Re: [dpdk-dev] [PATCH] net/ixgbe: remove hardcoded CRC STRIP config from ixgbe

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 12.08.2018 09:28, Shahaf Shuler wrote:
> Thursday, August 9, 2018 11:32 AM, Ferruh Yigit:
>> Subject: Re: [PATCH] net/ixgbe: remove hardcoded CRC STRIP config from
>> ixgbe
>>
>> On 7/24/2018 3:36 AM, Wei Zhao wrote:
>>> There is CRC related ifdefs for ixgbe:
>>> CONFIG_RTE_LIBRTE_IXGBE_PF_DISABLE_STRIP_CRC=n
>>> It is used in VF drivers ixgbevf_dev_configure() functions.
>>> VF cannot change the CRC strip behavior and based on what PF
>>> configured it needs to response proper to user
>>> ixgbevf_dev_configure() request. Right now what PF set is defined by
>>> above config options but this method is too static.
>>>
>>> Signed-off-by: Wei Zhao <wei.zhao1@intel.com>
>>> Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
>> <...>
>>> @@ -334,6 +334,7 @@ struct rte_eth_rxmode {
>>>   	 * structure are allowed to be set.
>>>   	 */
>>>   	uint64_t offloads;
>>> +	uint64_t offloads_disable;
>> Do we need a disable flag in ethdev, an offload not enabled is disabled by
>> default isn't it. This conflicts with offloads flag and makes is confusing.
> +1.
>
> **all** the offloads are disabled by default.
>
>> For igb/e1000 VF case, VF driver can't change what PF set and VF driver can't
>> learn the PF setting dynamically, so this information needs to be passed to VF
>> driver by application/user.
>> Currently this information passed by compile time config option, my
>> suggestion was using devargs.
>>
>> In your implementation testpmd parameter added to get this information
>> and pass to driver, but this means all applications needs to do this, instead
>> adding this support to driver looks better to me.

I think we should add fixed offloads to dev_info. I.e. if offlload is 
supported,
it could be marked as fixed (i.e. always enabled).
If offload is not supported, it is always disabled (and cannot/should not be
marked as fixed).
May be the right name for it is not "fixed", but "always_enabled".
Also it should be persistent. It should not be allowed in above ixgbe case
to change the offload state on PF if there are other users (drivers 
attached).
Otherwise, we need mechanism to notify apps about these changes -
overcomplicated.