On 2009-04-10 22:44, jecel at merlintec.com wrote:
> Michael van der Gulik wrote on Wednesday, April 08, 2009 9:39 PM
> > On 4/9/09, Jecel Assumpcao Jr wrote:
> > > My proposal is to use a separate system image and a user image. You
> > > can't allow full access without also allowing accidents, but a little
> > > structure goes a long way towards eliminating the latter. I described
> > > this in a post to the SqueakNOS list:
> >
> > ...so you'd have one acting as the operating system, and one acting as
> > the application?
>
> Exactly, though I see no reason not to allow many application images 
> at the same time. That would make using both Sophie and Scratch in a 
> machine with no underlying OS more practical, for example.
>
> For the operating system image, I would actually have two: an 
> emergencySystem.image which would boot up initially and then look for 
> a currentSystem.image to which it would transfer execution after 
> setting up a watchdog timer. If the currentSystem.image is not found 
> or it fails to execute well enough to disable the timer (resulting in 
> a reboot) then the emergencySystem.image would execute all by itself 
> and present the user with enough resources to restore the machine to a 
> usable state.
>
> The currentSystem would be a far smaller image (I imagine less than 
> 1MB) and wouldn't have any GUI or stuff like that. It would do all of 
> the low level stuff for the application images and would normally be 
> safe from anything that happens in these images. But it should be 
> possible to mess around the currentSystem.image from inside one of the 
> application images running remote tools (see Spoon). This would 
> require a series of steps on the user's part and would not normally 
> happen by accident. This is a reasonable balance between full freedom 
> and safety, in my opinion.
>
> Note that practically everything I have described above already exists 
> - it is mostly a matter of gathering the parts into a coherent system.
What lack is the last 20% of the work which takes 90% of the time and is 
5% as interesting as the rest of the system ;-)

The SqueakNOS on XO need work on the TCP stuff to ease communication to 
the rest of the world.
I think image saving needs work as well, so changes to the system is 
kept current.
I like the idea of using different images for different apps, but that 
need work to make it appear seamless.

Karl


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