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Subject: RE: [PATCH v2 1/5] build: add meson option to configure IOVA mode as
 VA
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Date: Wed, 7 Sep 2022 23:33:20 +0200
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Thread-Topic: [PATCH v2 1/5] build: add meson option to configure IOVA mode as
 VA
Thread-Index: AdjCz+b/5gU3WYq2QheJtiSHQBMt4QAMVHrw
References: <20220829151626.2101336-1-sthotton@marvell.com>
 <20220907134340.3629224-2-sthotton@marvell.com>
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From: =?iso-8859-1?Q?Morten_Br=F8rup?= <mb@smartsharesystems.com>
To: "Bruce Richardson" <bruce.richardson@intel.com>,
 "Stephen Hemminger" <stephen@networkplumber.org>,
 "Shijith Thotton" <sthotton@marvell.com>
Cc: <dev@dpdk.org>, <pbhagavatula@marvell.com>, <Honnappa.Nagarahalli@arm.com>,
 <jerinj@marvell.com>, <olivier.matz@6wind.com>, <thomas@monjalon.net>,
 "Nicolas Chautru" <nicolas.chautru@intel.com>,
 "Ciara Power" <ciara.power@intel.com>,
 "Konstantin Ananyev" <konstantin.v.ananyev@yandex.ru>,
 "Chengwen Feng" <fengchengwen@huawei.com>,
 "Kevin Laatz" <kevin.laatz@intel.com>,
 "Reshma Pattan" <reshma.pattan@intel.com>,
 "Maxime Coquelin" <maxime.coquelin@redhat.com>,
 "Chenbo Xia" <chenbo.xia@intel.com>
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> From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> Sent: Wednesday, 7 September 2022 17.38
>=20
> On Wed, Sep 07, 2022 at 08:31:09AM -0700, Stephen Hemminger wrote:
> > On Wed, 7 Sep 2022 19:13:36 +0530 Shijith Thotton
> <sthotton@marvell.com>
> > wrote:
> >
> > > IOVA mode in DPDK is either PA or VA. The new build option
> iova_as_va
> > > configures the mode to VA at compile time and prevents setting it
> to PA
> > > at runtime. For now, all drivers which are not always enabled are
> > > disabled with this option. Supported driver can set the flag
> > > pmd_iova_as_va in its build file to enable build.
> > >
> > > mbuf structure holds the physical (PA) and virtual address (VA) of
> a
> > > buffer. if IOVA mode is set to VA, PA is redundant as it is the
> same as
> > > VA. So PA field need not be updated and marked invalid if the =
build
> is
> > > configured to use only VA.
> > >
> > > Signed-off-by: Shijith Thotton <sthotton@marvell.com>
> >
> > NAK This works ok for use cases where NFV is building local version
> of
> > DPDK, but meson options dont work for distro vendors.
> >
> I think for something of this magnitude a build-time option is
> definitely
> the way to go. Sure, it won't be available in distro-packages, but for
> something like this it's just too invasive - and rather niche IMHO - =
to
> make a runtime option.
+1