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

[Chuck Ebbert]

On Wed, 25 Feb 2009 14:15:37 +0100
Thorsten Leemhuis <fedora at leemhuis.info> wrote:

> On 25.02.2009 13:27, Chris Lalancette wrote:
> > Gerd Hoffmann wrote:
> >> We can also simply do this:
> >>
> >>  - Install PAE kernel if the CPU supports PAE.
> >>
> >> i.e. make PAE the default kernel.
> > 
> > Yes, I really think we should just do this.  It's simple, it means we get the
> > logic right for Xen as well as bare-metal (without any special cases), and the
> > performance hit for those who have PAE and < 4GB isn't that bad, I don't think
> > (although numbers one way or the other would be interesting to see).
> 
> What about compatibility problems? My old laptop had a PAE capable CPU 
> but could not boot a PAE kernel -- I noticed when I was trying a PAE 
> kernel for some tests two or three years ago. I asked a kernel-developer 
> back then if it was worth reporting and I got told that such problems 
> are not unusual and often BIOS or hardware problems. Those likely didn't 
> vanish magically is that statement is correct.
> 
>

The algorithm I posted should handle that. If you support NX or you have >4GB
of memory then it's pretty much impossible for you to have one of those old CPUs.
And all SVM/VMX capable machines support NX so we'd always have the right kernel
for them too.