[SqNOS] Small fix and questions

[Javier Pimás]

On Sun, Aug 14, 2011 at 6:38 PM, Ryan Macnak <rmacnak at gmail.com> wrote:

> Hi,
>
> The keyboard event integration needs a small change to work with
> Squeak4.2.  In PS2Keyboard>>newKeyboardEvent:type:
> at: 6 put: 0
> needs to be
> at: 6 put: aCharacter asciiValue
> The Pharo-based image continues to work with this change.
>

excelent! save it locally and send it to me so I can upload it to
squeaksource. If you keep working I think richie may give you write
permissions.

>
> I notice the idle primitive is implemented with a HLT now, but
> SqueakNOS still uses full processor for me.  Any idea why?
>

There must be something wrong, because it doesn't (use to) happen to us. On
a core i3 380 laptop, over VMWare it should take 5% of CPU. I'd bet there is
a smalltalk process running in background hogging the cpu. Does it happen
with all images (squeak and pharo)?


>
> I see what looks like work-in-progress for paging support.  What would
> paging support be for?  A traditional operating system would use it to
> isolate processes in separate address spaces, but Smalltalk is already
> pointer safe.
>

Hardware paging requires many things, so yes, it's a work in progress.
Buuuut
there's a lot of things solved now. That includes: 1. a st model of X86 mmu,
so that you can manage memory directly in smalltalk. 2. A mechanism to
handle page fault interrupts via callbacks, so that when they occur, a st
method is called in order to handle their resolution. 3. A st model of ATA
disks and FAT32 filesystems, so that you could mix them with paging.
4. A good and heavy usage example, which is to save the image. When
saving the image, we set all the image as read only and then save its
contents. Should a page fault occur for writing, we place a copy of the
original contents in a buffer and then we set the page as read-only.

There still isn't a way for offloading segments of the image to disk, we
didn't
take the time to develop it, so we can't swap memory yet. But as there is
disk support now, the way is cleared for that.

Lastly, a problem of smalltalk (at least in Pharo/Squeak) is that there
isn't
any kind of isolation, all processes live in the same address space. It
would be really good to have a way of segmenting the image, having separate
processes in separate address spaces, an some kind of protection. I think
that's the next step.



> Finally, what license is SqueakNOS under?
>

squeaksource.com says MIT, but Richie should know better.


>
> Thanks,
> Ryan
>

Hope it helps!

Best,
     Javier.


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-- 
Lic. Javier Pimás
Ciudad de Buenos Aires
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