On Thu, Nov 17, 2016 at 6:29 AM, Shreyansh Jain <shreyansh.jain at nxp.com> wrote: > DPDK has been inherently a PCI inclined framework. Because of this, the > design of device tree (or list) within DPDK is also PCI inclined. A non-PCI > device doesn't have a way of being expressed without using hooks started from > EAL to PMD. > > With this cover letter, some patches are presented which try to break this > strict linkage of EAL with PCI devices. Aim is to generalize the device > hierarchy on the lines of how Linux handles it: > > device A1 > | > +==.===='==============.============+ Bus A. > | `--> driver A11 \ > device A2 `-> driver A12 \______ > |CPU | > /````` > device A1 / > | / > +==.===='==============.============+ Bus A` > | `--> driver B11 > device A2 `-> driver B12 > > Simply put: > - a bus is connect to CPU (or core) > - devices are conneted to Bus > - drivers are running instances which manage one or more devices > - bus is responsible for identifying devices (and interrupt propogation) > - driver is responsible for initializing the device > > (*Reusing text from email [1]) > In context of DPDK EAL: > - a generic bus (not a driver, not a device). I don't know how to categorize > a bus. It is certainly not a device, and then handler for a bus (physical) > can be considered a 'bus driver'. So, just 'rte_bus'. > - there is a bus for each physical implementation (or virtual). So, a rte_bus > Object for PCI, VDEV, ABC, DEF and so on. > - Buses are registered just like a PMD - RTE_PMD_BUS_REGISTER() > - Each registered bus is part of a doubly list. > -- Each device inherits rte_bus > -- Each driver inherits rte_bus > -- Device and Drivers lists are part of rte_bus > - eth_driver is no more required - it was just a holder for PMDs to register > themselves. It can be replaced with rte_xxx_driver and corresponding init/ > uninit moved to rte_driver > - rte_eth_dev modified to disassociate itself from rte_pci_device and connect > to generic rte_device > > Once again, improvising from [1]: > > __ rte_bus_list > / > +----------'---+ > |rte_bus | > | driver_list------> List of rte_bus specific > | device_list---- devices > | scan | `-> List of rte_bus associated > | match | drivers > | dump | > | ..some refcnt| (#) > +--|------|----+ > _________/ \_________ > +--------/----+ +-\---------------+ > |rte_device | |rte_driver | > | rte_bus | | rte_bus | > | rte_driver |(#) | init | > | | | uninit | > | devargs | | dev_private_size| > +---||--------+ | drv_flags |(#) > || | intr_handle(2*) |(#) > | \ +----------\\\----+ > | \_____________ \\\ > | \ ||| > +------|---------+ +----|----------+ ||| > |rte_pci_device | |rte_xxx_device | (4*) ||| > | PCI specific | | xxx device | ||| > | info (mem,) | | specific fns | / | \ > +----------------+ +---------------+ / | \ > _____________________/ / \ > / ___/ \ > +-------------'--+ +------------'---+ +--'------------+ > |rte_pci_driver | |rte_vdev_driver | |rte_xxx_driver | > | PCI id table, | | <probably, | | .... | > | other driver | | nothing> | +---------------+ > | data | +----------------+ > +----------------+ > > (1*) Problem is that probe functions have different arguments. So, > generalizing them might be some rework in the respective device > layers > (2*) Interrupt handling for each driver type might be different. I am not > sure how to generalize that either. This is grey area for me. > (3*) Probably exposing a bitmask for device capabilities. Nothing similar > exists now to relate it. Don't know if that is useful. Allowing > applications to question a device about what it supports and what it > doesn't - making it more flexible at application layer (but more code > as well.) > (4*) Even vdev would be an instantiated as a device. It is not being done > currently. > (#) Items which are still pending > > With this cover letter, some patches have been posted. These are _only_ for > discussion purpose. They are not complete and neither compilable. > All the patches, except 0001, have sufficient context about what the changes > are and rationale for same. Obviously, code is best answer.
As said by Jan B., I too think that splitting the patches into smaller patchsets is important. Looking at your datamodel, some quick comments : - Why init/uninit in rte_driver ? Why not probe/remove ? - I don't think dev_private_size makes sense in rte_driver. The bus is responsible for creating rte_device objects (embedded or not in rte_$bus_device objects). If a driver needs to allocate some priv (for whatever needs), the driver should do the allocation itself (or maybe a helper for current eth_driver), then reference the original rte_$bus_device object it got from the probe method. For a first patchset, I would see: - introduce the rte_bus object. In rte_eal_init, for each bus, we call the scan method. Then, for each bus, we find the appropriate rte_driver using the bus match method then call the probe method. If the probe succeeds, the rte_device points to the associated rte_driver, - migrate the pci scan code to a pci bus (scan looks at sysfs for linux / ioctl for bsd + devargs for blacklist / whitelist ?), match is the same at what is done in rte_eal_pci_probe_one_driver() at the moment, - migrate the vdev init code to a vdev bus (scan looks at devargs): this is new, we must create rte_device objects for vdev drivers to use later Then we can talk about the next steps once the bus is in place. -- David Marchand