ msr_t msr, maskm;
+ int vcnt;
+ int i;
+
+ /* Read MTRRCap and get vcnt - variable memory type ranges. */
+ msr = rdmsr(MTRR_CAP_MSR);
+ vcnt = msr.lo & 0xff;
+
+ /* Identify the first var mtrr which is not valid. */
+ for (i = 0; i < vcnt; i++) {
+ maskm = rdmsr(MTRR_PHYS_MASK(i));
+ if ((maskm.lo & MTRR_PHYS_MASK_VALID) == 0)
+ return i;
+ }
+
+ /* No free var mtrr. */
+ return -1;
+}
+
#ifdef __ROMCC__
static
#endif