[GSoC|virtLayer] HelloWorld sample runs

[Philipp Eppelt]

Hi,

I wrote a new blog post about the clock and interrupt issues
http://phipse.github.io/rtems/blog/2013/07/09/how-late-is-it/

Excerpt:

What we need to provide clock ticks to a partition ...
.. in POK
* Forward interrupts to registered partitions
* Register several partitions to the same interrupt, aka interrupt chaining
* Keep a count for every partition’s pending interrupt
* Checkpointing the time in the scheduler at partition entry and exit

.. in RTEMS
* A time warp function to cover the time, when the partition was not 
scheduled

The post describes the current situation, proposes a meta-handler 
structure for interrupts and how interrupts can be forwarded to the 
partition.


# Questions to be discussed:

## Scheduler Time Checkpoints

The POK scheduler needs to keep track of each partition entry and exit, 
so it can tell the partition how many clock ticks it missed. I haven’t 
come around to take a look at the scheduler implementation and how this 
can be inserted, but on the other hand I think, that pending clock 
interrupts will pretty much have the same effect. They accumulate during 
the time the partition is off-line and are delivered, when it comes 
on-line again.

What do you think?
I would prefer to only mess around with one subsystem at a time.


Regards,
Philipp