Re: [gentoo-hardened] Using the NX bit on VIA C7

[Philipp Riegger]

On 11.01.2007, at 08:39, pageexec@××××××××.hu wrote:

>> I have some problems enabling the nx bit on my VIA C7.
>
> what are those problems exactly?

I found a tutorial and some pages explaining how to use it and that  
the kernel should print something like "NX is enabled now", i  
followed the steps (basically enabling up to 64 GB RAM in the kernel,  
if i remember correctly, it was on the wikpedia page about NX and on  
some redhat page) but i never got the kernel message (dmesg | grep Nx  
should show it to me, shouldn't it?).

>> First i  thought, the Kernel might not know that my processor
>> supports
>> that,  but it shows up in /proc/cpuinfo. So... where do i have to
>> enable  (and use) it and how can i check if it is enabled (and used
>> correctly)?
>
> maybe this affects you:
>
> http://marc.theaimsgroup.com/?l=gentoo-hardened&m=114987924519660&w=2

This seems to be exactly my problem, since it's a 32 bit CPU. I also  
read that before, but i thought it was about grsec or PAX extension  
only and that the kernel itself without PAX or grsec also supports  
the NX bit. Maybe i understood something wron, because it is quite  
confusing when hardware NX and when software NX is used and who  
enables that in the programs (for example, do i have to use special  
compiler flags? Does the programmer of some application has to take  
care of anything?).

Thanks,
	Philipp
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