Tegra/Nouveau Render-Only Gallium3D Support

[phoronix]

Phoronix: Tegra/Nouveau Render-Only Gallium3D Support

With the Etnaviv driver bringing the Gallium3D "renderonly" library to Mesa Git, Alexandre Courbot of NVIDIA has sent out an updated patch for adding renderonly support to Tegra/Nouveau...

http://www.phoronix.com/scan.php?page=news_item&px=Tegra-Nouveau-Renderonly

[slacka]

Could someone explain briefly what is "renderonly"? And how is it useful?

[haagch]

nvidia SOCs (at least the Tegra K1 chromebook I have) have an annoying setup. The nvidia GPU can "only render", and it is not hooked up to the display at all. There is a second wannabe "tegra" GPU, that can only drive the display, but can't do any real 3D rendering, this latter one is also referred to as the "scanout" device.

The renderonly library is basically a wrapper around both of these GPUs that presents them as one to the system and "does the right thing" automagically.

In practice you can look at the bottom of the linked patch:

.gpu_fd = drmOpenWithType("nouveau", NULL, DRM_NODE_RENDER),

So you're running on the "tegra" GPU by default, but if you try to render something in 3D, it actually offloads that to a rendernode that the nouveau driver created for the real nvidia GPU.

[geearf]

Thank you for the detailed explanation, I had no clue what it was before.