Re: [PATCH v3 02/12] eal/bus: introduce bus abstraction
From: Shreyansh Jain <hidden>
Date: 2016-12-22 05:49:22
On Thursday 22 December 2016 10:42 AM, Shreyansh Jain wrote:
On Thursday 22 December 2016 05:03 AM, Stephen Hemminger wrote:quoted
On Wed, 21 Dec 2016 16:38:42 +0100 Jan Blunck [off-list ref] wrote:quoted
On Tue, Dec 20, 2016 at 6:11 PM, Stephen Hemminger [off-list ref] wrote:quoted
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.One of the motivations seems to be "lets be able to handle lots of devices", but the current model with an array of ports is not going to scale well for that. It is time to make rte_eth_devices into rb-tree and get rid of MAX_PORTS config option.That is a nice idea. Probably once we get the EAL compatible for 'lots of devices', this would be next good change.
Just out of curiosity - I think only need here is to do away with 'MAX_PORTS'. There is no need for a 'fast' lookup of ports as this part wouldn't be part of datapath. Am I wrong in assuming this?
- Shreyansh