Re: sfc userland MCDI - request for guidance

Fri, Jan 15, 2016 at 06:34:04PM CET, ecree@solarflare.com wrote:

I have a design problem with a few possible solutions and I'd like some
guidance on which ones would be likely to be acceptable.

The sfc driver communicates with the hardware using a protocol called MCDI -
Management Controller to Driver Interface - and for various reasons
(ranging from test automation to configuration utilities) we would like to
be able to do this from userspace.  We currently have two ways of handling
this, neither of which is satisfactory.

It is wrong to send commands to HW directly to userspace. Please, do
proper in-kernel vendor neutral feature abstraction and the implement
in your driver. That is how things work. Userspace->HW bypass
is simply unacceptable.