Snap hangs when accessing a special /dev/file (/dev/vcio) [ubuntu-core 16 / RaspberryPi2]

[Simon Fels]

On 09.11.2016 21:25, Jacques Supcik wrote:
> Thank you Oliver for your constructive feedback.
> 
> I like the idea of a "mailbox-device" and I will open a bug in the
> whishlist of snappy.
> 
> My snap needs also write access to "/dev/mem":
> 
> = AppArmor =
> Time: Nov  9 19:09:52
> Log: apparmor="ALLOWED" operation="open"
> profile="snap.telecom-tower.daemon" name="/dev/mem" pid=3643
> comm="tower" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0
> File: /dev/mem (write)
> 
> Should this also be addressed by the "mailbox-device" interface or
> should I fill another bug for a "physical-memory" interface? Or do you
> have an idea for a better name? Or is there already something available
> for accessing /dev/mem?

This would be definitely a different interface but the more interesting
question is why your app needs access to /dev/mem. That would give blind
access to the whole system memory space which is a highly privileged
operation I would say not many applications will need or even get
because of the obvious access to everything on the system.

Can you elaborate a bit more on what your application is doing with
/dev/mem and why it needs access to the full system memory?

regards,
Simon