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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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The intel-gpu-tools package mentioned on the 01.org page is recommended as it can be used to dump current register values for examination.
=== ATI
[[topic:14887|Since September 2007]], AMD started opening up specifications for their recent GPUs.
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 a specific email address for support.
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 on [https://developer.amd.com/resources/developer-guides-manuals/#open_gpu AMD's website] and an implementation for the Linux kernel is available on [https://github.com/GPUOpen-Drivers/AMDVLK GitHub].
=== NVIDIA ===
<!-- NVIDIA now provides official documents for their GPUs and open sources their GPU drivers for Linux
NVidia doesn't provide official specifications, but a lot of community effort is spent in the [http://nouveau.freedesktop.org/wiki/ nouveau] project, which can be sourced for examples and documentation even though such reverse engineered specifications aren't complete nor guaranteed to be accurate. Marcin Kościelnicki has been writing down unofficial specs in his [http://0x04.net/cgit/cgit.cgi/envytools/tree/ envytools] repository. ▼
▲
Although having missing bits here and there, they are certainly an interesting resource for learning about the internals of these graphic cards. These docs cover the entire range of NVIDIA hardware, from the first to the latest card, and might prove sufficient to write a native driver.
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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 projects like [http://nouveau.freedesktop.org Nouveau] and [https://github.com/envytools/envytools EnvyTools] and a group of hackers even leaked most of NVIDIA's GPU stuff like documentation and even full-on reference FPGA codes, which led to NVIDIA officially open sourcing of their GPU documentation and Linux kernel module. Most of these reverse engineering project aren't complete unlike NVIDIA's official documentation but you can still use it as an another source of NVIDIA GPU documentation in addition with NVIDIA's official open source documentation.
=== VMWare SVGA-II ===▼
Not exactly a card, but the SVGA-II device makes for a nice virtual machine device for some 3d acceleration. It is available on both VMWare and QEMU. A well documented and easy to port reference driver has also been made available by VMWare under the MIT license. Although it is deprecated, the device works perfectly fine under QEMU and is relatively simple to work with, thus it makes for a very good starting point for graphics acceleration. Reference driver available at [http://vmware-svga.sourceforge.net/index.old.html the old vmware-svga page on sourceforge].▼
== Where can I find low-level information about nVidia/Matrox/ATI/... 3D graphic cards? ==▼
▲Not exactly
▲== Where can I find low-level information about
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
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'''
* Tiles. You enter a small NxN dataset (usually a bitmap of between 8x8 and 32x32), a foreground color and a mixing style plus some coordinates and the card "paints" the area with the given pattern. That can be handy to render Win95-like backgrounds (tiled ones) or even to draw fonts quickly.
== How do 3D-accelerated programs talk to 3D-accelerating hardware? ==
▲I'll be assuming that you have a strong knowledge of OpenGL etc and that you don't need it covered here. If you take the example of nVidia's 3D driver for linux (if you have a correctly configured nVidia card, 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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