Add a new cn_flags fields to struct consdev, the low-level console

definition structure.  Define one flag, CN_FLAG_NODEBUG, which
indicates the console driver cannot be used in the context of the
debugger.  This may be used, for example, if the console device
interacts with kernel services that cannot be used from the
debugger context, such as the network stack.  These drivers are
skipped over for calls to cn_checkc() and cn_putc(), and the
calling function simply moves on to the next available console.

2 files changed, 14 insertions, 6 deletions

diff --git a/sys/kern/tty_cons.c b/sys/kern/tty_cons.c
index a8221a4..d94747e 100644
--- a/sys/kern/tty_cons.c
+++ b/sys/kern/tty_cons.c
@@ -538,9 +538,11 @@ cncheckc(void)
 		return (-1);
 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
 		cn = cnd->cnd_cn;
-		c = cn->cn_checkc(cn);
-		if (c != -1) {
-			return (c);
+		if (!db_active || (cn->cn_flags & CN_FLAG_NODEBUG)) {
+			c = cn->cn_checkc(cn);
+			if (c != -1) {
+				return (c);
+			}
 		}
 	}
 	return (-1);
@@ -557,9 +559,11 @@ cnputc(int c)
 		return;
 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
 		cn = cnd->cnd_cn;
-		if (c == '\n')
-			cn->cn_putc(cn, '\r');
-		cn->cn_putc(cn, c);
+		if (!db_active || (cn->cn_flags & CN_FLAG_NODEBUG)) {
+			if (c == '\n')
+				cn->cn_putc(cn, '\r');
+			cn->cn_putc(cn, c);
+		}
 	}
 #ifdef DDB
 	if (console_pausing && !db_active && (c == '\n')) {
diff --git a/sys/sys/cons.h b/sys/sys/cons.h
index e8994bf..d7face7 100644
--- a/sys/sys/cons.h
+++ b/sys/sys/cons.h
@@ -70,6 +70,7 @@ struct consdev {
 	short	cn_pri;		/* pecking order; the higher the better */
 	void	*cn_arg;	/* drivers method argument */
 	int	cn_unit;	/* some drivers prefer this */
+	int	cn_flags;	/* capabilities of this console */
 	char	cn_name[SPECNAMELEN + 1];	/* console (device) name */
 };
 
@@ -80,6 +81,9 @@ struct consdev {
 #define CN_INTERNAL	3	/* "internal" bit-mapped display */
 #define CN_REMOTE	4	/* serial interface with remote bit set */
 
+/* Values for cn_flags. */
+#define	CN_FLAG_NODEBUG	0x00000001	/* Not supported with debugger. */
+
 #ifdef _KERNEL
 extern int cons_unavail;