netdev - Re: [PATCH v2 00/17] octeontx2-af: NPC parser and NIX blocks initialization

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Date:   Fri, 26 Oct 2018 22:03:18 +0530
From:   Sunil Kovvuri <sunil.kovvuri@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Linux Netdev List <netdev@...r.kernel.org>,
        linux-soc@...r.kernel.org, Sunil Goutham <sgoutham@...vell.com>
Subject: Re: [PATCH v2 00/17] octeontx2-af: NPC parser and NIX blocks initialization

On Fri, Oct 26, 2018 at 9:56 PM Sunil Kovvuri <sunil.kovvuri@...il.com> wrote:
>
> On Fri, Oct 26, 2018 at 7:34 PM Arnd Bergmann <arnd@...db.de> wrote:
> >
> > On 10/26/18, Sunil Kovvuri <sunil.kovvuri@...il.com> wrote:
> > > On Fri, Oct 26, 2018 at 6:24 PM Arnd Bergmann <arnd@...db.de> wrote:
> > >>
> > >> I see this has been applied, but I'd still like to understand better how
> > >> the
> > >> configuration interface is expected to work once the driver is complete.
> > >>
> > >> In particular, so far the interfaces all assume that configuration is
> > >> done through the mailbox between PCI devices, which could be done
> > >> from a virtual machine kernel with access to PCI, or through the use
> > >> of VFIO from a user application.
> > >>
> > >> Is that the only method of configuring it that you support, or will there
> > >> also be a devlink based interface or something like that to configure
> > >> the aspects of a virtual device that should not be accessible to the
> > >> VF itself?
> > >>
> > >
> > >
> > > As of now it's only mbox based configuration that is supported.
> >
> > Ok, thanks for the clarification.
> >
> > Does this mean that you intend to have user space tools that use
> > the mbox based interface on VFIO devices to perform configuration
> > for virtual network devices, or just that the configuration interface
> > is something that needs to be designed later?
> >
>
> No there is no need for any userspace tools.
> It's the virtual network device's driver which will send commands
> like resource allocation, configuration, stats retrieval to this
> AF device via mbox interface.
>
> eg: A user using ethtool changes RSS settings for the network device,
> network device's driver receives the data, prepares a mailbox command
> sends it to this driver for configuring the same in HW.
>
> Thanks,
> Sunil.

To be more clear there is no mbox 'interface' as such.
Here PCI devices shares a memory region, one device prepares a command
in this shared memory and writes into a doorbell kind of register which triggers
an IRQ to other device. Which then takes the command processes it.

Thanks,
Sunil.