To NX or not to NX

[Lamont Peterson]

On Monday 01 January 2007 08:56am, Ralf Ertzinger wrote:
> Hi.
>
> 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:
>
> $ grep nx /proc/cpuinfo
> flags           : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov
> pat clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc pni
> monitor vmx est tm2 xtpr flags           : fpu vme de pse tsc msr pae mce
> cx8 apic mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss ht tm
> pbe nx constant_tsc pni monitor vmx est tm2 xtpr

Are you certain the proc(s) really does/do support nx?  Intel chips are 
infamous for reporting flags for features that they don't actually support.  
For example, on this notebook:

# grep flags /proc/cpuinfo
flags           : fpu vme de pse tsc msr pae mce cx8 mtrr pge mca cmov pat 
pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm

I know for certain that this proc does not support HyperThreading or PAE, but 
there they are anyway.

> Is there a reason this is not used?

Sorry, I can't comment on this as I have no knowledge about what the fedora 
kernels configured regarding NX.

> kernel is 2.6.19-1.2891, processor is a Intel Core Duo CPU L2400
-- 
Lamont Peterson <lamont at gurulabs.com>
Senior Instructor
Guru Labs, L.C. [ http://www.GuruLabs.com/ ]

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