[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/arch/x86/interface/pcbios/bios_console.c

@@ -68,6 +68,13 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  */
 #define SCANCODE_RSHIFT		0x36
 
+/** Scancode for the "non-US \ and |" key
+ *
+ * This is the key that appears between Left Shift and Z on non-US
+ * keyboards.
+ */
+#define SCANCODE_NON_US		0x56
+
 /* Set default console usage if applicable */
 #if ! ( defined ( CONSOLE_PCBIOS ) && CONSOLE_EXPLICIT ( CONSOLE_PCBIOS ) )
 #undef CONSOLE_PCBIOS
@@ -383,6 +390,8 @@ static int bios_getchar ( void ) {
 	if ( character && ( character < 0x80 ) ) {
 		if ( scancode < SCANCODE_RSHIFT ) {
 			return key_remap ( character );
+		} else if ( scancode == SCANCODE_NON_US ) {
+			return key_remap ( character | KEYMAP_PSEUDO );
 		} else {
 			return character;
 		}

src/core/keymap.c

@@ -48,5 +48,8 @@ unsigned int key_remap ( unsigned int character ) {
 		}
 	}
 
+	/* Clear pseudo key flag */
+	character &= ~KEYMAP_PSEUDO;
+
 	return character;
 }

src/drivers/usb/usbkbd.c

@@ -114,13 +114,19 @@ static unsigned int usbkbd_map ( unsigned int keycode, unsigned int modifiers,
 			};
 			key = keypad[ keycode - USBKBD_KEY_PAD_1 ];
 		};
+	} else if ( keycode == USBKBD_KEY_NON_US ) {
+		/* Non-US \ and | */
+		key = ( ( modifiers & USBKBD_SHIFT ) ?
+			( KEYMAP_PSEUDO | '|' ) : ( KEYMAP_PSEUDO | '\\' ) );
 	} else {
 		key = 0;
 	}
 
 	/* Remap key if applicable */
-	if ( keycode < USBKBD_KEY_CAPS_LOCK )
+	if ( ( keycode < USBKBD_KEY_CAPS_LOCK ) ||
+	     ( keycode == USBKBD_KEY_NON_US ) ) {
 		key = key_remap ( key );
+	}
 
 	/* Handle upper/lower case and Ctrl-<key> */
 	if ( islower ( key ) ) {

src/drivers/usb/usbkbd.h

@@ -75,6 +75,7 @@ enum usb_keycode {
 	USBKBD_KEY_PAD_ENTER = 0x58,
 	USBKBD_KEY_PAD_1 = 0x59,
 	USBKBD_KEY_PAD_DOT = 0x63,
+	USBKBD_KEY_NON_US = 0x64,
 };
 
 /** USB keyboard LEDs */

src/hci/keymap/keymap_al.c

@@ -30,4 +30,6 @@ struct key_mapping al_mapping[] __keymap = {
 	{ 0x7c, 0x7d },	/* '|' => '}' */
 	{ 0x7d, 0x27 },	/* '}' => '\'' */
 	{ 0x7e, 0x7c },	/* '~' => '|' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_az.c

@@ -21,4 +21,6 @@ struct key_mapping az_mapping[] __keymap = {
 	{ 0x40, 0x22 },	/* '@' => '"' */
 	{ 0x5e, 0x3a },	/* '^' => ':' */
 	{ 0x7c, 0x2f },	/* '|' => '/' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_by.c

@@ -12,4 +12,6 @@ FILE_LICENCE ( PUBLIC_DOMAIN );
 
 /** "by" keyboard mapping */
 struct key_mapping by_mapping[] __keymap = {
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_de.c

@@ -36,4 +36,6 @@ struct key_mapping de_mapping[] __keymap = {
 	{ 0x7a, 0x79 },	/* 'z' => 'y' */
 	{ 0x7c, 0x27 },	/* '|' => '\'' */
 	{ 0x7d, 0x2a },	/* '}' => '*' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_dk.c

@@ -28,4 +28,6 @@ struct key_mapping dk_mapping[] __keymap = {
 	{ 0x5e, 0x26 },	/* '^' => '&' */
 	{ 0x5f, 0x3f },	/* '_' => '?' */
 	{ 0x7c, 0x2a },	/* '|' => '*' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_es.c

@@ -28,4 +28,6 @@ struct key_mapping es_mapping[] __keymap = {
 	{ 0x5e, 0x26 },	/* '^' => '&' */
 	{ 0x5f, 0x3f },	/* '_' => '?' */
 	{ 0x7d, 0x2a },	/* '}' => '*' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_et.c

@@ -26,4 +26,6 @@ struct key_mapping et_mapping[] __keymap = {
 	{ 0x5e, 0x26 },	/* '^' => '&' */
 	{ 0x5f, 0x3f },	/* '_' => '?' */
 	{ 0x7c, 0x2a },	/* '|' => '*' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_fi.c

@@ -26,4 +26,6 @@ struct key_mapping fi_mapping[] __keymap = {
 	{ 0x5e, 0x26 },	/* '^' => '&' */
 	{ 0x5f, 0x3f },	/* '_' => '?' */
 	{ 0x7c, 0x2a },	/* '|' => '*' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_fr.c

@@ -57,4 +57,6 @@ struct key_mapping fr_mapping[] __keymap = {
 	{ 0x71, 0x61 },	/* 'q' => 'a' */
 	{ 0x77, 0x7a },	/* 'w' => 'z' */
 	{ 0x7a, 0x77 },	/* 'z' => 'w' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_gr.c

@@ -12,4 +12,6 @@ FILE_LICENCE ( PUBLIC_DOMAIN );
 
 /** "gr" keyboard mapping */
 struct key_mapping gr_mapping[] __keymap = {
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_il.c

@@ -24,4 +24,6 @@ struct key_mapping il_mapping[] __keymap = {
 	{ 0x60, 0x3b },	/* '`' => ';' */
 	{ 0x7b, 0x7d },	/* '{' => '}' */
 	{ 0x7d, 0x7b },	/* '}' => '{' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_it.c

@@ -30,4 +30,6 @@ struct key_mapping it_mapping[] __keymap = {
 	{ 0x60, 0x5c },	/* '`' => '\\' */
 	{ 0x7d, 0x2a },	/* '}' => '*' */
 	{ 0x7e, 0x7c },	/* '~' => '|' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_mk.c

@@ -12,4 +12,6 @@ FILE_LICENCE ( PUBLIC_DOMAIN );
 
 /** "mk" keyboard mapping */
 struct key_mapping mk_mapping[] __keymap = {
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_nl.c

@@ -33,4 +33,6 @@ struct key_mapping nl_mapping[] __keymap = {
 	{ 0x60, 0x40 },	/* '`' => '@' */
 	{ 0x7c, 0x3e },	/* '|' => '>' */
 	{ 0x7d, 0x7c },	/* '}' => '|' */
+	{ 0xdc, 0x5d },	/* Pseudo-'\\' => ']' */
+	{ 0xfc, 0x5b },	/* Pseudo-'|' => '[' */
 };

src/hci/keymap/keymap_no-latin1.c

@@ -32,4 +32,6 @@ struct key_mapping no_latin1_mapping[] __keymap = {
 	{ 0x60, 0x7c },	/* '`' => '|' */
 	{ 0x7c, 0x2a },	/* '|' => '*' */
 	{ 0x7d, 0x5e },	/* '}' => '^' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_no.c

@@ -30,4 +30,6 @@ struct key_mapping no_mapping[] __keymap = {
 	{ 0x5f, 0x3f },	/* '_' => '?' */
 	{ 0x60, 0x7c },	/* '`' => '|' */
 	{ 0x7c, 0x2a },	/* '|' => '*' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_pl.c

@@ -12,4 +12,6 @@ FILE_LICENCE ( PUBLIC_DOMAIN );
 
 /** "pl" keyboard mapping */
 struct key_mapping pl_mapping[] __keymap = {
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_pt.c

@@ -29,4 +29,6 @@ struct key_mapping pt_mapping[] __keymap = {
 	{ 0x60, 0x5c },	/* '`' => '\\' */
 	{ 0x7b, 0x2a },	/* '{' => '*' */
 	{ 0x7e, 0x7c },	/* '~' => '|' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_ru.c

@@ -13,4 +13,6 @@ FILE_LICENCE ( PUBLIC_DOMAIN );
 /** "ru" keyboard mapping */
 struct key_mapping ru_mapping[] __keymap = {
 	{ 0x0d, 0x0a },	/* Ctrl-M => Ctrl-J */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_sg.c

@@ -38,4 +38,6 @@ struct key_mapping sg_mapping[] __keymap = {
 	{ 0x7a, 0x79 },	/* 'z' => 'y' */
 	{ 0x7c, 0x24 },	/* '|' => '$' */
 	{ 0x7d, 0x21 },	/* '}' => '!' */
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_sr-latin.c

@@ -12,4 +12,6 @@ FILE_LICENCE ( PUBLIC_DOMAIN );
 
 /** "sr-latin" keyboard mapping */
 struct key_mapping sr_latin_mapping[] __keymap = {
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

src/hci/keymap/keymap_ua.c

@@ -12,4 +12,6 @@ FILE_LICENCE ( PUBLIC_DOMAIN );
 
 /** "ua" keyboard mapping */
 struct key_mapping ua_mapping[] __keymap = {
+	{ 0xdc, 0x3c },	/* Pseudo-'\\' => '<' */
+	{ 0xfc, 0x3e },	/* Pseudo-'|' => '>' */
 };

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 */

src/util/genkeymap.py

@@ -219,12 +219,28 @@ class KeyMapping(UserDict[KeyModifiers, Sequence[Key]]):
 
 
 class BiosKeyMapping(KeyMapping):
-    """Keyboard mapping as used by the BIOS"""
+    """Keyboard mapping as used by the BIOS
+
+    To allow for remappings of the somewhat interesting key 86, we
+    arrange for our keyboard drivers to generate this key as "\\|"
+    with the high bit set.
+    """
+
+    KEY_PSEUDO: ClassVar[int] = 0x80
+    """Flag used to indicate a fake ASCII value"""
+
+    KEY_NON_US_UNSHIFTED: ClassVar[str] = chr(KEY_PSEUDO | ord('\\'))
+    """Fake ASCII value generated for unshifted key code 86"""
+
+    KEY_NON_US_SHIFTED: ClassVar[str] = chr(KEY_PSEUDO | ord('|'))
+    """Fake ASCII value generated for shifted key code 86"""
 
     @property
     def inverse(self) -> MutableMapping[str, Key]:
         inverse = super().inverse
         assert len(inverse) == 0x7f
+        inverse[self.KEY_NON_US_UNSHIFTED] = self.unshifted[self.KEY_NON_US]
+        inverse[self.KEY_NON_US_SHIFTED] = self.shifted[self.KEY_NON_US]
         assert all(x.modifiers in {KeyModifiers.NONE, KeyModifiers.SHIFT,
                                    KeyModifiers.CTRL}
                    for x in inverse.values())
@@ -251,12 +267,13 @@ class KeyRemapping:
         raw = {source: self.target[key.modifiers][key.keycode].ascii
                for source, key in self.source.inverse.items()}
         # Eliminate any null mappings, mappings that attempt to remap
-        # the backspace key, or identity mappings
+        # the backspace key, or mappings that would become identity
+        # mappings after clearing the high bit
         table = {source: target for source, target in raw.items()
                  if target
                  and ord(source) != 0x7f
                  and ord(target) != 0x7f
-                 and ord(source) != ord(target)}
+                 and ord(source) & ~BiosKeyMapping.KEY_PSEUDO != ord(target)}
         # Recursively delete any mappings that would produce
         # unreachable alphanumerics (e.g. the "il" keymap, which maps
         # away the whole lower-case alphabet)
@@ -281,13 +298,17 @@ class KeyRemapping:
         """C variable name"""
         return re.sub(r'\W', '_', self.name) + "_mapping"
 
-    @staticmethod
+    @classmethod
-    def ascii_name(char: str) -> str:
+    def ascii_name(cls, char: str) -> str:
         """ASCII character name"""
         if char == '\\':
             name = "'\\\\'"
         elif char == '\'':
             name = "'\\\''"
+        elif ord(char) & BiosKeyMapping.KEY_PSEUDO:
+            name = "Pseudo-%s" % cls.ascii_name(
+                chr(ord(char) & ~BiosKeyMapping.KEY_PSEUDO)
+            )
         elif char.isprintable():
             name = "'%s'" % char
         elif ord(char) <= 0x1a: