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I am trying to setup a Tegra 3 (Toradex Apalis T30) based system that will have an OpenGL ES based user interface on a touch screen. Unfortunately the standard Linux4Tegra kernel is seriously outdated and the provided graphics driver requires X11 integration. I have found though that I can build the Vanilla Linux kernel and get it running just fine on my board (tested 3.18). I have also found that a DRM Tegra driver is included in the kernel these days and I enabled it in menuconfig and built the kernel using it. I have also managed to get many distros working with the kernel (though I haven't really tried getting X working on any one).

My problem is that beyond this point, I am stuck. I cannot figure out what to do next in order to get GLES rendering up and running with the DRM driver. I have looked around a bit and have seen that Mesa might support GLES via DRM but I am not sure if this will allow me to do so without X? Also, how on earth to I get Mesa configured and compiled for the Tegra DRM driver?

Also, how does one go about configuring the output display using this DRM driver? My target screen is a 24bit parallel RGB display but I have not got that hooked up yet and would like to test with HDMI first. I have literally no idea how one should go about configuring the output display. The only information that I can find that might help involves X and xorg.conf which I will hopefully not be using. My device does output the console correctly on the HDMI display, how does it know to do that? Might this process somehow involve the device tree?

PS. I guess this question is a bit stupid but I am very new to embedded Linux and have just figured out how to build the vanilla kernel etc. and have really no idea of how the Linux display system works beyond just configuring X. Finding information regarding this is also proving hard.

EDIT: I have gotten XFCE sort of running on HDMI (login does not work and the login windows is very tiny) on Fedora using the OpenTegra driver which in term uses the DRM driver if I am not mistaken so hopefully that is good news?

Gerharddc
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  • You can build with [Noveau support](http://nouveau.freedesktop.org/wiki/), although it may take some work if no one has ported it from x86 to the ARM. I would guess Nvidia might be doing this. – artless noise Mar 30 '15 at 05:59
  • As far as I have it only the Tegra K1 has Noveau at this moment. The one for the the Tegra 2 and 3 is called Grate or something but that is not really my problem at the moment. – Gerharddc Mar 30 '15 at 06:11
  • The pages I read said the GPU is a GEForce chipset, so the basic command FIFO should be the same as a PC version supporting this chipset (without PCIe, etc) which Noveau supports. It would take some coding possibly; why did you ask on StackOverflow? – artless noise Mar 30 '15 at 14:14
  • If you look more closely, you'll see its actually called a 'ULP GeForce' and this supposedly bears no resemble to the proper GeForce whatsoever. I thought someone here might be able to help... – Gerharddc Mar 31 '15 at 04:38
  • Ok, if you say it is different. I read *Ultra-low power (ULP) GeForce GPU architected for low-power applications. The ULP GeForce GPU delivers outstanding game playability and a visually engaging, highly responsive user interface.* That sounds like a GeForce, but you maybe correct and that is why I only left a comment. – artless noise Mar 31 '15 at 16:09
  • [Phoronix](http://www.phoronix.com/scan.php?page=news_item&px=MTY0MTY) seems to be saying that at least some Tegra GPUs are the same. It is odd they would invent something new and call it the same thing; but I don't put it beyond the realm of comprehension. – artless noise Mar 31 '15 at 16:22

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Nvidia-setting can usually clear things up if you've gotten this far. Typically the video will work if the kernel has been given the correct vesa mode to show the system bootup messages. These are somewhat cryptic but they simple turn into an argument you append to the kernel boot parameters "vga=###".

James
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  • sorry I don't quite understand, am I supposed to configure the display using the vga setting? Also, how does this compare with the video=#### setting and what exactly should these arguments be? – Gerharddc Mar 29 '15 at 11:35