[openbeos] Re: Architecture

"David A. Rogers" <darogers@xxxxxxxxxxxxx> wrote:
> I'm a little confused about the overall architecture of OBOS.  I'm 
> looking
> at the architecture graphic in the OReilly book.  Hardware on the 
> bottom.
> Microkernel above that.  Servers above that.  Software Kits talk to
> servers and microkernel.  Applications on top.
> 
> Where do drivers fit in this picture?  When writing drivers for OBOS, 
> are
> they OBOS drivers or NewOS drivers?

(I'll take a shot at this.. Feel free to correct me)

I think BeOS may have started as a true microkernel,
before the PowerPC and x86 releases.
Perhaps Marco Nelissen can shed some light on that.
It was a great buzzword. Be used it in their marketing,
but I'm not sure there is a clear definition of what it really is.

The NewOS kernel and the OBOS adaptation of it 
is not a microkernel in the QNX or Mach sense.
Neither is it monolithic.

Our device drivers run in kernel-space.
They're loaded on demand, and unloaded when not in use.

(Video drivers are loaded by the app_server though,
similar to how X works in Unix.)

OBOS uses the NewOS kernel to replace the original
BeOS kernel. NewOS was not a perfect match, but still 
close enough. The kernel team is working on making 
it more BeOS-like, so that we maintain binary 
compatibility with BeOS R5 applications. A fork was 
necessary to avoid forcing these changes on the 
NewOS project.

As the kernels of OpenBeOS and NewOS are drifting apart  
(AFAIK) our drivers must be considered simply BeOS drivers,
or whatever the new name of OBOS will be.. 

(SpeedOS? ;)

/Jonas Sundström.                        www.kirilla.com

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