Re: [dpdk-dev] [PATCH] net/thunderx: sync mailbox definitions with Linux PF driver

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

On Tue, Mar 21, 2017 at 02:53:29PM +0000, Ferruh Yigit wrote:
> On 3/21/2017 2:38 PM, Jerin Jacob wrote:
> > On Tue, Mar 21, 2017 at 02:31:41PM +0000, Ferruh Yigit wrote:
> >> On 3/20/2017 2:10 PM, Jerin Jacob wrote:
> >>> - bgx_link_status mbox definition was changed in Linux
> >>> commit 1cc702591bae ("net: thunderx: Add ethtool support")
> >>> - NIC_MBOX_MSG_RES_BIT related changes were never part of Linux PF driver
> >>>
> >>> Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> >>
> >> <...>
> >>
> >>> @@ -157,6 +151,7 @@ struct rss_cfg_msg {
> >>>  /* Physical interface link status */
> >>>  struct bgx_link_status {
> >>>  	uint8_t    msg;
> >>> +	uint8_t    mac_type;
> >>
> >> Hi Jerin,
> >>
> >> Is this modification related to this patch?
> > 
> > Yes Ferruh.
> > 
> > This was related to the following section in git log comment.
> > ----
> > - bgx_link_status mbox definition was changed in Linux
> > commit 1cc702591bae ("net: thunderx: Add ethtool support") 
> > ---
> 
> I see now, thanks. Since this is to sync with Linux PF, shouldn't it be
> used in driver, perhaps something like in Linux driver:
> "nic->mac_type = mbx.link_status.mac_type"
> 
> What is the point of just adding definition without using it?

That is to keep "link_up"(next element in the struct bgx_link_status) points
to correct location after the kernel change. I thought about, the backward
compatibility with older kernel, Is it OK to use linux/version.h in PMD drivers
to detect the kernel version? drivers/net/mlx5/mlx5_ethdev.c has similar
kernel detection mechanism to make it backward compatible.
If there are no issue with such approach, I will roll out a new revision.


> 
> > 
> > 
> >>
> >>>  	uint8_t    link_up;
> >>>  	uint8_t    duplex;
> >>>  	uint32_t   speed;
> >>>
> >>
>