arch/x86: Adjust size of postcar stack

With VBOOT=y && VBOOT_MEASURED_BOOT=y message
digest will be allocated from the stack and
1 KiB reserve used with the recent platforms
was no longer sufficient.

The comment of LZMA scratchpad consuming stack
was obsolete for postcar, so these can be reduced
to same 4 KiB.

Change-Id: Iba1fb5bfad6946f316feac2d8c998a782142a56a
Signed-off-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33775
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/arch/x86/include/arch/cpu.h b/src/arch/x86/include/arch/cpu.h
index 75f1f439b8..38066c15a2 100644
--- a/src/arch/x86/include/arch/cpu.h
+++ b/src/arch/x86/include/arch/cpu.h
@@ -309,8 +309,9 @@ struct postcar_frame {
 };
 
 /*
- * Initialize postcar_frame object allocating stack size in cbmem
- * with the provided size. Returns 0 on success, < 0 on error.
+ * Initialize postcar_frame object allocating stack from cbmem,
+ * with stack_size == 0, default 4 KiB is allocated.
+ * Returns 0 on success, < 0 on error.
  */
 int postcar_frame_init(struct postcar_frame *pcf, size_t stack_size);