Ubuntu Manpage: svgalib.mach32 - Information on the Mach32 chipset driver

NAME

       svgalib.mach32 - Information on the Mach32 chipset driver

        0. Introduction
        1. Specifying pixel clocks
        2. Copyrights
        3. The mach32info utility
        4. Third party cards
        5. Logical line width
        6. Noisy video signals
        7. The configuration EEPROM
        8. EEPROM woes
        9. The Mach32Eeprom command
       10. Setup of the memory aperture (linear framebuffer)
       11. Accelerator support and other weird features
       12. Ramdacs
       13. Meaning of the detection message from svgalib
       14. Conclusions

0. INTRODUCTION

       The  driver should allow you to use any of the graph-modes your Mach32 card supports. Note
       that there is no support for <8bpp modes and that I won't ever implement  that  because  I
       don't  see  any  reason  for doing so. All standard VGA-modes are supported, of course (by
       using the standard VGA driver routines).

       If you configured your Mach32 for a memory aperture and it is  at  least  as  big  as  the
       memory of your card (that is, not a 1MB memory aperture for a 2MB card) support for linear
       frame buffer access of svgalib is given.

       Auto detection of the Mach32 seems not to work on all cards. That's really strange since I
       got  the code from the X people. It should be OK regardless of my docs. Well, I fixed that
       (hopefully). Actually the bug was found by Daniel Lee Jackson (djackson@ichips.intel.com).
       (Thanks again.. It was so silly... I would have never found it) If you still have problems
       just put a chipset Mach32 in your config file.

1. SPECIFYING PIXEL CLOCKS

       WARNING!  The Mach32 driver needs to know  correct  clock  frequencies  for  graceful  DAC
       configuration.  Wrong clocks may damage your card! However, this version contains code for
       automatic clock detection. Since clock detection is time  critical,  please  do  it  on  a
       completely  idle  system.  Then  put  the printed out clocks line in your libvga.config(5)
       file.

       The driver tries to do this for you.  After that, you can restart whatever svgalib program
       you used and you are set. If you already put a clocks line in your config by hand, comment
       it out to have the driver check your clocks.

       Since clock probing is time critical, values differ from time to  time,  you  may  try  it
       multiple  times and see which values seem to be most exact. You can also compare them with
       the standard clock chips for Mach32 cards in libvga.config(5)).

       The clock probing relies on the 7th clock being 44.9MHz as this is what  Xfree  does.   If
       this is not true (and it is not always), probing is hosed. See libvga.config(5) for a list
       of the clocks used by common svgalib cards.

2. COPYRIGHTS

Some tiny routines are copied from Xfree86. The clock detection code is almost just
copied. So I repeat the copyright statements for these parts here:

Permission to use, copy, modify, distribute, and sell this software and its documentation
for any purpose is hereby granted without fee, provided that the above copyright notice
appear in all copies and that both that copyright notice and this permission notice appear
in supporting documentation, and that the names of Orest Zborowski and David Wexelblat not
be used in advertising or publicity pertaining to distribution of the software without
specific, written prior permission. Orest Zborowski and David Wexelblat make no
representations about the suitability of this software for any purpose. It is provided "as
is" without express or implied warranty.

Orest Zborowski and David Wexelblat disclaim all warranties with regard to this software,
including all implied warranties of merchantability and fitness, in no event shall Orest
Zborowski or David Wexelblat be liable for any special, indirect or consequential damages
or any damages whatsoever resulting from loss of use, data or profits, whether in an
action of contract, negligence or other tortious action, arising out of or in connection
with the use or performance of this software.

Permission to use, copy, modify, distribute, and sell this software and its documentation
for any purpose is hereby granted without fee, provided that the above copyright notice
appear in all copies and that both that copyright notice and this permission notice appear
in supporting documentation, and that the name of Thomas Roell not be used in advertising
or publicity pertaining to distribution of the software without specific, written prior
permission. Thomas Roell makes no representations about the suitability of this software
for any purpose. It is provided "as is" without express or implied warranty.

Thomas Roell, Kevin E. Martin, and Rickard E. Faith disclaim all warranties with regard to
this software, including all implied warranties of merchantability and fitness, in no
event shall the authors be liable for any special, indirect or consequential damages or
any damages whatsoever resulting from loss of use, data or profits, whether in an action
of contract, negligence or other tortious action, arising out of or in connection with the
use or performance of this software.

Author: Thomas Roell, roell@informatik.tu-muenchen.de

Rewritten for the 8514/A by Kevin E. Martin (martin@cs.unc.edu)
Modified for the Mach-8 by Rickard E. Faith (faith@cs.unc.edu)
Rewritten for the Mach32 by Kevin E. Martin (martin@cs.unc.edu)

And here is my own copyright:

This driver is free software; you can redistribute it and/or modify it without any
restrictions. This library is distributed in the hope that it will be useful, but without
any warranty.

Email addresses as of this writing:

eowmob@exp-math.uni-essen.de mat42b@spi.power.uni-essen.de

Michael Weller disclaims all warranties with regard to this software, including all
implied warranties of merchantability and fitness, in no event shall Michael Weller be
liable for any special, indirect or consequential damages or any damages whatsoever
resulting from loss of use, data or profits, whether in an action of contract, negligence
or other tortious action, arising out of or in connection with the use or performance of
this software.

3. THE MACH32INFO UTILITY

       The  mach32info(6)  utility  or  demo  reads  out  all  configuration  registers  and  the
       configuration EEPROM of your Mach32 card. If there is a problem with the  particular  card
       you have, compile and run the utility in the mach32/ directory of the svgalib distribution
       and send it's stdout to me This might also be useful if you need a lot  of  options  (e.g.
       clocks  on new models?) to get it to work so that this can be done automatically in future
       versions.

4. THIRD PARTY CARDS

I got a few reports about AST systems with onboard Mach32. They do feature an
incompatible EEPROM setup, but I think I got around that. Nevertheless the Mach32 chipset
driver doesn't work out of the box on any AST system I heard of.

Since original ATI Mach32 demos and tools don't work as well, I've to claim that the
Mach32 on these AST systems does not conform to ATI's Mach32 docs. Fortunately, Vernon C.
Hoxie <vern@zebra.alphacdc.com> found a work around after years (really!) of
investigating. AST Mach32 seems to work now. The work around was also submitted to Xfree
and will be incorporated to allow running it on the AST hardware too in recent versions.
Please read on the misc_ctl command below.

Dell users should have a look at the vendor, ramdac, and svgaclocks commands below (if
they have problems with the default settings).

Commands to support third party cards
I had to learn that those cards seem to use not only non standard clocks for the Mach32,
but also for the included SVGA. However, since people often like to use proprietary, non
standard VGA (read 80x25) text modes, the Mach32 driver has to set the included SVGA to a
VGA compatible clock frequency. Otherwise svgalib has problems using plain VGA modes. This
screws VGA modes up if these clocks have different values on third party Mach32 cards.

svgaclocks n
with n a number between 0 and 31 to select the svga clocks to be used in vga modes.
The bits of n refer to specific ATI register bits to complicated to explain here.
Even if I would, I can't tell which clocks they would select on your third party
card (which is the actual problem)

svgaclocks 9 is the default setting and correct for original ATI cards.

Often svgaclocks 0 (Dell cards) works.

svgaclocks keep
is special in that the driver will not touch any SVGA timings. This requires the
Mach32 SVGA part to be in a VGA compatible mode when the svgalib application is
started, that is, you must use 80x25 (maybe 80x50) console text modes.

As I mentioned already, Vernon C. Hoxie <vern@zebra.alphacdc.com> really seems to have
located the reason for the Mach32 AST problems. Any access to MISC_CTL locks up the card &
system. Fortunately MISC_CTL is only used for some DAC fine tuning (actually the setting
you can fine tune with the blank command) which is only of barely noticeable effect to the
screen.

The following configuration commands exist to support AST cards:

misc_ctl keep-off
Do not dare to touch MISC_CTL.

misc_ctl use
Use it for fine tuning of the Ramdac setup (default).

Finally, for your convenience there exist:

vendor ati
vendor dell
vendor ast
These are macros that expand to settings for svgaclocks, ramdac, misc_ctl, and
mach32eeprom that are usually correct for ATI, Dell, AST cards. Be aware that they
really work like macros. That is, they override any setting of svgaclocks, ramdac,
misc_ctl, and mach32eeprom made before them and individual aspects will be changed
by a following svgaclocks, ramdac, misc_ctl, and mach32eeprom command.

Note that the mach32eeprom ignore required for some Dell cards requires you to
include explicit timings for Mach32 modes other than 640x480x256. The
mach32/mach32.std-modes file in the svgalib distribution contains recommendations
for modes from ATI.

I heard about a bug in some ATI chipsets returning wrong memory amounts configs.
(But cannot confirm that)

You can enforce correct chipset identification from the configuration file:

chipset Mach32 chiptype memory
where chiptype is the sum of at exactly one value from each of the following two
groups

128 use no memory aperture.
160 use a 1MB memory aperture.
192 use a 4MB memory aperture.
0 choose size for the memory aperture automatically.

and

16 Ramdac is of type 0 (ATI68830)
17 Ramdac is of type 1 (IMS-G173, SC11486)
18 Ramdac is of type 2 (ATI68875, TLC34075)
19 Ramdac is of type 3 (INMOS176, INMOS178)
20 Ramdac is of type 4 (Bt481, Bt482)
21 Ramdac is of type 5 (ATI68860)
0 Ramdac type is queried from Mach32 chip.

memory is the amount of video memory in KB.

Note that the type of the ramdac can be set more conveniently with the ramdac command.

5. LOGICAL LINEWIDTH

       At least my VRAM card seems to be  very  peculiar  about  logical  line  widths.  From  my
       experience  a  multiple  of 64 pels is needed.  Your mileage may vary. Use the config file
       options to adjust it and tell me if your card needs a different value.  Include  the  name
       and model number of the card and what the correct numbers should be. This is so that I can
       correct the auto configuration of the driver.

       If some svgalib application has problems, note that you can force the logical  line  width
       to  the  default  value  from the config file. Probably this will lead to glitches in some
       800x600 resolutions. You can inhibit these resolutions  from  the  config  file  as  well.
       Apropos  glitches,  I  found  no  guidelines  as  to what clock rates to use due to memory
       restrictions. I adjusted the driver, such that I get a  stable  pic  in  all  resolutions.
       However  sometimes  the  screen  is disturbed by heavy video memory accesses. If you don't
       like that, reduce the clocks used with the maxclock16 or maxclock24 command,  resp.   This
       may of course lead to none of the predefined modes being used.  Then you can try to define
       your own mode via the define command.

6. NOISY VIDEO SIGNALS

If you get some flicker or heavy noise on your screen, some fine tuning may be needed. My
docs didn't give me hints as to what each card can stand. Especially DRAM cards may give
problems (I've VRAM). In that case, use the fine tuning config commands and send me your
results along with the output of mach32info(6). Then I can include them in my next
release.

Fine-tuning configuration commands
First you should think about the maxclock* configuration commands to reduce pixel clocks
used for each color depth.

Especially important for DRAM cards is the video FIFO depth used to queue memory values
for writing to the screen. Here is a command to set this value for the 8bpp modes:

vfifo8 number
where number is in range 0 - 15. The default is now 6.

Since vfifo is of some impact to the speed of the card, tell me the lowest setting
that satisfies your card.

For 16/24/32 modes, there are non-zero values preset from internal tables and the
EEPROM, however you can enforce minimal vfifo values with:

vfifo16 number
vfifo24 number
vfifo32 number

blank number
where number is 4 * pixel_delay + blank_adjust where pixel_delay and blank_adjust
are in range 0 .. 3. pixel_delay delays pixels before they are sent to the DAC and
blank_adjust adjusts the blank pulse for type 2 DAC's. blank should be set
correctly for each DAC type automatically. So use it only as a last resort.

latch number
where number is the sum of zero or more of the following numbers:

128 VRAM serial delay latch enable, DRAM latch bits 63 - 0 enable.

4096 Latch video memory data.

8192 Memory data delay latch enable for data bits 63 - 0.

16384 Memory full clock pulse enable.

Default is to switch all settings on (they are on on my card by default anyway).

Note that these commands may vanish again once they are no longer needed for debugging
purposes.

There is no 320x200 mode in the EEPROM of the Mach32 at all, however I defined one in the
default configuration file for you. This is the best thing I could get up on my
card/screen. Note that it will probably have big borders on your screen, and black lines
in between the pixel lines. This is because of the lack of low clocks < 16MHz on the
Mach32 and the lack of a line doubling mode as VGA has. The Mach32 is not intended for
such low resolutions. If you find a better mode or have an idea, please let me know. You
can also just remove my timings from the default configuration file.

7. THE CONFIGURATION EEPROM

Ah yes, about the EEPROM, I figured out how to read out the Mach32 EEPROM. I did it by
disassembling the BIOS routine mentioned in the docs. I then redid it in C. The driver
will use everything it finds there.

Use the Mach32 install tools (they should have reached you together with your Mach32 VGA
card) to setup your card/monitor combo correctly. The monitors setting from the config
file (or default of 35kHz or something) will be obeyed by the driver nevertheless (for
safety!).

As you probably know already, accessing the EEPROM causes some screen flickering. If this
annoys you (or even worse your monitor) have a look at the mach32eeprom command described
below. This allows you to put the data from the EEPROM into a file and which can be read
whenever it is required.

Don't even think about changing the contents of the file. (There is an easily faked
checksum in it.). Anyway the driver ensures (hopefully) that no damage can be caused.

Also, if some mode is not well aligned on your screen or you don't like it's sync
frequency, consider using the Mach32 install utility (setup for custom monitor) and set
one up interactively. If there is no valid faster (higher VSYNC) standard mode given in
the EEPROM the driver will use that mode. You will find that this is fun compared with
calculating video timings for /etc/XF86Config or /etc/vga/libvga.config.

However the install utility does restrict the maximum pixel depth for custom modes
sometimes unneeded hard and the driver obeys that. (Hmm.. actually it should be smart
enough to decide itself which pixel depth it can use in that mode.) Since the standard
modes are usually only slightly shifted to one side a file with the configuration commands
representing the standard modes is given in mach32/mach32.std-modes in the svgalib
distribution. You can use these as a starting point.

But here are some real problems:

8. EEPROM WOES

I got 2 reports of people having problems with incorrect EEPROM checksums. Both had
motherboards with onboard Mach32 VGA's from AST. I guessed a checksum algorithm from those
reports and put this in the code in addition to the standard ATI style. Still I got a
report of someone whose EEPROM was completely empty. If you have problems with checksums
send me the output of mach32info(6) and I'll see what I can do.

By default svgalib writes a complaining message and ignores the contents. You can have
svgalib ignore the checksum and contents with the configuration command

mach32eeprom ignore

Then you can decide to use the partial info that is still in it. Use

mach32eeprom ignore usetimings

to use the video modes that are defined in the EEPROM (if no better modes are known by the
driver). This is usually safe, because the driver knows which modes are safe for your
hardware (if clocks, monitor and ramdac are configured correctly). You can also allow the
driver to use the configuration for the linear frame buffer in the EEPROM:

mach32eeprom ignore useaperture

mach32eeprom ignore usetimings useaperture

However I discourage this because the driver will just enable what the EEPROM says about
the aperture. Use mach32info(6) to check the address it will choose is safe. It might be
better to use setuplinear to set up a 4MB aperture at a free address range.

9. THE MACH32EEPROM COMMAND

The mach32eeprom allows to work around these problems. Here is the complete description
for this configuration command.

mach32eeprom filename
The filename has to begin with a "/".

Unfortunately reading the EEPROM causes annoying screen flickering and is slow. To
avoid this, specify a filename from which to read the contents of the EEPROM.

If the file cannot be read, the EEPROM is read out and the file is created. There
is a very simple checksum put into this file. Although it can easily be fooled,
don't change the file except you know very, very well what you are doing.

Also, as long as the file exists, changes in the Mach32's EEPROM are ignored.
Delete the file to recreate an updated version on next use of svgalib. You should
ensure that the permissions of the file don't allow normal users to change it.
(This may happen if umask has a bad value when svgalib creates the file).

Example:

mach32eeprom /etc/vga/mach32.eeprom

Due to problems with some boards this command got heavily expanded:

mach32eeprom subcommand1 [subcommand2...]
At least one subcommand is needed. Valid subcommands are:

ignore Don't complain about checksum and don't use any EEPROM contents.

useaperture
Use the configuration for the memory aperture given in the EEPROM.

usetimings
Use video modes found in the EEPROM of the board.

nofile Forget about any filename that maybe was already configured. Don't read a
file, don't create one.

file filename
New style form to specify the filename; On contrary to the mach32eeprom
filename form it can be mixed with any other mach32eeprom subcommand.

updatefile
Don't read the file, always read the EEPROM (except when ignore is given)
and create an uptodate image of the EEPROM.

keepfile
Disable all previous updatefile commands.

compatible
Fall back to default behavior: If checksum on the EEPROM data is not ok, use
nothing of the configuration data. If it is ok, configure everything as
specified in the EEPROM.

The subcommands are intended to be used together and are performed in the order
specified. For example:

mach32eeprom ignore useaperture usetimings

will ignore the checksum of your EEPROM, but use its contents. Order is vital! So:

mach32eeprom useaperture usetimings ignore

won't use any configuration from your EEPROM. Be careful with the useaperture
subcommand. Please see the EEPROM WOES section. Note that any non understood
subcommand will terminate the mach32eeprom command silently! Use only one
subcommand per mach32eeprom command to avoid this.

The mach32eeprom command is usually not allowed in the environment variable
SVGALIB_CONFIG.

10. SETUP OF THE MEMORY APERTURE (LINEAR FRAMEBUFFER)

       Due  to  poor  design, Xfree86 insists on setting up the aperture itself. It doesn't reset
       the original settings at a VC switch once it runs. You should not start X  for  the  first
       time  after a boot as long as an svgalib application is running. This will result in pre X
       values being restored at a VC switch by  svgalib.  If  you  use  svgalib  and  XF86_Mach32
       together,  run  X  first  or  at  least  do  not start it while any svgalib appl. is still
       running. After X was started once you can use svgalib and X in all  combinations  w/o  any
       problems.  Xfree  uses  whatever address is given in the MEM_CFG Mach32 register for a 4MB
       aperture, even if the aperture is not already enabled and the value in  this  register  is
       pointless  garbage.  This is IMHO a dangerous bug as some systems may work only with a 1MB
       aperture.

       However, usage of a correct EEPROM circumvents any such problems. If you cannot use  that,
       use  mach32info (6) to find the address in MEM_CFG.  Then, if it is a sensible setting for
       your system, enable a 4MB aperture at that address with setuplinear.  Ensure that no other
       card or memory uses the address range you choose.

11. ACCELERATOR SUPPORT AND OTHER WEIRD FEATURES

       This  version now has support for all accelerator functions of svgalib.  However they were
       intended for use with the cirrus chips. It may happen  that  at  runtime  they  find  they
       cannot  emulate the function actually requested. Then you should disable the corresponding
       blit function (at least for that application) with the blit config command.

       Data transfer between the host and the Mach32 is normally  via  I/O.  This  proved  to  be
       pretty  slow. If a big enough aperture is available, a simple memory copy is used instead.
       This is usually much faster. You can change which method is used with  the  blit  command.
       This I/O option affects only vga_imageblt(3).  The other functions are incredible fast.

       For type 2 DACS, there is support for 8 bit per color (instead of the normal 6) in the RGB
       triple in the color lookup table of the 256  color  modes.  This  can  be  enabled  by  an
       application,  if  it  supports  it.  The  testaccel(6)  demo  uses it if supported by your
       hardware.  You can use vga_ext_set(3) to use it from your programs.

12. RAMDACS

Mach32 Ramdacs are specified by a type in range 1 .. 5. This type can be queried from the
Mach32 and then specifies how to set up the ramdac. A list of actual hardware chips used
for each type exists, but is not of much use. The Mach32 will return a type and the ramdac
will be completely hardware compatible to one of the given type.

Type 1 and 4 Dacs need different clock frequencies for high colormodes. For 32K/64K
colormodes the frequencies have to be doubled and for 16M colors (type 4 only) they have
to be tripled. I followed the ATI scheme and did this internally. However this means that
for 32K/64K you can use only clocks for which the doubled frequencies can be generated as
well.

This is no hard restriction as the 16 clocks of the Mach32 can be divided by 2. Thus if
you setup some mode yourself try to use one of the divided clocks in your timings and I
can use the undivided clocks internally.

It is a real restriction for 16M colors. ATI itself only supports 25MHz (640x480) here by
use of a 75MHz clock. Depending on your clock chip other values may be usable as well.
Even the doubled/tripled clocks have to be less than the magic 80 MHz. However the driver
does all this itself. It may just happen that some of the predefined or one of your
handmade mode-timings can't be used because the clock that is used cannot be
doubled/tripled. Even though there is already some tolerance in the driver you may fix
that by slightly changing the clock values that you set with the clocks command. But note
that this will as well affect the ability of the driver to calculate video timings and
thus it ability to check the monitor and DAC safety restrictions.

In addition (in complete contrast to my original ATI docs) RAMDAC 4 does not support RGB
with blue byte first but only with red first. This required special handling and me adding
a bunch of functions to all modules of svgalib and vgagl. The added functions are of lower
performance than the usual functions. However most data has to be completely mangled, so I
doubt that it can be done much faster. Sorry.

Of course, I might have forgotten to port some parts or even confused things. About bugs
in the gl and drawing libs, please ask Harm. But then, I'm able to emulate a BGR ramdac
on my card, so I should even be able to reproduce your problems.

Recently I hear often about type 6 ramdacs in non ATI Mach32 cards. There exists no info
about these dacs, thus I cannot support them. The driver assumes unknown DACs can stand up
to 80MHz in 256 color clut modes and does not touch the ramdac (that is, assumes it is in
the 256 color mode already)

To get rid of the warning message you can use the

ramdac n
configuration command. It allows to explicitly set the type of the dac to n (in
range 0 to 5). Ramdac 3 is the most dumbest ramdac possible, s.t. you can use it
without any fear for your hardware.

ramdac dumb
is equivalent to ramdac 3.

ramdac auto
switches back to the default autodetection.

13. MEANING OF THE DETECTION MESSAGE FROM SVGALIB

Some programs (which do not switch it off) will show a

Using Mach32 version (sizeM at adrM (how), memK mem, DAC dactype)

line. This will show up in testlinear(6) etc but will probably scroll away when you use
vgatest(6). In this line:

version
is the version of the driver (as of my counting, not the svgalib version).

size is the size of the memory aperture. It can be 1 or 4 (1 will lead to not using the
linear aperture if your card has more than 1MB memory, however applications can
still use the 1MB aperture and page the video memory through it in 1MB steps).
size can also be no if no aperture is setup at all.

adr is the base address of the aperture in MB.

how is autodetect if the aperture was setup this way already when the program started.
It is setup when the the setting was enforced with a setuplinear configuration
command. It is EEPROM when no aperture was detected, but parameters to set it up
were found in the EEPROM.

mem is the amount of memory the card reported to have.

dactype
is the type of the DAC that was detected.

If a special ramdac type was set with the ramdac command a (set) will be displayed
after dactype.

If mem, dactype and/or the chipset were enforced with chipset from the configuration file
or vga_setchipsetandfeatures(3) a forced will be appended to the line.

14. CONCLUSIONS

       A  final  word: I have an ATI ULTRA PRO/2MB/EISA with a Type 2 DAC.  My monitor is an EIZO
       F550i-M. Everything I tried works on it like a charm. However,  I  couldn't  try  it  with
       other  machines  myself  and esp.  other DAC's. Fortunately the Type 2 DAC is the worst to
       code. So I will probably have gotten the other DAC's right. But please be warned!

       I did my very best to code the driver to support the other DAC's by just reading the docs.
       But  i  can't  give  any  definitive  guarantee  for  it to work or even not damaging your
       hardware. So please be careful!

       Note that you will have to set the environment variable SVGALIB_MACH32 to ILLTRYIT if your
       DAC  is  not type 0, 2, 3 or 4. This will of course change if no one with a DAC equal to 1
       or 5 has serious problems. If you have a different DAC, making  patches  to  support  your
       card  will  be much more helpful instead of just complaining.  If you have a different DAC
       that works well tell me as well such that I can remove the need for SVGALIB_MACH32 in  the
       next  release. Still, even now, after years, I got no reports of a Mach32 card with a type
       1 or 5 ramdac. Go figure.

       Thank you for your audience and wishes you will enjoy this driver,
       Michael.

FILES

       /etc/vga/libvga.config
       /etc/vga/mach32.eeprom

AUTHOR

       The Mach32 driver and this  documentation  was  written  by  Michael  Weller  <eowmob@exp-
       math.uni-essen.de>.