That is not entirely true. Red Hat does not ship patches that are not accepted upstream,
They sometimes claim this, but it is not actually true. I have occasionally dug a bug fix out of RHEL 5 and sent it upstream.
but they do ship heavily patched kernels. I don't think Linus is still releasing 2.6.18, yet Red Hat Enterprise Linux 5 keeps growing new kernel based features (KVM being a notable example).
This has two good things. First, it increases the quality of the patches that Red Hat applies to the kernels it ships.
Still, they are backporting so far that there is plenty of opportunity to miss subtle semantic dependencies. For example, RHEL 5.4 added GRO but not the change to make TCP delayed-ACK work correctly with LRO or GRO.
Copyright © 2017, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds