[Developer] Newer names, newer documentations...

[Gernot Heiser]

Hi Joonion,

You will find the all-new and extensive OKL4 manual on the download
page. Other documentation will appear over time.

>>>>> On Mon, 23 Apr 2007 23:51:54 +0900, "Joonion Bae" <joonion at gmail.com> said:
JB> [...]

JB> And back to the virtualization.
JB> I am still confusing at the diff. between VMM and microkernel.

JB> OKL4 supports a good virtualization through microkernel.
JB> Fast, Secured, Multiple OSes could be running on OKL4.

Virtualisation requires a hypervisor as the lowest software layer. The
functional requirements on a hypervisor is a subset of the
requirements on a microkernel, hence, a good microkernel (like OKL4)
has all it needs to be an excellent hypervisor. In addition, OKL4
gives you things a straight hypervisor doesn't give you, especially
high-bandwidth, low-latency cross VM communication, fine-grain
encapsulation, and the ability to run subsystems with a minimal
trusted computing base.

The classical VM paradigm is not suited for embedded
systems. Virtualisation is all about resource partitioning and strict
isolation of subsystems. While OKL4 can do this as well as any
hypervisor, it isn't what you want in an embedded system. On an
embedded platform you don't normally run subsystems that have nothing
to do with each other. To the contrary, everything on an embedded
system must cooperate. This requires high-performance yet secure
communication primitives, with full control over system
resources. This is what OKL4 gives you, and what no other technology
out there gives you.

See http://www.ok-labs.com/technology/ for more info.

JB> Para-virtualization or Pre-virtualization seems to be another choice.
JB> VMMs like VirtualLogix or Xen running on ARM platform sounds good.

As Hal said earlier, so-called hypervisors that run guest operating
systems in privileged mode forfeit some of the core advantages of
virtualisation. In particular, the guest OS must be trusted.

Xen wasn't designed for embedded systems. It's *much* bigger than
OKL4, and doesn't provide high-performance communication. It's a
system for enterprise-style virtualisation.

JB> FASS is achieved in Wombat. But most people want to run their
JB> legacy linux kernel and applications on it.
JB> Should I change the existing Embedded Linux to run on OKL4?

Unless you have hardware support for virtualisation (such as
TrustZone), *every* guest OS must be modified (para- or
pre-virtualised) to run on a hypervisor. You cannot run an unmodified
Linux kernel on any hypervisor on say an ARM9.

Gernot