RE: Clarification on Minimum Supported Kernel Version for DPDK

["Morten Brørup" <mb@smartsharesystems.com>]

> From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> 
> On Fri, Mar 21, 2025 at 07:28:45AM +0100, Morten Brørup wrote:
> > @Kevin, @Stephen, @Bruce,
> >
> > I cannot reliably answer Cody's question, and it may need further
> discussion.
> >
> > What is your opinion on minimum Linux kernel version requirements?
> >
> > @Thomas: In the future, the DPDK release notes should mention the
> minimum Linux kernel requirements.
> >
> 
> Another question is - should we even have a minimum kernel version? Are
> we
> aware of any kernel features beyond vfio-pci driver which DPDK requires
> to
> run?
> As a userspace application, I think DPDK should just work with
> whatever distro-provided kernel is provided (assuming distro is
> relatively
> recent).

I agree regarding distros.

However, embedded systems may be stuck on ancient kernel versions for a variety of reasons.
Documenting the explicit requirements to the kernel are relevant for these.

I would expect all of the DPDK's EAL to behave as expected, so this should be the basis for defining DPDK's minimum kernel requirements - regarding both kernel version and optional kernel features required.
<noise>
In this context, "all of the EAL" really should mean the core of the EAL, exclusive the non-optional bloat that has nothing to do with abstracting the HW and O/S, and thus shouldn't be part of the EAL. But for now, I think we need to consider the EAL as-is, incl. any bloat.
</noise>

Some DPDK drivers may have additional kernel requirements.
Any such requirements should be documented with the individual drivers.
And, preferably, any driver should be able to degrade its capabilities gracefully when some optional requirements are not fulfilled.

In other words: We don't want DPDK's minimum kernel requirements to depend on some driver requiring some new and shiny kernel feature - the minimum kernel requirements should only depend on the EAL.

And - going back to the original question, triggering this discussion - we need to settle on a minimum kernel version for the CI testing at UNH.