[CentOS-devel] Balancing the needs around the RHEL platform

Fri Dec 25 10:40:22 UTC 2020
Nico Kadel-Garcia <nkadel at gmail.com>

On Fri, Dec 25, 2020 at 4:11 AM Simon Matter <simon.matter at invoca.ch> wrote:
> > On Thu, Dec 24, 2020 at 10:21 AM James Cassell
> > <fedoraproject at cyberpear.com> wrote:
> >> On Wed, Dec 23, 2020, at 9:25 PM, Mark Mielke wrote:
> >> > This is an interesting point. Oracle UEK R6, as used in OL 7 and OL 8,
> >> > is tied to Linux 5.4.17, and I think the above might be a good summary
> >> > of why this is a good thing. One part of this is to set the
> >> > expectation for what kABI is supported. The other part is to gain
> >> > access to newer features, and reduce the cost of maintaining a high
> >> > quality back port that still adheres to this kABI. By deploying Oracle
> >> > UEK R6 simultaneously to both OL 7 and OL 8, they have effectively
> >> > separated the kernel from the OS distro, allowing for both elements to
> >> > be achieved. This seems like something that could be useful to do for
> >> > the broader EL community.
> >> Red Hat already does this in effect, supporting RHEL 6,7,8 user spaces
> >> on RHEL 7 and 8 kernels, via containers.
> >
> > I'm not sure if I follow your reasoning... If you are saying that
> > "this permits somebody to run Linux 5.4.17 on the host, and the user
> > spaces can be provided by containers", then sure. But, that's not
> > really what Oracle UEK R6 is. With Oracle UEK R6, you can "yum install
> > kernel-uek" on either OL 7.9 or OL 8.3, and in both cases, you will
> > get Linux 5.4.17 installed that you can boot into, on the host.
> >
> > Yes, the userspace is often resilient to changes in kernels - that's
> > how containers generally work well, and that's how Oracle UEK R6 can
> > be so easily applied against an EL 7.x or EL 8.x machines, but
> > actually providing a choice of different kernels to use, is not
> > something that RHEL provides today (at least not something that comes
> > to mind for me, although perhaps I'm missing some specialty
> > repository, such as RHE-V?).
> >
> As for Oracle UEK kernels, the UEK repo also includes some updated
> packages which replace the original distro packages to make things work.
> If you don't need UEK you can remove the UEK kernels, disable the UEK
> repos and do a distro-sync to have a clean again.
> Regards,
> Simon

A "distro-sync" isn't enough. You need to replace *every single RPM*,
and pray that no RPM's have tweaks in the ir '%script' operations that
are not idempotent. It's actually not a bad bet: I've done it for
RHEL, CentOS, and Scientific Linux hosts to pull the host off of or
onto a license.