Re: Status of FLR in Xen 4.4

[David Vrabel <david.vrabel@citrix.com>]

On 26/09/13 18:48, Ross Philipson wrote:
> On 09/26/2013 12:20 PM, David Vrabel wrote:
>> On 26/09/13 17:05, Matthias wrote:
>>> Hi everyone,
>>>
>>> I would like to ask what the current status of FLR, or better of FLR
>>> emulation is in latest Xen and if we can expect better support in the
>>> future.
>>
>> What are these cards, are they multi-function and do they actually
>> support FLR?  Many graphics cards do not.
>>
>> I have the following hack to pciback to fallback to a bus reset for
>> multi-function devices without FLR.  Does it help for your use case?
>> You will need to ensure that all functions are co-assigned to the same
>> domain.
> 
> New kernels (e.g. 3.8) have full support for PCI-e and PCI AF FLRs as
> well as fallback support for D0-D3 and secondary bus resets. This
> functionality is also in the some of the last 2.6 kernels like 2.6.39.
> If you are using an older kernel I guess you might need to patch it.

It will only do a secondary bus reset iff the function to be reset is
the only function on that bus.  If you have a multi-function device
secondary bus reset is not tried.

David