<html> <head> <style></style></head> <body class='hmmessage'><div dir='ltr'>Hi Pekka Thank you very much for your reply. <pre>>It would definitely be easier if you only need one EGLDisplay, and >can use the EGLNativeWindowType argument of eglCreateWindowSurface() to >choose the target output for the EGLSurface. In this case the required >modifications would be limited to your version of compositor-fbdev.c.</pre>Now,i have adopted above solution. Best regards. Andy <div>> Date: Fri, 10 Oct 2014 09:29:24 +0300 > From: ppaalanen@gmail.com > To: williamyang13@hotmail.com > CC: wayland-devel@lists.freedesktop.org > Subject: Re: Question about multi-displays control on wayland protocolş > > On Fri, 10 Oct 2014 03:35:28 +0000 > Yang Andy <williamyang13@hotmail.com> wrote: > > > Hi Pekka > > > > Thank you very much for your reply. > > > > I got your meaning,but i have another question. > > > > Is there any necessary for modify weston/compositor? > > > > Because i investigate source code[compositor-fbdev.c],and find that compositor open device [/dev/fb0]. > > > > It seems that the compositor is constant with /dev/fb0,how does compositor direct surfaces to specific outputs(fb0/fb1...) > > > > Right, if you have multiple monitors attached, the legacy fbdev > interface is not going to be enough at all. Therefore you cannot use > compositor-fbdev.c. Even the EGL support in compositor-fbdev.c is a far > stretch we do not really like, because fbdev should just die. > > The recommended solution is to move to a kernel DRM driver, and use the > compositor-drm.c backend. I understand it might not be feasible for > you, if you don't have a DRM driver and an EGL stack to go with it, but > that is the direction you should be pushing for in the long run. > > If you really are stuck with using fbdev, you will need to write (fork) > and maintain your own fbdev backend. > > I'm not sure how your EGL integration would work, because obviously > EGL_DEFAULT_DISPLAY cannot specify which output to target. Probably > your proprietary EGL stack has proprietary ways to choose the right > /dev/fb* to target, but for that too you will need to modify the > existing code in Weston. > > If you need several EGLdisplays, e.g. one per /dev/fb*, then you may > need to modify Weston even more, because I don't think it supports > multiple renderer instances at the same time, and currently gl-renderer > assumes a single EGLDisplay. Furthermore, if you create multiple > EGLDisplays, then initializing EGL_WL_bind_wayland_display extension > properly may be an issue: will you initialize it for each EGLDisplay > separately, or for just one? Both ways cause side-effects that your EGL > stack needs to correctly handle, and they are probably unexpected (not > implemented or never tested), so proceed with caution. > > It would definitely be easier if you only need one EGLDisplay, and > can use the EGLNativeWindowType argument of eglCreateWindowSurface() to > choose the target output for the EGLSurface. In this case the required > modifications would be limited to your version of compositor-fbdev.c. > > It all depends on the EGL implementation you have. > > If you could use compositor-drm.c, it would all just work without > modifications. > > > Thanks, > pq </div> </div></body> </html>