[CentOS] RHEL / CentOS Kernel Updates

[Johnny Hughes]

nate wrote:
> Manish Kathuria wrote:
>> How are the updated kernels released by Red Hat / Cent OS related to
>> the latest vanilla kernels ? Are the changes, new features and
>> drivers, etc. available in the newer kernels also ported to the
>> updated kernels released by Red Hat in their entirety ?
> 
> If your comparing RHEL/CentOS kernels to kernel.org kernels they
> are similar but Red Hat adds a ton of patches(v4 is upwards of
> 100+ patches). 

Actually for CentOS-5:

[buildcentos at v20z-x86-64 SOURCES]$ ls *.patch | wc -l
1102

So ... there are 1102 patches in the CentOS-5 kernel

For the CentOS-4 kernel, that number is very similar at 1115.


New features are typically not backported to
> current versions of the kernel, newer drivers are often back
> ported, assuming the driver existed in the RHEL kernel. If the
> driver did not exist then it's much less likely to get included.
> 
>> For the lifetime of a distribution like RHEL 4 or RHEL 5, Red Hat
>> would stick to the same major and minor number of the kernel and would
>> just change release numbers. What  is the relation, if any, between
>> the new kernels and the updates released by Red Hat ?
> 
> They make their systems ABI compatible throughout the lifetime of
> the major version(4.x, 5.x).
> 
> If your looking to stay on the leading edge with kernel updates your
> best off using another distro maybe Fedora or something. If your
> looking for a stable system that you don't have to worry about even
> if it means you have to be more careful about picking what hardware
> you run it on, RHEL and CentOS are good choices.
> 
> You can always build your own kernels on RHEL/CentOS if you wanted,
> or rebuild Fedora kernels and install them on RHEL/CentOS, in most
> cases it should work.

All the rest of what you said is true though ... drivers get backported 
much more frequently than other features.

One thing to consider about new kernels is abi changes ... and things 
(like sar, top, system monitoring tools, etc.) not working because of 
the differences unless they are also upgraded.  Also, /proc changes 
considerably in newer kernels as well ... as will the things that you 
include in /etc/sysctl.conf

Also many times newer things like binutils, mkinitrd and 
module-init-tools will be required with a newer kernel.

Overall ... unless you really, Really, REALLY need a newer kernel, it is 
best to use the one provided by the distribution.

Thanks,
Johnny Hughes

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