[dpdk-dev] Having troubles binding an SR-IOV VF to uio_pci_generic on Amazon instance

[Avi Kivity]

On 10/01/2015 12:42 PM, Vincent JARDIN wrote:
> On 01/10/2015 11:22, Avi Kivity wrote:
>>> As far as I could see, without this kind of motivation, people do not
>>> even want to try.
>>
>> You are mistaken.  The problem is a lot harder than you think.
>>
>> People didn't go and write userspace drivers because they were lazy.
>> They wrote them because there was no other way.
>
> I disagree, it is possible to write a 'partial' userspace driver.
>
> Here it is an example:
>   http://dpdk.org/browse/dpdk/tree/drivers/net/mlx4
>
> It benefits of the kernel's capabilities while the userland manages 
> only the IOs.
>

That is because the device itself contains an iommu.

> There were some tentative to get it for other (older) drivers, named 
> 'bifurcated drivers', but it is stalled.

IIRC they still exposed the ring to userspace.