x86: emulation: Set an MTRR for the RAM

QEMU likes to have an MTRR set up, just like real machines. Add an MTRR
which covers the total RAM size.

This does nothing on machines without MTRRs.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/arch/x86/cpu/qemu/dram.c b/arch/x86/cpu/qemu/dram.c
index 62a301c..ba3638e 100644 (file)
--- a/arch/x86/cpu/qemu/dram.c
+++ b/arch/x86/cpu/qemu/dram.c
@@ -4,7 +4,9 @@
  */
 
 #include <init.h>
+#include <spl.h>
 #include <asm/global_data.h>
+#include <asm/mtrr.h>
 #include <asm/post.h>
 #include <asm/arch/qemu.h>
 #include <linux/sizes.h>
@@ -44,6 +46,22 @@ int dram_init(void)
        gd->ram_size += qemu_get_high_memory_size();
        post_code(POST_DRAM);
 
+       if (xpl_phase() == PHASE_BOARD_F) {
+               u64 total = gd->ram_size;
+               int ret;
+
+               if (total > SZ_2G + SZ_1G)
+                       total += SZ_1G;
+               ret = mtrr_add_request(MTRR_TYPE_WRBACK, 0, total);
+               if (ret != -ENOSYS) {
+                       if (ret)
+                               return log_msg_ret("mta", ret);
+                       ret = mtrr_commit(false);
+                       if (ret)
+                               return log_msg_ret("mtc", ret);
+               }
+       }
+
        return 0;
 }