Re: Clarification on Minimum Supported Kernel Version for DPDK

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 21 Mar 2025 07:28:45 +0100
Morten Brørup <mb@smartsharesystems.com> 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.
> 
> > From: Cody Cheng [mailto:ccheng@iol.unh.edu]
> > Sent: Thursday, 20 March 2025 21.28
> > 
> > Hi Morten,
> > 
> > I am in the process of setting up a test environment at the UNH DPDK
> > Community Test Lab that follows the minimum supported kernel version
> > for DPDK. According to the DPDK documentation, the minimum supported
> > kernel version is 4.19. However, the oldest long term stable kernel
> > version listed on kernel.org is 5.4.291.
> > 
> > Should the test environment be set up on kernel version 4.19 or
> > 5.4.291?  
> 
> The kernel 4.19 support stems from still supporting RHEL/CentOS 7.
> I wonder if this exception mentioned in the documentation [1] is still valid, or if we should bump it to RHEL/CentOS 8, which ships with kernel 4.18 [1].
> 
> RHEL/CentOS 7 support was discussed at by tech board long ago [2], but I cannot find a conclusion about the kernel version; the discussion was mostly about compiler support.
> 
> [1]: https://doc.dpdk.org/guides/linux_gsg/sys_reqs.html#system-software
> [2]: https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/html-single/8.0_release_notes/index#overview
> [3]: https://mails.dpdk.org/archives/dev/2023-February/263516.html

My opinion has always been that DPDK only offers certain guarantees about testing:
  - oldest current LTS
  - oldest supported version of Redhat/Ubuntu/SUSE enterprise kernels

after that in the embedded space, the user is likely to be ok but any kernel
related issues are their problem not the communities to deal with.

The two parts most likely to cause issues are vfio-pci and vhost related stuff.
There is also small chance of issues with the memory handling in EAL.