From: Simon Glass <sjg@chromium.org>
Date: Sat, 15 Mar 2025 14:25:47 +0000 (+0000)
Subject: x86: emulation: Set an MTRR for the RAM
X-Git-Tag: v2025.07-rc1~119^2~9^2~19
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=790baef3b93e0f194bca266f32f620898b84951f;p=pandora-u-boot.git

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 62a301c0fd3..ba3638e6acc 100644
--- 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;
 }