[okl4-developer] L4 root task info

[Geoffrey Lee]

On Thu, Nov 06, 2008 at 03:18:44PM -0800, uf65ca wrote:
> 
> can anyone shed some light on this task?  what does it do? is it a user land
> task?
> 

Traditionally the roottask is the address space and the
initial context of execution running in user mode.

Traditionally the roottask is privileged, unlike threads in the system 
threads in the roottask can perform privileged kernel system calls such 
as creating and destroying threads, or perform mapping operations.  
Note: the privilege check for the 3.0 release works differently.


> in a strictly priority based system, what is the right priority for a root
> task? 
> is there is any restriction as how low can it be? does it make sense to make
> it 
> one of the lowest priority task?
> 
> in term of scheduling, is it just another ordinary task? 

By default the initial thread running in the initial address space
starts with the highest priority.  You can make an L4 system
call to lower its priority.  What the priority should be will 
probably depend on how you construct your system.

L4 strictly obeys the priority for threads with different priority
numbers and performs round-robin scheduling within the same priority
number, which includes the initial thread as well as any threads living 
in the initial address space.

	-gl

> 
> TIA
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