GSOC2011 project RTEMS HyperVisor

Tobias Schoofs Tobias.Schoofs at
Mon Mar 21 13:43:52 UTC 2011

Dear Wenjie,

your understanding of the AIR system is not 100% correct.

AIR is a hypervisor that uses para-virtualisation.

RTEMS is a guest OS for this hypervisor. The guest has to be prepared (para-virtualised) to run on top of the hypervisor. RTEMS is currently our main target, but there may be other OSes as well (e.g. Linux).

Finally, the AIR hypervisor uses RTEMS *additionally* as hardware abstraction layer (HAL), i.e. the hypervisor itself is based on RTEMS. For this purpose, we have implemented MMU support as well as superuser/user level support in RTEMS.

The code is under Lesser GPL and will be made available to the RTEMS community. 

>From one of your previous e-mails, I got the impression that you plan a hypervisor that does run-time virtualisation. (You mentioned that you do not want to change the guest OS.) I am not sure that you will be able to provide sufficient certification/qualification evidence for such a complex software. At least in areas where ARINC 653 is applied, certification/qualification processes are very demanding. For this reason, available, commercial hypervirsors (VxWorks 653, PikeOS) use para-virtualisation, not full run-time virtualisation.



-------- Original-Nachricht --------
> Datum: Mon, 21 Mar 2011 20:31:31 +0800 (CST)
> Von: "张文杰" <157724595 at>
> An: "Metge Jean-Jacques" <Jean-Jacques.Metge at>
> CC: RTEMS Users <rtems-users at>
> Betreff: RE: GSOC2011 project RTEMS HyperVisor

> AIR/AIR IIseems that it hasimplemented ARINC 653 interface in RTEMS, but i
> do
> not know if these implements is opened. If it is opened we also modify
> their work,
> Because ARINC 653 interface should be based on Hypervisor architecture
> whereas
> AIR implement is based on native RTEMS. XtratuM is a independent
> Hypervisor which
> has nothing to do with other OS, but my thought is to add a Hypervisor to
> RTEMS. Just
> reference the implement of XtratuM
> At 2011-03-21 16:21:12,"Metge Jean-Jacques" <Jean-Jacques.Metge at>
> wrote:
> Hi,
> For my information, what do you exactly intend to do in the frame of this
> GSOC, that would not have been already done, either in the frame of AIR/AIR
> II or in the frame of XtratuM ?
> Best regards
> Jean-Jacques METGE
> French Space Agency
> De :rtems-users-bounces at [mailto:rtems-users-bounces at]De
> la part de ???
> Envoyé : dimanche 20 mars 2011 14:57
> À : 张文杰
> Cc : RTEMS Users
> Objet : Re:GSOC2011 project RTEMS HyperVisor
> Sorry for forgetting add the reference link.
> [1].
> [2].
> [3].
> [4].
> At 2011-03-20 21:50:39,"张文杰" <157724595 at> wrote:
> Hi, all:
> I am a student who is preparing for participating the GSOC2011 RTEMS. My
> interested project isRTEMS HyperVisor [1]. This
> project ‘s ultimate goal is to make RTEMS support to run multiple
> operating systems(like Linux or uclinux) and meantime RTEMS can be
> adapted to fullfill the requirements defined in the ARINC 653 standard. So
> the project is divided into two milestone tasks: 1) add a HyperVisor to
> RTEMS. the design of HyperVisor is compatible with ARINC 653 standard. 2).
> implement ARINC 653 interface in
> RTEMS which can reference the a ESA project named AIR[2].
> Hypervisor, also called virtual machine monitor (VMM), is one of 
> virtualization techniqueswhich allow multiple operating systems.
> For embedded systems it must have real-time capability. And there is also
> a challenge to the resource-constrained embedded
> systems, becausesupport for virtualization requiresmemory protection (in
> the form of a memory management unit or at least a
> memory protection unit) and a distinction between user mode and privileged
> mode, which rules out many microcontrollers. About the implement of
> HyperVisor for RTEMS there are two projects we can reference. First is project
> XtratuM [3] which is a small
> native (bare-metal) hypervisor, now the RTEMS has been ported to XtratuM
> run as a guest OS and its design use ARINC 653 as
> a reference although ARINC-653 is not directly applicable to the
> hypervisor systems. Another project is HelenOS operating
> system [4] which is designed as a relatively small microkernel assisted
> with a set of userspace drivers and server tasks, Its kernel
> is a good reference candidate for the design of Hypervisor.
> This is just my initial thoughts, if there is any inappropriate please
> point out.Do not hesitate to add your comments.
> Wenjie Zhang
> Best Regards

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