[dpdk-dev] new EAL mechanism proposal for driver options

[Matan Azrad <matan@mellanox.com>]

Hi all

It may be convenient that DPDK drivers can work in several modes.
Allowing driver option changes by the user can make the program more efficient.
For Example:
If user knows that all its Tx packets are 1 segment packets it can change the PMD
mode to work with different tx_burst function which is more efficient for 1 segment scenario,
As soon as multi segments packet are created, the user can change the mode back in run time.

Now let's discuss how to implement driver options.

I suggest new bus operation to set the driver options.

Each bus will expose new operation in rte_bus structure to set driver option by driver name:
int set_driver_option(const char* driver_name, const char* optargs)

Each bus will expose operation in rte_bus structure to set itself options:
int set_option(char* optargs)

Each PMD will expose operation to create option in its driver structure:
int set_option(char* optargs)

The EAL will expose API to set driver options by the user:
int eal_set_driver_option(const char* bus_name, const char* driver_name, const char* optargs)
int eal_set_bus_option(const char* bus_name, const char* optargs)

optargs format will be "key1=value1,key2=value2,key3=value3..." and should be validated by EAL.

Add new EAL command line parameter  to set the start options per driver:
"-driver-options bus_name=<driver bus name>,[name=<driver name>,]key1=value1[,key2=value2,key3=value3...]".


Thoughts?