Genode (x86_64) reboots on Thinkpad T420

[Alexander Boettcher]

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:

>> I could reproduce it after same configuration changes in the UEFI BIOS
>> of my test T420. When I set in the UEFI/BIOS the option "Security ->
>> Memory Protection -> Execution Prevention" to disabled, the machine
>> reboots.
>>
>> For my T420 test machine it is set to enabled, and then it works, log
>> attached.
>>
>> Hope it helps,
> Yes, that helps. I had "Execution prevention" disabled too. I thought
> that it may cause problems if enabled, but it is vice versa. So, I
> enabled it again. In case of NOVA and Fiasco.OC kernels, it boots now
> fine with "Execution prevention" enabled. With "hw" kernel, it now stops
> after bender's messages, instead of a reboot, though. I'm sorry that I
> didn't tried with "Execution prevention" enabled, before posting the
> message. Didn't wanted to disturb you with no reason

Nothing to excuse. Now the issue is documented via the mailing list
archive so that other can benefit from it. You're welcome.

> 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.

So, something new learned and now documented ;-)

Thanks,

Alex.

-- 
Alexander Boettcher
Genode Labs

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