Re: opengl=1?

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

Jun Koi wrote:

> On Thu, Dec 11, 2008 at 7:33 PM, Stefano Stabellini
> <stefano.stabellini@eu.citrix.com> wrote:
>> Jun Koi wrote:
>>
>>> Hi,
>>>
>>> I found that we have an option named opengl. What is that for? So if I
>>> put "opengl=1" in my VM configuration file, what advantage my VM will
>>> get??
>>>
>> opengl=1 is the default and makes qemu render the guest framebuffer
>> using opengl.
> 
> OK, so the patch you posted on QEMU mailing list is to enable this
> function on QEMU.

Yes.

>> Otherwise if you set opengl=0 qemu will use the sdl library.
>> opengl=1 makes sense if you don't use vnc
> 
> So this means "opengl=1" (default) and "vnc=0" will give a better
> performance than "vnc=1, sdl=0", right?


Just to be clear opengl is used only together with sdl: sdl is still
needed to create the window.
So the three possibilities are:

/* window on the host screen, opengl acceleration */
sdl=1 opengl=1 vnc=0

/* window on the host screen, no opengl acceleration */
sdl=1 opengl=0 vnc=0

/* no window on the host screen just a vnc server */
sdl=0 (opengl does not matter) vnc=0

 
>> and you have good drivers for
>> your graphic card in dom0.
> 
> I am using Ubuntu 8.10 with chipset Intel 945GM, so certainly I have
> "good driver", right?
> 

If you are using the intel driver (intel, i815, i915, etc.) in xorg,
yes; if you are using the vesa driver, no.

If you are using opengl=1 and the vesa driver in xorg, you'll notice
because it is really slow.