Re: [PATCH v3 1/1] net/nbl: add igb uio support for NBL VF devices

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 24 Feb 2026 19:39:42 -0800
Dimon Zhao <dimon.zhao@nebula-matrix.com> wrote:

> Due to a chip design limitation, only the VF
> supports the igb_uio driver. The PF does not.
> 
> The igb_uio driver requires allocating interrupts and configuring the
> PCIe MSI-X table before the driver's probe function is called.
> This pre-probe configuration is only possible on the VF due to the
> hardware limitation; the PF can only configure the MSI-X table during
> its probe process.
> 
> Therefore, using igb_uio on the PF will fail.
> This commit clarifies this restriction.
> 
> Signed-off-by: Dimon Zhao <dimon.zhao@nebula-matrix.com>
> ---
>  doc/guides/nics/nbl.rst                       | 11 ++++
>  doc/guides/rel_notes/release_26_03.rst        |  4 ++
>  drivers/net/nbl/nbl_core.c                    |  2 +
>  drivers/net/nbl/nbl_dev/nbl_dev.c             | 33 ++++++++++--
>  drivers/net/nbl/nbl_dev/nbl_dev.h             |  3 ++
>  drivers/net/nbl/nbl_dispatch.c                | 50 +++++++++++++++++++
>  drivers/net/nbl/nbl_ethdev.c                  | 13 +++++
>  .../nbl_hw/nbl_hw_leonis/nbl_hw_leonis_snic.c | 12 +++++
>  .../nbl_hw/nbl_hw_leonis/nbl_hw_leonis_snic.h |  9 ++++
>  .../nbl/nbl_hw/nbl_hw_leonis/nbl_res_leonis.c | 10 ++++
>  drivers/net/nbl/nbl_include/nbl_def_channel.h |  5 ++
>  .../net/nbl/nbl_include/nbl_def_dispatch.h    |  3 ++
>  drivers/net/nbl/nbl_include/nbl_def_hw.h      |  3 ++
>  .../net/nbl/nbl_include/nbl_def_resource.h    |  3 ++
>  14 files changed, 157 insertions(+), 4 deletions(-)
> 
> diff --git a/doc/guides/nics/nbl.rst b/doc/guides/nics/nbl.rst
> index ba0a119dfd..c74826a3c2 100644
> --- a/doc/guides/nics/nbl.rst
> +++ b/doc/guides/nics/nbl.rst
> @@ -101,3 +101,14 @@ Limitations or Known Issues
>  32-bit architectures are not supported.
>  
>  Windows and BSD are not supported yet.
> +
> +**igb_uio Driver Support**
> +
> +Due to chip design limitations, only the VF supports the ``igb_uio`` driver,
> +PF does not support this driver.
> +
> +**uio_pci_generic Driver Support**
> +
> +The ``uio_pci_generic`` driver is not supported on either PF or VF devices.
> +This is because the NBL PMD requires MSI-X interrupts to receive mailbox
> +messages, but the ``uio_pci_generic`` driver does not support MSI-X interrupts.

The igb_uio driver is deprecated at this point, it is not upstream and has
lots of issues. Can VFIO be used in no IOMMU mode for this instead?