On Sun, Apr 15, 2012 at 02:46:49PM -0500, Kevin K wrote:
> Depending on what special features you might use on your system (virtualization, third party drivers), it might be possible to build a kernel from kernel.org.  I've tried this in the past but since the latest kernel still didn't properly support the broken hardware I didn't pursue it further.


Yes, what you say is possible. I run a few SL5 machines with a custom
built 2.6.34 kernel (the funny hardware requires non-default access
method to PCI config space).

Last I remember, it was not too hard to build a vanilla linux kernel that
booted the SL5 userland. I do remember a few gotchas - some boot scripts expected
some drivers to be loadable modules (I had them compiled into the kernel),
autofs did not work because /dev/random broke (SL5 kernel uses the network
as source of randomness, but vanilla kernel does not, and there is no other
hardware present in the system). Took maybe half a day to sort this all out.
(I am not looking forward to repeat this with the 3.x kernels).


> On Apr 15, 2012, at 1:46 PM, Keith Lofstrom wrote:
> 
> > I'm running S.L. 5.6 on a few machines, and have grown somewhat
> > dependent on it.  However, there are features in the kernel 
> > that comes with 6.2 (like USB3) which I would like to have.
> > 
> > Is it possible to upgrade just the kernel and associated modules
> > and "miscellaneous"?
> > 
> > I assume this is tricky, and fraught with dangers, and the usual
> > cautions (make backups, work on a copy of the disk, tweak yum 
> > updates so they won't regress the 2.6.32 kernel, etc) apply.


I do not see any danger or special caution - if an SL6 kernel would boot
SL5 userland, it should run okey. But you will run into trouble with
userland stuff required to support the kernel - udev, mkinitrd, mdadm & co -
the SL5 stock tools might be too old for the recent kernels.

That said, where I am, lack of support for new hardware is the main reason
we move from SL3 to SL4 to SL5 to SL6.

For new kernel features, you can run mongrel systems with mismatched
userland and kernels, but at some point the cost of diverging
from the mainstream becomes bigger than the cost of moving
all your apps to latest SL. (At which point effort of creating
and maintaining a mongrel system is wasted; while the effort
of moving apps to latest SL is mostly in understanding your apps
and in keeping *them* up to date, which you should do anyway,
regardless).


K.O.



> > 
> > For now, I just want to know whether this is worthy of further
> > consideration, or instead I should set aside a few weeks to
> > upgrade everything then rebuild a lot of poorly written custom
> > apps.
> > 
> > Keith
> > 
> > -- 
> > Keith Lofstrom          [log in to unmask]         Voice (503)-520-1993
> > KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
> > Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs

-- 
Konstantin Olchanski
Data Acquisition Systems: The Bytes Must Flow!
Email: olchansk-at-triumf-dot-ca
Snail mail: 4004 Wesbrook Mall, TRIUMF, Vancouver, B.C., V6T 2A3, Canada