2002-08-24 08:13:32

by David Madore

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Subject: Disabling frame buffer

Hi.

Suppose I compiled a kernel (2.4.19) with graphical frame buffer
support (Radeon, to be precise, but I don't suppose it matters), and
suppose I decide I really want to boot in plain ol' text mode (80x25
with no embellishments and no penguin logo) just for once. Is there
some way I can do this (other than recompiling the same kernel but
without this frame buffer support)?

Before someone suggests this, I did try passing vga=259 as an option,
but that doesn't change anything, it still switches to graphic mode
sometime later in the boot process. Initially the log says

Console: colour VGA+ 80x25

and later it changes its mind,

radeonfb: ref_clk=2700, ref_div=12, xclk=16600 from BIOS
Console: switching to colour frame buffer device 80x30
radeonfb: ATI Radeon 7500 QW DDR SGRAM 64 MB
radeonfb: DVI port no monitor connected
radeonfb: CRT port CRT monitor connected
vga16fb: initializing
vga16fb: mapped to 0xc00a0000
fb1: VGA16 VGA frame buffer device

I know it's a bit silly to insist on getting a plain text mode, and
even sillier not to want to just recompile, but I'd still appreciate
some help here.

Thanks,

--
David A. Madore
([email protected],
http://www.eleves.ens.fr:8080/home/madore/ )


2002-08-25 00:23:41

by Petr Vandrovec

[permalink] [raw]
Subject: Re: Disabling frame buffer

On Sat, Aug 24, 2002 at 10:17:43AM +0200, David Madore wrote:
>
> and later it changes its mind,
>
> radeonfb: ref_clk=2700, ref_div=12, xclk=16600 from BIOS
> Console: switching to colour frame buffer device 80x30
> radeonfb: ATI Radeon 7500 QW DDR SGRAM 64 MB
> radeonfb: DVI port no monitor connected
> radeonfb: CRT port CRT monitor connected
> vga16fb: initializing
> vga16fb: mapped to 0xc00a0000
> fb1: VGA16 VGA frame buffer device

video=radeon:off to disable Radeon
video=vga16:off to disable VGA16
video=radeon:off video=vga16:off to get back text-based vgacon

But! if you have 'video=radeon:1024x768@60' in /etc/lilo.conf,
you are out of luck: 'video=radeon:off' will not work for you in
such configuration, because of kernel will see your
'video=radeon:XXX' from /etc/lilo.conf's append before 'video=radeon:off'
you typed interactively at LILO prompt. Maybe someone should
fix it, but it is not trivial...

> I know it's a bit silly to insist on getting a plain text mode, and
> even sillier not to want to just recompile, but I'd still appreciate
> some help here.

If you want text-based framebuffer, I still have vga16fb text mode
patch in my kernel tree:

mode "640x480-60"
# D: 25.176 MHz, H: 31.469 kHz, V: 59.942 Hz
geometry 640 480 640 6553 0
timings 39721 48 16 33 10 96 2
rgba 6/0,6/0,6/0,0/0
endmode

Frame buffer device information:
Name : VGA16 VGA
Address : 0xa0000
Size : 65536
Type : CGA/EGA/VGA Color text
Visual : PSEUDOCOLOR
XPanStep : 8
YPanStep : 1
YWrapStep : 0
LineLength : 160
Accelerator : No
Petr Vandrovec
[email protected]