[vbox-dev] D3D support in custom frontend

Klaus Espenlaub klaus.espenlaub at oracle.com
Tue Feb 10 17:01:04 GMT 2015

On 10.02.2015 15:33, Rūdolfs Bundulis wrote:
> Hi,
> I also wanted to ask are there any known release dates for the next 
> version where the GUI processes will be separated and won't face the 
> hardening issues?
We'll do the announcement when the code is out. If you look at previous 
releases it's reasonable to extrapolate that there will be a  
beta/release candidate quite a while before the next major version will 
be finalized.

Of course we can't stop you from trying out the latest code anyway...
> I've seen bugs regarding crashes with multiple CPUs (like 
> https://www.virtualbox.org/ticket/13319 ) being solved in 4.3.20 so I 
> wanted to know if a release of that codebase without the hardening is 
> planned in foreseeable future, that could also address the crashes I'm 
> having. Just a general inquiry.
I thought we answered this question many times already (not in this 
thread, but elsewhere). There will be no VirtualBox for Windows releases 
without the hardening. We were forced to do this by a security report 
(which does have a point), and as this security issue has not that much 
to do with VirtualBox we can't drop it. It's more an issue with Windows 
being inherently insecure and we're having to compensate for that by 
going extremely paranoid.

> Best Regards,
> Rudolfs Bundulis
> 2015-02-09 12:54 GMT+02:00 Rūdolfs Bundulis 
> <rudolfs.bundulis at gmail.com <mailto:rudolfs.bundulis at gmail.com>>:
>     Hi Klaus,
>     thanks for the response, yeah I suspected that the path was read
>     from somewhere, since running regsvr32 to unregister VBoxC.dll
>     from installation directory and then registering it from my path
>     didn't chagne anything, but I'm happy - it's not an issue to run
>     my binaries from the installation folder, the main thing is that
>     things seem to be working. Now the only thing I need is to see if
>     I can make OpenGL render to a custom FBO so I can live without the
>     window and access the OpenGL pixel data, but that is my issue, if
>     I come up with anything interesting maybe that can be use fro you
>     too. At least as far as I understand right now, due to the need of
>     a window on the host, VBoxHeadless.exe does not provide any 3D
>     acceleration support right?
>     Sorry to bother you so much, but the issue I'm more troubled by is
>     the crash I get - I've already described it before but I have made
>     little progress. Basically what happens is whenever I start my VM
>     with my custom frontend with more than 1 CPU it crashes on Windows
>     startup (longjmp_internal from Microsoft C runtime fails with
>     unaligned stack, the last stack entry I saw from VBoxREM.dll was
>     cpu_exit_loop or smth) - since VBoxREM.dll is built with MinGW
>     visual studio does not help a lot, and when running under debug
>     version under MinGW I also was unable to obtain any valuable info.
>     With 1 CPU it always works fine. I've tried CRT debug heap,
>     Application Verifier etc. to find potential issues with my code
>     (since the default Qt frontend does not crash with the same
>     configuration) I blame my part of the code, but still maybe there
>     are some peculiarities with the COM interface. Do you know any
>     bugs that have reported similar issues to what I'm seeing? Or
>     maybe you can give any pointers since currently I'm kind of stuck.
>     Again, great thanks for the support, my research would have hit
>     dead end without your help, yesterday I finally finished splitting
>     so thanks to VirtualBox I am able to run a single virtual
>     9600x5400 display on VirtualBox (what is weird, even with WDDM
>     drivers) and split/encode it to 25 displays, basically this cannot
>     be done with hardware (well in terms of a single homogeneous
>     display) so I'm very happy.
>     Best Regards,
>     Rudolfs Bundulis
>     2015-02-09 12:21 GMT+02:00 Klaus Espenlaub
>     <klaus.espenlaub at oracle.com <mailto:klaus.espenlaub at oracle.com>>:
>         Rūdolfs,
>         On 09.02.2015 10:28, Rūdolfs Bundulis wrote:
>>         Hi,
>>         yeah it turned out that when running from the VirtualBox
>>         installation path 3D support works for my frontend, seems
>>         that it comes from the fact that the COM API is using the
>>         dll's  from the installation folder. I'm just gonna leave
>>         this information here in case anyone else stumbles on the
>>         same issue.
>         VBoxC.dll contains "in-process" COM components (which live in
>         the "API client" process), and the path to it is kept in the
>         registry. Normal COM stuff.
>>         2015-02-07 18:37 GMT+02:00 Rūdolfs Bundulis
>>         <rudolfs.bundulis at gmail.com <mailto:rudolfs.bundulis at gmail.com>>:
>>             Hi,
>>             again thanks for all the previous help, I managed to
>>             build VBox with the LogRel() but when I copied the dll's
>>             over the installation i got a ton of errors about invalid
>>             image hashes (I guess that just copying over is not the
>>             way to go). Anyhow, I came up with a different approach
>>             and made a small frontend that would basically do the
>>             same stuff as my app but also draw the output to a
>>             window. When I launch the application from the VirtualBox
>>             installation folder everything works fine - 3D support
>>             works, when I take the app and all the virtualbox
>>             binaries and put them in a random folder, it again stops
>>             working. And what is interresting that using Process
>>             Explorer I was able to see that actually two copies of
>>             VBoxC.dll are loaded (one from the installation folder
>>             and one from my folder) and one VBoxRT.dll (only from the
>>             VirtualBox installation folder). I assume the ones from
>>             the installation folder are loaded by the COM object? Is
>>             this a very very bad practice to try and deploy the
>>             VirtualBox binaries outside the installation path?
>         The invalid image hashes most likely mean that VirtualBox
>         isn't accepting the signature in your binaries. It only
>         accepts the "one signer" of everything, so if you mix Oracle
>         and your own build then it won't work very well.
>         Deploying VirtualBox binaries outside the installation path
>         isn't exactly forbidden, but we don't test it right now. This
>         will stay for a while, we have still way too much noise on the
>         hardening related tickets.
>         Klaus
>>             2015-01-26 15:25 GMT+02:00 Rūdolfs Bundulis
>>             <rudolfs.bundulis at gmail.com
>>             <mailto:rudolfs.bundulis at gmail.com>>:
>>                 Hi Vitali,
>>                 this was what I was looking for, much appreciated :)
>>                 Best Regards,
>>                 Rudolfs Bundulis
>>                 2015-01-26 14:59 GMT+02:00 Vadim Galitsyn
>>                 <vadim.galitsyn at oracle.com
>>                 <mailto:vadim.galitsyn at oracle.com>>:
>>                     Hi Rudolfs,
>>                     you could add LogRel() messages and they should
>>                     appear in release log (VBox.log file) once VBox
>>                     has been built w/ corresponding flag. Note, that
>>                     this only works for guest R0 code (miniport).
>>                     Adding LogRel() to R3 code (display driver) will
>>                     not result in extra messages in log.
>>                     Please consider to add VBOX_WITH_R0_LOGGING=1
>>                     into LocalConfig.kmk in order to enable LogRel()’s.
>>                     Vadim
>>>                     On 26 Jan 2015, at 15:26, Rūdolfs Bundulis
>>>                     <rudolfs.bundulis at gmail.com
>>>                     <mailto:rudolfs.bundulis at gmail.com>> wrote:
>>>                     Hi Vadim,
>>>                     ok clear, thanks for the info. We'll so far I
>>>                     haven't patched anything in the VBox code
>>>                     itself, as I said I have a custom frontend. Does
>>>                     that code help you in any way? I'll make a debug
>>>                     build and look for more messages and mail back
>>>                     if it gives any additional info, thanks for all
>>>                     the help so far. The main thing I wanted to
>>>                     understand was is there any way to see the
>>>                     output from the WARN macros in the miniport
>>>                     driver, and as far as I understand there is none.
>>>                     Best Regards,
>>>                     Rudolfs Bundulis
>>>                     2015-01-26 13:42 GMT+02:00 Vadim Galitsyn
>>>                     <vadim.galitsyn at oracle.com
>>>                     <mailto:vadim.galitsyn at oracle.com>>:
>>>                         Hi Rudolfs,
>>>                         Debug build of VBox itself would probably
>>>                         add a bit more messages to VBox.log (and to
>>>                         debug log as well), but this definitely will
>>>                         not prevent the fact that debug version of
>>>                         GAs cause BSOD. Is it possible if you share
>>>                         a patch to OSE tree with your changes, so I
>>>                         could take a look at it later this week (or
>>>                         another)?
>>>                         Vadim
>>>>                         On 26 Jan 2015, at 14:00, Rūdolfs Bundulis
>>>>                         <rudolfs.bundulis at gmail.com
>>>>                         <mailto:rudolfs.bundulis at gmail.com>> wrote:
>>>>                         Hi Vadim,
>>>>                         Well since I also came to the the
>>>>                         conclusion that the WinId could cause this,
>>>>                         I tried making a dummy window for each of
>>>>                         the IFramebuffer instances, but nothing
>>>>                         changed. Though the windows do not have any
>>>>                         logic in the message loop, and I do not
>>>>                         resize them when the resolutions change -
>>>>                         maybe this causes some errors. That is why
>>>>                         I asked if any logs from the miniport
>>>>                         driver is available to see where does it
>>>>                         actually crash. If I make a debug
>>>>                         VirtualBox build then would debug GAs work?
>>>>                         Best Regards,
>>>>                         Rudolfs Bundulis
>>>>                         2015-01-26 12:50 GMT+02:00 Vadim Galitsyn
>>>>                         <vadim.galitsyn at oracle.com
>>>>                         <mailto:vadim.galitsyn at oracle.com>>:
>>>>                             Hi Rudolfs,
>>>>                             As far as I can understand, returning
>>>>                             NULL WinID might cause the behaviour
>>>>                             you are observing on Windows host
>>>>                             (please note, I have not tried that
>>>>                             locally, take it like a gesture).
>>>>                             Seems, you also already have 3D host
>>>>                             service running. Can you try to provide
>>>>                             valid WinID to Main/src-client stuff as
>>>>                             an experiment and see if things changed?
>>>>                             Regarding to GAs, I am afraid you’ll
>>>>                             have a BSOD in guest once you attempt
>>>>                             to boot VM with debug GAs installed. We
>>>>                             currently have some debug R0 assertion
>>>>                             there.
>>>>                             Vadim
>>>>>                             On 26 Jan 2015, at 13:12, Rūdolfs
>>>>>                             Bundulis <rudolfs.bundulis at gmail.com
>>>>>                             <mailto:rudolfs.bundulis at gmail.com>>
>>>>>                             wrote:
>>>>>                             Hi Vadim,
>>>>>                             thanks for the pointers, I'll look up
>>>>>                             the code, I was already afraid that
>>>>>                             something is simply missing.
>>>>>                             To describe what I am doing:
>>>>>                             I am running a research project in
>>>>>                             University of Latvia where we are
>>>>>                             trying to use VirtualBox for large
>>>>>                             scale high resolution display wall
>>>>>                             construction - basically we run
>>>>>                             VirtualBox with a custom frontend that
>>>>>                             takes the video data from the VRAM,
>>>>>                             encodes it and streams over to a
>>>>>                             display wall, currently we've been
>>>>>                             able to run a 9600x5400 surface with
>>>>>                             Windows XPDM (we set this resolution
>>>>>                             as a hint and then internally split it
>>>>>                             to  5*5 1920x1080 displays) , which is
>>>>>                             really impressive, so thanks again for
>>>>>                             the great software. In terms of
>>>>>                             resolution I guess this is as far as
>>>>>                             the existing 256MB VRAM limit in
>>>>>                             VirtualBox can go (at least according
>>>>>                             to the calculations for framebuffer
>>>>>                             needs provided by Klaus Erspenlaub and
>>>>>                             mentioned in your code). Since the
>>>>>                             resolution limit is reached we are
>>>>>                             trying to address two more issues - 3D
>>>>>                             support and a weird unaligned stack
>>>>>                             crash in VBoxREM.dll with more than 1
>>>>>                             CPU shared to the machine (for the
>>>>>                             second issue I need to do some more
>>>>>                             research as to where it is coming from
>>>>>                             before I ask any help here). As for
>>>>>                             the 3D - we'd basically want our
>>>>>                             software to function in the same way
>>>>>                             the VirtualBox QT client does, but
>>>>>                             currently it does not. Thanks for the
>>>>>                             pointer about the HGCM/OpenGL service,
>>>>>                             I'll check out that code and see what
>>>>>                             I can adapt.
>>>>>                             Our software basically uses the
>>>>>                             VirtualBox COM interface to create the
>>>>>                             needed machine, set the number of
>>>>>                             displays/resolutions, injects the
>>>>>                             IFramebuffer instances and powers up
>>>>>                             the machine via the IConsole
>>>>>                             interface. So I examined all the
>>>>>                             IFramebuffer implementations in
>>>>>                             VirtualBox frontends, and didn't see
>>>>>                             anything very special in the 3D
>>>>>                             related callbacks there. As for the
>>>>>                             log - I tried to compare the log of a
>>>>>                             session from our software with a
>>>>>                             session from the same machine under QT
>>>>>                             fronted where the 3D acceleration
>>>>>                             works. Basically there were no errors
>>>>>                             and differences, in both cases the
>>>>>                             logs contained the lines about OpenGL
>>>>>                             support (i guess this comes from the
>>>>>                             OpenGL capability test exe), I'll send
>>>>>                             both logs as soon as I get back to
>>>>>                             that machine but I doubt they'll give
>>>>>                             much help, since they don't have any
>>>>>                             errors, and in both of them the guest
>>>>>                             additions log line states that
>>>>>                             acceleration is supported. Basically
>>>>>                             the only thing that differs is that
>>>>>                             the D3D/OpenGL (we've tried both
>>>>>                             API's, since the test application is
>>>>>                             built on Unity it is trivial to force
>>>>>                             either mode) device creation fails on
>>>>>                             our frontend. That is why I asked
>>>>>                             about the get_WinId, I examined the
>>>>>                             miniport driver code and as far as I
>>>>>                             understood it uses the window id value
>>>>>                             to create a swap chain. Out frontend
>>>>>                             does not have an actual window, so I
>>>>>                             am always returning NULL, can this
>>>>>                             cause an error? I also saw that the
>>>>>                             miniport driver has a lot of WARN
>>>>>                             macros, is  the output visible
>>>>>                             anywhere? I tried using DebugView but
>>>>>                             that didn't help? Should I try
>>>>>                             building a debug version of guest
>>>>>                             additions to get some log information?
>>>>>                             Best Regards,
>>>>>                             Rudolfs Bundulis
>>>>>                             2015-01-26 10:34 GMT+02:00 Vadim
>>>>>                             Galitsyn <vadim.galitsyn at oracle.com
>>>>>                             <mailto:vadim.galitsyn at oracle.com>>:
>>>>>                                 Hi Rudolfs,
>>>>>                                 In order to provide 3D
>>>>>                                 acceleration, VBox HGCM/OpenGL
>>>>>                                 host service should be running. It
>>>>>                                 is currently a part of
>>>>>                                 VirtualBoxVM process (ShCrOpenGL
>>>>>                                 thread). In order to provide 3D
>>>>>                                 acceleration support for your
>>>>>                                 frontend, I am afraid, you need to
>>>>>                                 adapt stuff from this thread for
>>>>>                                 your code. And I am afraid this
>>>>>                                 might be not that easy (there is a
>>>>>                                 bit of magic when VBox GUI
>>>>>                                 conversates w/ 3D stuff). Please
>>>>>                                 refer to
>>>>>                                 src/VBox/HostServices/SharedOpenGL
>>>>>                                 and src/VBox/GuestHost/OpenGL sources.
>>>>>                                 Btw, if you describe a little bit
>>>>>                                 more why do you need this and what
>>>>>                                 you already have done, maybe I
>>>>>                                 could explain you more
>>>>>                                 things/steps you need to do in
>>>>>                                 order to reach the goal. VBox.log
>>>>>                                 also might be helpful.
>>>>>                                 Vadim
>>>>>                                 > On 24 Jan 2015, at 14:14,
>>>>>                                 Rūdolfs Bundulis
>>>>>                                 <rudolfs.bundulis at gmail.com
>>>>>                                 <mailto:rudolfs.bundulis at gmail.com>>
>>>>>                                 wrote:
>>>>>                                 >
>>>>>                                 > Hi,
>>>>>                                 >
>>>>>                                 > I'm having a bit of a hard time
>>>>>                                 understanding why my custom
>>>>>                                 framebuffer cannot use the 3D
>>>>>                                 acceleration feature. I have a
>>>>>                                 Windows 7 guest machine (3D
>>>>>                                 acceleration enabled, guest
>>>>>                                 additions installed) and a Unity
>>>>>                                 demo application. Under the
>>>>>                                 default QT GUI the application
>>>>>                                 launches fine, while under my
>>>>>                                 frontend Unity is not able to
>>>>>                                 create the D3D device. First I
>>>>>                                 though that this could be due to
>>>>>                                 incorrect implementation of
>>>>>                                 IFramebuffer, but when I looked at
>>>>>                                 UIFrameBuffer::Notify3DEvent(ULONG
>>>>>                                 uType, BYTE *pData) in
>>>>>                                 UIFrameBuffer.cpp there wasn't any
>>>>>                                 special magic there. Are there any
>>>>>                                 hints to guide me towards
>>>>>                                 understanding the cause of this?
>>>>>                                 Is there any tracing facilities
>>>>>                                 for the guest miniport driver?
>>>>>                                 Also, I don't have a window handle
>>>>>                                 for my frontend since there is no
>>>>>                                 actual window. If I am returning 0
>>>>>                                 in get_WinId in my framebuffer can
>>>>>                                 that mess things up?
>>>>>                                 >
>>>>>                                 > Best Regards,
>>>>>                                 > Rudolfs Bundulis
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