[CentOS-devel] moving the CR repo into mainstream release

Fri Nov 18 19:58:16 UTC 2011
Greg Lindahl <greg at blekko.com>

> What stability problems would you expect from updates beyond a point
> release?  The whole point of an 'enterprise' distribution is the
> effort they make to not break api's across a whole major-rev's life.
> Would an upstream system break if you selectively update packages
> beyond a point release without doing a full update?

Upstream backports big chunks of kernel code into point releases,
changing the kernel api/abi. You'll notice this if you have special
HPC hardware which need updated kernel modules. You'll also notice
this if you really care about performance. We carefully test
point-release kernels and only do casual testing of intermediate
kernels, because the intermediate kernels are the only ones with small
changes. (Ditto for HPC hardware vendors...)

Upstream sometimes does big updates of a few user-space rpms in point
releases, because it has become too hard to backport security fixes.
Firefix is a common example, and there are others. These sorts of
changes usually don't happen in an intermediate update.

Upstream has never tested the combination of packages available in CR.
It's easily possible that package A depends on package B being updated
to avoid an obscure bug, but the CR only has A's update. Gentoo users
are quite familiar with this issue.

It is likely that many CentOS users think they aren't bothered by
these issues, but CentOS is used in a lot of production environments,
and I bet there will be some surprises.

-- greg

p.s. Thanks for producing such a good distro!