mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-24 19:20:50 +07:00
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
277 lines
14 KiB
Plaintext
277 lines
14 KiB
Plaintext
Video Mode Selection Support 2.13
|
|
(c) 1995--1999 Martin Mares, <mj@ucw.cz>
|
|
--------------------------------------------------------------------------------
|
|
|
|
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).
|
|
|
|
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.
|
|
|
|
2. 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 (see CONFIG_VIDEO_SVGA in chapter 4 to see
|
|
how to enable it if you really want) 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.
|
|
|
|
3. 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:
|
|
|
|
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 CONFIG_VIDEO_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.
|
|
|
|
4. 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
|
|
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
|
|
ftp://ftp.phys.keio.ac.jp/pub/XFree86/800x600/XF86Configs/XF86Config.IBM_TP560).
|
|
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).
|
|
|
|
5. 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
|
|
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.
|
|
|
|
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.
|
|
|
|
6. 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.
|