Re: [Qemu-devel] hw/arm: add Lego NXT board

[Paolo Bonzini]

Il 14/07/2014 20:09, Alexander Graf ha scritto:
> So the protocol basically allows to forward read and write accesses on
> IO memory to processes outside of Qemu.
>
> Get and set transactions are triggered by Qemu on an IO memory read
> operation or write operation respectively. The pipe communication blocks
> Qemu until a value is available/the value was published.

The obvious thing to consider is whether this could be used to 
circumvent the GPL.

I think a generic memory-mapped I/O device interface is not a good idea 
in this respect, also because it's hard to get it right.  But i2c is 
simple enough, and there are so many devices with a 4-page datasheet, 
that I think it would be acceptable.  You could also write an i2c 
passthrough chardev backend that connects to /dev/i2c* and lets the 
guest access slaves in the host.

Paolo

> I like the *-over-chardev idea. This could be a benefit for people who
> want to couple simulators or test oracles for embedded system tests or
> in general to other software in a simple way.