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>

4 files changed, 38 insertions, 2 deletions

diff --git a/src/mainboard/emulation/qemu-i440fx/Kconfig b/src/mainboard/emulation/qemu-i440fx/Kconfig
index 78ca2d9d64..23526f96d9 100644
--- a/src/mainboard/emulation/qemu-i440fx/Kconfig
+++ b/src/mainboard/emulation/qemu-i440fx/Kconfig
@@ -12,7 +12,8 @@ config BOARD_SPECIFIC_OPTIONS
 	select BOARD_ROMSIZE_KB_256
 	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-i440fx/Makefile.inc b/src/mainboard/emulation/qemu-i440fx/Makefile.inc
index 8c19afc128..e3ca3002ff 100644
--- a/src/mainboard/emulation/qemu-i440fx/Makefile.inc
+++ b/src/mainboard/emulation/qemu-i440fx/Makefile.inc
@@ -3,3 +3,6 @@ ramstage-y += fw_cfg.c
 romstage-y += fw_cfg.c
 romstage-y += memory.c
 ramstage-y += memory.c
+postcar-y += memory.c
+postcar-y += fw_cfg.c
+postcar-y += exit_car.S
diff --git a/src/mainboard/emulation/qemu-i440fx/exit_car.S b/src/mainboard/emulation/qemu-i440fx/exit_car.S
new file mode 100644
index 0000000000..06f1256768
--- /dev/null
+++ b/src/mainboard/emulation/qemu-i440fx/exit_car.S
@@ -0,0 +1,18 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+.text
+.global chipset_teardown_car
+chipset_teardown_car:
+	/* There's no CAR to tear down */
+	ret
diff --git a/src/mainboard/emulation/qemu-i440fx/romstage.c b/src/mainboard/emulation/qemu-i440fx/romstage.c
index e31394c282..e1d4f62708 100644
--- a/src/mainboard/emulation/qemu-i440fx/romstage.c
+++ b/src/mainboard/emulation/qemu-i440fx/romstage.c
@@ -23,11 +23,25 @@
 
 asmlinkage void car_stage_entry(void)
 {
+	struct postcar_frame pcf;
+
 	console_init();
 
 	cbmem_recovery(0);
 
 	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);
 }