Re: [dpdk-dev] [PATCH] doc: Clarify IOMMU usage with "uio-pci" kernel module

["Gavin Hu (Arm Technology China)" <Gavin.Hu@arm.com>]

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of tone.zhang
> Sent: Tuesday, September 4, 2018 4:59 PM
> To: dev@dpdk.org
> Cc: nd <nd@arm.com>
> Subject: [dpdk-dev] [PATCH] doc: Clarify IOMMU usage with "uio-pci" kernel
> module
> 
> 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@arm.com>
Acked-by: Gavin Hu <gavin.hu@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.
> +
>  Since DPDK release 1.7 onward provides VFIO support, use of UIO is optional
> for platforms that support using VFIO.
> 
> --
> 2.7.4