missed this one.  3 is not big enough, should be UTFmax.
found by pad and reported on 9fans.

Reference: /n/atom/patch/applied/kbdputcutfmax
Date: Wed Jun 18 19:42:31 CES 2014
Signed-off-by: quansrto@quanstro.net

--- /sys/src/9/port/devcons.c	Wed Jun 18 19:42:02 2014
+++ /sys/src/9/port/devcons.c	Wed Jun 18 19:42:02 2014
@@ -304,9 +304,8 @@
 
 	kprintoq = nil;	/* don't try to write to /dev/kprint */
 
-	if(panicking)
+	if(ainc(&panicking)>1)
 		for(;;);
-	panicking = 1;
 
 	s = splhi();
 	strcpy(buf, "panic: ");
@@ -582,7 +581,7 @@
 kbdputc(Queue*, int ch)
 {
 	int i, n;
-	char buf[3];
+	char buf[UTFmax];
 	Rune r;
 	char *next;
 
--- /sys/src/nix/port/devcons.c	Wed Jun 18 19:42:02 2014
+++ /sys/src/nix/port/devcons.c	Wed Jun 18 19:42:02 2014
@@ -597,7 +597,7 @@
 kbdputc(Queue*, int ch)
 {
 	int i, n;
-	char buf[3];
+	char buf[UTFmax];
 	Rune r;
 	char *next;