mb/qemu-{i440fx,q35}: Use POSTCAR stage to load the ramstage

Qemu does not have a real CAR but postcar stage is still useful
for testing the stage.

The postcar stage is also mandatory for x86_64 to setup
pagetables for x86_64 ramstage.

Do not set up MTRRs, as qemu ignores them anyways.

Tested on qemu-i440fx and qemu-q35.

Change-Id: I6638534d99fde312e55b6a6be8c95e4cb25cca80
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/30499
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

3 files changed, 22 insertions, 2 deletions

diff --git a/src/mainboard/emulation/qemu-q35/Kconfig b/src/mainboard/emulation/qemu-q35/Kconfig
index 1ceb62c968..815b93b012 100644
--- a/src/mainboard/emulation/qemu-q35/Kconfig
+++ b/src/mainboard/emulation/qemu-q35/Kconfig
@@ -11,7 +11,8 @@ config BOARD_SPECIFIC_OPTIONS
 	select BOARD_ROMSIZE_KB_2048
 	select MAINBOARD_HAS_NATIVE_VGA_INIT
 	select MAINBOARD_FORCE_NATIVE_VGA_INIT
-	select NO_CAR_GLOBAL_MIGRATION
+	select POSTCAR_STAGE
+	select POSTCAR_CONSOLE
 
 config MAINBOARD_DIR
 	string
diff --git a/src/mainboard/emulation/qemu-q35/Makefile.inc b/src/mainboard/emulation/qemu-q35/Makefile.inc
index a52aad42fc..b18d2e4f97 100644
--- a/src/mainboard/emulation/qemu-q35/Makefile.inc
+++ b/src/mainboard/emulation/qemu-q35/Makefile.inc
@@ -3,4 +3,9 @@ ramstage-y += ../qemu-i440fx/memory.c
 ramstage-y += ../qemu-i440fx/fw_cfg.c
 romstage-y += ../qemu-i440fx/memory.c
 romstage-y += ../qemu-i440fx/fw_cfg.c
+
+postcar-y += ../qemu-i440fx/memory.c
+postcar-y += ../qemu-i440fx/exit_car.S
+postcar-y += ../qemu-i440fx/fw_cfg.c
+
 bootblock-y += bootblock.c
diff --git a/src/mainboard/emulation/qemu-q35/romstage.c b/src/mainboard/emulation/qemu-q35/romstage.c
index 2b8d9351c0..3e0870ffec 100644
--- a/src/mainboard/emulation/qemu-q35/romstage.c
+++ b/src/mainboard/emulation/qemu-q35/romstage.c
@@ -24,6 +24,7 @@
 
 asmlinkage void car_stage_entry(void)
 {
+	struct postcar_frame pcf;
 	i82801ix_early_init();
 	console_init();
 
@@ -31,5 +32,18 @@ asmlinkage void car_stage_entry(void)
 
 	timestamp_add_now(TS_START_ROMSTAGE);
 
-	run_ramstage();
+	/**
+	 * The LZMA decoder needs about 4 KiB stack.
+	 * Leave 1 KiB stack for general postcar code.
+	 */
+	if (postcar_frame_init(&pcf, 5 * KiB))
+		die("Unable to initialize postcar frame.\n");
+
+	/**
+	 * Run postcar to tear down CAR and load relocatable ramstage.
+	 * There's no CAR on qemu, but for educational purposes and
+	 * testing the postcar stage is used on qemu, too.
+	 */
+
+	run_postcar_phase(&pcf);
 }