Re: L4::BSD, Subclass your OS

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On May 11, 2006, at 1:05 PM, ernesto bascon wrote:

> As I could understand, you want to do something similar to L4Linux  
> but using BSD kernel instead of the Linux kernel and programming  
> the drivers are as plugins on top of the L4 microkernel, doesn't you?
>
> A lot of things are not enough clear to me yet, by example, how the  
> shared libraries are handled? they are loaded by every module? is  
> there some "library manager"? or should be a library manager  
> implemented as module? if it is so, the routine calls are done via  
> IPC too?
>

I definitely understand your thoughts, but I don't think you're  
completely clear on how shared libraries work in L4Linux (http:// 
os.inf.tu-dresden.de/L4/LinuxOnL4/overview.shtml). I'm not 100%  
certain, but as far as I can tell, since Linux runs as essentially  
"an application" (i.e. user-land address space) on top of the L4  
kernel, the Linux kernel is responsible for managing all that shared  
library nonsense, in effect L4::Pistachio runs L4Linux in the address  
space between 20 and 65 (very generalized from my understanding of  
the process) and then L4Linux manages the address space between 20  
and 65 as if it were running on any other machine, so if it decides  
to manage shared libs at 60-65, then that's fine, Linux applications  
would be directed to the address space between 60 and 65 to link up  
to those shared libraries.

Feel free to chime in (anybody) if I'm mistaken here.

In implementation I don't think an L4::BSD system would perform much  
differently, with the exception of working in some of Darbat's IOKit  
stuff (that unified driver idea really fascinates me ;))

Basically, I think we have two fantastic references to look at when  
deciding on how such an OS should be built, L4Linux, and L4/Darwin.  
(L4Linux moreso, since L4/Darwin seems to been more of "merely" (no  
small task) taking Mach in, and switching it for L4, and emulating  
anything else that Xnu did underneath Darwin)

Feel free to stop by #l4bsd, early a KDE and opendarwin developer  
dropped by as well as the project manager from NICTA's Darbat  
project, both offering up some very useful opinions and ideas.

Cheers,

- -R. Tyler Ballance

p.s. sorry about the triple-PGP signing of the initial post, GPGMail  
went nuts on me.
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