[console] Support AltGr to access ASCII characters via remapping

Several keyboard layouts define ASCII characters as accessible only
via the AltGr modifier.  Add support for this modifier to ensure that
all ASCII characters are accessible.

Experiments suggest that the BIOS console is likely to fail to
generate ASCII characters when the AltGr key is pressed.  Work around
this limitation by accepting LShift+RShift (which will definitely
produce an ASCII character) as a synonym for AltGr.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/hci/keymap/keymap_mt.c b/src/hci/keymap/keymap_mt.c
index ebff850..f5baf69 100644
--- a/src/hci/keymap/keymap_mt.c
+++ b/src/hci/keymap/keymap_mt.c
@@ -20,8 +20,15 @@ static struct keymap_key mt_basic[] = {
 	{ 0, 0 }
 };
 
+/** "mt" AltGr remapping */
+static struct keymap_key mt_altgr[] = {
+	{ 0x2d, 0x5c },	/* '-' => '\\' */
+	{ 0, 0 }
+};
+
 /** "mt" keyboard map */
 struct keymap mt_keymap __keymap = {
 	.name = "mt",
 	.basic = mt_basic,
+	.altgr = mt_altgr,
 };