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

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Date:	Thu, 8 May 2008 13:50:57 +0200 (CEST)
From:	Jan Engelhardt <jengelh@...ozas.de>
To:	David Miller <davem@...emloft.net>
cc:	linux-kernel@...r.kernel.org, adaplas@....net, hpa@...or.com,
	alan@...rguk.ukuu.org.uk, akpm@...ux-foundation.org,
	torvalds@...ux-foundation.org
Subject: Re: 2.6.26-rcX VC console scrolling regression


On Thursday 2008-05-08 06:46, David Miller wrote:
>
>Causes garbage characters to appear at the end of lines on my VCs when
>scrolling.
>
(Gotten past the initramfs now..)
>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.

I "reproduced" it this way on Ubuntu on i386 with fbcon (which you
are likely to be using on sparc64), when switching from a 256 to
512-glyph font. So far, only Ubuntu seems to exhibit this problem,
I am going to test Fedora for its fitness now.

# Right after boot...
	showconsolefont
# Trigger
	setfont Arabic-VGA16
	showconsolefont

# Resolve bug with 'reset'
	reset
	while $not_scrolled; do
		showconsolefont
	done;

My guess is that you see the effects of incomplete font table/position
switching, something along the lines a `cat /dev/urandom` would cause.
Using the very same kernel and boot params (vga=791 or anything to
switch it to fbcon), I cannot trigger the problem on opensuse.
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