linux-kernel - [PATCH] vt: add init_hide parameter to suppress boot output

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Date:	Tue, 19 Feb 2013 11:38:10 +0200
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>
Cc:	Pavel Machek <pavel@....cz>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Len Brown <len.brown@...el.com>, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, Andy Ross <andy.ross@...driver.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH] vt: add init_hide parameter to suppress boot output

From: Andy Ross <andy.ross@...driver.com>

When vt.init_hide=1 is set, suppress output on newly created consoles
until an affirmative switched to that console.  This prevents boot
output from displaying (and clobbering splash screens, etc...) without
disabling the console entirely.

Signed-off-by: Andy Ross <andy.ross@...driver.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 drivers/tty/vt/vt.c            |    7 +++++++
 include/linux/console_struct.h |    3 ++-
 include/linux/vt.h             |    2 ++
 kernel/power/console.c         |    2 --
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 8fd8968..3966ff5 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -165,6 +165,9 @@ 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);
 
+static int init_hide;
+module_param(init_hide, int, S_IRUGO);
+
 /*
  * ignore_poke: don't unblank the screen when things are typed.  This is
  * mainly for the privacy of braille terminal users.
@@ -734,6 +737,7 @@ static void visual_init(struct vc_data *vc, int num, int init)
 	__module_get(vc->vc_sw->owner);
 	vc->vc_num = num;
 	vc->vc_display_fg = &master_display_fg;
+	vc->vc_hidden = init_hide;
 	vc->vc_uni_pagedir_loc = &vc->vc_uni_pagedir;
 	vc->vc_uni_pagedir = 0;
 	vc->vc_hi_font_mask = 0;
@@ -2336,6 +2340,9 @@ static void console_callback(struct work_struct *ignored)
 	if (want_console >= 0) {
 		if (want_console != fg_console &&
 		    vc_cons_allocated(want_console)) {
+			if(want_console != SUSPEND_CONSOLE &&
+			   fg_console != SUSPEND_CONSOLE)
+				vc_cons[want_console].d->vc_hidden = 0;
 			hide_cursor(vc_cons[fg_console].d);
 			change_console(vc_cons[want_console].d);
 			/* we only changed when the console had already
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index 7f0c329..817db0e 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -91,6 +91,7 @@ struct vc_data {
 	unsigned int	vc_can_do_color	: 1;
 	unsigned int	vc_report_mouse : 2;
 	unsigned char	vc_utf		: 1;	/* Unicode UTF-8 encoding */
+	unsigned int    vc_hidden	: 1;    /* Set by vt.init_hide=1 */
 	unsigned char	vc_utf_count;
 		 int	vc_utf_char;
 	unsigned int	vc_tab_stop[8];		/* Tab stops. 256 columns. */
@@ -134,6 +135,6 @@ extern void vc_SAK(struct work_struct *work);
 
 #define CUR_DEFAULT CUR_UNDERLINE
 
-#define CON_IS_VISIBLE(conp) (*conp->vc_display_fg == conp)
+#define CON_IS_VISIBLE(conp) (*conp->vc_display_fg == conp && !conp->vc_hidden)
 
 #endif /* _LINUX_CONSOLE_STRUCT_H */
diff --git a/include/linux/vt.h b/include/linux/vt.h
index b186e04..0dc3e89 100644
--- a/include/linux/vt.h
+++ b/include/linux/vt.h
@@ -11,6 +11,8 @@
 #define VT_UPDATE		0x0004 /* A bigger update occurred */
 #define VT_PREWRITE		0x0005 /* A char is about to be written to the console */
 
+#define SUSPEND_CONSOLE	(MAX_NR_CONSOLES-1)
+
 #ifdef CONFIG_VT_CONSOLE
 
 extern int vt_kmsg_redirect(int new);
diff --git a/kernel/power/console.c b/kernel/power/console.c
index b1dc456..b74bdb8 100644
--- a/kernel/power/console.c
+++ b/kernel/power/console.c
@@ -10,8 +10,6 @@
 #include <linux/module.h>
 #include "power.h"
 
-#define SUSPEND_CONSOLE	(MAX_NR_CONSOLES-1)
-
 static int orig_fgconsole, orig_kmsg;
 
 int pm_prepare_console(void)
-- 
1.7.10.4

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