vc: Add support for hiding the cursor when creating VTs

Add support for setting a global default for whether or not a visible
cursor should be enabled when creating VCs. The default will be to do so,
unless overridden by the user at boot time or by a driver.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
LKML-Reference: <1258143251-5818-1-git-send-email-mjg@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Documentation/kernel-parameters.txt

@@ -2729,6 +2729,15 @@ and is between 256 and 4096 characters. It is defined in the file
 			Default is 1, i.e. UTF-8 mode is enabled for all
 			newly opened terminals.
 
+	vt.global_cursor_default=
+			[VT]
+			Format=<-1|0|1>
+			Set system-wide default for whether a cursor
+			is shown on new VTs. Default is -1,
+			i.e. cursors will be created by default unless
+			overridden by individual drivers. 0 will hide
+			cursors, 1 will display them.
+
 	waveartist=	[HW,OSS]
 			Format: <io>,<irq>,<dma>,<dma2>
 

drivers/char/vt.c

@@ -161,6 +161,8 @@ static void set_palette(struct vc_data *vc);
 static int printable;		/* Is console ready for printing? */
 int default_utf8 = true;
 module_param(default_utf8, int, S_IRUGO | S_IWUSR);
+int global_cursor_default = -1;
+module_param(global_cursor_default, int, S_IRUGO | S_IWUSR);
 
 /*
  * ignore_poke: don't unblank the screen when things are typed.  This is
@@ -775,6 +777,12 @@ int vc_allocate(unsigned int currcons)	/* return 0 on success */
 		vc_cons[currcons].d = NULL;
 		return -ENOMEM;
 	    }
+
+	    /* If no drivers have overridden us and the user didn't pass a
+	       boot option, default to displaying the cursor */
+	    if (global_cursor_default == -1)
+		    global_cursor_default = 1;
+
 	    vc_init(vc, vc->vc_rows, vc->vc_cols, 1);
 	    vcs_make_sysfs(currcons);
 	    atomic_notifier_call_chain(&vt_notifier_list, VT_ALLOCATE, &param);
@@ -1616,7 +1624,7 @@ static void reset_terminal(struct vc_data *vc, int do_clear)
 	vc->vc_decscnm		= 0;
 	vc->vc_decom		= 0;
 	vc->vc_decawm		= 1;
-	vc->vc_deccm		= 1;
+	vc->vc_deccm		= global_cursor_default;
 	vc->vc_decim		= 0;
 
 	set_kbd(vc, decarm);
@@ -4078,6 +4086,7 @@ EXPORT_SYMBOL(fg_console);
 EXPORT_SYMBOL(console_blank_hook);
 EXPORT_SYMBOL(console_blanked);
 EXPORT_SYMBOL(vc_cons);
+EXPORT_SYMBOL(global_cursor_default);
 #ifndef VT_SINGLE_DRIVER
 EXPORT_SYMBOL(take_over_console);
 EXPORT_SYMBOL(give_up_console);

drivers/video/console/vgacon.c

@@ -585,6 +585,8 @@ static void vgacon_init(struct vc_data *c, int init)
 	vgacon_uni_pagedir[1]++;
 	if (!vgacon_uni_pagedir[0] && p)
 		con_set_default_unimap(c);
+
+	hide_boot_cursor(screen_info.flags & VIDEO_FLAGS_NOCURSOR);
 }
 
 static void vgacon_deinit(struct vc_data *c)

include/linux/vt_kern.h

@@ -110,6 +110,7 @@ extern char con_buf[CON_BUF_SIZE];
 extern struct mutex con_buf_mtx;
 extern char vt_dont_switch;
 extern int default_utf8;
+extern int global_cursor_default;
 
 struct vt_spawn_console {
 	spinlock_t lock;
@@ -130,4 +131,6 @@ struct vt_notifier_param {
 extern int register_vt_notifier(struct notifier_block *nb);
 extern int unregister_vt_notifier(struct notifier_block *nb);
 
+extern void hide_boot_cursor(bool hide);
+
 #endif /* _VT_KERN_H */