Re: help? need to enable VT-d for 2.6.27

David Ahern
2011-08-30T18:31:08Z

On 08/30/2011 12:11 PM, Chris Friesen wrote:
> On 08/30/2011 11:55 AM, David Ahern wrote:
>> On 08/30/2011 10:29 AM, Chris Friesen wrote:
>>>
>>> I'm in a bit of an odd situation. We run an embedded version of linux
>>> on many different boards with different vendor agreements so it's
>>> painful to upgrade kernel versions.
>>>
>>> I've been asked to provide VT-d support for KVM on our kernel (primarily
>>> for mapping NIC VFs into the guests), and I'm trying to figure out my
>>> best option to get a working implementation.
>>
>> I've had pains with VF passthrough with as late as a Fedora 14 kernel
>> (2.6.35). Ended up punting and moving to 2.6.39.
>
> Ouch. Not good news, but not entirely unexpected. Are you doing
> anything complicated, or was this just basic functionality that wasn't
> working?

In my case I am setting the MAC address for the VFs in the host at boot;
they are getting reset on passthrough so the VM driver creates a random
one. A backport of commit a6b5ea3 fixes one aspect. Looking at the code
for the igb driver I think commit 8fa7e0f fixes the other reset problem.

On the plus side I can tell you that the VF driver for the VM
http://sourceforge.net/projects/e1000/files/igbvf%20stable/

compiles cleaning against WRL3 and appears to work fine (limited testing
with benchmarks).

kernel module wise I ran some basic KVM tests with kvm-kmod-2.6.32.27; I
have not tried VF passthrough. This is on my radar as well, so I would
be interested in what you learn.

David

>
>>> Looking at the kvm git tree, kvm-77 seems to be based off 2.6.27. Should
>>> I look at porting that?
>>
>> By 2.6.27 do you mean WRL3 or something else?
>
> Yes, that's correct. (Wind River Linux 3, for the non-embedded types
> out there.)
>
> Chris
>