3 files changed, 30 insertions, 3 deletions

diff --git a/sys/dev/vt/vt_buf.c b/sys/dev/vt/vt_buf.c
index 61ef86c4540d..3d307168d4ff 100644
--- a/sys/dev/vt/vt_buf.c
+++ b/sys/dev/vt/vt_buf.c
@@ -433,17 +433,22 @@ vtbuf_do_clearhistory(struct vt_buf *vb)
 	vtbuf_do_fill(vb, &rect, VTBUF_SPACE_CHAR(ch));
 }
 
-void
-vtbuf_init_early(struct vt_buf *vb)
+static void
+vtbuf_reset_scrollback(struct vt_buf *vb)
 {
-	vb->vb_flags |= VBF_CURSOR;
 	vb->vb_roffset = 0;
 	vb->vb_curroffset = 0;
 	vb->vb_mark_start.tp_row = 0;
 	vb->vb_mark_start.tp_col = 0;
 	vb->vb_mark_end.tp_row = 0;
 	vb->vb_mark_end.tp_col = 0;
+}
 
+void
+vtbuf_init_early(struct vt_buf *vb)
+{
+	vb->vb_flags |= VBF_CURSOR;
+	vtbuf_reset_scrollback(vb);
 	vtbuf_init_rows(vb);
 	vtbuf_do_clearhistory(vb);
 	vtbuf_make_undirty(vb);
@@ -477,6 +482,8 @@ vtbuf_clearhistory(struct vt_buf *vb)
 {
 	VTBUF_LOCK(vb);
 	vtbuf_do_clearhistory(vb);
+	vtbuf_reset_scrollback(vb);
+	vb->vb_flags &= ~VBF_HISTORY_FULL;
 	VTBUF_UNLOCK(vb);
 }
 
diff --git a/sys/dev/vt/vt_core.c b/sys/dev/vt/vt_core.c
index 950edabf6e1a..5311a8bd6788 100644
--- a/sys/dev/vt/vt_core.c
+++ b/sys/dev/vt/vt_core.c
@@ -2332,6 +2332,16 @@ skip_thunk:
 		return (0);
 	case CONS_CLRHIST:
 		vtbuf_clearhistory(&vd->vd_curwindow->vw_buf);
+		/*
+		 * Invalidate the entire visible window; it is not guaranteed
+		 * that this operation will be immediately followed by a scroll
+		 * event, so it would otherwise be possible for prior artifacts
+		 * to remain visible.
+		 */
+		VT_LOCK(vd);
+		vd->vd_flags |= VDF_INVALID;
+		VT_UNLOCK(vd);
+		vt_resume_flush_timer(vd->vd_curwindow, 0);
 		return (0);
 	case CONS_GET:
 		/* XXX */
diff --git a/sys/kern/subr_terminal.c b/sys/kern/subr_terminal.c
index 4d7665cf3377..6c49c68f24e6 100644
--- a/sys/kern/subr_terminal.c
+++ b/sys/kern/subr_terminal.c
@@ -480,6 +480,16 @@ termtty_ioctl(struct tty *tp, u_long cmd, caddr_t data, struct thread *td)
 	tty_unlock(tp);
 	error = tm->tm_class->tc_ioctl(tm, cmd, data, td);
 	tty_lock(tp);
+	if ((error == 0) && (cmd == CONS_CLRHIST)) {
+		/*
+		 * Scrollback history has been successfully cleared,
+		 * so reset the cursor position to the top left of the screen.
+		 */
+		teken_pos_t p;
+		p.tp_row = 0;
+		p.tp_col = 0;
+		teken_set_cursor(&tm->tm_emulator, &p);
+	}
 	return (error);
 }