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RE: [Xen-devel] X11_EnterFullScreen fails

  • To: "Jayant Mangalampalli" <Jayant_Mangalampalli@xxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
  • From: "Petersson, Mats" <Mats.Petersson@xxxxxxx>
  • Date: Wed, 30 May 2007 18:30:44 +0200
  • Delivery-date: Wed, 30 May 2007 09:34:05 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: Acei1Ejo3kWpdZgZRYGKOjnVMDGDTQAAEgKQAAAbokAAAG0yQAAAETcQ
  • Thread-topic: [Xen-devel] X11_EnterFullScreen fails

> -----Original Message-----
> From: Jayant Mangalampalli [mailto:Jayant_Mangalampalli@xxxxxxxxxxx] 
> Sent: 30 May 2007 17:23
> To: Petersson, Mats; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xen-devel] X11_EnterFullScreen fails
> If this is the case, though, why does only full-screen mode fail? Why
> not the normal non-full-screen mode?
> -----Original Message-----
> From: Jayant Mangalampalli 
> Sent: Wednesday, May 30, 2007 9:51 PM
> To: 'Petersson, Mats'; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xen-devel] X11_EnterFullScreen fails
> Highly likely. Unfortunately we cannot salvage any data during crash.
> But I think this is a great pointer, especially since I am also facing
> problems trying to get TinyX to start in the graphics mode - but the
> vesafb driver tries to access the BIOS and it fails for 
> exactly the same
> reason (it is in protected mode by that time). The result is, however,
> not a crash but a flimsy looking "text mode" like screen.

Well, I don't really know the answer. But I used to work on Windows
graphics drivers, and I know that sometimes switching the display mode
will incur a BIOS call (I never quite understood when this was and when
it wouldn't happen - I think it depends on several things, including the
driver-code itself which may support some modes and say "I don't care
about supporting this mode" - at which point the OS would call the
BIOS[1] code to attempt it that way). Non-full-screen mode doesn't
require BIOS calls, for the obvious reason that the graphics mode isn't
being changed then - full-screen mode may well switch from the current
display mode to a different display-mode even if it's the same
resolution, e.g. 16bits per pixel or 8 bits per pixel, just as an

Also, is the SDL screen in text or graphical mode when you switch to
full-screen? If it's in text-mode, then it's 99% sure that the BIOS is

I'm not saying this IS what happens, just that it's something to

You may be able to capture more of the trace-back if you use serial
console either from Linux or the hypervisor, and if it's hypervisor that
crashes [and you don't use serial console] you may get more info by
"noreboot" on the "xen" line in your grub.conf (or similar). 

[1] BIOS = VGA-BIOS, not the "start my PC BIOS". 


> Thanks
> Jayant  
> -----Original Message-----
> From: Petersson, Mats [mailto:Mats.Petersson@xxxxxxx] 
> Sent: Wednesday, May 30, 2007 9:38 PM
> To: Jayant Mangalampalli; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xen-devel] X11_EnterFullScreen fails
> > -----Original Message-----
> > From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> > [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> > Jayant Mangalampalli
> > Sent: 30 May 2007 17:05
> > To: xen-devel@xxxxxxxxxxxxxxxxxxx
> > Subject: [Xen-devel] X11_EnterFullScreen fails
> > 
> > I am trying to set the guest window to full-screen mode but 
> > the domain consistently crashes when I try to do that. The 
> > problem could be traced to a point where X11-driver used by 
> > SDL itself fails. Here is the call trace before system 
> > crashes (most recent call last):
> > 
> > SDL_video.c::SDL_SetVideoMode() makes a call to 
> > video->SetVideoMode(). (We use X11 video driver)
> > 
> > video->SetVideoMode() = SDL_x11video.c::X11_SetVideoMode()
> > 
> > The above makes a call to SDL_x11video.c::X11_ResizeWindow() 
> > which makes a call to X11_EnterFullScreen() (in SDL_x11modes.c)
> > 
> > X11 does support full-screen mode and I am unable to 
> > understand why it is initiated by xen. Has anyone tried this?
> What's the crash symptoms? Is it possible that the X11 driver 
> is calling
> the BIOS, and that this fails in Xen due to restrictions on running
> real-mode, which doesn't happen in native mode?
> --
> Mats
> > 
> > Thanks,
> > 
> > Jayant Mangalampalli
> > 
> > 

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