New MB recommendations

[Bill Campbell]

On Tue, Feb 27, 2007, Tony Alfrey wrote:
>Net Llama! wrote:
><snip>
>> 
>> The initrd has absolutely nothing to do with the CPU.  Its tied to your 
>> kernel, which is built for whichever CPU it was built against.
>> 
>
>Well, that's good.
>
>OK, so where does the *kernel* get built for some off-the-shelf distro? 
>  If I install SuSE  on a P2 box or a P4 box, is the kernel that comes 
>with the distro simply a pre-compiled kernel for the i386 (I think 
>that's the expression) or when I install the distro, is a specific 
>kernel compiled that is optimized for my CPU?  And since I have 
>re-compiled the kernel on my tweaked Caldera box (just a P2), would I 
>expect that kernel on that drive to boot on the P4?

During installation SuSE selects the kernel based on the CPU and
its configuration.  The machine I'm running on is running SLES-10
with an Athlon 64 X2 Dual Core, kernel version 2.6.16.21-0.8-smp.
Another SLES10 system we have here running an Athlon 64, is
running 2.6.16.21-0.8-default.  Looking at some other machines
running SLES9 and SLES10, the kernel type seems to be either smp
or default with no distinction between Intel and AMD.

I can't speak to other distributions as I haven't done any
serious work with others recently.

As I said in an earlier post, I have run into difficulties
running software compiled with gcc-3.4.3 and gcc-4.0.3 in which
some programs compiled on Intel throw illegal instructions when
run on AMD CPUs.  The only package that I can remember that did
this the gmp arbitrary precision math package used by the clamav
a/v software, and it's entirely possible that gcc optimizes this
for the CPU family.

This weekend I had to rebuild the machine here that does our
dialup uucp and HylaFAX because the primary SCSI drive died, and
I couldn't get it to boot off the newer SCSI drive.  This machine
had been running SuSE 9.0 Pro on SCSI disks.  After installing a
new PATA drive, a new SuSE OS, and 241 binary OpenPKG RPMS built
on an Intel Celeron 2.666GhZ, the machine was doing some Strange
Things(tm) on occassion.  This machine has a 32-bit AMD Athlon 2500+.

After rebuilding all the OpenPKG packages on the new machine
yesterday, there haven't been any problems.

I think the bottom line is that it's best to have things compiled
on the same type of CPU, preferably built on the destination
system to avoid possible problems caused by compiler optimization.

Bill
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