Re: [gentoo-user] Re: about boot with framebuffer

[Joshua Murphy]

On Mon, Jul 4, 2011 at 7:45 PM, Mark Knecht <markknecht@×××××.com> wrote:
> On Mon, Jul 4, 2011 at 2:34 PM, Alan McKinnon <alan.mckinnon@×××××.com> wrote:
>> On Monday 04 July 2011 14:15:12 Mark Knecht did opine thusly:
> <SNIP>
>>> I'm curious, however, about my Gentoo VMs. Can KMS run on a VM's
>>> kernel and do anything useful there? This is more for learning and
>>> not about any practical need at this time.
>>
>> From my understanding, this topic gets yucky. There's a whole bunch of
>> ways this could be done, from software emulation to para-
>> virtualization to full virtualization. Emulation is easy - KMS in the
>> guest sees what looks for all the world like hardware so everything
>> works if KMS supports the emulated card (albeit slowly). For
>> everything else, you'd need kernel drivers intercepting efforts to
>> talk to the hardware and be traffic cop. My brain is already spinning
>> on this so please excuse me while I go dunk my head in a bucket and
>> not think about it anymore :-)
>>
>
> So I'm wondering if the Virtualbox graphics driver
> (xf86-video-virtualbox) is a framebuffer local to the VM or something
> else?
>
> My NVidia GFX465 running the NVidia driver does about 11,000 FPS in
> glxgears in Linux. glxgears running in the VM does about 130FPS, or
> around 1% of the performance outside. Yes, it's 'slow', depending on
> how we define slow. It's faster then machine I ran native in Linux 5
> years ago, and it's very usable for things like browsers, etc.
>
> I don't know what tool to use to measure graphics performance on
> Windows but my Windows XP VM is more than fast enough to watch Netflix
> full screen at 1920x1080 without any major amount of tearing, so
> Virtualbox graphics performance there is fine.
>
> Anyway, just data.
>
> Thanks,
> Mark
>
>

GLX is also doing OpenGL 3D rendering which, outside the VM is
hardware accelerated while inside of it the driver has no true,
direct, access to hardware, though if you're one of the very lucky,
there's a chance of halfway workable pass-through via the guest
additions and such, but even that's slow (and I'm not certain it's
available to a *nix guest).

-- 
Poison [BLX]
Joshua M. Murphy