illumos gate

Description

While working on another issue I noticed that one of my i40e ports was sending a lot of pause frames.

# kstat -p i40e::pfstats: | grep link_x
i40e:0:pfstats:link_xoff_rx     9408693
i40e:0:pfstats:link_xoff_tx     0
i40e:0:pfstats:link_xon_rx      6
i40e:0:pfstats:link_xon_tx      0
i40e:1:pfstats:link_xoff_rx     0
i40e:1:pfstats:link_xoff_tx     9408694
i40e:1:pfstats:link_xon_rx      0
i40e:1:pfstats:link_xon_tx      6

After discussing with Robert Mustacchi, I learned that, by default, Ethernet flow control should be disabled on i40e. For example, dladm reports it as "off" even though it's not.

# dladm show-linkprop -p flowctrl i40e0 
LINK         PROPERTY        PERM VALUE          DEFAULT        POSSIBLE
i40e0        flowctrl        r-   no             no             no,tx,rx,bi

We need to update the driver to properly initialize FC. I'm narrowing the scope of this issue to simply initialize FC based on the default settings. If we require user-controller FC (via dladm) in the future then a separate ticket should be filed.

I tested this by verifying the i40e_hw_space.fc.current_mode is set to I40E_FC_NONE.

Here's the current platform.

> ::walk mac_impl_cache |::printf "0x%p %s\n" mac_impl_t . mi_name
0xfffffe59420f1848 i40e0

> 0xfffffe59420f1848::print mac_impl_t mi_driver |::print i40e_t i40e_hw_space.fc
i40e_hw_space.fc = {
    i40e_hw_space.fc.current_mode = 3 (I40E_FC_FULL)
    i40e_hw_space.fc.requested_mode = 0 (I40E_FC_NONE)
}
>

Here's the patched platform.

> ::walk mac_impl_cache |::printf "0x%p %s\n" mac_impl_t . mi_name
0xfffffe59421ad848 i40e0
> 
> 0xfffffe59421ad848::print mac_impl_t mi_driver |::print i40e_t i40e_hw_space.fc
i40e_hw_space.fc = {
    i40e_hw_space.fc.current_mode = 0 (I40E_FC_NONE)
    i40e_hw_space.fc.requested_mode = 0 (I40E_FC_NONE)
}
>