From mboxrd@z Thu Jan  1 00:00:00 1970
From: Luca Boccassi <bluca@debian.org>
Subject: Re: [PATCH] doc: Clarify IOMMU usage with "uio-pci"
 kernel module
Date: Tue, 04 Sep 2018 11:15:09 +0100
Message-ID: <1536056109.11823.52.camel@debian.org>
References: <1536051547-8797-1-git-send-email-tone.zhang@arm.com>
 <20180904100626.GA19424@bricha3-MOBL.ger.corp.intel.com>
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Cc: dev@dpdk.org, nd@arm.com
To: Bruce Richardson <bruce.richardson@intel.com>, "tone.zhang"
 <tone.zhang@arm.com>
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On Tue, 2018-09-04 at 11:06 +0100, Bruce Richardson wrote:
> On Tue, Sep 04, 2018 at 04:59:07PM +0800, tone.zhang wrote:
> > When binding the devices used by DPDK to the "uio-pci" kernel
> > module,
> > the IOMMU should be disabled in order not to break the IO
> > transmission
> > because of the virtual / physical address mapping.
> >=20
> > The patch clarifies the IOMMU configuration on both x86_64 and
> > arm64
> > systems.
> >=20
> > Signed-off-by: tone.zhang <tone.zhang@arm.com>
> > ---
> > =C2=A0doc/guides/linux_gsg/linux_drivers.rst | 7 +++++++
> > =C2=A01 file changed, 7 insertions(+)
> >=20
> > diff --git a/doc/guides/linux_gsg/linux_drivers.rst
> > b/doc/guides/linux_gsg/linux_drivers.rst
> > index 371a817..8f9ec8f 100644
> > --- a/doc/guides/linux_gsg/linux_drivers.rst
> > +++ b/doc/guides/linux_gsg/linux_drivers.rst
> > @@ -48,6 +48,13 @@ be loaded as shown below:
> > =C2=A0=C2=A0=C2=A0=C2=A0``vfio-pci`` kernel module rather than ``igb_ui=
o`` or
> > ``uio_pci_generic``.
> > =C2=A0=C2=A0=C2=A0=C2=A0For more details see :ref:`linux_gsg_binding_ke=
rnel` below.
> > =C2=A0
> > +.. note::
> > +
> > +=C2=A0=C2=A0=C2=A0If the devices for used DPDK bound to the ``uio-pci`=
` kernel
> > module, please make
> > +=C2=A0=C2=A0=C2=A0sure that the IOMMU is disabled. We can add ``intel_=
iommu=3Doff``
> > or ``amd_iommu=3Doff``
> > +=C2=A0=C2=A0=C2=A0in ``GRUB_CMDLINE_LINUX`` in grub on x86_64 systems,=
 or add
> > ``iommu.passthrough=3D1``
> > +=C2=A0=C2=A0=C2=A0on arm64 system.
> > +
>=20
> I think passthrough mode should work on x86 too. I remember running
> with
> iommu=3Dpt setting in the kernel in the past.
>=20
> /Bruce

It does, can confirm.

--=20
Kind regards,
Luca Boccassi