pckbd: support for commands 0xf0-0xff: Pulse output bit
I have a guest OS which sends the command 0xfd to the keyboard
controller during initialization. To get rid of the message
"qemu: unsupported keyboard cmd=0x%02x\n" I added support for
the pulse output bit commands.
I found the following explanation here:
http://www.win.tue.nl/~aeb/linux/kbd/scancodes-11.html#ss11.3
Command 0xf0-0xff: Pulse output bit
Bits 3-0 of the output port P2 of the keyboard controller may
be pulsed low for approximately 6 µseconds. Bits 3-0 of this
command specify the output port bits to be pulsed. 0: Bit should
be pulsed. 1: Bit should not be modified. The only useful version
of this command is Command 0xfe.
(For MCA, replace 3-0 by 1-0 in the above.)
Command 0xfe: System reset
Pulse bit 0 of the output port P2 of the keyboard controller.
This will reset the CPU.
Signed-off-by: Bernhard Kohl <bernhard.kohl@nsn.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/hw/pckbd.c b/hw/pckbd.c
index 0533b1d..6e4e406 100644
--- a/hw/pckbd.c
+++ b/hw/pckbd.c
@@ -56,7 +56,9 @@
#define KBD_CCMD_WRITE_MOUSE 0xD4 /* Write the following byte to the mouse */
#define KBD_CCMD_DISABLE_A20 0xDD /* HP vectra only ? */
#define KBD_CCMD_ENABLE_A20 0xDF /* HP vectra only ? */
-#define KBD_CCMD_RESET 0xFE
+#define KBD_CCMD_PULSE_BITS_3_0 0xF0 /* Pulse bits 3-0 of the output port P2. */
+#define KBD_CCMD_RESET 0xFE /* Pulse bit 0 of the output port P2 = CPU reset. */
+#define KBD_CCMD_NO_OP 0xFF /* Pulse no bits of the output port P2. */
/* Keyboard Commands */
#define KBD_CMD_SET_LEDS 0xED /* Set keyboard leds */
@@ -238,6 +240,21 @@
KBDState *s = opaque;
DPRINTF("kbd: write cmd=0x%02x\n", val);
+
+ /* Bits 3-0 of the output port P2 of the keyboard controller may be pulsed
+ * low for approximately 6 micro seconds. Bits 3-0 of the KBD_CCMD_PULSE
+ * command specify the output port bits to be pulsed.
+ * 0: Bit should be pulsed. 1: Bit should not be modified.
+ * The only useful version of this command is pulsing bit 0,
+ * which does a CPU reset.
+ */
+ if((val & KBD_CCMD_PULSE_BITS_3_0) == KBD_CCMD_PULSE_BITS_3_0) {
+ if(!(val & 1))
+ val = KBD_CCMD_RESET;
+ else
+ val = KBD_CCMD_NO_OP;
+ }
+
switch(val) {
case KBD_CCMD_READ_MODE:
kbd_queue(s, s->mode, 0);
@@ -294,8 +311,8 @@
case KBD_CCMD_RESET:
qemu_system_reset_request();
break;
- case 0xff:
- /* ignore that - I don't know what is its use */
+ case KBD_CCMD_NO_OP:
+ /* ignore that */
break;
default:
fprintf(stderr, "qemu: unsupported keyboard cmd=0x%02x\n", val);
