[dpdk-dev] [PATCH v3 1/6] net/tap: add MAC address management ops

Ferruh Yigit ferruh.yigit at intel.com
Thu Mar 9 15:05:51 CET 2017


On 3/7/2017 4:31 PM, Pascal Mazon wrote:
> Set a random MAC address when probing the device, as to not leave an
> empty MAC in pmd->eth_addr.
> 
> This MAC will be set on the tap netdevice as soon as it's been created
> using tun_alloc(). As the tap_mac_add() function depend on the fd in
> the first rxq, move code from tun_alloc() to tap_setup_queue(),
> after it's been set.
> 
> Signed-off-by: Pascal Mazon <pascal.mazon at 6wind.com>
> ---
>  doc/guides/nics/features/tap.ini |  1 +
>  drivers/net/tap/rte_eth_tap.c    | 97 ++++++++++++++++++++++++++++++++++------
>  2 files changed, 85 insertions(+), 13 deletions(-)
> 
> diff --git a/doc/guides/nics/features/tap.ini b/doc/guides/nics/features/tap.ini
> index f4aca6921ddc..d9b47a003654 100644
> --- a/doc/guides/nics/features/tap.ini
> +++ b/doc/guides/nics/features/tap.ini
> @@ -9,6 +9,7 @@ Jumbo frame          = Y
>  Promiscuous mode     = Y
>  Allmulticast mode    = Y
>  Basic stats          = Y
> +Unicast MAC filter   = Y
>  Other kdrv           = Y
>  ARMv7                = Y
>  ARMv8                = Y
> diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
> index ece3a5fcc897..1e46ee36efa2 100644
> --- a/drivers/net/tap/rte_eth_tap.c
> +++ b/drivers/net/tap/rte_eth_tap.c
> @@ -63,6 +63,8 @@
>  #define RTE_PMD_TAP_MAX_QUEUES	1
>  #endif
>  
> +#define RTE_PMD_TAP_MAX_MAC_ADDRS 1

mac_addr_add and mac_addr_remove not really supported, because only one
MAC is supported. For mac_addr_add() all indexes other than 0 will give
an error. So only mac_addr_set is supported.

For this case what is the benefit of implementing these functions and
claim support, instead of just leaving mac_addr_add and mac_addr_remove
NULL?


<...>

> +	if (qid == 0) {
> +		/*
> +		 * tap_setup_queue() is called for both tx and rx.
> +		 * Let's use dev->data->r/tx_queues[qid] to determine if init
> +		 * has already been done.
> +		 */
> +		if (dev->data->rx_queues[qid] && dev->data->tx_queues[qid])
> +			return fd;
> +
> +		tap_mac_set(dev, &pmd->eth_addr);

What is the reason of changing behavior here?

Tap devices assigned random MAC by kernel, and previous implementation
was reading that value and using it for DPDK.

Now kernel assigns a random MAC, and DPDK overwrites it another random
MAC, previous implementation was simpler I think.

It is OK to move this code tap_setup_queue(), I just missed the benefit
of overwriting with DPDK random MAC?

<...>


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