Re: [dpdk-dev] [PATCH v4 2/4] eal: fix IOVA mode selection as VA for PCI drivers

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 25-Nov-19 12:36 PM, David Marchand wrote:
> On Mon, Nov 25, 2019 at 1:03 PM Ferruh Yigit <ferruh.yigit@intel.com> wrote:
>>>> I would like to get your comment on the issue.
>>>>
>>>> For the OvS mode, hopefully binding the device to 'vfio-pci'
>>>> can be a solution, but for the cases we don't have that option,
>>>> can/should we force the DPDK to PA mode after initialization?
>>>
>>> I think this is expected, because VA is the new default since 19.08:
>>> http://doc.dpdk.org/guides/rel_notes/release_19_08.html#new-features
>>>
>>> In case, there is no constraint on initialization,
>>> we have to decide which mode is preferred.
>>> Previously PA was preferred.
>>> For the sake of modernity (and because it fits with some new devices),
>>> the preference has been changed to VA.
>>>
>>> If igb_uio device is used at initialization,
>>> the PA mode should be used.
>>> If igb_uio (PA-only) device is hotplugged, no luck!
>>> If VA-only device is hotplugged, it works!
>>>
>>> I think this change is one step in deprecating igb_uio.
>>>
>>
>> I just want to confirm/clarify that this behavior change is by design, not a defect.
>> Should we document this behavior change more clearly, or highlight more, to not
>> let catch others too?
> 
> The behavior change happened with:
> https://git.dpdk.org/dpdk/commit?id=bbe29a9bd7ab6feab9a52051c32092a94ee886eb
> And there is an entry in the 19.08 release notes:
> http://doc.dpdk.org/guides/rel_notes/release_19_08.html#new-features
> 
> 

Should we perhaps also provide LTS release notes, i.e. "all changes 
since last LTS"? I think it's unreasonable to expect people using LTS's 
to trace through every release notes between LTS's.

-- 
Thanks,
Anatoly