Why distinction between task and thread ?

[Robert Kaiser]

Hello all,

this may be a stupid question, but...

It seems to me that address spaces and activities (to avoid the
words "task" and "thread") are othogal concepts. What is the reason
for L4 to not keep them seperate in it's API ? (i.e. there is
task_new to create an activity _and_ an address space and there is
lthread_ex_regs to create an activity in an already existing address
space). It would seem a lot "cleaner" to me if there was one system
call to create an address space (without any activity in it) and
another one to create an activity, specifying as a parameter
the address space in which it will execute. Is there a reason
(perhaps security ?) why it wasn't done like that in L4 ?

Thanks for any insights.

Rob

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Robert Kaiser                          email: rkaiser at sysgo.de
SYSGO RTS GmbH
Am Pfaffenstein 14
D-55270 Klein-Winternheim / Germany    fax:   (49) 6136 9948-10