I guess you are going to become the hero of all the OPENSTEP veterans ;-) (I'm one of the impatient and would appreciate receiving your code).
In principal vmware is supposed to support frame buffer access, i.e. it runs without any additional vmware-graphics driver. I think it works at least for windows. I have not tried Openstep on vmware yet, but does it work seamlessly under VGA resolution? If so, I would rather have a closer look at your driver.
>From what I heard from the list vmware Inc. seems to be very cooperative (license donation). Perhaps the contacts used earlier could work again and some information of the exact way of "screen virtualization" by vmware could be acquired.
Personally I would hope for a direct access to the frame buffer in full screen mode (as I understand it both the virtualization and XFree could allow for direct access), but this is clearly beyond our control.
I do not understand how you would like to force flushing. If you remain in your virtualized machine, all you can do is modifying the frame buffer and hoping for the virtualizer to reflect your changes properly. If vmware doesn't this is clearly a vmware "bug". Otherwise you have to cooperate with the virtualizing application (i.e. vmware) itself to direct it to the rectangles to flush.
Best wishes,
Stefan
Frederic Stark wrote:
> Hi,
>
> I looked more closely to what happens, and things are not as simple as I
> described.
>
> The clock and the caret works perfectly (ie: they update in real time,
> without any phantom). But fast-moving the mouse or moving large chunk of
> graphics (ie: opening/moving/closing a window or scrolling) let large
> 'bands' of the diplay untouched.
>
> What I suspect is that vmware knows when the application touches the
> framebuffer and blit it to the real screen a few milliseconds later. But
> it looks like there is a race condition, and what is displayed during
> the blit is not displayed onscreen. So parts of large transfers are
> lost. I'll ask on the vmware newsgroups.
>
> The MD5 trick (well, with a easier to compute CRC) could work. I could
> take a look at what VNC does...
>
> Cheers,
>
> --fred
>
> Pascal Bourguignon wrote:
> >
> > Frederic Stark <fred@almonde.com> wrote:
> >
> >>Hi,
> >>
> >>Boring weekend. I took my OS42 CDs, vmware, the diff to the vmware
> >>module of XFree86, the drivers example from OS42, a dozen of cup of
> >>coffee and started to hack an OPENSTEP42 vmware SVGA driver.
> >>
> >>I am to the point where I get it running in 1024x768/24bits (yep, the
> >>values are hard-coded for now). Code is _very_ ugly, as this is my first
> >>OS42 driver (OS42 have no documentation on the DriverKit, and I can't
> >>get my hands back on my 3.3 CDs). I can probably get something more
> >>usable next week-end. I can release what I have for the impatient, of
> >>course.
> >>
> >>The problem is that the DPS server never tell my driver when screen have
> >>been written to, so vmware don't know when to update the real screen
> >>(ie: there are 'phantoms' left in a lot of places). I don't think the
> >>NeXT window server was ready to work with a 'buffered' device.
> >>
> >>Any idea about how I can solve that ? I can think about several solutions:
> >>
> >>1/ Don't care (by moving the vmware window, the 'phantoms' disapear
> >>because vmware flushes the screen)
> >>
> >>2/ Implement a /dev device and a user-land utility to tell the driver to
> >>flush the screen (every one second, for instance).
> >>
> >>3/ Get a PostSript master to try to hack WindowPackage.ps to know if the
> >>server did something. Alternatively, I could try to patch the
> >>WindowServer binary.
> >>
> >>4/ Play with mach memory to know if window server wrote to the
> >>framebuffer. Issue a flush to vmware 1/10th of a second later. It must
> >>be possible, but I have the slighest clue about how to do it.
> >>
> >>Any other trick ?
> >>
> >
> > The best solution would be something like 3/, to have a hook in the
> > low-level DPS raster routines. That would be in
> > /usr/lib/NextStep/WindowServer, but it's death-row software, not free
> > software.
> >
> > But it would be enough to have your driver flush automatically 10 or
> > 20 times a second. Since flushing to the screen could be costly, it
> > may be interesting to divide the frame buffer of your driver in tiles
> > and compute a md5sum over each tile, and flush only the tiles that
> > have changed.
> >
> > Since there are the blinking carets, the clock, the cursor, the screen
> > will need updating continuously, in small parts of it at least.
> >
> > The check sum computing frequency could be varied depending on whether
> > the tile or its neighbor changed recently or not.
> >