I'm curious about how Oracle is patching the Red Hat-compatible kernels in OEL v6 for example. I've noticed that Oracle will release patches for Red Hat kernels and then will increment the patches with .0.1 and the changelog will show sometimes just that they added their own Enterprise Linux name, or they will make actual changes to the kernel.
So I am just wondering what Oracle is usually changing and why they are patching the Red Hat-compatible kernels with bug fixes of their own.
Let me provide an example from OEL v5 actually.
Here is a kernel from OEL v5.10 which has been incremented slightly from the actual Red Hat kernel of 2.6.18-371.1.2. My big question is: why is Oracle patching these kernels when they are supposed to be Red Hat kernels and OEL deployed in this manner is supposed to be virtually identical to Red Hat Enterprise Linux?
# rpm -q -p kernel-2.6.18-322.214.171.124.1.el5.x86_64.rpm --changelog | less
- [mm] Patch shrink_zone to yield during severe mempressure events, avoiding
hangs and evictions (John Sobecki,Chris Mason) [orabug 6086839]
- [mm] Enhance shrink_zone patch allow full swap utilization, and also be
NUMA-aware (John Sobecki,Chris Mason,Herbert van den Bergh) [orabug 9245919]
- fix aacraid not to reset during kexec (Joe Jin) [orabug 8516042]
- [xen] PVHVM guest with PoD crashes under memory pressure (Chuck Anderson)
- [xen] PV guest with FC HBA hangs during shutdown (Chuck Anderson)
- Support 256GB+ memory for pv guest (Mukesh Rathor) [orabug 9450615]
- fix overcommit memory to use percpu_counter for el5 (KOSAKI Motohiro,
Guru Anbalagane) [orabug 6124033]
- [ipmi] make configurable timeouts for kcs of ipmi [orabug 9752208]
- [ib] fix memory corruption (Andy Grover) [orabug 9972346]
- [usb] USB: fix __must_check warnings in drivers/usb/core/ (Junxiao Bi) [orabug 14795203]
- [usb] usbcore: fix endpoint device creation (Junxiao Bi) [orabug 14795203]
- [usb] usbcore: fix refcount bug in endpoint removal (Junxiao Bi) [orabug 14795203]
I'm afraid you may have to ask someone from Oracle support to get the right answer. Oracle does not officially provide support via the OTN forum.
I think the goal of Oracle Linux is to provide the best support for Oracle's database products. It requires to implement product specific optimizations or patches that are not released by Red Hat. Unfortunately, Red Hat is afraid to loose customers to Oracle Linux and has changed kernel patching policies, which make it very difficult for anyone else to provide patches to the kernel. Which is a good reason to use the more modern Oracle UEK kernel instead of the Red Hat kernel, but apparently some people have to use the RHCK kernel due to specific hardware or other requirements.
Perhaps the following info is related: