Re: version bump of minimal kernel version supported by systemd?

[Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>]

On Wed, Mar 23, 2022 at 11:28:29AM +0000, Luca Boccassi wrote:
> On Wed, 2022-03-23 at 11:59 +0100, Zbigniew Jędrzejewski-Szmek wrote:
> > On Wed, Mar 23, 2022 at 09:26:05AM +0100, Greg KH wrote:
> > > On Wed, Mar 23, 2022 at 09:17:36AM +0100, Zbigniew Jędrzejewski-Szmek wrote:
> > > > On Wed, Mar 23, 2022 at 08:07:48AM +0100, Greg KH wrote:
> > > > > On Tue, Mar 22, 2022 at 05:27:07PM +0100, Zbigniew Jędrzejewski-Szmek wrote:
> > > > > > Hi all,
> > > > > > 
> > > > > > we are considering dropping upstream support for kernel versions < 4.4.
> > > > > > Would this be a problem for anyone? (*).
> > > > > 
> > > > > Given that upstream (i.e. kernel.org) has dropped support for kernel
> > > > > 4.4, why not just move to not supporting kernels older than 4.9?
> > > > 
> > > > It seems Civil Infrastructure Platform (a project under the Linux
> > > > Foundation) still uses 4.4 [1].
> > > 
> > > Yes, but they are not going to be updating to a newer version of
> > > systemd, right?
> > > 
> > > And they are going to be "supporting" that for 20+ years.  If they want
> > > to do something crazy like this, make them handle supporting code that
> > > is older than 6+ years to start with.  That's not the community's issue,
> > > that's the companies that demand such crazy requirement's issue.
> > 
> > That's why I (we) asked the question on the list. If people are compling
> > systemd on such old systems, or even older, we want to know about it.
> > 
> > > > In the Debian world, Stretch which has EOL scheduled for June 2022 has 4.9,
> > > > and after that Buster has 4.19.
> > > 
> > > 4.9 is fine, and is supported by kernel.org until next year as seen
> > > here:
> > > 	https://kernel.org/category/releases.html
> > > 
> > > I wrote "4.9" above, not "4.19" :)
> > 
> > Yep. I'd vote for bumping to 4.9, unless some other voices pop up.
> > 
> > Zbyszek
> 
> Let's do 4.4 at most please - what's on kernel.org is not really that
> important, as real usage is downstream from there anyway.

And I will publically state that anyone still using 4.4.y today has an
insecure and unsupported system.  Please let's not encourage _ANYONE_ to
do this.

CIP is "special" in that they know what they are doing, and are using
4.4.y in a very limited set of use cases and configurations.  And even
they are going to have big problems keeping that kernel alive and
secure.  I would never expect anyone else to be able to do it, and I
have doubts that they will either.

So any "real usage" of 4.4 after today, should not matter.  And if
someone complains, send them to me please.

thanks,

greg k-h