> On 9 May 2017, at 16:51, Christophe de Dinechin <cdupo...@redhat.com> wrote: > > Hi Oscar, > > > For 3D acceleration in virtual machines, you need a multiplicity of > components to cooperate: > > 1. The physical GPU needs to be supported by the host. > > 2. It needs to expose an API that the virtual machine software can access, > e.g. OpenGL on Linux > > 3. The virtualisation software, e.g. KVM/QEMU, talks to the host GPU e.g. for > graphic operations. That happens irrespective of how the guest sees the > virtual hardware, i.e. irrespective of which of the methods Frediano referred > to is used. > > 4. The virtual hardware exposed to the guest by the virtualisation software > correspond to any of the solutions Frediano listed. This is true of any > hardware, not just graphic cards (i.e. the same is true for networking > cards). Again: > > a) A complete emulation of a real physical card, generally chosen to be > a widely supported hardware standard (e.g. VGA) > > b) A simplified card that makes it easier to emulate, typically by > accepting “higher level” commands. This is generally called > “paravirtualization” > > c) A pass-through to a real hardware card, which is exposed to the > guest by “poking a hole” in the virtualization so that the guest can see the > real hardware. In general, that means the guest has complete control of that > hardware, so you can’t share it with the host or with other guests. > > d) A smarter pass-through that only exposes part of the hardware. We > talk about exposing “functions” of the host physical card. > > 5. Guest software, generally in the form of device drivers, that knows how to > talk to the appropriate device listed in 4. In other words, you need a > different driver to talk to an emulated VGA card (where you’d only use the > regular VGA driver that comes with your OS) or to a para-virtualized card > (where you’d use a special driver that knows about para-virtualization).
I forgot to point out the key thing. What we are missing for 3D in Windows currently is this piece. > > In addition, for displays, you need to see what is happening in your guest. > Except in cases 4c and possibly 4d, you don’t connect a screen directly to > the graphic card of the guest, since there is no graphic card, only software. > So instead: > > 6. You have special software in the virtualisation stack, a “server”, that > takes whatever frame buffer the physical emulator in 4a or the > paravirtualized driver in 4b has, and exposes it, typically in the form of > some remote-viewing protocol like Spice or VNC. > > 7. The “client” will talk to that protocol and display that on your screen. > The client itself may use 3D acceleration to display things on your screen, > but it’s not the “same” 3D acceleration as used in the guest. For example, if > it gets a video stream from the server in 6, now it’s using the video > decoding capabilities of the 3D card, even if your application in the guest > is rendering 3D objects. > > In conclusion, people often understand “client” as something like “the spice > client”, i.e. the program in 7 used to connect to the server that exposes the > virtual screen of the virtual machine. For the virtual machine itself, we > generally prefer to use the term “guest”. > > I hope this makes sense. > > > Cheers, > Christophe > >> On 9 May 2017, at 16:29, Oscar Segarra <oscar.sega...@gmail.com >> <mailto:oscar.sega...@gmail.com>> wrote: >> >> Sorry Fredigano... >> >> I have read again your detailed response... and I cannot see the option >> where the client GPU is used... Is it expected the client GPU used with >> "option 2" >> >> Can you tell us when client GPU is used? >> >> Thanks a lot. >> >> 2017-05-09 13:31 GMT+02:00 Oscar Segarra <oscar.sega...@gmail.com >> <mailto:oscar.sega...@gmail.com>>: >> Ok, thanks for the detailed explanation... I'd suggest to publish it in your >> webpage in order to help other users. >> >> Óscar. >> >> 2017-05-09 13:24 GMT+02:00 Frediano Ziglio <fzig...@redhat.com >> <mailto:fzig...@redhat.com>>: >> There's a bit of confusion. >> >> The VM sees which cards the hypervisor (Qemu in this case) is configured to >> provide. As >> any card GPUs can be >> 1) physical, fully virtual >> 2) paravirtual >> 3) pass-through, specifically: >> 3.1) full pass-through >> 3.2) function pass-through >> >> 1) like VGA, a physical card is fully emulated, quite slow, there are >> some cards which are better than others as requires less guest <-> hypervisor >> switches; >> 2) there are no physical card, the card is created just for virtual >> environment. >> This reduce the switches guest <-> hypervisor and optimized a lot of >> functions. >> Virgl cards, like QXL or VirtIO cards are like that. Are much more efficient >> and allows lot of features provided by virtual environment (like suspend >> or migration). The "best" for Qemu and 3d is surely Virgl but as said there's >> no Windows drivers at the moment; >> 3) you pass a full physical card or part of it. This CAN'T be used by the >> host >> and reduce control not allowing (usually) suspend and migration; >> 3.1) basically an entire physical card is passed to the guest. If you have >> an additional >> GPU (graphical card) you can do it; >> 3.2) some cards allow to provide part of its functions to be assigned like >> if were a physical card. For GPU currently Qemu/KVM does not provide >> much. Work is going to support Intel solutions and Nvidia ones. >> Nvidia ones are usually quite expensive (cards do not fit in either laptops >> or even desktops) while Intel offers some really cheap solutions using a >> mix of hardware/software solution. >> >> Frediano >> >> >> Hi Christophe, >> >> Thanks a lot for your clarifications... can you help me with the other >> questions? >> >> Is there any way to check if is it using client GPU or host CPU? >> >> Is there any Grpahics card to be plugged in the host in order to use host >> GPU? >> >> thanks a lot. >> >> >> 2017-05-09 12:03 GMT+02:00 Christophe Fergeau <cferg...@redhat.com >> <mailto:cferg...@redhat.com>>: >> Hey, >> >> On Tue, May 09, 2017 at 10:42:31AM +0200, Oscar Segarra wrote: >> > Hi, >> > >> > What kind of drivers are required in windows? (I supose you mean Windows >> > guest). >> >> A video driver able to use virtio-gpu + virgl would be needed, but does >> not exist at the moment. This is one of the Google Summer of Code >> projects for this year though. >> >> Christophe >> >> >> >> >> _______________________________________________ >> Spice-devel mailing list >> Spice-devel@lists.freedesktop.org <mailto:Spice-devel@lists.freedesktop.org> >> https://lists.freedesktop.org/mailman/listinfo/spice-devel > > _______________________________________________ > Spice-devel mailing list > Spice-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/spice-devel
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