[console] Handle remapping of scancode 86

The key with scancode 86 appears in the position between left shift
and Z on a US keyboard, where it typically fails to exist entirely.
Most US keyboard maps define this nonexistent key as generating "\|",
with the notable exception of "loadkeys" which instead reports it as
generating "<>".  Both of these mapping choices duplicate keys that
exist elsewhere in the map, which causes problems for our ASCII-based
remapping mechanism.

Work around these quirks by treating the key as generating "\|" with
the high bit set, and making it subject to remapping.  Where the BIOS
generates "\|" as expected, this allows us to remap to the correct
ASCII value.

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

src/include/ipxe/keymap.h

@@ -27,6 +27,9 @@ struct key_mapping {
 /** Define a keyboard mapping */
 #define __keymap __table_entry ( KEYMAP, 01 )
 
+/** Pseudo key flag */
+#define KEYMAP_PSEUDO 0x80
+
 extern unsigned int key_remap ( unsigned int character );
 
 #endif /* _IPXE_KEYMAP_H */