[Help]Question about graphics architecture for weson/wayland

[Jasper St. Pierre]

On Mon, Aug 18, 2014 at 1:32 AM, Yang Andy <williamyang13 at hotmail.com>
wrote:

> Hi Pekka
>
> Thank you very much for your reply.
>
>
> > > 3.In order to run weston-launch,do i have to use gpu?
> > No, you can choose e.g. the fbdev backend for Weston, and so Weston
> > will run on the /dev/fb, software rendered. No GPU used there in that
> > sense. Software rendering also means that no application under Weston
> > can use the GPU for rendering windows.
>
> If i choose fbdev backend for weston,can i use EFL/Evas and EGL/OpenGL for
> draw graphics?
>
I mean that EGL/OpenGL which implement Software rendering.
>

I don't think you can use the fbdev backend with EGL. Somebody could
attempt to try to make that work, but bringing up DRM/KMS on your platform
would be a much better choice of your time.

What the difference between
> drm-backend/fbdev-backend/wayland-backend/x11-backend?
>

fbdev, or /dev/fb, is the deprecated simple API for doing any sort of
rendering to a front-buffer. It's quite limited and doesn't have lots of
functionality, so we replaced it with a newer API known as "DRM". The
fbdev-backend uses the deprecated /dev/fb API.

The DRM uses the newer "DRM" API that replaces /dev/fb. The kernel
implements the DRM API for a bunch of different GPUs, and apps like Weston
and libraries like mesa can use these to do rendering and modesetting.

The X11 and Wayland backends are nested backends for testing. The X11
backend lets you test Weston on top of an existing X11 session, and the
Wayland backend lets you test Weston on top of an existing Wayland session.

Best regards.
>
> Andy
> > Date: Thu, 14 Aug 2014 16:57:26 +0300
> > From: ppaalanen at gmail.com
> > To: williamyang13 at hotmail.com
> > CC: wayland-devel at lists.freedesktop.org
> > Subject: Re: [Help]Question about graphics architecture for weson/wayland
>
> >
> > On Thu, 14 Aug 2014 08:36:43 +0000
> > Yang Andy <williamyang13 at hotmail.com> wrote:
> >
> > > Hi everyone
> > >
> > > When i run 3D application through weston-launch, it failed because the
> graphics driver is not right.
> >
> > weston-launch starts weston, you cannot use it to launch something else.
> >
> > > I have some questions for help.
> > >
> > > 1.Is there any requirement for Hardware(GPU??) / Drivers?
> >
> > Yes, see hardware enabling at
> > http://wayland.freedesktop.org/architecture.html
> >
> > > 2.Is DRM must for weston(compositor),how to setup DRM?
> >
> > Weston's DRM backend depends on DRM. Make sure your kernel has a DRM
> > driver for your graphics chip.
> >
> > > 3.In order to run weston-launch,do i have to use gpu?
> >
> > No, you can choose e.g. the fbdev backend for Weston, and so Weston
> > will run on the /dev/fb, software rendered. No GPU used there in that
> > sense. Software rendering also means that no application under Weston
> > can use the GPU for rendering windows.
> >
> > You can also choose Weston's DRM backend with the software (Pixman)
> > renderer. That will not use the GPU either, but does need DRM and KMS.
> >
> > > 4.Does GPU kernel drvier consist of kernel/driver/gpu/xxxx(xxxx.ko??)
> and of kernel/driver/gpu/drm/xxxx(DRM_xxxx.ko)?
> >
> > Roughly yes.
> >
> > > 5.Does user side drvier consist of EGL/OpenGLES?
> >
> > The user space side of the driver usually implements EGL and OpenGL
> > (desktop/ES/whatever).
> >
> > > 6.graphics architecture is
> Application⇒EGL/OpenGLES/⇒libDRM⇒DRM_xxxx.ko⇒xxxx.ko⇒GPU?
> >
> > Yes, where EGL/OpenGLES is actually Mesa, since you have libdrm there.
> > This is specific to the open source drivers.
> >
> >
> > Thanks,
> > pq
>
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>


-- 
  Jasper
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