[Soekris] net 5501 and RHEL5.2

[Chris Babcock]

Przemyslaw Maszenda wrote:
> Hi
> 
> I try to boot and install RedHat Enterprise Linux 5.2 on net5501-70 
> (with sandisk CF but this doesn't matter, I think), but without success.
> 
<snip>
> 
> 
> I know, I lame :), but what should I do run to RHEL5.2 with net5501-70?
> 
> 1) Should I recompile kernel? (For me is important to have kernel 
> version and patchlevel exactly as RHEL5.2, changing arch is acceptable)
> 
RedHat does not distribute a RHEL5.2 binary kernel that supports 
anything other than a i686 or greater CPU, which means that out of the 
box RHEL5.2 WILL NOT RUN on a Soekris.  It is completely possible build 
your own kernel, and use a different CPU type.  Unfortunately, in all of 
my past experiences with vendors and RHEL, you will be expected to run 
the BINARY kernel as distributed by RedHat.  I have NEVER run into a 
situation where a vendor would support custom built kernels on RHEL, 
even built from RedHat's source packages.  In addition, RedHat HEAVILY 
modifies their kernels, and if they are building their kernels _only_ 
for i686 you have no assurance whatsoever that there aren't RedHat 
specific patches that have been added that depend on using i686 only 
constructs, regardless of how you build the kernel.

If this is being done as a personal or academic exercise this can be 
"made to work".  The easiest way is to use a kernel downloaded from 
kernel.org, and tweaked to have similar settings to a RHEL kernel, but 
set for a i586 CPU (or lower).  Yes, some things will not work, but most 
userspace programs will work.

If this is for a *production* system, it's critically important that you 
either choose a different distro (that supports Soekris class hardware) 
or use hardware certified for RHEL.  In all honesty, I have had 
HORRIBLE, CATASTROPHIC DATA LOSS on multiple occasions using RHEL on 
non-RHEL certified hardware.  The patches that RedHat applies to their 
kernels are NOT community tested, they are ONLY TESTED ON HARDWARE THEY 
HAVE CERTIFIED.  As a result, catastrophic bugs and regressions can and 
sometimes *DO* occur on hardware they haven't tested.

The only reliable, safe way to run RHEL, is to run it on certified 
hardware.  In fact, if you are running an app that is certified on RHEL, 
the certification only applies if all of the hardware is also RHEL 
certified.

> 2) For best performance and stability what should I choose in 
> menuconfig. Which arch and CPU?
> 
> PS.
> I checked that over PXE I could boot kernel from RHEL4.6 ...
> 
> thanks.