Don't probe for a disk unless explicitly enabled by a tunable.

This allows boot to proceed on a real system until the issue
of calling back into certain OpenFirmware calls (e.g. finddevice)
in thread context is understood.

(this commit only affects psim users, of which I think I am the
only one...)

1 files changed, 6 insertions, 0 deletions

diff --git a/sys/dev/ofw/ofw_disk.c b/sys/dev/ofw/ofw_disk.c
index 54a3d2a..67a9451 100644
--- a/sys/dev/ofw/ofw_disk.c
+++ b/sys/dev/ofw/ofw_disk.c
@@ -73,6 +73,9 @@ struct g_class g_ofwd_class = {
 
 DECLARE_GEOM_CLASS(g_ofwd_class, g_ofwd);
 
+static int ofwd_enable = 0;
+TUNABLE_INT("kern.ofw.disk", &ofwd_enable);
+
 static int
 ofwd_startio(struct ofwd_softc *sc, struct bio *bp)
 {
@@ -139,6 +142,9 @@ g_ofwd_init(struct g_class *mp __unused)
 	ihandle_t ifd;
 	int	error;
 
+	if (ofwd_enable == 0)
+		return;
+
 	ofd = OF_finddevice("ofwdisk");
 	if (ofd == -1)
 		return;