Add "panic key" function to syscons. When this key is defined in a

keymap and pressed, the system panic will be forced.

This feature must be specifically enabled by a new sysctl variable:
machdep.enable_panic_key.  Its default value is 0.  The panic key
won't do anything unless this variable is set to non-zero.

To use the panic key, add a keyword 'panic' to a key in your
keymap file.  The following example assigns the panic function
to SysReq (Alt-PrintScreen) key (keycode 84).

  083   del    '.'    '.'    '.'    '.'    '.'    boot   boot    N
  084   panic  nop    nop    nop    panic  nop    nop    nop     O
  085   nop    nop    nop    nop    nop    nop    nop    nop     O

PR: kern/13721

1 files changed, 10 insertions, 0 deletions

diff --git a/sys/dev/syscons/syscons.c b/sys/dev/syscons/syscons.c
index f3ffa83..7c5958e 100644
--- a/sys/dev/syscons/syscons.c
+++ b/sys/dev/syscons/syscons.c
@@ -44,6 +44,7 @@
 #include <sys/conf.h>
 #include <sys/proc.h>
 #include <sys/signalvar.h>
+#include <sys/sysctl.h>
 #include <sys/tty.h>
 #include <sys/kernel.h>
 #include <sys/malloc.h>
@@ -114,6 +115,10 @@ static	void		(*current_saver)(sc_softc_t *, int) = none_saver;
 
 static	bios_values_t	bios_value;
 
+static	int		enable_panic_key;
+SYSCTL_INT(_machdep, OID_AUTO, enable_panic_key, CTLFLAG_RW, &enable_panic_key,
+	   0, "");
+
 #define SC_MOUSE 	128
 #define SC_CONSOLECTL	255
 
@@ -3738,6 +3743,11 @@ next_code:
 #endif /* SC_DISABLE_DDBKEY */
 		break;
 
+	    case PNC:
+		if (enable_panic_key)
+			panic("Forced by the panic key");
+		break;
+
 	    case NEXT:
 		this_scr = scp->index;
 		for (i = (this_scr - sc->first_vty + 1)%sc->vtys;