I was not able to find any documentation on a VNC loadable module anywhere. Is there a place where one can find out about this?
On Thu, May 26, 2011 at 7:34 AM, Pat Kane <pekan...@gmail.com> wrote: > I like VNC and have built both loadable module and DDX version. > > The main problem with the DDX version is that since VNC > has a GPL license I can not merge the code into my Xorg > source tree. > > Pat > --- > > > On Wed, May 25, 2011 at 6:07 PM, David Jackson <djackson...@gmail.com> > wrote: > > > > > > On Wed, May 25, 2011 at 4:36 PM, Glynn Clements < > gl...@gclements.plus.com> > > wrote: > >> > >> David Jackson wrote: > >> > >> > A display driver that contains a VNC server. The problem with x11vnc > is > >> > that > >> > it is slow, very slow. XVnc server, which is a X server that contains > a > >> > VNC > >> > server but has no hardware drivers, is much faster since the VNC > server > >> > is > >> > built directly into the X server, > >> > >> What sample size does your analysis use? How many different hardware > >> configurations, and how many different applications? > >> > >> x11vnc has the drawback that it's reading a framebuffer which is > >> typically in video memory, so the data has to be read over the bus. > >> The speed of this operation may vary significantly depending upon the > >> hardware being used. It may also vary depending upon the amount of > >> activity (i.e. if it has to wait for the outstanding rendering > >> operations to complete before it's allowed to read the framebuffer). > >> > >> Xvnc has the advantage that the framebuffer is in system memory. But > >> this is also a drawback, as it means that all rendering is performed > >> in software. Try running an application which uses OpenGL to render > >> detailed scenes; you might want to reconsider your assertion about > >> Xvnc is fast. > >> > >> IOW, it's a case of "choose your poison". x11vnc has fast rendering > >> but slow export, Xvnc has slow rendering but fast export. A similar > >> tradeoff exists for X11 verus VNC for remote display. > >> > >> > however this does not allow one to export > >> > their main X display which is also displayed directly to video > hardware. > >> > The > >> > solution here is to include a driver in the X.org main server > >> > distribution > >> > for a VNC server that can be loaded into the X server. The VNC server > >> > driver > >> > should be able to be dynamically loaded while the server is running > and > >> > the > >> > output of the server displayed simultaneously to VNC clients and to > the > >> > local video hardware. This can be controlled from provided command > line > >> > and > >> > GUI utilities. > >> > >> Does the VNC driver read the framebuffer on the video card (which > >> suffers from the same performance issues as x11vnc), or does it > >> attempt to duplicate the framebuffer by emulating whatever video > >> hardware is installed? If it's the latter, the application will be > >> slowed to the speed of the VNC driver's software renderer (which will > >> be extremely complex, as it will have to mimic every feature which is > >> available in at least one hardware driver). > >> > >> > One of the very severe problems I have been having is that Xvnc does > not > >> > support Render extensions, and many applications no longer work > without > >> > the > >> > Render extension. VNC driver with X.org therefore must support the > >> > Render > >> > extension and other ones. > >> > >> The main "other one" being OpenGL, for which a software implementation > >> will be much, much slower than a modern GPU. > >> > >> > Dynamic runtime enabling and disabling, configuration and setup and > >> > removal > >> > of display output and input drivers while the server runs without > server > >> > restart. this allows for instance, the user to have the X server > display > >> > to > >> > a new target while the server runs, or display to many different > display > >> > outputs at the same time This includes the VNC Server driver above, > this > >> > allows a person to easily swtich the VNC on and off from displaying to > >> > certain outputs, such as they could turn off display to the local > >> > monitor > >> > and then turn it back on again, or turn on and off VNC display. > >> > > >> > Another feature that increases flexibility to the user would be to > allow > >> > the > >> > user to direct display of a certain window or the entire root window > and > >> > display over an X client connection to another server, or any number > of > >> > other servers. This would also forward the windows children who would > >> > also > >> > be displayed on the remote server inside the parent window. > >> > >> To do this at the protocol level requires a completely new protocol > >> and significant support from the toolkit. The X protocol exposes a > >> significant amount of implementation detail to the client. Much of > >> that information is required to remain constant for the lifetime of > >> the client. > >> > >> E.g. if the client queries the list of OpenGL extensions, and starts > >> using some of them, there's no mechanism by which to inform the client > >> that an extension is suddenly unavailable, which would be required if > >> you were to "redirect" the window to a different server with different > >> hardware. > >> > >> Even if such a mechanism existed, it's debatable how many applications > >> would support it. Reconstructing the current server-side state from > >> scratch is a lot of work, and toolkits can't always help (e.g. they > >> won't help reconstruct the server-side OpenGL state, as the toolkit > >> doesn't get involved in the rendering process). > >> > >> > Many users, including myself, want to have many X servers running at > the > >> > same time and then at run time be able to change to where these > servers > >> > are > >> > being displayed, and as well when an app is started, to which server > it > >> > is > >> > displayed with the -display option. > >> > >> AFAICT, there are only two feasible approaches to window "mobility": > >> > >> 1. VNC-like framebuffer sharing. The application connects to a > >> specific X server which performs all rendering. You have the option to > >> forward rendered images to other systems for physical display. > >> > >> 2. Use GUI toolkits which offer an abstract, high-level interface to > >> the client. The toolkit has the ability reconstruct and clone windows > >> at will. > >> > >> -- > >> Glynn Clements <gl...@gclements.plus.com> > >> _______________________________________________ > >> xorg@lists.freedesktop.org: X.Org support > >> Archives: http://lists.freedesktop.org/archives/xorg > >> Info: http://lists.freedesktop.org/mailman/listinfo/xorg > >> Your subscription address: djackson...@gmail.com > > > > > > x11vnc is noticeably slower. I think the really annoying thing that makes > it > > hard to use is that there is a longer delay when typing for characters to > > display on the screen than there is with Xvnc. I can notice this. When > you > > are typing characters do display much more quickly to the screen on Xvnc. > > That is a big issue, because, it is really hard to type when you have a > long > > delay of characters appearing when you type them.Perhaps this is due the > > polling of the framebuffer. > > > > The VNC driver could do its own rendering, get the graphics commands > from > > the application directly. Yes, you are correct that is slow for many > complex > > operations. You are correct, the other alternative is to grab the > > framebuffer. You are correct it might be faster for those complex > graphics. > > Grabbing the framebuffer inside the X server and feeding it out to VNC > > clients via a VNC server in the X server, might save a little bit of time > by > > avoiding having to be sent over a socket to another process, but i do not > > know if that is true. It may be it might do all that being interrupted > fewer > > or no times, where with x11vnc you are gauranteed a task switch and some > > time for x11vnc to get the CPU. I guess x11vnc asks for the framebuffer > over > > an X connection, then wait for the X server to get the CPU to process the > > request, then wait again for x11vnc to get CPU and the data to be sent to > > VNC clients. if we have a framebuffer based VNC driver inside the X > server, > > it may allow for tighter synchronisation and less delay. I cannot say how > > significant it would be. > > > > The other issue mentioned, about the window forward feature. You are > > correct. I have been thinking about these issues. It would be best for it > to > > be invisible to clients. Ive been thinking about these problems. > > > > I am know C, however I know little about X internals or X protocol. Is > there > > a good source of documentation that would give a person a full > introduction > > and overview of how the X server works,including how it all fits > together, > > and a tour of the system and documentation of the internals such as > > functions, variables etc? Basically everything need for a person who only > > knows C to learn all about how the X server works? > > > > > > > > _______________________________________________ > > xorg@lists.freedesktop.org: X.Org support > > Archives: http://lists.freedesktop.org/archives/xorg > > Info: http://lists.freedesktop.org/mailman/listinfo/xorg > > Your subscription address: pekan...@gmail.com > > >
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