[dpdk-dev] [PATCH] doc: Clarify IOMMU usage with "uio-pci" kernel module
Tone Zhang (Arm Technology China)
Tone.Zhang at arm.com
Tue Sep 4 12:25:35 CEST 2018
-----Original Message-----
From: Luca Boccassi <bluca at debian.org>
Sent: Tuesday, September 4, 2018 6:15 PM
To: Bruce Richardson <bruce.richardson at intel.com>; Tone Zhang (Arm Technology China) <Tone.Zhang at arm.com>
Cc: dev at dpdk.org; nd <nd at arm.com>
Subject: Re: [dpdk-dev] [PATCH] doc: Clarify IOMMU usage with "uio-pci" kernel module
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.
> >
> > The patch clarifies the IOMMU configuration on both x86_64 and
> > arm64
> > systems.
> >
> > Signed-off-by: tone.zhang <tone.zhang at arm.com>
> > ---
> > doc/guides/linux_gsg/linux_drivers.rst | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > 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:
> > ``vfio-pci`` kernel module rather than ``igb_uio`` or
> > ``uio_pci_generic``.
> > For more details see :ref:`linux_gsg_binding_kernel` below.
> >
> > +.. note::
> > +
> > + If the devices for used DPDK bound to the ``uio-pci`` kernel
> > module, please make
> > + sure that the IOMMU is disabled. We can add ``intel_iommu=off``
> > or ``amd_iommu=off``
> > + in ``GRUB_CMDLINE_LINUX`` in grub on x86_64 systems, or add
> > ``iommu.passthrough=1``
> > + on arm64 system.
> > +
>
> I think passthrough mode should work on x86 too. I remember running
> with iommu=pt setting in the kernel in the past.
>
> /Bruce
It does, can confirm.
--
Kind regards,
Luca Boccassi
@Luca, @Bruce,
Thanks for the comments. I will update the change and push V2. Thanks!
Br,
Tone
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