northbridge/intel/sandybridge: Enable x86_64 for mrc.bin
Enable x86_64 support for MRC.bin:
- Add a wrapper function for console printing that calls into
long mode to call native do_putchar
- Remove Kconfig guard for x86_64 when MRC is being used
Tested: Booted Lenovo X220 using mrc.bin under x86_64 and
MRC is able to print to the console.
Change-Id: I21ffcb5f5d4bf155593e8111531bdf0ed7071dfc
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79754
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/northbridge/intel/sandybridge/mrc_wrapper.S b/src/northbridge/intel/sandybridge/mrc_wrapper.S
index 860526b..d68ce09 100644
--- a/src/northbridge/intel/sandybridge/mrc_wrapper.S
+++ b/src/northbridge/intel/sandybridge/mrc_wrapper.S
@@ -25,3 +25,13 @@
mov %ebp, %esp
popal
ret
+
+ /*
+ * Callback for MRC to print a character on the console.
+ * As MRC is x86_32 call into long mode and use the x86_64
+ * function do_putchar to print to console.
+ */
+
+#include <src/cpu/x86/64bit/prot2long.inc>
+
+prot2lm_wrapper do_putchar