Heads-up: Requiring PAE for running Xen

[Axel Thimm]

On Wed, May 17, 2006 at 02:07:59PM -0400, Jeremy Katz wrote:
> As we move forward with Xen enablement, there's a desire for
> being able to access more than 4 gigs of RAM on 32-bit Xen hosts.  The
> options for handling this are
> 1) Another kernel.  This is bad due to 
>    a) we're running out of CD space already
>    b) keeping things matched up between the HV and the guest kernels
>    c) migration is worlds of pain with two types of kernels
> 2) Switch the 32-bit xen kernels to require PAE.  For most "current"
> non-laptop hardware, this is a non-issue.  It does mean that xen won't
> work a lot of earlier PentiumM laptops
> 3) Do nothing, tell people to use 64bit if they want more than 4 gigs of
> RAM
> 4) Make the PAE code handled at runtime.  This is a pretty non-trivial
> amount of work :)
> 
> Given these, we're looking at going with #2 and thus only having Xen
> work on PAE-capable hardware in the development tree.  And we're
> planning to try to execute this switchover the beginning of next week.
> Note that this will not affect bare metal installs at all.
> 
> Jeremy

Judging from the feedback I would derive that

o in later production environments usually hardware with PAE support
  will be used.

o during development, though, people would like to test xen on their
  non-PAE hardware like their laptops.

So maybe rawhide should continue with both PAE and non-PAE kernels and
decide on dropping the non-PAE when a release is about to be cut?
Otherwise you will keep out a large amount of (admittedly casual)
testers.

And maybe until then the runtime handling emerges out of the blue and
solves all issues. It's that improbable that it has to happen ;)
-- 
Axel.Thimm at ATrpms.net
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