[vox-tech] Debian bf2.4 base kernel (disable framebuffer, enable ide DMA)

[vox-tech@lists.lugod.org]

Took a while to send this, since I wanted to double check what I wrote.
On Tue, Feb 18, 2003 at 09:17:27PM -0800, Troy Arnold wrote:
> On Tue, Feb 18, 2003 at 04:46:03PM -0500, msimons@moria.simons-clan.com wrote:
> > - get rid of the VGA VESA frame buffer mode that is enabled in that kernel.
> > 
> >   This weekend I discovered that you can turn off the vesa frame buffer
> > with a boot time command line option:
> > ===
> > video=vga16:off
> > ===
> 
> Yup, it's documented in Debian's lilo.conf along with:
> #vga=ask
> 
> Which gives you some other modes to choose from.  The mode that I
> happen to prefer is not in the list:
> vga=0x305

  I'm am a little puzzled... vga= and video= do completely different things.
I do not see where the "video=vga16:off" option is documented in the default
lilo.conf or any other files on a installed Debian system.

  I see "vga=" options documented in many places like
/usr/src/linux/Documentation/svga.txt and mentioned in lilo.conf, but that 
configures the vga mode (screen size of text consoles in characters).  
  Whereas "video=" options effect the framebuffer system (size in pixels, 
bits per pixel, refresh rate), and appear to be documented sporadically
in /usr/src/linux/Documentation/fb (depending on the device that is the
framebuffer like vga16 is not documented at all).

  I stumbled upon the video= option while reading the special bootup 
options on the debian bf2.4 install disks... 

F5 - SPECIAL BOOT ARGUMENTS - VARIOUS HARDWARE
====
HARDWARE                            PARAMETER TO SPECIFY
Disable framebuffer for monitor      video=vga16:off
====

  I was surprised to see it mentioned there.  I hunted through 
documentation looking for an option like that maybe a year ago
and couldn't find any option to disable framebuffer.
  I still can't find documentation on the "vga16" framebuffer driver... 


> > - the stock kernels don't enabled DMA mode by default on many systems.
> >   Also one can enable dma mode with another boottime option:
> > ===
> > ide0=dma ide1=dma
> > ===
> 
> There's also the 'hdparm' command:
> hdparm -d 1 -m16 /dev/hda
> -d 1 == turn on DMA
> -m16 == turn on multi-sector IO
> 
> These two options vastly improve performance on modern IDE drives.

  Yes, I thought so too... I used to use: -d 1 -m 16 -c 1 -u 1 

  In my own testing I found that multi-block mode doesn't appear to 
improve performance if dma mode is available.  If dma mode is available 
enable that and it's as good as you get.  If dma is _not_ available 
(because it's a really old IDE drive), then multi-mode helps some.