GSOC2011 project RTEMS HyperVisor

Mon Mar 21 19:17:08 UTC 2011

Mh. Why do you say that LGPL is insufficient for RTEMS? RTEMS is based on GPL with an exception that is similar to the "Lesser". 

Actually, for the code directly linked to RTEMS (MMU, superuser mode), the license will be the license of the modules that are changed (the SPARC-LEON BSP, for instance) and hence, the RTEMS license. 

For our own code, the plan is to use an "RTEMS-friendly" license that is widely used. 

You say "it was established" that LGPL is not sufficient. Is this documented somewhere? Is there perhaps a rationale for license-related decisions?

Thanks,

Tobias

-------- Original-Nachricht --------
> Datum: Mon, 21 Mar 2011 12:34:39 -0400
> Von: Gedare Bloom <gedare at gwmail.gwu.edu>
> An: Tobias Schoofs <Tobias.Schoofs at gmx.net>
> CC: "å¼ æ–‡æ °" <157724595 at 163.com>, rtems-users at rtems.org
> Betreff: Re: RE: GSOC2011 project RTEMS HyperVisor

> I think it was established that LGPL is not sufficient for RTEMS code
> base. I believe this makes an AIR-based project an unlikely candidate
> for a GSOC project. Especially if the student used the AIR kernel as a
> resource.  Perhaps if the AIR kernel is released under an
> RTEMS-friendly license, a suitable project might be possible.
> 
> Even if a "clean room" implementation of a hypervisor is the intended
> project, I'm not sure it is appropriate for a GSOC at this point in
> time.  My guess is that using RTEMS as a hypervisor requires three
> sub-projects that are all at or beyond the scope of a single GSOC:
> 
> 1) Adding virtual memory / MMU support to RTEMS is a necessary
> pre-requisite to any attempt at making a true hypervisor, and it is a
> large project by itself.
> 
> 2) Adding privileged/unprivileged distinction is also a pre-requisite
> to implementing a hypervisor. Each candidate target will have to be
> identified, and the CPU-specific context switching and interrupt
> handling would need some tweaking to ensure that privilege bits are
> properly managed. As far as I know, most processors just have full
> privilege for the application at all times. This is a large project by
> itself.
> 
> 3) Implement the hypervisor itself involves primarily copying of page
> tables, swapping out guests, exporting a HAL (device drivers), and
> writing handlers for paravirtualized exceptions, hypercalls, and true
> guest exceptions.  This is also a large project.
> 
> -Gedare
> 
> 
> On Mon, Mar 21, 2011 at 10:57 AM, Tobias Schoofs <Tobias.Schoofs at gmx.net>
> wrote:
> > 1) Yes, it does. There is a library that implements all services from
> ARINC 653 Part 1 and a subset of Part2. This library, however, is closed
> software.
> >
> > 2) The AIR kernel is Lesser GPL and, as such, open source.
> >
> > 3) The code will be release very soon, i.e. in the course of the next
> months.
> >
> > I will provide more information in an e-mail directly to you, since this
> is not of general interest to the mailing list.
> >
> > Regards,
> >
> > Tobias
> >
> > -------- Original-Nachricht --------
> >> Datum: Mon, 21 Mar 2011 22:07:39 +0800 (CST)
> >> Von: "张文杰" <157724595 at 163.com>
> >> An: "Tobias Schoofs" <Tobias.Schoofs at gmx.net>
> >> CC: Jean-Jacques.Metge at cnes.fr, rtems-users at rtems.org
> >> Betreff: RE: GSOC2011 project RTEMS HyperVisor
> >
> >> Dear Tobias:
> >> Thanks for your replay, actually i misunderstand the AIR system. And
> the
> >> work AIR system has done is what i want to implement. My thought is
> also
> >> to implement a para-virtualisation hypervisor that can run RTEMS and
> other
> >> OS.(RTEMS as a guest OS). I do not plan to implement a
> full-virtualisation
> >> hypervisor.
> >> I has some question about AIR:
> >> 1). AIR has also implement the ARINC 653 APEX on RTEMS?
> >> 2). All the AIR source code is released  under GPL?
> >> 3). When does AIR source code released? could you send me a copy of
> source
> >> code foracademic research now?
> >>
> >> Wenjie
> >> Best Regards
> >>
> >>
> >>
> >>
> >> At 2011-03-21 21:43:52，"Tobias Schoofs" <Tobias.Schoofs at gmx.net>
> wrote:
> >>
> >> >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.
> >> >
> >> >Regards,
> >> >
> >> >Tobias
> >> >
> >> >
> >> >-------- Original-Nachricht --------
> >> >> Datum: Mon, 21 Mar 2011 20:31:31 +0800 (CST)
> >> >> Von: "张文杰" <157724595 at 163.com>
> >> >> An: "Metge Jean-Jacques" <Jean-Jacques.Metge at cnes.fr>
> >> >> CC: RTEMS Users <rtems-users at rtems.org>
> >> >> 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 cnes.fr>
> >> >> 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 rtems.org
> >> [mailto:rtems-users-bounces at rtems.org]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]. http://www.rtems.com/wiki/index.php/RTEMSHyperVisor
> >> >> [2]. http://air.di.fc.ul.pt/air/?Home
> >> >> [3].http://www.xtratum.org/
> >> >> [4]. http://www.helenos.org/
> >> >>
> >> >>
> >> >> At 2011-03-20 21:50:39，"张文杰" <157724595 at 163.com> 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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