vt: make the default cursor shape configurable

For embedded systems, the blinking cursor at startup time can be annoying
and unintended.  Add a new kernel parameter to change the default cursor
shape.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: Daniel Mack <daniel@caiaq.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: David Newall <davidn@davidnewall.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/kernel-parameters.txt

@@ -2729,6 +2729,11 @@ and is between 256 and 4096 characters. It is defined in the file
 	vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
 			Format: <command>
 
+	vt.cur_default=	[VT] Default cursor shape.
+			Format: 0xCCBBAA, where AA, BB, and CC are the same as
+			the parameters of the <Esc>[?A;B;Cc escape sequence;
+			see VGA-softcursor.txt. Default: 2 = underline.
+
 	vt.default_blu=	[VT]
 			Format: <blue0>,<blue1>,<blue2>,...,<blue15>
 			Change the default blue palette of the console.

drivers/char/vt.c

@@ -164,6 +164,9 @@ module_param(default_utf8, int, S_IRUGO | S_IWUSR);
 int global_cursor_default = -1;
 module_param(global_cursor_default, int, S_IRUGO | S_IWUSR);
 
+static int cur_default = CUR_DEFAULT;
+module_param(cur_default, int, S_IRUGO | S_IWUSR);
+
 /*
  * ignore_poke: don't unblank the screen when things are typed.  This is
  * mainly for the privacy of braille terminal users.
@@ -1636,7 +1639,7 @@ static void reset_terminal(struct vc_data *vc, int do_clear)
 	/* do not do set_leds here because this causes an endless tasklet loop
 	   when the keyboard hasn't been initialized yet */
 
-	vc->vc_cursor_type = CUR_DEFAULT;
+	vc->vc_cursor_type = cur_default;
 	vc->vc_complement_mask = vc->vc_s_complement_mask;
 
 	default_attr(vc);
@@ -1838,7 +1841,7 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c)
 				if (vc->vc_par[0])
 					vc->vc_cursor_type = vc->vc_par[0] | (vc->vc_par[1] << 8) | (vc->vc_par[2] << 16);
 				else
-					vc->vc_cursor_type = CUR_DEFAULT;
+					vc->vc_cursor_type = cur_default;
 				return;
 			}
 			break;