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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> magcius@gmail.com [mailto:magcius@gmail.com]
<b>On Behalf Of </b>Jasper St. Pierre<br>
<b>Sent:</b> Sunday, February 09, 2014 12:23 AM<br>
<b>To:</b> Wang, Quanxian<br>
<b>Cc:</b> wayland-devel@lists.freedesktop.org<br>
<b>Subject:</b> Re: Is there any way to let compositor set the data in client space and then return back to client?<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US">Well, there's not really anything that allows process A to arbitrarily modify process B's memory. The only thing that's close is memory-mapped files, and that's already what we use to share
image data between the client and the compositor.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">There's also memfd, which is "more secure" than a memory-mapped tmpfile, simply because it allows sealing the fd, so you can be sure it will never change as you try to read from it. But memfd isn't a public API yet.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">What exactly are you trying to do here?<o:p></o:p></span></p>
<p class="MsoNormal"><b><i><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif";color:#1F497D">[Wang, Quanxian] I want to create a protocol to get the output data from compositor, I don’t know where to put it for client. So shared
memory should be a good way to do that. Anyway, I need to check it how to make it happen. Thanks for your idea.<o:p></o:p></span></i></b></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">On Sat, Feb 8, 2014 at 3:19 AM, Wang, Quanxian <<a href="mailto:quanxian.wang@intel.com" target="_blank">quanxian.wang@intel.com</a>> wrote:<o:p></o:p></span></p>
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<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Hi, All<o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif"">I want to allocate some space in client, and let compositor set some data in this space and then return
back to client. <o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt"> </span><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif"">It seems like user data mechanism.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt"> </span><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Any way to implement that?<o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt"> </span><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif""><o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Thanks<o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif""> <o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif"">Regards<o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif";color:#888888"> <o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif";color:#888888">Quanxian Wang<o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:justify;text-justify:inter-ideograph"><span lang="EN-US" style="font-size:10.5pt;color:#888888"> </span><span lang="EN-US" style="font-size:10.5pt;font-family:"Calibri","sans-serif";color:#888888"><o:p></o:p></span></p>
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<br>
-- <br>
Jasper<o:p></o:p></span></p>
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