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Accelerated Graphic Cards: Difference between revisions
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While it is nice to have some graphics on the screen, it would be even nicer to have the video card do the dirty work. Beware though, things are not always as easy as they seem.
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== Cards with documentation ==
=== 3Dfx ===
These are a sort of good news for 3dfx cards (those with a Voodoo chipset). These cards could be the only ones with relatively fast 3D support (Glide/OpenGL) and [http://darwin-3dfx.sourceforge.net/ open specifications]. Voodoo cards are still available from sources such as eBay.
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=== ATI/AMD ===
The ones regarding a R630 or M56 chip can be downloaded from [https://www.x.org/docs/AMD/old/ X.org].
Since early 2014, AMD maintains up to date open programming guides for all their GPUs, including
X.org provides a documentation for AMD GPUs in [https://www.x.org/wiki/RadeonFeature/#index13h2 their website]. An official AMD Open GPU documentation is also available
=== NVIDIA ===
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NVIDIA now provides official documentations for most of their GPUs [https://nvidia.github.io/open-gpu-doc/ on GitHub] and open sourced their Linux kernel module for their GPUs [https://github.com/NVIDIA/open-gpu-kernel-modules also on GitHub]. Before NVIDIA officially open sourced their GPU stuff, there are many NVIDIA GPU reverse engineering
=== VMware SVGA-II ===
Not exactly
== Where can I find low-level information about NVIDIA
Good question. Unless you find something else, there is virtually no information publicly available (for free or otherwise) about the internal workings of current
Now, if you have a VIA
▲Good question. Unless you find something else, there is virtually no information publicly available (for free or otherwise) about the internal workings of current 3D graphics cards. There are only small bits that are relevant to game programmers but nothing an OS developer could use.
▲Now, if you have a VIA graphics chip, things may be better since they recently released an [http://linux.via.com.tw/ open source driver] for both 2D and 3D operations.
There are virtually no tutorials or datasheets for the 2D acceleration features either, but at least we have open-source code for them. Among other sources, the Xfree drivers, [https://github.com/haiku/haiku/tree/master/src/add-ons/accelerants Haiku (was Open BeOS) accelerants] and [http://www.shawnhargreaves.com/freebe/ FreeBE/AF]. They may provide enough information to reverse-engineer and figure out a model that could be used to program/port for your environment. Some older cards with only 2D acceleration might be documented by the [https://pdos.csail.mit.edu/6.828/2018/readings/hardware/vgadoc/ VGADoc] ([https://pdos.csail.mit.edu/6.828/2018/readings/hardware/vgadoc4b.zip vgadoc4b.zip], also on [https://github.com/achernya/iap-6.828-website/tree/master/readings/hardware/vgadoc Github]).▼
▲There are virtually no tutorials or datasheets for the 2D acceleration features either, but at least we have open-source code for them. Among other sources, the
Anyone who wishes to put time into that kind of research is welcome to post their results here.
== What can 2D acceleration do for me? ==
* Hardware mouse cursor, drawn and managed (e.g. you provide coordinates, the card does the rest)
* Bitblt (for "'''BIT''' '''BL'''ock '''T'''ransfer") can be used for screen-to-screen memory copy like window moving, scrolling, etc. You provide from and to boxes and the card does the rest. Some might know this as the "rasterop" or remember the hardware "blitter" in Amiga computers.
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== How do 3D-accelerated programs talk to 3D-accelerating hardware? ==
Let's assume that you have a strong knowledge of OpenGL and that you don't need it covered here. If you take the example of NVIDIA's GPU driver for Linux (if you have a correctly configured NVIDIA GPU, you can see almost all this by a simple "strace" on a 3D program in linux), things are organized this way:
* Two libraries libGL.so and libGLcore.so will be loaded by any program that wishes to do accelerated 3D operations. Upon startup, those libraries open "/dev/nvidiactl" and "/dev/nvidia0".
<!-- Since the kernel module is now open sourced, should this section removed completely? -->
* The kernel module is made of an "obscure" file nv-kernel.o which contains only "anonymized" symbols and
* The actual "conversation" between the library and the driver cannot be traced by conventional means: /dev/nvidia* only allows "ioctl" operations and mmap. The values you can observe in "/proc/XXXXX/maps" while the 3D program is running, which let
l /proc/pci
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== External links ==
* [[topic:23548|A topic on duplicating/reverse engineering existing driver code]]
[[Category:Video]]
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