Jolla Ports Wayland To Android GPU Drivers

An anonymous reader writes "A Jolla Sailfish OS engineer has ported Wayland to run on Android GPU drivers. The implementation uses libhybis with the Android driver so that the rest of the operating system can be a conventional glibc-based Linux operating system, such as Mer / Sailfish OS. The code is to be LGPL licensed. The reported reasoning for making Wayland support Android GPU drivers was difficulty in ODM vendors not wishing to offer driver support for platforms aside from Android."

Comments

Re:Eh?

[jbolden]

Jolla is a bunch of x-Nokia engineers continuing the work Nokia was doing on MeeGo. The name of their version of MeeGo is Sailfish. Wayland is a next generation display manager similar to Aqua on Mac that is currently looking to replace some of X11's functionality. Jolla ported the Android drivers over to Wayland so that Sailfish can run on GPUs designed for Android. This allows Jolla to buy off the shelf (cheap) GPUs and run Sailfish on it i.e. keep hardware parts costs down.

The use of inexpensive hardware means that Jolla is not going to be only at higher price points. They are producing a mainstream phone and there had been debate about that. This is important because we now for sure that Sailfish is going with Wayland unlike MeeGo which used a more primitive direct system.

In short
a) Wayland is cool
b) Sailfish is cool
c) Jolla is cool

So all around a classic /. news for nerds story.

Re:Sailfish

[preflex]

No, Sailfish does run android apps.. IIRC, they licensed Alien Dalvik.

Let's try to explain the technology

[Bostik]

Phoronix article is quite low on information, and even the original post at http://mer-project.blogspot.fi/2013/04/wayland-utilizing-android-gpu-drivers.html assumes some technical knowledge of graphics stack. The basic idea is actually pretty simple. I'll try to break it down.

1. The SoC vendors are willing to target only Android
2. Android GPU drivers are built against Bionic libc
3. The GPU drivers talk to hardware, and expose themselves via EGL and GLESv2
4. EGL is basically a common API for GPU memory management, buffer (region of memory used for rendering) allocation and display updates
5. GLESv2 stands in for the functionality we commonly associate with OpenGL

6. GPU drivers form a combination of EGL and GLESv2 libraries, each GPU vendor providing their own

This is where libhybris comes into play. The GPU driver libraries don't work without Bionic libc - so libhybris, while running on top of regular linux (and thus [e]glibc), keeps a private Bionic libc open for the GPU drivers' use, and redirects all the EGL/GLESv2 calls to the GPU driver libraries. These libraries run in their own Bionic universe, and tell the actual display hardware what to do.

The new part about Wayland support is just a logical extension of the same behaviour. Wayland already depends on EGL for buffer management, so "all" it really needs is a native display handler. Now as it happens, the native Android display structure can be mapped to the Wayland-EGL display structure. It's not trivial, but it's certainly doable. Thanks to libhybris, the Wayland libraries see a correct native display type and operate on that, while the Android GPU libraries see their respective native display type and thus can drive the hardware as ever before. After all, it's still the SAME hardware regardless of what operating system we may be running. Registers are registers and memory is still memory. From the GPU drivers' point of view nothing has changed.

So what has happened? In addition to just redirecting graphics stack calls to Android drivers, we are now also translating the display subsystem between two somewhat different systems.

If all of the above sounds eerily familiar, you are correct. In networking this kind of design is called a proxy, or if we're talking about link layer, it would be a multi-protocol label switch. Logically there's not much difference.