[dpdk-dev] [PATCH v3 0/3] force IOVA to a particular mode
alejandro.lucero at netronome.com
Tue Oct 30 15:03:02 CET 2018
On Tue, Oct 30, 2018 at 1:48 PM Burakov, Anatoly <anatoly.burakov at intel.com>
> On 30-Oct-18 12:02 PM, Alejandro Lucero wrote:
> > On Sun, Oct 28, 2018 at 11:04 PM Thomas Monjalon <thomas at monjalon.net
> > <mailto:thomas at monjalon.net>> wrote:
> > 11/10/2018 12:08, Thomas Monjalon:
> > > +Cc more maintainers in order to collect more reviews
> > >
> > > 04/10/2018 11:19, Burakov, Anatoly:
> > > > On 03-Oct-18 9:53 PM, eric zhang wrote:
> > > > > This patchset introduces an EAL command line option
> > > > > to give the user a facility to force IOVA mode to a special
> > value.
> > > > >
> > > > > Auto detection of the IOVA mode, based on probing the bus and
> > IOMMU
> > > > > configuration, may not report the desired addressing mode
> > when virtual
> > > > > devices that are not directly attached to the bus are present.
> > > > > The EAL command line option "--iova-mode" can be used to
> > select either
> > > > > physical addressing('pa') or virtual addressing('va').
> > > >
> > > > Acked-by: Anatoly Burakov <anatoly.burakov at intel.com
> > <mailto:anatoly.burakov at intel.com>>
> > Rebased and applied, thanks
> > Could not this lead to a problem if a device can not wok with the mode
> > For example, IOVA mode set to VA and IOMMU hw with less bits than those
> > required for the virtual addresses?
> > IMO any device should be attached to a bus, and a bus should have a
> > function for setting IOVA mode and the --iova-mode option just allowed
> > with supported IOVA modes within the bus.
> I don't think it should work that way. It should warn the user that an
> incompatible IOVA mode was selected, but the user has specified an IOVA
> mode for a reason - it probably implies he really means it, so let him :)
Yes, that's true, but setting IOVA VA when a device has problems with it,
it is a bad idea and it could lead to a system crash.
My concern is not with the user knowing what he is doing but with the user
that "uhmm, what is this for, let's try this option".
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