linux-kernel - Re: [PATCH 1/2] Colored kernel output (run3)

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Message-Id: <1191887614.5508.47.camel@daplas>
Date:	Tue, 09 Oct 2007 07:53:34 +0800
From:	"Antonino A. Daplas" <adaplas@...il.com>
To:	Jan Engelhardt <jengelh@...putergmbh.de>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Oleg Verych <olecom@...wer.upol.cz>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH 1/2] Colored kernel output (run3)

On Tue, 2007-10-09 at 01:31 +0200, Jan Engelhardt wrote:
> On Oct 9 2007 07:12, Antonino A. Daplas wrote:
> >> 
> >> References: http://lkml.org/lkml/2007/4/1/162
> >> 	http://lkml.org/lkml/2007/10/5/199
> >
> >This is quite a long thread :-)
> 
> It was a patch series after all. But as Greg puts it, be persistent.
> 
> >> +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".
> 
> "The value for this kconfig entry" it should read in the minds.
> 
> >> +	(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.
> 
> Are there any other drivers besides vgacon and fbcon that use vt.c?

All drivers under drivers/video/console. That would be:

vgacon
dummycon
fbcon
newport_con
sticon
promcon
mdacon

There are perhaps a few more drivers outside this directory, such as
sisusbcon or something.

<snip>

> >You may want to leave out the blink attribute (0x80) from this part.
> >Otherwise setterm -blink on|off will produce the opposite effect. 
> 
> But 0x80 might be interpreted in a different fashion for some othercon, 
> yielding for example superbold rather than blinking.

That's right. But setting the blink attribute is done with an XOR (^).
So 'setterm -blink' on will unset the blink attribute (0x80 ^ 0x80).

> I'll have to try this, because usually, setterm operates on TTYs
> rather than VCs.

Yes, but if the tty driver type is a virtual console, then vt.c is still
affected. 

Well the blink attribute is ignored by most drivers, if I'm not
mistaken. So you generally won't see the effect :-). But with fbcon, the
blink attribute is interpreted as "change background color from black to
light gray".

Tony

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