Re: Switch GPIO direction on Raspberry Pi using ioctl()

[Marc Balmer <marc%msys.ch@localhost>]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

Am 04.04.15 um 17:19 schrieb Greg Troxel:
> 
> Marc Balmer <marc%msys.ch@localhost> writes:
> 
>> No, once the securelevel is raised all games are final, the GPIO 
>> configuration can not be changed anymore.  That is on purpose.
>> 
>> Whether that rule should be relaxed can be the topic of a
>> discussion.  I could imagine a setting where in runlevel 0 you
>> could specify that certain pins remain changeable, even after the
>> secure level had been raised.
> 
> What's the rationale for GPIO direction being a security issue, vs 
> viewing that as input/output ports?  I can see that hooking up
> some things to gpio might want to be fixed, but that seems like an 
> exceptional case, not the norm.    So perhaps controllable should
> be default, with a lockdown ioctl for people who have a security
> reason to tie this to securelevel.
> 
> Or perhaps I'm missing some obvious use case that's normal.

With a misconfigured GPIO subsystem you can fry your system (not in
all cases, of course), so the idea is to lay down the GPIO layout
early and make it "read-only".

Being able to fry a system should be the exception, not the norm.


-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
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=QoSE
-----END PGP SIGNATURE-----