Due to an influx of spam, we have had to impose restrictions on new accounts. Please see this wiki page for instructions on how to get full permissions. Sorry for the inconvenience.
Admin message
The migration is almost done, at least the rest should happen in the background. There are still a few technical difference between the old cluster and the new ones, and they are summarized in this issue. Please pay attention to the TL:DR at the end of the comment.
@@ -91,7 +91,19 @@ The `VK_EXT_acquire_xlib_display`/`VK_EXT_direct_mode_display` Vulkan extensions
...
@@ -91,7 +91,19 @@ The `VK_EXT_acquire_xlib_display`/`VK_EXT_direct_mode_display` Vulkan extensions
For standalone XR systems or systems that don't support these extensions, it is possible to use `VK_KHR_display` and `VK_KHR_display_swapchain` directly on KMS/DRM without running X.Org altogether.
For standalone XR systems or systems that don't support these extensions, it is possible to use `VK_KHR_display` and `VK_KHR_display_swapchain` directly on KMS/DRM without running X.Org altogether.
This is currently not implemented in Monado, but will be supported eventually.
Monado v21.0.0 introduces such a VkDisplayKHR based backend. Its internal structure is very similar to the nvidia backend.
This backend requires the Vulkan driver to gain exclusive ("drm master") control over the display hardware. This means that an X server or wayland compositor must not be control the "active" vt, it must be a text vt (an X server running "in the background" can still be running in the background). The active vt can be switched with Ctrl+Alt+F1 to F12 or `sudo chvt 1` to 12.
This backend is only enabled when the environment variable `XRT_COMPOSITOR_FORCE_VK_DISPLAY=0` is used. Its value is the nth display connector. Using a too big number like `XRT_COMPOSITOR_FORCE_VK_DISPLAY=100` will print the available display connectors and the names of the connected displays.
Note that X servers may not handle well switching to them while the monado compositor is running. Switching to another text vt should work fine.
Many OpenXR applications will require to be started with an X server - however X servers that are "running in the background" may not accept connections for applications that use the GPU. See [Tegra]({% link tegra.md %}) for an example of how to get it working on the proprietary nvidia driver.
An OpenXR application that does not require an X server is hello_xr with the Vulkan backend: `hello_xr -G Vulkan`.
This implementation has been tested on amd (radv) and the proprietary nvidia driver.
Otherwise the instructions from [Getting Started]({% link getting-started.md %}) work on Tegra for extended mode on X11.
# Direct Mode
The Vulkan driver for nvidia Tegra does not support vulkan based direct mode (VK_EXT_acquire_xlib_display, VK_EXT_direct_mode_display).
[Response from nvidia](https://forums.developer.nvidia.com/t/vk-ext-direct-mode-display-not-present-in-vulkan-1-2-on-jetpack-4-4/161593/2):
> VK_EXT_direct_mode_display is not required for doing direct mode through Vulkan on Jetson. VK_KHR_display and VK_KHR_display_swapchain are supported and those can be used for direct display mode.
See the `Vulkan on KMS/DRM` section in [Direct Mode]({% link direct-mode.md %}) for details of the implementation in Monado.
## Applications that require X11
Graphical applications do not properly connect to a normally running X server.
It is possible to run an offscreen X server that runs graphical applications.
Save a modified copy of the xorg.conf file as
/etc/X11/xorg.conf.offscreen
```
# Copyright (c) 2011-2013 NVIDIA CORPORATION. All Rights Reserved.
#
# This is the minimal configuration necessary to use the Tegra driver.
# Please refer to the xorg.conf man page for more configuration
# options provided by the X server, including display-related options
# provided by RandR 1.2 and higher.
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0"
EndSection
Section "Monitor"
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Unknown"
HorizSync 28.0 - 33.0
VertRefresh 43.0 - 72.0
Option "DPMS"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
SubSection "Display"
Virtual 1920 1080
EndSubSection
Option "UseDisplayDevice" "none"
EndSection
Section "Module"
Disable "dri"
SubSection "extmod"
Option "omit xfree86-dga"
EndSubSection
EndSection
Section "Device"
Identifier "Tegra0"
Driver "nvidia"
# Allow X server to be started even if no display devices are connected.
Option "AllowEmptyInitialConfiguration" "true"
EndSection
```
Then run an X server with the command `Xorg -config ./xorg.conf.offscreen :10`. It should drop to a text vt console.
Now it is possible to use both `XRT_COMPOSITOR_FORCE_VK_DISPLAY=0` to let the Monado compositor use the display, and to start an OpenGL application that requires an X server with `DISPLAY=:10`, for example `DISPLAY=:10 hello_xr -G OpenGL`.
