[PATCH] tty: vt: initialize softcursor_original correctly

From: Melchior FRANZ
Date: Sun Nov 01 2015 - 13:48:30 EST

add_softcursor() stores the contents of the text buffer position in this
variable before drawing the softcursor, whereas hide_softcursor() writes
the value back. A value of -1 means that no cursor has been drawn and
therefore no character is to be restored. softcursor_original, however,
is only implicitly initialized with 0. Therefore, when hide_softcursor
is called for the first time (console_init -> con_init -> redraw_screen
-> hide_cursor), it wrongly writes 0x0000 in the top left corner of
the text buffer. Normally, this is just as black as the rest of the
screen (vc_video_erase_char) and can't be seen, but it appears as a
black cursor rectangle on non-black backgrounds e.g. with boot option
"vt.global_cursor_default=0 vt.color=0xf0". softcursor_original needs
to be initialized with -1.

Signed-off-by: Melchior FRANZ <mfranz@xxxxxx>

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 4462d16..8ea3543 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -568,7 +568,7 @@ static void delete_char(struct vc_data *vc, unsigned int nr)
vc->vc_cols - vc->vc_x);

-static int softcursor_original;
+static int softcursor_original = -1;

static void add_softcursor(struct vc_data *vc)
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