[systemd-devel] how to bind to other drivers using systemd

[Kay Sievers]

On Mon, Sep 28, 2015 at 8:48 PM, Flavio Leitner <fbl at sysclose.org> wrote:
> On Mon, Sep 28, 2015 at 08:06:50PM +0200, Kay Sievers wrote:
>> On Sun, Sep 27, 2015 at 11:37 PM, Flavio Leitner <fbl at sysclose.org> wrote:
>> > I am looking for guidance on how to properly resolve driver binding
>> > with systemd (which seems to me the best place to do that).
>>
>> This seems to be a too exotic and niche use case, nothing
>> general-purpose enough to implement high-level knobs in systemd.
>
> These alternative drivers might be new yet, so there is no much around
> them, but we need to start right to avoid problems in the future.
>
> Accelerated userspace datapath is one use case that changes the default
> NIC driver to UIO or VFIO driver. Then you use DPDK applications for
> fast packet processing or use DPDK integrated Open vSwitch for switching.
>
> Consider that Open Stack (WIP), Open Shift and maybe containers can use
> the above setup, so isn't really a niche use case.  It's pretty much a
> requirement for NFV projects as well.
>
>> As you mention, you could use custom udev rules to actually bind a
>> specific driver. I don't think we want anything more abstract in
>> systemd.
>
> The problem with that is we can't stop the service to roll back the
> driver.  Or more importantly, create a dependency to, let's say,
> start Open vSwitch only after the ports are bound to the right driver.
> Or start an application that requires the NIC to be bound first.

Sure, I understand all that. I would still call all that a niche and I
still don't think it's systemd's job to solve such a problem.

Kay