Re: impossible to access /dev/mem on RPi B+ [Was: Sound issues on RPi B+, Jun's latest image]

[mlelstv%serpens.de@localhost (Michael van Elst)]

domelevo%gmail.com@localhost (Jean-Baka Domelevo Entfellner) writes:

>> I get your point about security concerns, you are right, I am now running
>at securitylevel = 1, which disallows access to /dev/mem. I will take my
>time to go through gpio(4), but for now I really don't have time and I
>would like to do a quick test with my RPi running at securitylevel=0. I
>have been struggling so far to prevent rc or init to raise the
>securitylevel from 0 to 1, it seems I can't see where it happens, I have
>patched /etc/rc/d/securelevel so that it doesn't raise it, I have set the
>securelevel to 0 in /etc/rc.conf, but amazingly for some reason it gets to
>1 maybe after /etc/rc.d/securelevel changes it to 0, so I don't really know
>what brings the securitylevel up to the value 1.


This will not work, if the rc scripts fail to set a securelevel of 1
or more, then the init process will do this for you and you cannot
stop it.

The only way to have a securelevel < 1 after multiuser boot is to
run an INSECURE kernel. I.e. you have to compile it yourself.



-- 
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."