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

[Thomas Monjalon <thomas@monjalon.net>]

25/11/2019 13:58, Burakov, Anatoly:
> 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.

I don't think it is unreasonable.
There are only 4 releases since last LTS.
But I am OK for switching to 3 releases per year :)