Commit 0cf9bb67 authored by Randy Dunlap's avatar Randy Dunlap Committed by Jonathan Corbet
Browse files

documentation/svga.txt: update outdated file

Drop CONFIG_VIDEO_400_HACK info completely.
Drop CONFIG_VIDEO_SVGA info since it has been removed.
Drop chapter number & section number references since they are wrong.
Drop (bad) ftp URL for 800x600 Thinkpad XF86Config.

Rename CONFIG_VIDEO_GFX_HACK to VIDEO_GFX_HACK since it is not a
Kconfig symbol. And to match the source code.

Build options are controlled by the kernel kconfig utility.
Signed-off-by: default avatarRandy Dunlap <>
Acked-By: default avatarMartin Mares <>
Cc: "H. Peter Anvin" <>
Signed-off-by: default avatarJonathan Corbet <>
parent 80416fb4
......@@ -67,8 +67,7 @@ The menu looks like::
<name-of-detected-video-adapter> tells what video adapter did Linux detect
-- it's either a generic adapter name (MDA, CGA, HGC, EGA, VGA, VESA VGA [a VGA
with VESA-compliant BIOS]) or a chipset name (e.g., Trident). Direct detection
of chipsets is turned off by default (see CONFIG_VIDEO_SVGA in chapter 4 to see
how to enable it if you really want) as it's inherently unreliable due to
of chipsets is turned off by default as it's inherently unreliable due to
absolutely insane PC design.
"0 0F00 80x25" means that the first menu item (the menu items are numbered
......@@ -138,7 +137,7 @@ The ID numbers can be divided to those regions::
0x0f05 VGA 80x30 (480 scans, 16-point font)
0x0f06 VGA 80x34 (480 scans, 14-point font)
0x0f07 VGA 80x60 (480 scans, 8-point font)
0x0f08 Graphics hack (see the CONFIG_VIDEO_HACK paragraph below)
0x0f08 Graphics hack (see the VIDEO_GFX_HACK paragraph below)
0x1000 to 0x7fff - modes specified by resolution. The code has a "0xRRCC"
form where RR is a number of rows and CC is a number of columns.
......@@ -160,58 +159,22 @@ end of the display.
Some options can be set in the source text (in arch/i386/boot/video.S).
All of them are simple #define's -- change them to #undef's when you want to
switch them off. Currently supported:
CONFIG_VIDEO_SVGA - enables autodetection of SVGA cards. This is switched
off by default as it's a bit unreliable due to terribly bad PC design. If you
really want to have the adapter autodetected (maybe in case the ``scan`` feature
doesn't work on your machine), switch this on and don't cry if the results
are not completely sane. In case you really need this feature, please drop me
a mail as I think of removing it some day.
CONFIG_VIDEO_VESA - enables autodetection of VESA modes. If it doesn't work
on your machine (or displays a "Error: Scanning of VESA modes failed" message),
you can switch it off and report as a bug.
CONFIG_VIDEO_COMPACT - enables compacting of the video mode list. If there
are more modes with the same screen size, only the first one is kept (see above
for more info on mode ordering). However, in very strange cases it's possible
that the first "version" of the mode doesn't work although some of the others
do -- in this case turn this switch off to see the rest.
CONFIG_VIDEO_RETAIN - enables retaining of screen contents when switching
video modes. Works only with some boot loaders which leave enough room for the
buffer. (If you have old LILO, you can adjust heap_end_ptr and loadflags
in setup.S, but it's better to upgrade the boot loader...)
CONFIG_VIDEO_LOCAL - enables inclusion of "local modes" in the list. The
local modes are added automatically to the beginning of the list not depending
on hardware configuration. The local modes are listed in the source text after
the "local_mode_table:" line. The comment before this line describes the format
of the table (which also includes a video card name to be displayed on the
top of the menu).
CONFIG_VIDEO_400_HACK - force setting of 400 scan lines for standard VGA
modes. This option is intended to be used on certain buggy BIOSes which draw
some useless logo using font download and then fail to reset the correct mode.
Don't use unless needed as it forces resetting the video card.
CONFIG_VIDEO_GFX_HACK - includes special hack for setting of graphics modes
to be used later by special drivers (e.g., 800x600 on IBM ThinkPad -- see
Build options for arch/x86/boot/* are selected by the kernel kconfig
utility and the kernel .config file.
VIDEO_GFX_HACK - includes special hack for setting of graphics modes
to be used later by special drivers.
Allows to set _any_ BIOS mode including graphic ones and forcing specific
text screen resolution instead of peeking it from BIOS variables. Don't use
unless you think you know what you're doing. To activate this setup, use
mode number 0x0f08 (see section 3).
mode number 0x0f08 (see the Mode IDs section above).
Still doesn't work?
When the mode detection doesn't work (e.g., the mode list is incorrect or
the machine hangs instead of displaying the menu), try to switch off some of
the configuration options listed in section 4. If it fails, you can still use
the configuration options listed under "Options". If it fails, you can still use
your kernel with the video mode set directly via the kernel parameter.
In either case, please send me a bug report containing what _exactly_
......@@ -228,10 +191,6 @@ contains the most common video BIOS bug called "incorrect vertical display
end setting". Adding 0x8000 to the mode ID might fix the problem. Unfortunately,
this must be done manually -- no autodetection mechanisms are available.
If you have a VGA card and your display still looks as on EGA, your BIOS
is probably broken and you need to set the CONFIG_VIDEO_400_HACK switch to
force setting of the correct mode.
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment