svgalib(7) Svgalib User Manual svgalib(7) 1mNAME0m svgalib - a low level graphics library for linux 1mTABLE OF CONTENTS0m 1m0. 22mIntroduction 1m1. 22mInstallation 1m2. 22mHow to use svgalib 1m3. 22mDescription of svgalib functions 1m4. 22mOverview of supported SVGA chipsets and modes 1m5. 22mDetailed comments on certain device drivers 1m6. 22mGoals 1m7. 22mReferences (location of latest version, apps etc.) 1m8. 22mKnown bugs 1m0. INTRODUCTION0m This is a low level graphics library for Linux, originally based on VGAlib 1.2 by Tommy Frandsen. VGAlib supported a number of standard VGA graphics modes, as well as Tseng ET4000 high resolution 256-color modes. As of now, support for many more chipsets has been added. See section 1m4 Overview of supported SVGA chipsets and modes0m It supports transparent virtual console switching, that is, you can switch consoles to and from text and graphics mode consoles using alt-[function key]. Also, svgalib corrects most of VGAlib's textmode corruption behaviour by catching 1mSIGSEGV22m, 1mSIGFPE22m, 1mSIGILL22m, and other fatal signals and ensuring that a program is running in the currently visible virtual console before setting a graphics mode. Note right here that 1mSIGUSR1 22mand 1mSIGUSR2 22mare used to manage console switching internally in 1msvgalib22m. You can not use them in your pro- grams. If your program needs to use one of those signals, svgalib can be compiled to use other signals, by editing libvga.h This version includes code to hunt for a free virtual console on its own in case you are not starting the program from one (but instead over a network or modem login, from within 1mscreen22m(1) or an 1mxterm22m(1)). Pro- vided there is a free console, this succeeds if you are root or if the svgalib calling user own the current console. This is to avoid people not using the console being able to fiddle with it. On graceful exit the program returns to the console from which it was started. Other- wise it remains in text mode at the VC which svgalib allocated to allow you to see any error messages. In any case, any I/O the svgalib makes in text mode (after calling 1mvga_init22m(3)) will also take place at this new console. Alas, some games misuse their suid root privilege and run as full root process. svgalib cannot detect this and allows Joe Blow User to open a new VC on the console. If this annoys you, 1mROOT_VC_SHORTCUT 22min 4mMake-0m 4mfile.cfg24m allows you to disable allocating a new VC for root (except when he owns the current console) when you compile svgalib. This is the default. When the library is used by a program at run-time, first the chipset is detected and the appropriate driver is used. This means that a graphics program will work on any card that is supported by svgalib, if the mode it uses is supported by the chipset driver for that card. The library is upwardly compatible with VGAlib. The set of drawing functions provided by svgalib itself is limited (unchanged from VGAlib) and unoptimized; you can however use 1mvga_set-0m 1mpage22m(3) and 1mvga_getgraphmem22m(3) (which points to the 64K VGA framebuffer) in a program or graphics library. A fast external frame- buffer graphics library for linear and banked 1, 2, 3 and 4 bytes per pixel modes is included (it also indirectly supports planar VGA modes). It is documented in 1mvgagl22m(7). One obvious application of the library is a picture viewer. Several are available, along with animation viewers. See the 1m7. References 22mat the end of this document. I have added a simple VGA textmode font restoration utility (1mrestore-0m 1mfont22m(1)) which may help if you suffer from XFree86 textmode font cor- ruption. It can also be used to change the textmode font. It comes with some other textmode utilities: 1mrestoretextmode22m(1) (which saves/restores textmode registers), 1mrestorepalette22m(1), and the script 1mtextmode22m(1). If you run the 1msavetextmode22m(1) script to save textmode information to 4m/tmp24m, you'll be able to restore textmode by running the 1mtextmode22m(1) script. 1m1. INSTALLATION0m Installation is easy in general but there are many options and things you should keep in mind. This document however assumes that 1msvgalib 22mis already installed. If you need information on installation see 4m0-INSTALL24m which comes with the svgalib distribution. However, even after installation of the library you might need to con- figure svgalib using the file 4m/etc/vga/libvga.config24m. Checkout section 1m4 Overview of supported SVGA chipsets and modes 22mand 1mlibvga.config22m(5) for information. 1m2. HOW TO USE SVGALIB0m For basic svgalib usage (no mouse, no raw keyboard) add 1m#include0m 1m 22mat the beginning your program. Use 1mvga_init22m(3) as your first 1msvgalib 22mcall. This will give up root privileges right after initializa- tion, making setuid-root binaries relatively safe. The function 1mvga_getdefaultmode22m(3) checks the environment variable 1mSVGALIB_DEFAULT_MODE 22mfor a default mode, and returns the corresponding mode number. The environment string can either be a mode number or a mode name as in (1mG640x480x222m, 1mG640x480x1622m, 1mG640x480x256 22m, 1mG640x480x32K22m, 1mG640x480x64K22m, 1mG640x480x16M22m). As an example, to set the default graph- ics mode to 640x480, 256 colors, use: 1mexport SVGALIB_DEFAULT_MODE=G640x480x2560m on the 1mbash(1) 22mcommand line. If a program needs just a linear VGA/SVGA resolution (as required by 1mvgagl22m(7)), only modes where 1mbytesperpixel 22min the 1mvga_modeinfo 22mstructure returned by 1mvga_getmodeinfo22m(3) is greater or equal to 1 should be accepted (this is 0 for tweaked planar 256-color VGA modes). Use 1mvga_setmode(4m22mgraphicsmode24m1m) 22mto set a graphics mode. Use 1mvga_set-0m 1mmode(TEXT) 22mto restore textmode before program exit. Programs that use svgalib must 1m#include22m; if they also use the external graphics library 1mvgagl22m(7), you must also 1m#include22m. Linking must be done with 1m-lvga 22m(and 1m-lvgagl 22mbefore 1m-lvga22m, if 1mvgagl22m(7) is used). You can save binary space by removing the unused chipset drivers in 4mMakefile.cfg24m if you only use specific chipsets. However this reduces the flexibility of svgalib and has a significant effect only when you use the static libraries. You should better use the shared libraries and these will load only the really used parts anyway. Functions in the 1mvgagl22m(7) library have the prefix 1mgl_22m. Please see 1mvgagl22m(7) for details. There are demos with sources available which will also help to get you started, in recomended order of interest: 1mvgatest22m(6), 1mkeytest22m(6), 1mmousetest22m(6), 1meventtest22m(6), 1mforktest22m(6), 1mbg_test22m(6), 1mscrolltest22m(6), 1mspeedtest22m(6), 1mfun22m(6), 1mspin22m(6), 1mtestlinear22m(6), 1mlineart22m(6), 1mtestgl22m(6), 1maccel22m(6), 1mtestaccel22m(6), 1mplane22m(6), and 1mwrapdemo22m(6). Debugging your programs will turn out to be rather difficult, because the svgalib application can not restore textmode when it returns to the debugger. Happy are the users with a serial terminal, X-station, or another way to log into the machine from network. These can use 1mtextmode . Supports 640x480x256, 800x600x256, 1024x768x256 (interlaced and non- interlaced) Might be useful to add 16-color modes (for those equipped with a 512K TVGA9000) for the 8900 and 9000 cards. 320x200x{32K, 64K, 16M}, 640x480x{256, 32K, 64K, 16M}, 800x600x{256, 32K, 64K, 16M}, 1024x768x{16, 256}, 800x600x{16, 256, 32K, 64K} modes are supported for the TVGA 9440. Autodetection can be forced with a: 1mchipset TVGA 4m22mmemory24m 4mflags0m line in the config file. 4mmemory24m is the amount of VGA memory in KB, 4mflags24m is composed of three bits: 1mbit2 = false, bit1 = false0m force 8900. 1mbit2 = false, bit1 = true0m force 9440. 1mbit2 = true, bit1 = false0m force 9680. 1mbit0 = true0m force noninterlaced. 1mbit0 = false0m force interlaced which only matters on 8900's with at least 1M since there is no 512K interlaced mode on the 8900 or any of the other cards. 1mTseng ET4000/ET4000W32(i/p)0m Derived from VGAlib; not the same register values. ET4000 register values are not compatible; see 1msvgalib.et400022m(7). Make sure the colors are right in hicolor mode; the vgatest program should draw the same color bars for 256 and hicolor modes (the DAC type is defined at compilation in 4met4000.regs24m or the dynamic registers file). ET4000/W32 based cards usually have an AT&T or Sierra 15025/6 DAC. With recent W32p based cards, you might have some luck with the AT&T DAC type. If the high resolution modes don't work, you can try dumping the registers in DOS using the program in the 4met4000/24m directory and putting them in a file (4m/etc/vga/libvga.et400024m is parsed at runtime if 1mDYNAMIC 22mis defined in 4mMakefile.cfg24m at compilation (this is default)). Supported modes are 640x480x256, 800x600x256, 1024x768x256, 640x480x32K, 800x600x32K, 640x480x16M, etc. Reports of ET4000/W32i/p functionality are welcome. There may be a problem with the way the hicolor DAC register is han- dled; dumped registers may use one of two timing methods, with the value written to the register for a particular DAC for a hicolor mode (in vgahico.c) being correct for just one of the these methods. As a consequence some dumped resolutions may work while others don't. 1mTseng ET60000m Most modes of which the card is capable are supported. The 8 15 16 24 and 32 bit modes are supported. The ET6000 has a built in DAC and there is no problem coming from that area. The ET6000 is capable of acceleration, but this as well as sprites are not yet implemented in the driver. The driver now uses modelines in libvga.config for user defined modes. It is sometimes useful to add a modeline for a resolution which does not display well. For example, the G400x600 is too far to the right of the screen using standard modes. This is corrected by including in 1mlibvga.config 22mthe line Modeline "400x600@72" 25.000 400 440 488 520 600 639 644 666 More examples are given below. This driver was provided by Don Secrest. 1mVESA0m Please read README.vesa and README.lrmi in doc subdirectory of the standard distribution. Go figure! I turned off autodetection in the release, as a broken bios will be called too, maybe crashing the machine. Enforce 1mVESA 22mmode by putting a 1mchipset VESA 22min the end of your 4mlibvga.config24m(5). Note that it will leave protected mode and call the cards bios opening the door to many hazards. 1m5. DETAILED COMMENTS ON CERTAIN DEVICE DRIVERS0m This section contains detailed information by the authors on certain chipsets. 1mAT3D (AT25)0m Also known as Promotion at25. Popular as the 2D part of a voodoo rush card. I have written a driver for this chipset, based on the XF86 driver for this chipset. The programs that work with this driver include all the programs in the demos directory, zgv and dvisvga (tmview). I believe it should be easy to make it work on AT24, AT6422. 1mATI Mach320m Please see 1msvgalib.mach3222m(7). 1mATI Mach640m The rage.c driver works only on mach64 based cards with internal DAC. The driver might misdetect the base frequency the card uses, so if when setting any svgalib modes the screen blanks, or complains about out of bound freqencies, or the display is unsynced, then try adding the option 1mRageDoubleClock 22mto the config file. 1mChips and Technologies chipsets 65525, 65535, 65546, 65548, 65550, and0m 1m65554 (usually in laptops).0m Please see 1msvgalib.chips22m(7). 1mTseng ET4000/ET4000W32(i/p)0m Please see 1msvgalib.et400022m(7). 1mTseng ET60000m I have only 2 Mbytes of memory on my ET6000 card, so I am not able to get all possible modes running. I haven't even tried to do all of the modes which I am capable of doing, but I am confident that I can manage more modes when I have time. I have enough modes working to make the card useful, so I felt it was worth while to add the driver to svgalib now. Linear graphics is working on this card, both with and without BACK- GROUND enabled, and vga_runinbackground works. I decided it was best to quit working on more modes and try to get acceleration and sprites working. My et6000 card is on a PCI bus. The card will run on a vesa bus, but since I don't have one on my machine I couldn't develop vesa bus han- dling. I quit if the bus is a vesa bus. I check for an et6000 card, which can be unequivocally identified. The et4000 driver does not properly identify et4000 cards. It thinks the et6000 card is an et4000, but can only run it in vga modes. I have found the following four modelines to be useful in 1mlibvga.config0m or in 1m~/.svgalibrc 22mfor proper display of some modes. Modeline "512x384@79" 25.175 512 560 592 640 384 428 436 494 Modeline "400x300@72" 25.000 400 456 472 520 300 319 332 350 DOUBLES- CAN Modeline "512x480@71" 25.175 512 584 600 656 480 500 510 550 Modeline "400x600@72" 25.000 400 440 488 520 600 639 644 666 Don Secrest Aug 21, 1999 1mOak Technologies OTI-037/67/77/870m First a few comments of me (Michael Weller ): As of this writing (1.2.8) fixes were made to the oak driver by Frodo Looijaard to reenable OTI-067 support. It is unknown right now if they might have broken OTI-087 support. The author of the '87 support Christopher Wiles owns no longer an OTI-087 card and can thus no longer give optimal support to this driver. Thus you might be better off contacting me or Frodo for ques- tions. If you are a knowledgable OTI-087 user and experience problems you are welcome to provide fixes. No user of a OTI-087 is currently known to me, so if you are able to fix problems with the driver please do so (and contact me) as noone else can. Michael. Now back to the original Oak information: The original OTI driver, which supported the OTI-067/77 at 640x480x256, has been augmented with the following features: 1m1) 22mSupported resolutions/colors have been expanded to 640x480x32K, 800x600x256/32K, 1024x768x256, and 1280x1024x16. 1m2) 22mThe OTI-087 (all variants) is now supported. Video memory is correctly recognized. The driver as it exists now is somewhat schizoid. As the '87 incorpo- rates a completely different set of extended registers, I found it nec- essary to split its routines from the others. Further, I did not have access to either a '67 or a '77 for testing the new resolutions. If using them causes your monitor/video card to fry, your dog to bite you, and so forth, I warned you. The driver works on my '87, and that's all I guarantee. Period. Heh. Now, if someone wants to try them out ... let me know if they work. New from last release: 32K modes now work for 640x480 and 800x600. I found that the Sierra DAC information in VGADOC3.ZIP is, well, wrong. But, then again, the information for the '87 was wrong also. 64K modes 1mdo not 22mwork. I can't even get Oak's BIOS to enter those modes. I have included a 1280x1024x16 mode, but I haven't tested it. My moni- tor can't handle that resolution. According to the documentation, with 2 megs the '87 should be able to do an interlaced 1280x1024x256 ... again, I couldn't get the BIOS to do the mode. I haven't 2 megs any- way, so there it sits. I have included routines for entering and leaving linear mode. They 1mshould 22mwork, but they don't. It looks like a pointer to the frame buffer is not being passed to SVGALIB. I've been fighting with this one for a month. If anyone wants to play with this, let me know if it can be make to work. I've got exams that I need to pass. Tidbit: I pulled the extended register info out of the video BIOS. When the information thus obtained failed to work, I procured the OTI-087 data book. It appears that Oak's video BIOS sets various modes incorrectly (e.g. setting 8-bit color as 4, wrong dot clock frequen- cies, etc.). Sort of makes me wonder ... Christopher M. Wiles (a0017097@wsuaix.csc.wsu.edu) 12 September 1994 1m6. GOALS0m I think the ability to use a VGA/SVGA graphics resolution in one vir- tual console, and being able to switch to any other virtual console and back makes a fairly useful implementation of graphics modes in the Linux console. Programs that use 1msvgalib 22mmust be setuid root. I don't know how desir- able it is to have this changed; direct port access can hardly be done without. Root privileges can now be given up right after initializa- tion. I noticed some unimplemented stuff in the kernel header files that may be useful, although doing all register I/O via the kernel would incur a significant context-switching overhead. An alternative might be to have a pseudo 4m/dev/vga24m device that yields the required per- missions when opened, the device being readable by programs in group vga. It is important that textmode is restored properly and reliably; it is fairly reliable at the moment, but fast console switching back and forth between two consoles running graphics can give problems. Wild virtual console switching also sometimes corrupts the contents of the textmode screen buffer (not the textmode registers or font). Also if a program crashes it may write into the area where the saved textmode registers are stored, causing textmode not be restored correctly. It would be a good idea to somehow store this information in a 'safe' area (say a kernel buffer). Note that the 1mvga_safety_fork22m(3) thing has the same idea. Currently, programs that are in graphics mode are suspended while not in the current virtual console. Would it be a good idea to let them run in the background, virtualizing framebuffer actions (this should not be too hard for linear banked SVGA modes)? It would be nice to have, say, a raytracer with a real-time display run in the background (although just using a separate real-time viewing program is much more elegant). Anyone wanting to rewrite it all in a cleaner way (something with load- able kernel modules shouldn't hurt performance with linear frame- buffer/vgagl type applications) is encouraged. Also, if anyone feels really strongly about a low-resource and true- color supporting graphical window environment with cut-and-paste, I believe it would be surprisingly little work to come up with a simple but very useful client-server system with shmem, the most useful appli- cations being fairly trivial to write (e.g. shell window, bitmap viewer). And many X apps would port trivially. This is old information, please be sure to read 1msvgalib.faq22m(7) if you are interested in further goals. 1m7. REFERENCES0m The latest version of svgalib can be found on 4msunsite.unc.edu24m in 4m/pub/Linux/libs/graphics24m or 4mtsx-11.mit.edu24m in 4m/pub/linux/sources/libs0m as 4msvgalib-X.X.X.tar.gz24m. As of this writing the latest version is 4msvgalib-1.4.1.tar.gz24m. There are countless mirrors of these ftp servers in the world. Certainly a server close to you will carry it. The original VGAlib is on 4mtsx-11.mit.edu24m, 4mpub/linux/sources/libs/vgalib12.tar.Z24m. 4mtvgalib-1.0.tar.Z24m is in the same directory. SLS has long been distributing an old version of VGAlib. Slackware keeps a fairly up-to-date version of svgalib, but it may be installed in different directories from what svgalib likes to do by default. The current svgalib install tries to remove most of this. It also removes 4m/usr/bin/setmclk24m and 4m/usr/bin/convfont24m, which is a security risk if setuid-root. Actually the recent makefiles try to do a really good job to cleanup the mess which some distributions make. If you want to recompile the a.out shared library, you will need the DLL 'tools' package (found on 4mtsx-11.mit.edu24m, 4mGCC24m dir). To make it work with recent ELF compiler's you actually need to hand patch it. You should probably not try to compile it. Compiling the ELF library is deadly simple. And here is a list of other references which is horribly outdated. There are many more svgalib applications as well as the directories might have changed. However, these will give you a start point and names to hunt for on CD's or in ftp archives. 1mViewers (in /pub/Linux/apps/graphics/viewers on sunsite.unc.edu):0m 1mspic 22mPicture viewer; JPG/PPM/GIF; truecolor; scrolling. 1mzgv 22mFull-featured viewer with nice file selector. 1msee-jpeg0m Shows picture as it is being built up. 1mmpeg-linux0m svgalib port of the Berkeley MPEG decoder (mpeg_play); it also includes an X binary. 1mflip 22mFLI/FLC player (supports SVGA-resolution). 1mGames (in /pub/Linux/games on sunsite.unc.edu):0m 1mbdash 22mB*lderdash clone with sound. 1msasteroids0m Very smooth arcade asteroids game. 1myatzy 22mNeat mouse controlled dice game. 1mvga_cardgames0m Collection of graphical card games. 1mvga_gamespack0m Connect4, othello and mines. 1mwt 22mFree state-of-the-art Doom-like engine. 1mMaelstrom0m A very nice asteroids style game port from Mac. 1mKoules 22mA game. (I've no idea what it looks like) 1mDocs0m In the vga directory of the 1mSIMTEL MSDOS 22mcollection, there is a package called 4mvgadoc324m which is a collection of VGA/SVGA register information. The XFree86 driver sources distributed with the link-kit may be help- ful. 1mMiscellaneous0m There's an alternative RAW-mode keyboard library by Russell Marks for use with 1msvgalib 22mon 4msunsite.unc.edu24m. 1mLIBGRX22m, the extensive framebuffer library by Csaba Biegl distributed with 1mDJGPP22m, has been ported to Linux. Contact Hartmut Schirmer (phc27@rz.uni-kiel.d400.de, subject prefix "HARTMUT:"). A more up-to- date port by Daniel Jackson (djackson@icomp.intel.com) is on 4msun-0m 4msite.unc.edu24m. The vgalib ghostscript device driver sources can be found on 4msun-0m 4msite.unc.edu24m, 4m/pub/Linux/apps/graphics24m. Ghostscript patches from Slackware: 4mftp.cdrom.com24m, 4m/pub/linux/misc24m. 1mgnuplot 22mpatches are on 4msun-0m 4msite.unc.edu24m. Mitch D'Souza has written font functions that work in 16 color modes and can use VGA textmode (codepage format) fonts; these can be found in his 1mg3fax 22mpackage in 4msunsite.unc.edu24m. These functions may go into a later version of 1msvgalib22m. 1m8. KNOWN BUGS0m This section is most probably outdated, none of these problems are no longer reported. Using a 132 column textmode may cause graphics modes to fail. Try using something like 80x28. The console switching doesn't preserve some registers that may be used to draw in planar VGA modes. Wild console switching can cause the text screen to be corrupted, espe- cially when switching between two graphics consoles. On ET4000, having run XFree86 may cause high resolution modes to fail (this is more XFree86's fault). The Trident probing routine in the XFree86 server may cause standard VGA modes to fail after exiting X on a Cirrus. Try putting a 'Chipset' line in your Xconfig to avoid the Trident probe, or use the link kit to build a server without the Trident driver. Saving and restoring the textmode registers with savetextmode/textmode (restoretextmode) should also work. [Note: svgalib now resets the particular extended register, but only if the Cirrus driver is used (i.e. the chipset is not forced to VGA)] [This is fixed in XFree86 v2.1] Some Paradise VGA cards may not work even in standard VGA modes. Can anyone confirm this? Piping data into a graphics program has problems. I am not sure why. A pity, since zcatting a 5Mb FLC file into flip on a 4Mb machine would be fun. The 1mtseng3.exe 22mDOS program include as source in the svgalib distribu- tion doesn't recognize any modes on some ET4000 cards. Also ET4000 cards with a Acumos/Cirrus DAC may only work correctly in 64K color mode. 1mFILES0m 4m/etc/vga/libvga.config0m 4m/etc/vga/libvga.et40000m 1mSEE ALSO0m 1msvgalib.et400022m(7), 1msvgalib.chips22m(7), 1msvgalib.mach3222m(7), 1mvgagl22m(7), 1mlib-0m 1mvga.config22m(5), 1m3d22m(6), 1maccel22m(6), 1mbg_test22m(6), 1meventtest22m(6), 1mforktest22m(6), 1mfun22m(6), 1mkeytest22m(6), 1mlineart22m(5), 1mmousetest22m(6), 1mjoytest22m(6), 1mmjoytest22m(6), 1mscrolltest22m(6), 1mspeedtest22m(6), 1mspin22m(6), 1mtestaccel22m(6), 1mtestgl22m(6), 1mtestlin-0m 1mear22m(6), 1mvgatest22m(6), 1mplane22m(6), 1mwrapdemo22m(6), 1mconvfont22m(1), 1mdumpreg22m(1), 1mfix132x4322m(1), 1mrestorefont22m(1), 1mrestorepalette22m(1), 1mrestoretextmode22m(1), 1mrunx22m(1), 1msavetextmode22m(1), 1msetmclk22m(1), 1mtextmode22m(1), 1mmach32info22m(1). 1mAUTHOR0m There are many authors of svgalib. This page was edited by Michael Weller . The original documentation and most of 1msvgalib 22mwas done by Harm Hanemaayer though. Svgalib 1.4.1 16 December 1999 svgalib(7)