ui: normalize the 'sysrq' key into the 'print' key

The 'sysrq' key was mistakenly added to QEMU to deal with incorrect handling
of the 'print' key in the ps2 device:

  commit f2289cb6924afc97b2a75d21bfc9217024d11741
  Author: balrog <balrog@c046a42c-6fe2-441c-8c8c-71466251a162>
  Date:   Wed Jun 4 10:14:16 2008 +0000

    Add sysrq to key names known by "sendkey".

    Adding sysrq keycode to the table enabling running sysrq debugging in
    the guest via the monitor sendkey command, like:

    (qemu) sendkey alt-sysrq-t

    Tested on x86-64 target and Linux guest.

    Signed-off-by: Ryan Harper <ryanh@us.ibm.com>

The ps2 device is now fixed wrt modifiers and the 'print' key. Further the
handling of the 'sysrq' key has some problems of its own, documented in the
previous commit. To cleanup this mess, we convert any use of 'sysrq' into
'print' prior to dispatching the event to device models.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20171019142848.572-9-berrange@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

qapi/ui.json

@@ -748,6 +748,13 @@
 # @ac_bookmarks: since 2.10
 # altgr, altgr_r: dropped in 2.10
 #
+# 'sysrq' was mistakenly added to hack around the fact that
+# the ps2 driver was not generating correct scancodes sequences
+# when 'alt+print' was pressed. This flaw is now fixed and the
+# 'sysrq' key serves no further purpose. Any further use of
+# 'sysrq' will be transparently changed to 'print', so they
+# are effectively synonyms.
+#
 # Since: 1.3.0
 #
 ##

ui/input.c

@@ -353,6 +353,20 @@ void qemu_input_event_send(QemuConsole *src, InputEvent *evt)
     assert(!(evt->type == INPUT_EVENT_KIND_KEY &&
              evt->u.key.data->key->type == KEY_VALUE_KIND_NUMBER));
 
+
+    /*
+     * 'sysrq' was mistakenly added to hack around the fact that
+     * the ps2 driver was not generating correct scancodes sequences
+     * when 'alt+print' was pressed. This flaw is now fixed and the
+     * 'sysrq' key serves no further purpose. We normalize it to
+     * 'print', so that downstream receivers of the event don't
+     * neeed to deal with this mistake
+     */
+    if (evt->type == INPUT_EVENT_KIND_KEY &&
+        evt->u.key.data->key->u.qcode.data == Q_KEY_CODE_SYSRQ) {
+        evt->u.key.data->key->u.qcode.data = Q_KEY_CODE_PRINT;
+    }
+
     if (!runstate_is_running() && !runstate_check(RUN_STATE_SUSPENDED)) {
         return;
     }