[PATCH 1/2] Colored kernel output (run2)

[Jan Engelhardt <jengelh@computergmbh.de>]

Colored kernel message output (1/2)

This patch makes it possible to give kernel messages a selectable
color. It can be chosen at compile time, overridden at boot time,
and changed at run time.

There is no way to disable this option. It would only add ugly
ifdefs, and the default color is the one that vt.c used for all the
past years anyway, so apart from the config option, nothing changes
for the conservative user.

References: http://lkml.org/lkml/2007/4/1/162
	http://lkml.org/lkml/2007/10/5/199

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>

---
 drivers/char/Kconfig |   33 +++++++++++++++++++++++++++++++++
 drivers/char/vt.c    |   17 +++++++++++++++++
 2 files changed, 50 insertions(+)

Index: linux-2.6.23/drivers/char/Kconfig
===================================================================
--- linux-2.6.23.orig/drivers/char/Kconfig
+++ linux-2.6.23/drivers/char/Kconfig
@@ -58,6 +58,39 @@ config VT_CONSOLE
 
 	  If unsure, say Y.
 
+config VT_PRINTK_COLOR
+	hex "Colored kernel message output"
+	range 0x00 0xFF
+	depends on VT_CONSOLE
+	default 0x07
+	---help---
+	This option defines with which color kernel messages will be
+	printed to the console.
+
+	The value you need to enter here is the value is composed
+	(OR-ed) of a foreground and a background color.
+
+	Foreground:
+	0x00 = black,   0x08 = dark gray,
+	0x01 = red,     0x09 = light red,
+	0x02 = green,   0x0A = light green,
+	0x03 = brown,   0x0B = yellow,
+	0x04 = blue,    0x0C = light blue,
+	0x05 = magenta, 0x0D = light magenta,
+	0x06 = cyan,    0x0E = light cyan,
+	0x07 = gray,    0x0F = white,
+
+	(Foreground colors 0x08 to 0x0F do not work when a VGA
+	console font with 512 glyphs is used.)
+
+	Background:
+	0x00 = black,   0x40 = blue,
+	0x10 = red,     0x50 = magenta,
+	0x20 = green,   0x60 = cyan,
+	0x30 = brown,   0x70 = gray,
+
+	For example, 0x1F would yield white on red.
+
 config HW_CONSOLE
 	bool
 	depends on VT && !S390 && !UML
Index: linux-2.6.23/drivers/char/vt.c
===================================================================
--- linux-2.6.23.orig/drivers/char/vt.c
+++ linux-2.6.23/drivers/char/vt.c
@@ -73,6 +73,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/moduleparam.h>
 #include <linux/types.h>
 #include <linux/sched.h>
 #include <linux/tty.h>
@@ -2344,6 +2345,17 @@ struct tty_driver *console_driver;
 
 #ifdef CONFIG_VT_CONSOLE
 
+static unsigned int printk_color __read_mostly = CONFIG_VT_PRINTK_COLOR;
+module_param(printk_color, uint, S_IRUGO | S_IWUSR);
+
+static inline void vc_set_color(struct vc_data *vc, unsigned char color)
+{
+	vc->vc_color = color_table[color & 0xF] |
+	               (color_table[(color >> 4) & 0x7] << 4) |
+	               (color & 0x80);
+	update_attr(vc);
+}
+
 /*
  *	Console on virtual terminal
  *
@@ -2384,12 +2396,14 @@ static void vt_console_print(struct cons
 		hide_cursor(vc);
 
 	start = (ushort *)vc->vc_pos;
+	vc_set_color(vc, printk_color);
 
 	/* Contrived structure to try to emulate original need_wrap behaviour
 	 * Problems caused when we have need_wrap set on '\n' character */
 	while (count--) {
 		c = *b++;
 		if (c == 10 || c == 13 || c == 8 || vc->vc_need_wrap) {
+			vc_set_color(vc, vc->vc_def_color);
 			if (cnt > 0) {
 				if (CON_IS_VISIBLE(vc))
 					vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, vc->vc_x);
@@ -2402,6 +2416,7 @@ static void vt_console_print(struct cons
 				bs(vc);
 				start = (ushort *)vc->vc_pos;
 				myx = vc->vc_x;
+				vc_set_color(vc, printk_color);
 				continue;
 			}
 			if (c != 13)
@@ -2409,6 +2424,7 @@ static void vt_console_print(struct cons
 			cr(vc);
 			start = (ushort *)vc->vc_pos;
 			myx = vc->vc_x;
+			vc_set_color(vc, printk_color);
 			if (c == 10 || c == 13)
 				continue;
 		}
@@ -2430,6 +2446,7 @@ static void vt_console_print(struct cons
 			vc->vc_need_wrap = 1;
 		}
 	}
+	vc_set_color(vc, vc->vc_def_color);
 	set_cursor(vc);
 
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