<br><br><div class="gmail_quote">On Sun, Jun 24, 2012 at 12:59 PM, Pekka Paalanen <span dir="ltr"><<a href="mailto:ppaalanen@gmail.com" target="_blank">ppaalanen@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">On Sat, 23 Jun 2012 22:21:28 +0530<br>
Sannu K <<a href="mailto:sannumail4foss@gmail.com">sannumail4foss@gmail.com</a>> wrote:<br>
<br>
> On Sat, Jun 23, 2012 at 2:04 AM, Casey Dahlin <<a href="mailto:cdahlin@redhat.com">cdahlin@redhat.com</a>> wrote:<br>
><br>
> > On Fri, Jun 22, 2012 at 10:29:04PM +0300, Pekka Paalanen wrote:<br>
> > > The trick is in the kernel DRM, which has to be able to deal with the<br>
> > > buffer and actually push it to the USB device. This may require special<br>
> > > allocation flags or somehow using the dmabuf infrastructure to allocate<br>
> > > the buffer, where the composite is drawn.<br>
> ><br>
> > Pretty sure it's possible right now to just copy the buffer out to normal<br>
> > userspace memory and then in to another DRM buffer. Not the quickest<br>
> > transition, but functional.<br>
> ><br>
> > --CJD<br>
> ><br>
><br>
> Does this mean wayland (rather weston) does not support multiple graphics<br>
> card seamlessly (as of now without dmabuf patches)?<br>
<br>
</div>To my understanding, for now, correct.<br>
<div class="im"><br>
> Consider that an<br>
> application creates a DRM buffer and uses it for rendering, when user moves<br>
> the window to another screen that is driven by another graphics card this<br>
> case could appear. Will the memory content be copied (in current state)?<br>
<br>
</div>In current state, I do not think it would work at all.<br>
<br>
You do not even have to think that far. Just think about how Weston<br>
composites per output, and how a resulting buffer could be used on<br>
an output that is on a different graphics card than what Weston uses<br>
for compositing.<br>
<br>
I have also never heard of a Wayland developer using a multi-card setup.<br>
<div class="im"><br>
> Will there be a better solution without buffer sharing (what if the window<br>
> buffer is in graphics card's RAM)? Please provide some pointers and/or<br>
> documentation on how wayland and weston works (which libraries it calls for<br>
> what purpose).<br>
<br>
</div>I don't think it works right now. Anyway, the libraries are the usual:<br>
libdrm, Mesa (GBM). And of course the kernel DRM. You can look at Weston's<br>
DRM backend.<br>
<br>
Just like for many other concerns, you can be sure (I am, at least) that<br>
all this will work somehow, some day. There are just more pressing<br>
matters for now.<br>
<br>
A key point here is to realise, that GPU interoperability is not<br>
really a Wayland problem, but a problem for the whole graphics stack.<br>
<br>
<br>
Thanks,<br>
pq<br>
</blockquote></div><br>Thanks for the details. Hope the multi GPU setup will come soon to wayland and weston.<br>