How should anaconda check for PAE? (was Re: arch fun.)

[Will Woods]

On Fri, 2009-02-06 at 10:19 -0500, Bill Nottingham wrote:
> Chris Lalancette (clalance at redhat.com) said: 
> > Do we know if anaconda is going to change
> > to choose kernel-PAE for any machine with the PAE flag, regardless of the amount
> > of memory?
> 
> That's the plan - the patch should be pretty trivial.

I haven't seen this patch yet. As far as I can tell, current anaconda
installs the PAE kernel by default if isPaeAvailable() returns true[1].

isPaeAvailable() uses the (somewhat odd) test of checking to see
if /proc/iomem has a line where the start address is more than 32 bits
long[2] - AFAICT it ignores the cpu flags entirely.

In a discussion on IRC earlier today, cebbert mentioned that we might
want a check more like:

(PAE_flag and >=4GB RAM) or (PAE_flag and vmx_flag and >=1GB RAM)

where vmx_flag is the flag for hardware virt stuff. Is this a good test?

Some further questions:
- Is a PAE kernel required for proper virt support?
- Should we be using the PAE kernel *regardless* of memory size (as
implied above) or do we want some memory requirements?

-w

[1]
http://git.fedorahosted.org/git/anaconda.git?p=anaconda.git;a=blob;f=yuminstall.py;hb=HEAD#l1259
[2]
http://git.fedorahosted.org/git/anaconda.git?p=anaconda.git;a=blob;f=isys/isys.py#l1038