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

David Ahern
2011-08-30T19:54:41Z

On 08/30/2011 01:39 PM, Chris Friesen wrote:
> On 08/30/2011 12:31 PM, David Ahern wrote:
>
>> 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.
>
> I downloaded the latest kvm-kmod release. It looks interesting, but it
> has some issues:
>
> 1) I use separate source and build output directories. kvm-kmod assumes
> that there is a "source" link in my build output directory pointing back
> to the source directory. This doesn't exist, so the build breaks.
>
> 2) If I create such a link, it builds a few files, and then gives the
> following:
>
> /home/cfriesen/Download/kvm-kmod-3.0b/x86/x86.c: In function
> ‘vcpu_enter_guest’:
> /home/cfriesen/Download/kvm-kmod-3.0b/x86/x86.c:5539:26: error:
> ‘prof_on’ undeclared (first use in this function)
> /home/cfriesen/Download/kvm-kmod-3.0b/x86/x86.c:5539:26: note: each
> undeclared identifier is reported only once for each function it appears in
>
>
> This appears to be due to the fact that KVM_PROFILING is defined
> unconditionally in my kernel, but "prof_on" is only defined if
> CONFIG_PROFILING is enabled. Commenting out that chunk of code in x86.c
> lets everything build.

I was a bit nervous trying kmod's from that much ahead of 2.6.27; that's
why I picked the 2.6.32 train.

Also, the notes for adding the device assignment to Fedora 11 might come
in handy:
http://fedoraproject.org/wiki/Features/KVM_PCI_Device_Assignment

I have not walked through the bug references yet, but Fedora 11 is not
too far ahead of WRL3. When I backported perf to WRL3 I used Fedora 10
as a reference. For VT-d, Fedora 11 would be interesting to look at --
is the support complete in F-11 and if so take a look at its kernel source.

David

>
> I haven't tried actually loading it yet, that will be next.
>
> Thanks for the pointer.
> Chris
>
>