[PATCH v2] doc: update kernel version requirement

[Kevin Traynor]

On 10/04/2025 16:20, Stephen Hemminger wrote:
> The 4.19 kernel version was end of life in December 2024.
> Update to 5.4 and also add better description of what "not supported"
> means in this case.
> 
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> Acked-by: Morten Brørup <mb at smartsharesystems.com>
> ---
> v2 - better wording
> 
>  doc/guides/linux_gsg/sys_reqs.rst | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/doc/guides/linux_gsg/sys_reqs.rst b/doc/guides/linux_gsg/sys_reqs.rst
> index 5a7d9e4a43..ba48b8afc0 100644
> --- a/doc/guides/linux_gsg/sys_reqs.rst
> +++ b/doc/guides/linux_gsg/sys_reqs.rst
> @@ -105,11 +105,20 @@ System Software
>  
>  **Required:**
>  
> -*   Kernel version >= 4.19
> -
> -    The kernel version required is based on the oldest long term stable kernel available
> -    at kernel.org when the DPDK version is in development.
> -    Compatibility for recent distribution kernels will be kept, notably RHEL/CentOS 7.
> +*   Kernel version >= 5.4
> +
> +    The Linux userspace API is compatible across releases but there are some
> +    restrictions. The oldest kernel tested by the DPDK testing infrastructure
> +    is the oldest maintained Long Term Stable (LTS) at time of release.
> +    The DPDK is likely to still work with older releases but it is not guaranteed.

It's just word semantics, but I mentioned before, I don't like the use
of "guarantee" that is is implied for newer kernels.

We can simply say that older kernels are not tested with and/or that
DPDK is not maintained to keep compatibility with them etc.

> +    Compatibility for recent distribution kernels will be kept, notably RHEL, and Ubuntu.
> +    It may work on older distributions, that are no longer under standard period
> +    but this is no longer but this is no longer tested or guaranteed to work.

"but this is no longer" is repeated

Again, it is implying there are "guarantees" for newer kernels

> +    The following are outside the current support window: RHEL 7, SLES 15.5, Ubuntu 20.04
> +    and earlier.
> +
> +    Some drivers and hardware support may require more recent kernels, check the
> +    documentation (e.g. :doc:`../nics/index`)
>  
>      The kernel version in use can be checked using the command::
>  

With some minor tweaks,
Acked-by: Kevin Traynor <ktraynor at redhat.com>