Re: [Xen-devel] [GSoc] GSoc Introduction : Xen on ARM: create multiple guests from device tree

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 28 Mar 2017, Methuku Karthik wrote:
> Hi Stefano,
> 
> Kindly suggest me reading material that could help me understand and
> come up with the proposal.

Sure! For the "Xen on ARM: create multiple guests from device tree"
project, the idea is that on many embedded systems the user knows how
many guests to create beforehand, and usually it is a small number, like
2 or 3. Often these guests don't even have any PV frontends, but just a
set of devices assigned to them. An example could be an extremely simple
guest that only accesses one physical device (which is assigned to it at
boot) and prints messages using the debug hypercalls (see
xen/arch/arm/traps.c:do_debug_trap).

In this scenario, there is no need to wait for Dom0 to boot to create
this second guest (I'll call it Dom1, to distinguish it from Dom0). Xen
could actually create it directly by itself, the same way it starts Dom0
(see xen/arch/arm/domain_build.c:construct_dom0 and
docs/misc/arm/device-tree/booting.txt).

The project is about extending the existing device interface to pass an
additional kernel, initrd, command line arguments for the second virtual
machine. It would also need to include which devices should be assigned
to it. In response, Xen should build the second VM the same way it would
do normally when done via the toolstack (xl/libxl), but it would happen
at boot time, before Dom0 is fully up and running.



For the "Share a page in memory from the VM config file" project, 


> On Tue, Mar 28, 2017 at 1:38 PM, Stefano Stabellini
> <sstabellini@xxxxxxxxxx> wrote:
> > I would also like to take the opportunity to remind you of the upcoming
> > deadline for applications submissions, which is the 3rd of April for
> > GSoC, see:
> >
> > http://marc.info/?l=xen-devel&m=149071502330534
> >
> > The GSoC application system is
> > https://summerofcode.withgoogle.com/get-started/.
> >
> > Please give a look at the Xen Project application template here:
> >
> > https://wiki.xenproject.org/wiki/GSoC_Student_Application_Template
> >
> > It also includes an "Implementation Plan", where you have the chance to
> > explain the implementation plan for the projects you would like to apply
> > for. You can apply for more than one project if you want to.
> 
> Thanks for the reminder Stefano. I will post some questions about my
> implementation plan.
> 
> I would like to spend my time fixing the bug but as deadline is
> approaching , I would like to know the bare essential expected in the
> proposal?

It needs to include the basic milestones and how long you estimate it is
going to take to complete each of them. More details you add, more
you'll show your understanding of the problem.


> >
> > Thanks,
> >
> > Stefano
> >
> >
> > On Mon, 27 Mar 2017, Stefano Stabellini wrote:
> >> Hello Methuku,
> >>
> >> It is great to hear that you are interested in working on Xen on ARM.
> >> It's good that you already know how to build and install Xen on an ARM
> >> board.
> >>
> >> Do you have serial access to your Nvidia Jetson TK1? If not, I would
> >> suggest to setup another test environment based on a different board, or
> >> simply use the ARM Foundation Platform which is a free (as in beer)
> >> software emulator.
> >>
> >> In terms of bug fixes, you could give a look at
> >>
> >> https://xenproject.atlassian.net/projects/XEN/issues
> >>
> >> Most of the items listed are large projects, but some of them are pretty
> >> small, small enough to be a starting point. For example XEN-29 (Add
> >> -fstack-protector support to the hypervisor), XEN-30 (Make out-of-tree
> >> builds work) or XEN-38 (Xen - Embed .config in Xen binary).
> 
> I  started working on XEN-38 for now. But i am also interested to look
> into XEN-30.

Be careful that XEN-30 is longer than it looks because there are lots of
Makefiles to fix. However, even if you don't convert all Makefiles to
support out-of-tree builds but only some, it would still be OK.


> >> Cheers,
> >>
> >> Stefano
> >>
> >>
> >> On Mon, 27 Mar 2017, Methuku Karthik wrote:
> >> > Hi Everyone,
> >> >
> >> > My name is Karthik. I am a first year graduate student in Embedded 
> >> > Systems at University of Pennsylvania. I am avid c, c++ and python 
> >> > programmer.I have 4 years of
> >> > work experience as Embedded Software developer at Airbus.
> >> >
> >> > For the last four months I have been working as a research assistant in 
> >> > PRECISE lab at the University of Pennsylvania, helping Meng Xu (cc.ed) 
> >> > to evaluate the
> >> > performance of the Xen's RTDS scheduler.
> >> >
> >> > I'm interested in the following two projects. I'm happy to work on one 
> >> > of them.
> >> > (1) Share a page in memory from the VM config file.
> >> > (2)  Xen on ARM: create multiple guests from device tree.
> >> >
> >> > I have experience in compiling Xen and installing it on ARM board(Nvidia 
> >> > Jetson TK1). I'm also well equiped in using the xl tool to manage the 
> >> > VMs.
> >> >
> >> > I noticed that I should contribute some bug fixes to be able to get the 
> >> > ticket to the Xen GSoC.
> >> > Do you have some suggestions on how I should start?
> >> > Do you have a list of simple bugs that I can fix?
> >> >
> >> > I'm very interested in the Xen Project. I want to become a Xen 
> >> > contributor in the near future.
> >> >
> >> > Thank you very much for your help!
> >> >
> >> > Best,
> >> > Karthik
> >> >
> >> >
> 
> Best,
> Karthik.
> 

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