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    SubjectRe: [PATCH 1/2] Colored kernel output (run3)
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    On Sat, 2007-10-06 at 22:09 +0200, Jan Engelhardt wrote: 
    > 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.
    >
    > References: http://lkml.org/lkml/2007/4/1/162
    > http://lkml.org/lkml/2007/10/5/199

    This is quite a long thread :-)

    >
    > Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
    >
    > ---
    > drivers/char/Kconfig | 42 ++++++++++++++++++++++++++++++++++++++++++
    > drivers/char/vt.c | 23 +++++++++++++++++++++++
    > 2 files changed, 65 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 +58,48 @@ config VT_CONSOLE
    >
    > If unsure, say Y.
    >
    > +config VT_CKO
    > + bool "Colored kernel message output"
    > + depends on VT_CONSOLE
    > + ---help---
    > + This option enables kernel messages to be emitted in
    > + colors other than the default.
    > +
    > + If unsure, say N.
    > +
    > +config VT_PRINTK_COLOR
    > + hex "Colored kernel message output"
    > + range 0x00 0xFF
    > + depends on VT_CKO
    > + 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

    The more correct term for "The value" is probably "The attribute".

    > + (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.)

    You might have to include a warning that those values or attributes are
    interpreted differently depending on the driver used, and the above is
    mostly true for 16-color console drivers only.

    For 2-colors (we still have quite a few of them) only bit 0 is true for
    color (0x00 and 0x01). The rest of the bits are interpreted as
    attributes:

    0x02 - italic
    0x04 - underline
    0x08 - bold
    0x80 - blink

    The italic, underline and bold attributes will show up in a 2-color
    framebuffer console. The blink attribute is ignored.

    With a 4-color fb console (4-level grayscale), those values are again
    interpreted differently.

    0x00 - 0x00 : black
    0x01 - 0x06 : white
    0x07 - 0x08 : gray
    the rest : intense white

    (If by mistake 0x0106 is used, it will produce a white on white display)

    With an 8-color console, only the first 8 values are considered.

    With a 16-color console, that is also not consistent:

    With vgacon, it supports 16-color foreground (fg), 8-color
    background (bg) at 256 chars. Becomes 8 fg and 8 bg with 512 chars.

    With fbcon, it supports 16 fg and 16 bg at 256, 16 fg and 8 bg at
    512 chars.

    And for drivers that have their own con_build_attr() hook, they will be
    interpreted differently again.

    > +
    > + 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.
    > +

    You may need to specify that the values here are the console default,
    ie, the default_blue|grn|red boot options are not filled up.

    > 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 +2345,23 @@ struct tty_driver *console_driver;
    >
    > #ifdef CONFIG_VT_CONSOLE
    >
    > +static unsigned int printk_color __read_mostly = CONFIG_VT_PRINTK_COLOR;
    > +#ifdef CONFIG_VT_CKO
    > +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);

    You may want to leave out the blink attribute (0x80) from this part.
    Otherwise setterm -blink on|off will produce the opposite effect.

    Tony



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