L4 implementations

[Gernot Heiser]

>>>>> On Sun, 3 Jun 2007 19:44:04 +1200, "Shams" <shams at orcon.net.nz> said:
S> Hi Marcus,
S> Thanks for the info.

S> 1. Since L4.Pistachio and L4.Fiasco both are now implemented in C++ and
S> L4.Pisctatio
S> implements the "latest" L4 API ie. L4-X.2 (L4-V.4), does this conclude that
S> L4.Pistachio
S> is more superior implementation than L4.Fiasco?

There are presently 3 actively-maintained versions, Fiasco, Pistachio
and OKL4 (a descendent of Pistachio). The APIs are evolving as R&D is
progressing (although I guess it's fair to say that OKL4 is evolving
most rapidly, for better or worse). 

S> 3. With L4.Linux is this just a virtualised version of Linux to run on
S> either L4.Pistachio or L4.Fiasco
S> or is this just another implementation of Linux that implements the L4 API?

L4.Linux is a para-virtualised Linux on L4, but it isn't the only
one. Karlsruhe has their afterburned Linux that runs on Pistachio, and
NICTA/OK have Wombat, which is a portable para-vitrualised Linux that
runs on OKL4 on several architectures (x86, ARM and MIPS).

S> 4. If I want to use L4 for research purposes should I be using L4.Pistachio
S> or L4.Fiasco
S> or L4.Linux?

L4Ka::Pistachio and Fiasco (like the OKL4 kernel) are microkernels,
L4Linux isn't (it's a paravirtualised Linux on L4, as is Wombat).

You can use either of the three for research, including OKL4 (just
because it's commercial doesn't mean it cannot be used for research
purposes, to the contrary, it's a very mature platform given that it
is running in consumer products).

Gernot