6. Hello World Sample Application

6.3.1. EAL Initialization

The first task is to initialize the Environment Abstraction Layer (EAL). This is done in the main() function using the following code:

int

main(int argc, char **argv)

{
    ret = rte_eal_init(argc, argv);
    if (ret < 0)
        rte_panic("Cannot init EAL\n");

This call finishes the initialization process that was started before main() is called (in case of a Linuxapp environment). The argc and argv arguments are provided to the rte_eal_init() function. The value returned is the number of parsed arguments.

6.3.2. Starting Application Unit Lcores

Once the EAL is initialized, the application is ready to launch a function on an lcore. In this example, lcore_hello() is called on every available lcore. The following is the definition of the function:

static int
lcore_hello( attribute ((unused)) void *arg)
{
    unsigned lcore_id;

    lcore_id = rte_lcore_id();
    printf("hello from core %u\n", lcore_id);
    return 0;
}

The code that launches the function on each lcore is as follows:

/* call lcore_hello() on every slave lcore */

RTE_LCORE_FOREACH_SLAVE(lcore_id) {
   rte_eal_remote_launch(lcore_hello, NULL, lcore_id);
}

/* call it on master lcore too */

lcore_hello(NULL);

The following code is equivalent and simpler:

rte_eal_mp_remote_launch(lcore_hello, NULL, CALL_MASTER);

Refer to the DPDK API Reference for detailed information on the rte_eal_mp_remote_launch() function.