> From: Jakub Kicinski <kuba@xxxxxxxxxx> > Sent: Wednesday, December 16, 2020 6:31 AM > > On Tue, 15 Dec 2020 01:03:57 -0800 Saeed Mahameed wrote: > > +Subfunctions are lightweight functions that has parent PCI function > > +on which it is deployed. Subfunctions are created and deployed in > > +unit of 1. Unlike SRIOV VFs, they don't require their own PCI virtual > > +function. They communicate with the hardware through the parent PCI > > +function. Subfunctions can possibly scale better. > > + > > +To use a subfunction, 3 steps setup sequence is followed. > > +(1) create - create a subfunction; > > +(2) configure - configure subfunction attributes; > > +(3) deploy - deploy the subfunction; > > + > > +Subfunction management is done using devlink port user interface. > > +User performs setup on the subfunction management device. > > + > > +(1) Create > > +---------- > > +A subfunction is created using a devlink port interface. User adds > > +the subfunction by adding a devlink port of subfunction flavour. The > > +devlink kernel code calls down to subfunction management driver > > +(devlink op) and asks it to create a subfunction devlink port. Driver > > +then instantiates the subfunction port and any associated objects > > +such as health reporters and representor netdevice. > > + > > +(2) Configure > > +------------- > > +Subfunction devlink port is created but it is not active yet. That > > +means the entities are created on devlink side, the e-switch port > > +representor is created, but the subfunction device itself it not > > +created. User might use e-switch port representor to do settings, > > +putting it into bridge, adding TC rules, etc. User might as well > > +configure the hardware address (such as MAC address) of the subfunction > while subfunction is inactive. > > + > > +(3) Deploy > > +---------- > > +Once subfunction is configured, user must activate it to use it. Upon > > +activation, subfunction management driver asks the subfunction > > +management device to instantiate the actual subfunction device on > particular PCI function. > > +A subfunction device is created on the > > +:ref:`Documentation/driver-api/auxiliary_bus.rst <auxiliary_bus>`. At this > point matching subfunction driver binds to the subfunction's auxiliary device. > > + > > +Terms and Definitions > > +===================== > > + > > +.. list-table:: Terms and Definitions > > + :widths: 22 90 > > + > > + * - Term > > + - Definitions > > + * - ``PCI device`` > > + - A physical PCI device having one or more PCI bus consists of one or > > + more PCI controllers. > > + * - ``PCI controller`` > > + - A controller consists of potentially multiple physical functions, > > + virtual functions and subfunctions. > > + * - ``Port function`` > > + - An object to manage the function of a port. > > + * - ``Subfunction`` > > + - A lightweight function that has parent PCI function on which it is > > + deployed. > > + * - ``Subfunction device`` > > + - A bus device of the subfunction, usually on a auxiliary bus. > > + * - ``Subfunction driver`` > > + - A device driver for the subfunction auxiliary device. > > + * - ``Subfunction management device`` > > + - A PCI physical function that supports subfunction management. > > + * - ``Subfunction management driver`` > > + - A device driver for PCI physical function that supports > > + subfunction management using devlink port interface. > > + * - ``Subfunction host driver`` > > + - A device driver for PCI physical function that host subfunction > > + devices. In most cases it is same as subfunction management driver. > When > > + subfunction is used on external controller, subfunction management > and > > + host drivers are different. > > Would be great if someone from Mellanox could proof read this before we > spend cycles on correcting spelling in public review. Will get it done.
