[v3,0/2] support MAC changes when no live changes allowed
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Message ID 1535120736-785-1-git-send-email-alejandro.lucero@netronome.com
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  • support MAC changes when no live changes allowed
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Alejandro Lucero Aug. 24, 2018, 2:25 p.m. UTC
This is a patched to fix a functionality coming with the first public
release: changing/setting MAC address.

The original patch assumes all NICs can safely change or set the MAC
in any case. However, this is not always true. NFP depends on the firmware
capabilities and this is not always supported. There are other NICs with
this same limitation, although, as far as I know, not in DPDK. Linux kernel
has a IFF_LIVE_ADDR_CHANGE flag and two NICs are checking this flag for
allowing or not live MAC changes.

The flag proposed in this patch is just the opposite: advertise if live
change not supported and assuming it is supported other way.

Although most NICs support rte_eth_dev_default_mac_addr_set and this
function returns and error when live change is not supported, note that
this function is invoked during port start but the value returned is not
checked. It is likely this is good enough for most of the cases, but
bonding is relying on this start then mac set/change, and a PMD ports is
not properly configured for being used as an slave port in some bonding
modes.

v2:
 - add RTE_ETH_DEV_NOLIVE_MAC_ADDR comment in rte_eth_dev_default_mac_addr_set doc
 - add rte_eth_dev_start change in release API changes

v3:
 - merge doc API changes with first patch
 - comment behaviour change in rte_eth_dev_start
 - remove comment on rte_eth_dev_default_mac_addr_set

Comments

Stephen Hemminger Aug. 24, 2018, 2:46 p.m. UTC | #1
On Fri, 24 Aug 2018 15:25:34 +0100
Alejandro Lucero <alejandro.lucero@netronome.com> wrote:

> The original patch assumes all NICs can safely change or set the MAC
> in any case. However, this is not always true. NFP depends on the firmware
> capabilities and this is not always supported. There are other NICs with
> this same limitation, although, as far as I know, not in DPDK. Linux kernel
> has a IFF_LIVE_ADDR_CHANGE flag and two NICs are checking this flag for
> allowing or not live MAC changes

The semantic in Linux is different than what I think you are trying to do.
Some devices can not change MAC address at all because of hardware or hypervisor
restrictions. Other devices can not change address while device is up (started
in DPDK API).

With Linux the policy was to assume by default device could change address while up.
And then let a few virtual devices allow it.
Ferruh Yigit Aug. 27, 2018, 12:37 p.m. UTC | #2
On 8/24/2018 3:25 PM, Alejandro Lucero wrote:
> This is a patched to fix a functionality coming with the first public
> release: changing/setting MAC address.
> 
> The original patch assumes all NICs can safely change or set the MAC
> in any case. However, this is not always true. NFP depends on the firmware
> capabilities and this is not always supported. There are other NICs with
> this same limitation, although, as far as I know, not in DPDK. Linux kernel
> has a IFF_LIVE_ADDR_CHANGE flag and two NICs are checking this flag for
> allowing or not live MAC changes.
> 
> The flag proposed in this patch is just the opposite: advertise if live
> change not supported and assuming it is supported other way.
> 
> Although most NICs support rte_eth_dev_default_mac_addr_set and this
> function returns and error when live change is not supported, note that
> this function is invoked during port start but the value returned is not
> checked. It is likely this is good enough for most of the cases, but
> bonding is relying on this start then mac set/change, and a PMD ports is
> not properly configured for being used as an slave port in some bonding
> modes.
> 
> v2:
>  - add RTE_ETH_DEV_NOLIVE_MAC_ADDR comment in rte_eth_dev_default_mac_addr_set doc
>  - add rte_eth_dev_start change in release API changes
> 
> v3:
>  - merge doc API changes with first patch
>  - comment behaviour change in rte_eth_dev_start
>  - remove comment on rte_eth_dev_default_mac_addr_set

Series applied to dpdk-next-net/master, thanks.