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.
