Re: [dpdk-dev] [PATCH v3] doc: Clarify IOMMU usage with "uio_pci_generic" kernel module

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

> -----Original Message-----
> From: tone.zhang <tone.zhang@arm.com>
> Sent: Wednesday, September 5, 2018 1:18 PM
> To: dev@dpdk.org
> Cc: Gavin Hu (Arm Technology China) <Gavin.Hu@arm.com>;
> bruce.richardson@intel.com; bluca@debian.org; roszenrami@gmail.com; nd
> <nd@arm.com>
> Subject: [PATCH v3] doc: Clarify IOMMU usage with "uio_pci_generic" kernel
> module
> 
> If the devices used for DPDK are bound to the "uio_pci_generic" 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 configurations 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..b46fc6a 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 used for DPDK are bound to the ``uio_pci_generic`` kernel
> module,
> +   please make sure that the IOMMU is disabled. One can add
> ``intel_iommu=off`` or
> +   ``intel_iommu=pt`` or ``amd_iommu=off`` in GRUB command line 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