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svga.txt: standardize document format 

Each text file under Documentation follows a different
format. Some doesn't even have titles!

Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:
- Use standard notation for titles;
- Use the note mark;
- mark literal blocks;
- adjust identation;
- mark the table.

Acked-By: Martin Mares <mj@ucw.cz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
zero-colors
Mauro Carvalho Chehab 2017-05-17 09:00:17 -03:00 committed by Jonathan Corbet
parent 603699bbfb
commit aa4d520358
1 changed files with 80 additions and 66 deletions
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76
Documentation/svga.txt
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@ -1,24 +1,31 @@
Video Mode Selection Support 2.13
(c) 1995--1999 Martin Mares, <mj@ucw.cz>
--------------------------------------------------------------------------------
.. include:: <isonum.txt>
=================================
Video Mode Selection Support 2.13
=================================
:Copyright: |copy| 1995--1999 Martin Mares, <mj@ucw.cz>
Intro
~~~~~
1. Intro
~~~~~~~~
This small document describes the "Video Mode Selection" feature which
allows the use of various special video modes supported by the video BIOS. Due
to usage of the BIOS, the selection is limited to boot time (before the
kernel decompression starts) and works only on 80X86 machines.
** Short intro for the impatient: Just use vga=ask for the first time,
** enter `scan' on the video mode prompt, pick the mode you want to use,
** remember its mode ID (the four-digit hexadecimal number) and then
** set the vga parameter to this number (converted to decimal first).
.. note::
Short intro for the impatient: Just use vga=ask for the first time,
enter ``scan`` on the video mode prompt, pick the mode you want to use,
remember its mode ID (the four-digit hexadecimal number) and then
set the vga parameter to this number (converted to decimal first).
The video mode to be used is selected by a kernel parameter which can be
specified in the kernel Makefile (the SVGA_MODE=... line) or by the "vga=..."
option of LILO (or some other boot loader you use) or by the "vidmode" utility
(present in standard Linux utility packages). You can use the following values
of this parameter:
of this parameter::
NORMAL_VGA - Standard 80x25 mode available on all display adapters.
@ -37,15 +44,16 @@ of this parameter:
for exact meaning of the ID). Warning: rdev and LILO don't support
hexadecimal numbers -- you have to convert it to decimal manually.
2. Menu
~~~~~~~
Menu
~~~~
The ASK_VGA mode causes the kernel to offer a video mode menu upon
bootup. It displays a "Press <RETURN> to see video modes available, <SPACE>
to continue or wait 30 secs" message. If you press <RETURN>, you enter the
menu, if you press <SPACE> or wait 30 seconds, the kernel will boot up in
the standard 80x25 mode.
The menu looks like:
The menu looks like::
Video adapter: <name-of-detected-video-adapter>
Mode: COLSxROWS:
@ -54,7 +62,7 @@ Mode: COLSxROWS:
2 0F02 80x43
3 0F03 80x26
....
Enter mode number or `scan': <flashing-cursor-here>
Enter mode number or ``scan``: <flashing-cursor-here>
<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
@ -89,25 +97,26 @@ program will try to ask the BIOS for all possible video mode numbers and test
what happens then. The screen will be probably flashing wildly for some time and
strange noises will be heard from inside the monitor and so on and then, really
all consistent video modes supported by your BIOS will appear (plus maybe some
`ghost modes'). If you are afraid this could damage your monitor, don't use this
function.
``ghost modes``). If you are afraid this could damage your monitor, don't use
this function.
After scanning, the mode ordering is a bit different: the auto-detected SVGA
modes are not listed at all and the modes revealed by `scan' are shown before
modes are not listed at all and the modes revealed by ``scan`` are shown before
all VESA modes.
3. Mode IDs
~~~~~~~~~~~
Mode IDs
~~~~~~~~
Because of the complexity of all the video stuff, the video mode IDs
used here are also a bit complex. A video mode ID is a 16-bit number usually
expressed in a hexadecimal notation (starting with "0x"). You can set a mode
by entering its mode directly if you know it even if it isn't shown on the menu.
The ID numbers can be divided to three regions:
The ID numbers can be divided to those regions::
0x0000 to 0x00ff - menu item references. 0x0000 is the first item. Don't use
outside the menu as this can change from boot to boot (especially if you
have used the `scan' feature).
have used the ``scan`` feature).
0x0100 to 0x017f - standard BIOS modes. The ID is a BIOS video mode number
(as presented to INT 10, function 00) increased by 0x0100.
@ -148,15 +157,16 @@ eliminate some annoying bugs of certain VGA BIOSes (usually those used for
cards with S3 chipsets and old Cirrus Logic BIOSes) -- mainly extra lines at the
end of the display.
4. Options
~~~~~~~~~~
Options
~~~~~~~
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
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.
@ -196,8 +206,9 @@ 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).
5. Still doesn't work?
~~~~~~~~~~~~~~~~~~~~~~
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
@ -221,8 +232,10 @@ this must be done manually -- no autodetection mechanisms are available.
is probably broken and you need to set the CONFIG_VIDEO_400_HACK switch to
force setting of the correct mode.
6. History
~~~~~~~~~~
History
~~~~~~~
=============== ================================================================
1.0 (??-Nov-95) First version supporting all adapters supported by the old
setup.S + Cirrus Logic 54XX. Present in some 1.3.4? kernels
and then removed due to instability on some machines.
@ -268,9 +281,10 @@ force setting of the correct mode.
- Added the CONFIG_VIDEO_GFX_HACK switch.
- Code cleanup.
2.11(03-May-97) - Yet another cleanup, now including also the documentation.
- Direct testing of SVGA adapters turned off by default, `scan'
- Direct testing of SVGA adapters turned off by default, ``scan``
offered explicitly on the prompt line.
- Removed the doc section describing adding of new probing
functions as I try to get rid of _all_ hardware probing here.
2.12 (25-May-98)- Added support for VESA frame buffer graphics.
2.13 (14-May-99)- Minor documentation fixes.
2.12(25-May-98) Added support for VESA frame buffer graphics.
2.13(14-May-99) Minor documentation fixes.
=============== ================================================================