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

[Ferruh Yigit]

On 3/23/2017 2:00 PM, Jerin Jacob wrote:
> On Thu, Mar 23, 2017 at 01:26:15PM +0000, Ferruh Yigit wrote:
>> On 3/23/2017 1:20 PM, Jerin Jacob wrote:
>>> On Wed, Mar 22, 2017 at 10:33:14AM +0000, Ferruh Yigit wrote:
>>>> On 3/22/2017 9:39 AM, Jerin Jacob wrote:
>>>>> 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 at 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 see, thanks. It is pity that new field added into middle (or beginning
>>>> if you exclude msg) of the struct.
>>>>
>>>>> 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?
>>>>
>>>> Technically possible, but kernel version check has its problems:
>>>> 1) Adds maintenance cost, which gets worse by time.
>>>> 2) If added a compile time check, it creates binary distribution
>>>> problems, distro guys may not like PMD has dependency to kernel.
>>>> 3) It will create dependency to Linux, assuming Thunderx PMD supported
>>>> in FreeBSD
>>>>
>>>>> drivers/net/mlx5/mlx5_ethdev.c has similar
>>>>> kernel detection mechanism to make it backward compatible.
>>>>
>>>> Yes, at least mlx added a dynamic check which prevents above issue 2.
>>>>
>>>>> If there are no issue with such approach, I will roll out a new revision.
>>>>
>>>> Is there any way to detect this dynamically, first things I can think of:
>>>> - Any mbx versioning to rely on?
>>>> - Any common NIC user header file provided by kernel, to use in DPDK, to
>>>> prevent any this kind of issues in the future?
>>>> - Any msg size value to detect if mac_type exists or not?
>>>> - Heuristic approach to other values to detect mac_type existence?
>>>
>>> Thanks for sharing the options.
>>> First three options wont work. Heuristic option is pretty limited,
>>> mac_type value can also be 0 or 1(same as link_up)
>>> So I think, The best option now to use the patch as is(without kernel
>>> check).
>>> What do you think?
>>
>> If this won't cause a problem for you with older kernels, I would prefer
>> no kernel check option.
> 
> OK. I will ask our kernel team to backport the offending the kernel change
> to old versions based on the requirement. Please merge this patch if you don't
> see any other issue.
> I can post a separate patch add to the kernel version check if it
> is really required.

OK

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