# System Configuration User Guide {#system_configuration}

This system configuration guide describes how to configure a system for use with SPDK.

# IOMMU configuration {#iommu_config}

An IOMMU may be present and enabled on many platforms. When an IOMMU is present and enabled, it is
recommended that SPDK applications are deployed with the `vfio-pci` kernel driver. SPDK's
`scripts/setup.sh` script will automatically select `vfio-pci` in this case.

However, some devices do not function correctly when bound to `vfio-pci` and instead must be
attached to the `uio_pci_generic` kernel driver. In that case, users should take care to disable
the IOMMU or to set it into passthrough mode prior to running `scripts/setup.sh`.

To disable the IOMMU or place it into passthrough mode, add `intel_iommu=off`
or `amd_iommu=off` or `intel_iommu=on iommu=pt` to the GRUB command line on
x86_64 system, or add `iommu.passthrough=1` on arm64 systems.

There are also some instances where a user may not want to use `uio_pci_generic` or the kernel
version they are using has a bug where `uio_pci_generic` [fails to bind to NVMe drives](https://github.com/spdk/spdk/issues/399).
In these cases, users building with the DPDK submodule can build the `igb_uio` kernel module by
supplying `--with-igb-uio-driver` to `./configure`. Upon a successful make, the file will be
located at `dpdk/build/build/kmod/igb_uio.ko`. To ensure that the driver is properly bound, users
should specify `DRIVER_OVERRIDE=/path/to/igb_uio.ko`.