Intel GPU with KMS locks up when visualization enabled

[Kevin Oberman]

On Mon, Jul 16, 2012 at 7:04 AM, Konstantin Belousov
<kostikbel at gmail.com> wrote:
> On Sun, Jul 15, 2012 at 04:09:18PM -0700, Kevin Oberman wrote:
>> I don't have much information on this, but I wanted to enable VY-x on
>> my Lenovo T520 (Sandybridge). IT has been running for a few months
>> with the Intel GPU patches and now WITH_NEW_XORG and WITH_KMS. The
>> current system is 9.1-BETA1 installed yesterday.
>>
>> If I enable "Virtualization" in BIOS, the system boots and runs fine,
>> but if I start Xorg and Gnome, I get several windows including
>> terminal windows and gkrellm up, but after a few seconds, the display
>> freezes. The only thing I have been able to do is to power it down. I
>> then disabled "Virtualization again, and all is well.
>>
>> Any idea on what other information I can dig up? It's not critical as
>> I only use VirtualBox to boot Windows 7 when I need Visio or something
>> else that is only available on Windows.(No, no serial console. Darn!)
>
> SandyBridges has several absolutely show-stopper erratas for interoperation
> of VT-d engine and GPU. Linux disables several features, including RC6
> and fake PPGT, when it detects that VT-d is active for GPU PCI device.
> And even then, it seems to still exhibit problems, last time I watched.
>
> Since FreeBSD has no VT-d driver, we cannot know the state of VT-d. Just
> disable it if you want to use GPU.

Thanks, Konstantin. Unfortunately, VT-x is required to allow a
VirtualBox VM to use more than one CPU, so I guess I'll just have to
live with a single CPU.

By the way, I see this when I enable "Virtualization" on the system
even though VT-d is disabled. I'll admit I don't know exactly what
the BIOS "Virtualization" actually enables, but it is a separate
option from VT-d.
-- 
R. Kevin Oberman, Network Engineer
E-mail: kob6558 at gmail.com