Re: [ethtool 1/1] ethtool: Add DMA Coalescing support

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 25 Aug 2017 15:39:10 -0700
Jeff Kirsher <jeffrey.t.kirsher@intel.com> wrote:

> diff --git a/ethtool-copy.h b/ethtool-copy.h
> index 06fc04c..4bb91eb 100644
> --- a/ethtool-copy.h
> +++ b/ethtool-copy.h
> @@ -400,6 +400,7 @@ struct ethtool_modinfo {
>   *	a TX interrupt, when the packet rate is above @pkt_rate_high.
>   * @rate_sample_interval: How often to do adaptive coalescing packet rate
>   *	sampling, measured in seconds.  Must not be zero.
> + * @dmac: How many usecs to store packets before moving to host memory.
>   *
>   * Each pair of (usecs, max_frames) fields specifies that interrupts
>   * should be coalesced until
> @@ -450,6 +451,7 @@ struct ethtool_coalesce {
>  	__u32	tx_coalesce_usecs_high;
>  	__u32	tx_max_coalesced_frames_high;
>  	__u32	rate_sample_interval;
> +	__u32	dmac;
>  };
>  

Because of backwards ABI compatibility, it is not safe to extend
an existing structure.