On Tue, Dec 20, 2016 at 6:11 PM, Stephen Hemminger
[off-list ref] wrote:

On Tue, 20 Dec 2016 14:17:14 +0100
Jan Blunck [off-list ref] wrote:

quoted

On Fri, Dec 16, 2016 at 2:10 PM, Shreyansh Jain [off-list ref] wrote:

quoted

This patch introduces the rte_bus abstraction for devices and drivers in
EAL framework. The model is:
 - One or more buses are connected to a CPU (or core)
 - One or more devices are conneted to a 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

This patch adds a 'rte_bus' class which rte_driver and rte_device refer.
This way, each device (rte_xxx_device) would have reference to the bus
it is based on. As well as, each driver (rte_xxx_driver) would have link
to the bus and devices on it for servicing.

                                  __ rte_bus_list
                                 /
                     +----------'---+
                     |rte_bus       |
                     | driver_list------> List of rte_bus specific
                     | device_list----    devices
                     |              | `-> List of rte_bus associated
                     |              |     drivers
                     +--|------|----+
              _________/        \_________
    +--------/----+                     +-\---------------+
    |rte_device   |                     |rte_driver       |
    | rte_bus     |                     | rte_bus         |
    | rte_driver  |                     | ...             |
    | ...         |                     +---------...-----+
    |             |                               |||
    +---||--------+                               |||
        ||                                        |||
        | \                                        \\\
        |  \_____________                           \\\
        |                \                          |||
 +------|---------+ +----|----------+               |||
 |rte_pci_device  | |rte_xxx_device |               |||
 | ....           | | ....          |               |||
 +----------------+ +---------------+              / | \
                                                  /  |  \
                            _____________________/  /    \
                           /                    ___/      \
            +-------------'--+    +------------'---+    +--'------------+
            |rte_pci_driver  |    |rte_vdev_driver |    |rte_xxx_driver |
            | ....           |    | ....           |    | ....          |
            +----------------+    +----------------+    +---------------+

This patch only enables the bus references on rte_driver and rte_driver.
EAL wide global device and driver list continue to exist until an instance
of bus is added in subsequent patches.

This patch also introduces RTE_REGISTER_BUS macro on the lines of
RTE_PMD_REGISTER_XXX. Key difference is that the constructor priority has
been explicitly set to 101 so as to execute bus registration before PMD.

Signed-off-by: Shreyansh Jain <redacted>

Ok, but let's keep this as bus type not bus. It gets really hard and complex
to enumerate all layers of PCI bus and bridges.

As far as I understand it this isn't the intention to replicate the
hierarchy of buses we have in the kernel. The PCI bus in this case
becomes a list of PCI devices.