mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 10:49:33 +00:00
![Randy Dunlap](/assets/img/avatar_default.png)
Drop CONFIG_VIDEO_400_HACK info completely. Drop CONFIG_VIDEO_RETAIN and CONFIG_VIDEO_LOCAL completely. Drop CONFIG_VIDEO_COMPACT and CONFIG_VIDEO_VESA 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: Randy Dunlap <rdunlap@infradead.org> Acked-By: Martin Mares <mj@ucw.cz> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
249 lines
12 KiB
Text
249 lines
12 KiB
Text
.. include:: <isonum.txt>
|
|
|
|
=================================
|
|
Video Mode Selection Support 2.13
|
|
=================================
|
|
|
|
:Copyright: |copy| 1995--1999 Martin Mares, <mj@ucw.cz>
|
|
|
|
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.
|
|
|
|
.. 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::
|
|
|
|
NORMAL_VGA - Standard 80x25 mode available on all display adapters.
|
|
|
|
EXTENDED_VGA - Standard 8-pixel font mode: 80x43 on EGA, 80x50 on VGA.
|
|
|
|
ASK_VGA - Display a video mode menu upon startup (see below).
|
|
|
|
0..35 - Menu item number (when you have used the menu to view the list of
|
|
modes available on your adapter, you can specify the menu item you want
|
|
to use). 0..9 correspond to "0".."9", 10..35 to "a".."z". Warning: the
|
|
mode list displayed may vary as the kernel version changes, because the
|
|
modes are listed in a "first detected -- first displayed" manner. It's
|
|
better to use absolute mode numbers instead.
|
|
|
|
0x.... - Hexadecimal video mode ID (also displayed on the menu, see below
|
|
for exact meaning of the ID). Warning: rdev and LILO don't support
|
|
hexadecimal numbers -- you have to convert it to decimal manually.
|
|
|
|
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::
|
|
|
|
Video adapter: <name-of-detected-video-adapter>
|
|
Mode: COLSxROWS:
|
|
0 0F00 80x25
|
|
1 0F01 80x50
|
|
2 0F02 80x43
|
|
3 0F03 80x26
|
|
....
|
|
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
|
|
with VESA-compliant BIOS]) or a chipset name (e.g., Trident). Direct detection
|
|
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
|
|
from "0" to "9" and from "a" to "z") is a 80x25 mode with ID=0x0f00 (see the
|
|
next section for a description of mode IDs).
|
|
|
|
<flashing-cursor-here> encourages you to enter the item number or mode ID
|
|
you wish to set and press <RETURN>. If the computer complains something about
|
|
"Unknown mode ID", it is trying to tell you that it isn't possible to set such
|
|
a mode. It's also possible to press only <RETURN> which leaves the current mode.
|
|
|
|
The mode list usually contains a few basic modes and some VESA modes. In
|
|
case your chipset has been detected, some chipset-specific modes are shown as
|
|
well (some of these might be missing or unusable on your machine as different
|
|
BIOSes are often shipped with the same card and the mode numbers depend purely
|
|
on the VGA BIOS).
|
|
|
|
The modes displayed on the menu are partially sorted: The list starts with
|
|
the standard modes (80x25 and 80x50) followed by "special" modes (80x28 and
|
|
80x43), local modes (if the local modes feature is enabled), VESA modes and
|
|
finally SVGA modes for the auto-detected adapter.
|
|
|
|
If you are not happy with the mode list offered (e.g., if you think your card
|
|
is able to do more), you can enter "scan" instead of item number / mode ID. The
|
|
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.
|
|
|
|
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
|
|
all VESA modes.
|
|
|
|
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 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).
|
|
|
|
0x0100 to 0x017f - standard BIOS modes. The ID is a BIOS video mode number
|
|
(as presented to INT 10, function 00) increased by 0x0100.
|
|
|
|
0x0200 to 0x08ff - VESA BIOS modes. The ID is a VESA mode ID increased by
|
|
0x0100. All VESA modes should be autodetected and shown on the menu.
|
|
|
|
0x0900 to 0x09ff - Video7 special modes. Set by calling INT 0x10, AX=0x6f05.
|
|
(Usually 940=80x43, 941=132x25, 942=132x44, 943=80x60, 944=100x60,
|
|
945=132x28 for the standard Video7 BIOS)
|
|
|
|
0x0f00 to 0x0fff - special modes (they are set by various tricks -- usually
|
|
by modifying one of the standard modes). Currently available:
|
|
0x0f00 standard 80x25, don't reset mode if already set (=FFFF)
|
|
0x0f01 standard with 8-point font: 80x43 on EGA, 80x50 on VGA
|
|
0x0f02 VGA 80x43 (VGA switched to 350 scanlines with a 8-point font)
|
|
0x0f03 VGA 80x28 (standard VGA scans, but 14-point font)
|
|
0x0f04 leave current video mode
|
|
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 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.
|
|
E.g., 0x1950 corresponds to a 80x25 mode, 0x2b84 to 132x43 etc.
|
|
This is the only fully portable way to refer to a non-standard mode,
|
|
but it relies on the mode being found and displayed on the menu
|
|
(remember that mode scanning is not done automatically).
|
|
|
|
0xff00 to 0xffff - aliases for backward compatibility:
|
|
0xffff equivalent to 0x0f00 (standard 80x25)
|
|
0xfffe equivalent to 0x0f01 (EGA 80x43 or VGA 80x50)
|
|
|
|
If you add 0x8000 to the mode ID, the program will try to recalculate
|
|
vertical display timing according to mode parameters, which can be used to
|
|
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.
|
|
|
|
Options
|
|
~~~~~~~
|
|
|
|
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 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 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_
|
|
happens and how do the configuration switches affect the behaviour of the bug.
|
|
|
|
If you start Linux from M$-DOS, you might also use some DOS tools for
|
|
video mode setting. In this case, you must specify the 0x0f04 mode ("leave
|
|
current settings") to Linux, because if you don't and you use any non-standard
|
|
mode, Linux will switch to 80x25 automatically.
|
|
|
|
If you set some extended mode and there's one or more extra lines on the
|
|
bottom of the display containing already scrolled-out text, your VGA BIOS
|
|
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.
|
|
|
|
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.
|
|
2.0 (28-Jan-96) Rewritten from scratch. Cirrus Logic 64XX support added, almost
|
|
everything is configurable, the VESA support should be much more
|
|
stable, explicit mode numbering allowed, "scan" implemented etc.
|
|
2.1 (30-Jan-96) VESA modes moved to 0x200-0x3ff. Mode selection by resolution
|
|
supported. Few bugs fixed. VESA modes are listed prior to
|
|
modes supplied by SVGA autodetection as they are more reliable.
|
|
CLGD autodetect works better. Doesn't depend on 80x25 being
|
|
active when started. Scanning fixed. 80x43 (any VGA) added.
|
|
Code cleaned up.
|
|
2.2 (01-Feb-96) EGA 80x43 fixed. VESA extended to 0x200-0x4ff (non-standard 02XX
|
|
VESA modes work now). Display end bug workaround supported.
|
|
Special modes renumbered to allow adding of the "recalculate"
|
|
flag, 0xffff and 0xfffe became aliases instead of real IDs.
|
|
Screen contents retained during mode changes.
|
|
2.3 (15-Mar-96) Changed to work with 1.3.74 kernel.
|
|
2.4 (18-Mar-96) Added patches by Hans Lermen fixing a memory overwrite problem
|
|
with some boot loaders. Memory management rewritten to reflect
|
|
these changes. Unfortunately, screen contents retaining works
|
|
only with some loaders now.
|
|
Added a Tseng 132x60 mode.
|
|
2.5 (19-Mar-96) Fixed a VESA mode scanning bug introduced in 2.4.
|
|
2.6 (25-Mar-96) Some VESA BIOS errors not reported -- it fixes error reports on
|
|
several cards with broken VESA code (e.g., ATI VGA).
|
|
2.7 (09-Apr-96) - Accepted all VESA modes in range 0x100 to 0x7ff, because some
|
|
cards use very strange mode numbers.
|
|
- Added Realtek VGA modes (thanks to Gonzalo Tornaria).
|
|
- Hardware testing order slightly changed, tests based on ROM
|
|
contents done as first.
|
|
- Added support for special Video7 mode switching functions
|
|
(thanks to Tom Vander Aa).
|
|
- Added 480-scanline modes (especially useful for notebooks,
|
|
original version written by hhanemaa@cs.ruu.nl, patched by
|
|
Jeff Chua, rewritten by me).
|
|
- Screen store/restore fixed.
|
|
2.8 (14-Apr-96) - Previous release was not compilable without CONFIG_VIDEO_SVGA.
|
|
- Better recognition of text modes during mode scan.
|
|
2.9 (12-May-96) - Ignored VESA modes 0x80 - 0xff (more VESA BIOS bugs!)
|
|
2.10(11-Nov-96) - The whole thing made optional.
|
|
- Added the CONFIG_VIDEO_400_HACK switch.
|
|
- 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``
|
|
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.
|
|
=============== ================================================================
|