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.

1 files changed, 10 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')) {