Genode (x86_64) reboots on Thinkpad T420

[Valery V. Sedletski]

On Fri Mar   8 15:57:20 2019 Alexander Boettcher <alexander.boettcher at genode-labs.com> wrote:
> On 08.03.19 11:25, Valery V. Sedletski via users wrote:
> > On 07.03.19 23:10, Valery V. Sedletski via users wrote:
> > > Alexander Boettcher wrote:
> 

> > P.S.: I wondered why 32-bit works fine, but cnuke on the irc channel
> > supposed that it could be because of NX bit, which is enabled on 32-bit
> > normally only if PAE is enabled.
> 
> Some kernels don't use PAE in 32bit, or in the kernel configuration it
> is not enabled. That means the kernels in 32bit just don't use it and
> therefore they booted up.
> 
> In 64bit mode the NX-bit is supposed to be supported by all CPUs, never
> have seen (until today) that you can disable such a security feature. It
> makes no sense for modern OSes at all.
> 

IIRC, the bit prevents execution of code in DATA segments (?), It's supposed as a measure against viruses. Usually, such measures break some programs, which aren't viruses. So, I suspected that enabling the NX bit could break something, not vice versa, but it appears, I'm not right. I am still wondering why disabling it can cause traps or reboots. Do the kernels functionality depend on the NX bit somehow?

> So, something new learned and now documented ;-)
> 
> Thanks,
> 
> Alex.
> 

Thank you very much for help too!

WBR,
valery

> -- 
> Alexander Boettcher
> Genode Labs
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