May 29, 2013 - 05:20 PM | Tim Verry
The Raspberry Pi Foundation has been working with Collabora to fund development of a Wayland display server that is compatible with the Raspberry Pi and also allows the continued use of legacy X applications.
So far, operating systems that run on the Raspberry Pi have used X as the display server and window compositor. The Raspberry Pi Foundation wants to move to a window compositor that will take advantage of the Raspberry Pi's Hardware Video Scaler (HVS) and take the burden of window composition off of the relatively much slower ARM CPU. The Raspberry Pi Foundation has chosen Wayland as the display server for the task.
The Raspberry Pi Model A.
Taking advantage of the HVS and OpenGL ES compatible GPU will make the system feel much more responsive and allow for advanced effects (fading, Expose'-like window browsers, et al) for those that like a little more bling with their OS.
The Wayland/Weston display server allows for GPU acceleration and window composition using the Pi's VideoCore IV GPU and HVS (which is independent of the hardware units that run OpenGL code). The display server will feed the entire set of windows along with how they should be laid out on screen (stacking order, transparency, 2D transform, ect.) to the HVS which will hardware accelerate the process and free the ARM CPU up for other tasks.
According to the Raspberry Pi Foundation, the Raspberry Pi's HVS is fairly powerful for a mobile-class SoC with 500 Megapixel/s scaling throughput and 1 Gigapixel per second blending throughput.
[inline:files/news/2013-05-29/Wayland running on Raspberry Pi.jpg]
In addition to GPU acceleration, Wayland will allow non-rectangular windows, fading and other effects, support for legacy X applications with Xwayland, and a scaled window browser.
The Raspberry Pi Foundation has been working with developers since late last year and is nearly ready to roll a technology preview into the next Raspian operating system release. The developers are still working on improving the performance and reducing memory usage. As a result, the new Wayland/Weston display server is not expected to become the new default in the various Raspberry Pi operating systems until late 2013 at the earliest.
This is a project that is really nice to see, especially since at least a small part of the development work going into supporting the ARM-based Raspberry Pi on Wayland will help other ARM devices and Wayland in general which is becoming an increasingly popular choice in new Linux distributions and the best X alternative so far. Of course, this is primarily going to be a useful update for those Raspberry Pi users that run OSes with GUIs as the responsiveness should be a lot snappier!
If you simply can't wait until later this year, it is possible to install the technology preview (beta) of Wayland/Weston onto the current version of Raspbian Linux by cloning the git project or installing a Raspbian package of Weston 1.0. Blogger Daniel Stone has all the details for installing the display server onto your Pi under the section titled "sounds great; how do i get it?" on this post.
See a video of Wayland technology preview in action on the Raspberry Pi on the Raspberry Pi Foundation's blog.
Read more about the Raspberry Pi at PC Perspective.