[CentOS-devel] CentOS-5 on i586

Manuel Tuthill Manuel at Nebula-IT.co.uk
Mon Apr 7 10:31:09 UTC 2008

> What real life samples are there of hardware that need i586 support? Is
> it just older hardware or is there newer hardware that would benefit
> from i586 support? Do other restrictions apply? Memory constraints, disk
> limitations, specific installation requirements, .....?
> Hugo.

I think it is "newer" hardware also. Newer, as defined by still currently
being actively sold (Geode).

The problem is that the information we require to make a decision is very
hard to come by. No processor manufacture AFAIAW states "this is an
i586/i686 class processor" the simply place the CPU on the market and let
the community deal with it. Further to this the community then interprets
information incorrectly, as in case with the CMOV instruction and the via
EPIA board. 

"The GNU compiler people have assumed that all 686's implement cmov's, so
code compiled for the i686 architecture may not execute on the C3. Code
generated by GCC does not check for these optional features as the intel
documentation says you should"


Also some of Intel's own chips suffer from a problem with PAE instruction
that certain distro's run into.


but this is probably failing away from the issue of i586 to more issues with
current i686.

I believe that there are now only 3 manufactures producing x86 chips, Intel,
AMD and VIA. 

Via chips up to and including the Ezra core have the CMOV issues.
AMD Geode chips appear to be i586, some ultra portable/ low power laptop
appear to be using this chip (OLPC among others)
Intel is still selling i586 class ships for embedded.

There is no reason why most of these can't have decent RAM and or hard disks
these are current and not recently out of production of which there may
still be a still significant amount.

Overall not everyone can run i686 for whatever reason. The fact remains IMO
that there is still a fair amount of need for an i586 image regardless of it
it's for fall back issues or run natively I also believe that this isn't
catered for by Centos 4 with support that run's out in ~4 years.


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