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<p class="MsoNormal"><span style="color:#002060">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#002060">I posted this on the OSE forum some weeks ago, but I did not get any response. I hope someone on this list can give me some guidance, because this is getting critical for me. Thanks.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#002060">I have a virtual device model plugged in through PDM, in which a PCIe switch is plugged into the ICH9 host bus, and a PCIe endpoint is connected to the secondary bus of the PCIe switch (each is a different PDM
instance). The endpoint is capable of accessing system memory via DMA, which I model by calling PDMDevHlpPhysRead() and PDMDevHlpPhysWrite() from a separate thread that I have. So far so good.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#002060">Now I need to add support for PCIe "atomic" operations. These are a set of endpoint initiated read/modify/write operations that are carried out without interruption. It's quite easy to implement the read/modify/write
part in my model, but I am concerned about the possibility of another VirtualBox thread doing another memory access in between the read/modify/write phases.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#002060">Is there a way to ensure nothing else can access memory during the critical steps of the read/modify/write? I have mutual exclusion between my own two threads, but I'm worried about guest software or other device
models that are not in my control.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#002060"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#002060">_____________________________________________<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;color:#002060"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="color:#002060">Ric Vilbig</span></b><span style="color:#002060"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#002060">Mentor Graphics, Emulation Division</span><span style="font-size:10.0pt;color:#002060"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#002060">46871 Bayside Parkway, Fremont CA, 94538<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#002060">Phone: 510-354-7360<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#002060">Mobile: 408-529-2365<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#002060">email: <a href="mailto:ric_vilbig@mentor.com">
<span style="color:blue">ric_vilbig@mentor.com</span></a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#002060"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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