L4 implementations

Gernot Heiser gernot at nicta.com.au
Mon Jun 4 11:22:06 CEST 2007

>>>>> On Mon, 4 Jun 2007 07:43:12 +1200, "Shams" <shams at orcon.net.nz> said:
S> Thanks for the info.
S> 1. After reading up on http://www.ok-labs.com/ I still couldn't find the 
S> following info.

S> Does OKL4 only run on ERTOS or can it run on other architectures like 
S> L4.Pistachio
S> eg. PowerPC, IA32, IA64, see: http://l4ka.org/projects/pistachio/?

not sure what you mean with "only run on ERTOS".

OKL4 presently is supported on x86, ARM and MIPS. Others will be
released in the future.  Some Pistachio ports (like Alpha, Itanium)
aren't presently maintained by anyone. In fact, I don't think anyone
is really maintaining Pistachio on anything but x86 (but I could be mistaken).

S> 2. Since OKL4 is evolving as a commercial project (and being a descendant of 
S> L4.Pistachio)
S> how much contribution is OKL4 making back to the L4 community in particular 
S> L4.Pistachio
S> in terms of API, ABI, Architecture, Documentation etc, I mean for 
S> significant commercial
S> improvements to OKL4 are most/some of them integrated back into 
S> L4-V4/.Pistachio?

Given that OKL4 has forked from L4Ka::Pistachio a couple years ago,
there is a limit to what code can be contributed back. However, OKL4
is distributed under a compatible license, so people are welcome to
take stuff back into Pistachio.

As far as API is concerned, I don't think that the KA Pistachio
maintainers want to go the way OKL4 is going. 

S> 3. Also if L4-V4/L4.Pistachio evolves then doe the changes get followed 
S> through into
S> OKL4.

Maybe, maybe not. KA changes are motivated by different deployment
scenarios, and the code and API has diverged significantly.

S> 4. So OKL4 can be used commercially or in a research environment (free of 
S> charge) but if one
S> wants commercial support/development then they have to pay for it, right? 
S> Sorry just getting my
S> BSD license understanding clarified.

OKL4 is presently licensed under a straight BSD license. You can do
with it pretty much whatever you can do with Pistachio. In addition,
you can get commercial support (services such as porting, system
architecture, training etc). Also, OK has code which builds on OKL4
that is under proprietary licenses.

In addition, while the KA folks have always maintained very high
standards of code quality, they are a research team and cannot
possibly put as much effort into QA as Open Kernel does.


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