svn commit: r367663 - stable/12/sys/dev/vt

[Kyle Evans]

Author: kevans
Date: Sat Nov 14 01:58:33 2020
New Revision: 367663
URL: https://svnweb.freebsd.org/changeset/base/367663

Log:
  MFC r367448: vt: resolve conflict between VT_ALT_TO_ESC_HACK and DBG
  
  When using the ALT+CTRL+ESC sequence to break into kdb, the keyboard is
  completely borked when you return. watch(8) shows that it's working, but
  it's inserting escape sequences.
  
  Further investigation revealed that VT_ALT_TO_ESC_HACK is the default and
  directly conflicts with this sequence, so upon return from the debugger
  ALKED is set.
  
  If they triggered the break to debugger, it's safe to assume they didn't
  mean to use VT_ALT_TO_ESC_HACK, so just unset it to reduce the surprise when
  the keyboard seems non-functional upon return.

Modified:
  stable/12/sys/dev/vt/vt_core.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/dev/vt/vt_core.c
==============================================================================
--- stable/12/sys/dev/vt/vt_core.c	Sat Nov 14 01:55:54 2020	(r367662)
+++ stable/12/sys/dev/vt/vt_core.c	Sat Nov 14 01:58:33 2020	(r367663)
@@ -725,13 +725,22 @@ vt_scroll(struct vt_window *vw, int offset, int whence
 }
 
 static int
-vt_machine_kbdevent(int c)
+vt_machine_kbdevent(struct vt_device *vd, int c)
 {
 
 	switch (c) {
 	case SPCLKEY | DBG: /* kbdmap(5) keyword `debug`. */
-		if (vt_kbd_debug)
+		if (vt_kbd_debug) {
 			kdb_enter(KDB_WHY_BREAK, "manual escape to debugger");
+#if VT_ALT_TO_ESC_HACK
+			/*
+			 * There's an unfortunate conflict between SPCLKEY|DBG
+			 * and VT_ALT_TO_ESC_HACK.  Just assume they didn't mean
+			 * it if we got to here.
+			 */
+			vd->vd_kbstate &= ~ALKED;
+#endif
+		}
 		return (1);
 	case SPCLKEY | HALT: /* kbdmap(5) keyword `halt`. */
 		if (vt_kbd_halt)
@@ -864,7 +873,7 @@ vt_processkey(keyboard_t *kbd, struct vt_device *vd, i
 		return (0);
 #endif
 
-	if (vt_machine_kbdevent(c))
+	if (vt_machine_kbdevent(vd, c))
 		return (0);
 
 	if (vw->vw_flags & VWF_SCROLL) {