linux-kernel - Re: 2.6.26-rcX VC console scrolling regression

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Date:	Wed, 7 May 2008 23:02:47 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	David Miller <davem@...emloft.net>
Cc:	linux-kernel@...r.kernel.org, jengelh@...putergmbh.de,
	adaplas@....net, hpa@...or.com, alan@...rguk.ukuu.org.uk,
	torvalds@...ux-foundation.org
Subject: Re: 2.6.26-rcX VC console scrolling regression

On Wed, 07 May 2008 21:46:37 -0700 (PDT) David Miller <davem@...emloft.net> wrote:

> 
> This change:
> 
> commit c9e587abfdec2c2aaa55fab83bcb4972e2f84f9b
> Author: Jan Engelhardt <jengelh@...putergmbh.de>
> Date:   Tue Apr 29 00:59:46 2008 -0700
> 
>     vt: fix background color on line feed
>     
>     A command that causes a line feed while a background color is active,
>     such as
>     
>     	perl -e 'print "x" x 60, "\e[44m", "x" x 40, "\e[0m\n"'
>     and
>     	perl -e 'print "x" x 40, "\e[44m\n", "x" x 40, "\e[0m\n"'
>     
>     causes the line that was started as a result of the line feed to be completely
>     filled with the currently active background color instead of the default
>     color.
>     
>     When scrolling, part of the current screen is memcpy'd/memmove'd to the new
>     region, and the new line(s) that will appear as a result are cleared using
>     memset.  However, the lines are cleared with vc->vc_video_erase_char, causing
>     them to be colored with the currently active background color.  This is
>     different from X11 terminal emulators which always paint the new lines with
>     the default background color (e.g.  `xterm -bg black`).
>     
>     The clear operation (\e[1J and \e[2J) also use vc_video_erase_char, so a new
>     vc->vc_scrl_erase_char is introduced with contains the erase character used
>     for scrolling, which is built from vc->vc_def_color instead of vc->vc_color.
>     
>     Signed-off-by: Jan Engelhardt <jengelh@...putergmbh.de>
>     Cc: "Antonino A. Daplas" <adaplas@....net>
>     Cc: "H. Peter Anvin" <hpa@...or.com>
>     Cc: Alan Cox <alan@...rguk.ukuu.org.uk>
>     Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
>     Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
> 
> Causes garbage characters to appear at the end of lines on my VCs when
> scrolling.
> 
> They look like lowercase 'c' characters with a '.' above them, and they
> are colored light blue.  The rest of the console text is fine.
> 
> I think it might be because my VC gets put into a UTF8 mode or something
> like that via the init scripts?  It seems to start happening right when
> the init scripts print "Setting up console font and keymap", which seems
> to come from /etc/init.d/console-setup which runs /bin/setupcon
> 
> This is with a stock Ubuntu 7.10 installation.

Thanks, Dave.  I queued the revert but I'll hold off for 48-odd hours if
that's OK - it might just be something silly.


If we continue in this way, patch-2.6.26 will consist solely of:

--- a/Makefile
+++ a/Makefile
@@ -1,6 +1,6 @@
 VERSION = 2
 PATCHLEVEL = 6
-SUBLEVEL = 25
+SUBLEVEL = 26
 EXTRAVERSION =
 NAME = Funky Weasel is Jiggy wit it
 
:(
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