Features/ArchitectureSupport - changing what we build for

Chris Adams cmadams at hiwaay.net
Fri Jan 30 21:29:55 UTC 2009


Once upon a time, Bill Nottingham <notting at redhat.com> said:
> As a followup to the discussion on compiler flags, this feature was
> written up to describe a plan for what to do overall about what
> architectures we support. The main points are:
> 
> - install x86_64 kernel on 32-bit OS where appropriate

IIRC, I asked about this a few years ago and got told that there was a
performance hit (not big but measurable) for running the 64 bit kernel
and 32 bit userland.  Maybe that was wrong or is now outdated.

Right now, it is still possible to install on one i686 system and plug
the drive into another, which this could break (installing on i686 and
moving to <i686 has been broken for a long time, so maybe this isn't a
big consideration).

What are the chances GRUB/syslinux could be taught to look at a few
special CPU flags (can you fetch the important flags from real mode?)
and only present "compatible" (as determined by config arguments, not
GRUB/syslinux poking into kernels) boot options?  That would help the
LiveCD case as well.  You could have both 32-PAE and 64 kernels on the
CD and choose at boot time, although that would take up a large amount
of space (so maybe not feasible for LiveCD).

-- 
Chris Adams <cmadams at hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.




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