To NX or not to NX

[Jeremy Katz]

On Mon, 2007-01-01 at 19:40 +0100, Arjan van de Ven wrote:
> On Mon, 2007-01-01 at 13:17 -0500, Jeremy Katz wrote:
> > On Mon, 2007-01-01 at 16:56 +0100, Ralf Ertzinger wrote:
> > > Looking through dmesg on my laptop, I noticed the following:
> > > 
> > > Using x86 segment limits to approximate NX protection
> > > 
> > > While this is certainly nice, the processor is quite capable of real
> > > NX:
> > [snip]
> > > Is there a reason this is not used?
> > 
> > Unfortunately, you have to use a PAE kernel to use real NX :(
> 
> doesn't anaconda default to this on NX capable machines?
> (all NX capable machines have PAE support as well obviously)

We tried doing so with an FC5 test release, but things didn't go so well
so we reverted back for the final.  CONFIG_HIGHMEM64G also isn't that
great for laptops.

The work really needs to get done so that pae can be done at runtime,
much like smp alternatives lets us do for smp.  Separate kernels is
_always_ a losing battle for someone ;-)

Jeremy