OS porting on Xen on ARM

OS porting on Xen on ARM

[Dario Faggioli]

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Hi Arianna!

First of all, some context for the Xen on ARM people that I'm Cc-ing.
Arianna will be working on porting an embedded --targeted specifically
at automotive-- OS on top of Xen on ARM. The OS is Erika, and Claudio
could give any kind of information about it (and correct me, if I said
something wrong):
http://wiki.automotive.linuxfoundation.org/index.php/Erika_Enterprise_Open-Source_RTOS
http://erika.tuxfamily.org/

This mail is mainly meant at giving her some clues and pointers about
how to get on with it. I'll do my best but, given it's ARM, with which
I'm not super familiar with, feel free to chime in and fill the gaps or
correcting the mistakes I may make.

The goal is (for now) to have the Erika OS running as a DomU, on top of
a Linux Dom0. She'll be using a Cubie* as a platform. There is
definitely some similar/related activity going on (writing/porting
embedded OSes on Xen) these days, but, if I'm not mistaken, this would
be the first example of doing it on ARM (except, perhaps, from Julien's
work on FreeBSD, but that's not embedded! :-P)... Pretty cool, eh?

Arianna, all the information about running Xen on Allwinner is here:
http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/Allwinner
Also, there is a thread right about this on xen-devel going on in these.
Perhaps you can have a look at it:
http://bugs.xenproject.org/xen/mid/%3CWC20131216075445.88000B@perkbv.com%3E
(look at the whole thread, e.g., via marc.info).

About Xen in embedded in general, there has been a thread recently,
which may contain some useful info. In case you want to skim through it,
here it is:
http://bugs.xenproject.org/xen/mid/%3C1384802050.16918.219.camel@Solace%3E

About how a small, and an hopefully easy enough to understand, OS that
runs as a Xen DomU looks like, check out Mini-OS in the Xen Source tree:
http://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=extras/mini-os;hb=HEAD
As I said, it's small, and definitely simpler, for instance, than Linux,
but it's quite feature complete, which is something you probably won't
need.

In fact, there are people working on even smaller and simpler solutions,
for the most diverse purposes. Some links below (again, check the entire
threads):
http://bugs.xenproject.org/xen/mid/%3Cem4158cadd-9eab-4a26-80ba-b3a3b311bee2@smartin-alien%3E
http://bugs.xenproject.org/xen/mid/%3Cem40e5807b-ac20-4c2a-ad66-d1056397e07b@smartin-alien%3E
http://bugs.xenproject.org/xen/mid/%3Cembc004940-1dbb-4924-bbab-76901c75e44e@smartin-alien%3E
http://osdir.com/ml/general/2013-12/msg26912.html
http://bugs.xenproject.org/xen/mid/%3C723A93B1-0345-42C6-949B-F6070CE40043@recoil.org%3E

Simon also sent the code out already, here: https://github.com/FurryFuttock/micro-pv
For anything about MirageOS: http://openmirage.org/ , https://github.com/mirage/

In case you need something bigger, Julien ported FreeBSD on Xen on ARM
(as a DomU). That lives here (Julien, correct me if I'm wrong):
http://xenbits.xen.org/gitweb/?p=people/julieng/freebsd.git;a=shortlog;h=refs/heads/xen-arm
I expect this to be super-overkill, but perhaps it could help to get an
idea of what an actual port (rather than a 'write from scratch') would
require.

Last but not least, the hypercall interface official documentation is
all in the public header files, in the repository, as well as here:
http://xenbits.xen.org/docs/unstable-staging/hypercall/index.html
http://xenbits.xen.org/docs/unstable-staging/hypercall/arm/index.html

That is all for now I guess... Ask if there is anything you do not
understand that you think this community could help with. :-)

Best Regards,
Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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Re: OS porting on Xen on ARM

[Simon Martin]

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Good luck Arianna.

When I started my micro-pv implementation it took me a long time to get 
anything to run. It eventually ended up being that I hadn't set the 
XEN_INTERFACE macro in the makefile. Please don't get caught out by that 
one! The rest was reading the mini-os code, the documentation, web 
search engines, and asking questions on this mail list.

Regards.


On 17/12/2013 08:05:45, "Dario Faggioli" <dario.faggioli@citrix.com> 
wrote:

>Hi Arianna!
>
>First of all, some context for the Xen on ARM people that I'm Cc-ing.
>Arianna will be working on porting an embedded --targeted specifically
>at automotive-- OS on top of Xen on ARM. The OS is Erika, and Claudio
>could give any kind of information about it (and correct me, if I said
>something wrong):
>http://wiki.automotive.linuxfoundation.org/index.php/Erika_Enterprise_Open-Source_RTOS
>http://erika.tuxfamily.org/
>
>This mail is mainly meant at giving her some clues and pointers about
>how to get on with it. I'll do my best but, given it's ARM, with which
>I'm not super familiar with, feel free to chime in and fill the gaps or
>correcting the mistakes I may make.
>
>The goal is (for now) to have the Erika OS running as a DomU, on top of
>a Linux Dom0. She'll be using a Cubie* as a platform. There is
>definitely some similar/related activity going on (writing/porting
>embedded OSes on Xen) these days, but, if I'm not mistaken, this would
>be the first example of doing it on ARM (except, perhaps, from Julien's
>work on FreeBSD, but that's not embedded! )... Pretty cool, eh?
>
>Arianna, all the information about running Xen on Allwinner is here:
>http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/Allwinner
>Also, there is a thread right about this on xen-devel going on in 
>these.
>Perhaps you can have a look at it:
>http://bugs.xenproject.org/xen/mid/%3CWC20131216075445.88000B@perkbv.com%3E
>(look at the whole thread, e.g., via marc.info).
>
>About Xen in embedded in general, there has been a thread recently,
>which may contain some useful info. In case you want to skim through 
>it,
>here it is:
>http://bugs.xenproject.org/xen/mid/%3C1384802050.16918.219.camel@Solace%3E
>
>About how a small, and an hopefully easy enough to understand, OS that
>runs as a Xen DomU looks like, check out Mini-OS in the Xen Source 
>tree:
>http://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=extras/mini-os;hb=HEAD
>As I said, it's small, and definitely simpler, for instance, than 
>Linux,
>but it's quite feature complete, which is something you probably won't
>need.
>
>In fact, there are people working on even smaller and simpler 
>solutions,
>for the most diverse purposes. Some links below (again, check the 
>entire
>threads):
>http://bugs.xenproject.org/xen/mid/%3Cem4158cadd-9eab-4a26-80ba-b3a3b311bee2@smartin-alien%3E
>http://bugs.xenproject.org/xen/mid/%3Cem40e5807b-ac20-4c2a-ad66-d1056397e07b@smartin-alien%3E
>http://bugs.xenproject.org/xen/mid/%3Cembc004940-1dbb-4924-bbab-76901c75e44e@smartin-alien%3E
>http://osdir.com/ml/general/2013-12/msg26912.html
>http://bugs.xenproject.org/xen/mid/%3C723A93B1-0345-42C6-949B-F6070CE40043@recoil.org%3E
>
>Simon also sent the code out already, here: 
>https://github.com/FurryFuttock/micro-pv
>For anything about MirageOS: http://openmirage.org/ , 
>https://github.com/mirage/
>
>In case you need something bigger, Julien ported FreeBSD on Xen on ARM
>(as a DomU). That lives here (Julien, correct me if I'm wrong):
>http://xenbits.xen.org/gitweb/?p=people/julieng/freebsd.git;a=shortlog;h=refs/heads/xen-arm
>I expect this to be super-overkill, but perhaps it could help to get an
>idea of what an actual port (rather than a 'write from scratch') would
>require.
>
>Last but not least, the hypercall interface official documentation is
>all in the public header files, in the repository, as well as here:
>http://xenbits.xen.org/docs/unstable-staging/hypercall/index.html
>http://xenbits.xen.org/docs/unstable-staging/hypercall/arm/index.html
>
>That is all for now I guess... Ask if there is anything you do not
>understand that you think this community could help with.
>
>Best Regards,
>Dario
>
>--
><<This happens because I choose it to happen!>> (Raistlin Majere)
>-----------------------------------------------------------------
>Dario Faggioli, Ph.D, http://about.me/dario.faggioli
>Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
>

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Re: OS porting on Xen on ARM

[Arianna Avanzini]

On 12/17/2013 12:05 PM, Dario Faggioli wrote:
> Hi Arianna!
> 
> First of all, some context for the Xen on ARM people that I'm Cc-ing. 
> Arianna will be working on porting an embedded --targeted specifically at
> automotive-- OS on top of Xen on ARM. The OS is Erika, and Claudio could
> give any kind of information about it (and correct me, if I said something
> wrong): 
> http://wiki.automotive.linuxfoundation.org/index.php/Erika_Enterprise_Open-Source_RTOS
>
> 
http://erika.tuxfamily.org/
> 
> This mail is mainly meant at giving her some clues and pointers about how
> to get on with it. I'll do my best but, given it's ARM, with which I'm not
> super familiar with, feel free to chime in and fill the gaps or correcting
> the mistakes I may make.
> 
> The goal is (for now) to have the Erika OS running as a DomU, on top of a
> Linux Dom0. She'll be using a Cubie* as a platform. There is definitely
> some similar/related activity going on (writing/porting embedded OSes on
> Xen) these days, but, if I'm not mistaken, this would be the first example
> of doing it on ARM (except, perhaps, from Julien's work on FreeBSD, but
> that's not embedded! :-P)... Pretty cool, eh?
> 
> Arianna, all the information about running Xen on Allwinner is here: 
> http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/Allwinner 
> Also, there is a thread right about this on xen-devel going on in these. 
> Perhaps you can have a look at it: 
> http://bugs.xenproject.org/xen/mid/%3CWC20131216075445.88000B@perkbv.com%3E
>
> 
(look at the whole thread, e.g., via marc.info).
> 
> About Xen in embedded in general, there has been a thread recently, which
> may contain some useful info. In case you want to skim through it, here it
> is: 
> http://bugs.xenproject.org/xen/mid/%3C1384802050.16918.219.camel@Solace%3E
> 
> About how a small, and an hopefully easy enough to understand, OS that runs
> as a Xen DomU looks like, check out Mini-OS in the Xen Source tree: 
> http://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=extras/mini-os;hb=HEAD As
> I said, it's small, and definitely simpler, for instance, than Linux, but
> it's quite feature complete, which is something you probably won't need.
> 
> In fact, there are people working on even smaller and simpler solutions, 
> for the most diverse purposes. Some links below (again, check the entire 
> threads): 
> http://bugs.xenproject.org/xen/mid/%3Cem4158cadd-9eab-4a26-80ba-b3a3b311bee2@smartin-alien%3E
>
> 
http://bugs.xenproject.org/xen/mid/%3Cem40e5807b-ac20-4c2a-ad66-d1056397e07b@smartin-alien%3E
> http://bugs.xenproject.org/xen/mid/%3Cembc004940-1dbb-4924-bbab-76901c75e44e@smartin-alien%3E
>
> 
http://osdir.com/ml/general/2013-12/msg26912.html
> http://bugs.xenproject.org/xen/mid/%3C723A93B1-0345-42C6-949B-F6070CE40043@recoil.org%3E
>
>  Simon also sent the code out already, here:
> https://github.com/FurryFuttock/micro-pv For anything about MirageOS:
> http://openmirage.org/ , https://github.com/mirage/
> 
> In case you need something bigger, Julien ported FreeBSD on Xen on ARM (as
> a DomU). That lives here (Julien, correct me if I'm wrong): 
> http://xenbits.xen.org/gitweb/?p=people/julieng/freebsd.git;a=shortlog;h=refs/heads/xen-arm
>
> 
I expect this to be super-overkill, but perhaps it could help to get an
> idea of what an actual port (rather than a 'write from scratch') would 
> require.
> 
> Last but not least, the hypercall interface official documentation is all
> in the public header files, in the repository, as well as here: 
> http://xenbits.xen.org/docs/unstable-staging/hypercall/index.html 
> http://xenbits.xen.org/docs/unstable-staging/hypercall/arm/index.html
> 
> That is all for now I guess... Ask if there is anything you do not 
> understand that you think this community could help with. :-)
> 

Thank you for the very useful pointers, I've started to carefully read the
threads you recommended and to study the code of the mini-os. I'll definitely
check out also the other OSs you suggested.
Thank you also for being so helpful, I surely won't hesitate to ask in case
anything is not clear enough to me (hoping I won't be too much annoying).


> Best Regards, Dario
> 


-- 
/*
 * Arianna Avanzini
 * avanzini.arianna@gmail.com
 * 73628@studenti.unimore.it
 */

Re: OS porting on Xen on ARM

[Arianna Avanzini]

On 12/17/2013 12:44 PM, Simon Martin wrote:
> Good luck Arianna.
>  
> When I started my micro-pv implementation it took me a long time to get anything
> to run. It eventually ended up being that I hadn't set the XEN_INTERFACE macro
> in the makefile. Please don't get caught out by that one! The rest was reading
> the mini-os code, the documentation, web search engines, and asking questions on
> this mail list.

Thank you for the hint, that must have been a nasty pitfall. I'll definitely
check out the mini-os code and the online documentation.


>  
> Regards.
>  
>  
> On 17/12/2013 08:05:45, "Dario Faggioli" <dario.faggioli@citrix.com
> <mailto:dario.faggioli@citrix.com>> wrote:
>  
>> Hi Arianna!
>>  
>> First of all, some context for the Xen on ARM people that I'm Cc-ing.
>> Arianna will be working on porting an embedded --targeted specifically
>> at automotive-- OS on top of Xen on ARM. The OS is Erika, and Claudio
>> could give any kind of information about it (and correct me, if I said
>> something wrong):
>> http://wiki.automotive.linuxfoundation.org/index.php/Erika_Enterprise_Open-Source_RTOS
>>
>> http://erika.tuxfamily.org/
>>  
>> This mail is mainly meant at giving her some clues and pointers about
>> how to get on with it. I'll do my best but, given it's ARM, with which
>> I'm not super familiar with, feel free to chime in and fill the gaps or
>> correcting the mistakes I may make.
>>  
>> The goal is (for now) to have the Erika OS running as a DomU, on top of
>> a Linux Dom0. She'll be using a Cubie* as a platform. There is
>> definitely some similar/related activity going on (writing/porting
>> embedded OSes on Xen) these days, but, if I'm not mistaken, this would
>> be the first example of doing it on ARM (except, perhaps, from Julien's
>> work on FreeBSD, but that's not embedded! :-P)... Pretty cool, eh?
>>  
>> Arianna, all the information about running Xen on Allwinner is here:
>> http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/Allwinner
>> Also, there is a thread right about this on xen-devel going on in these.
>> Perhaps you can have a look at it:
>> http://bugs.xenproject.org/xen/mid/%3CWC20131216075445.88000B@perkbv.com%3E
>> (look at the whole thread, e.g., via marc.info).
>>  
>> About Xen in embedded in general, there has been a thread recently,
>> which may contain some useful info. In case you want to skim through it,
>> here it is:
>> http://bugs.xenproject.org/xen/mid/%3C1384802050.16918.219.camel@Solace%3E
>>  
>> About how a small, and an hopefully easy enough to understand, OS that
>> runs as a Xen DomU looks like, check out Mini-OS in the Xen Source tree:
>> http://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=extras/mini-os;hb=HEAD
>> As I said, it's small, and definitely simpler, for instance, than Linux,
>> but it's quite feature complete, which is something you probably won't
>> need.
>>  
>> In fact, there are people working on even smaller and simpler solutions,
>> for the most diverse purposes. Some links below (again, check the entire
>> threads):
>> http://bugs.xenproject.org/xen/mid/%3Cem4158cadd-9eab-4a26-80ba-b3a3b311bee2@smartin-alien%3E
>>
>> http://bugs.xenproject.org/xen/mid/%3Cem40e5807b-ac20-4c2a-ad66-d1056397e07b@smartin-alien%3E
>>
>> http://bugs.xenproject.org/xen/mid/%3Cembc004940-1dbb-4924-bbab-76901c75e44e@smartin-alien%3E
>>
>> http://osdir.com/ml/general/2013-12/msg26912.html
>> http://bugs.xenproject.org/xen/mid/%3C723A93B1-0345-42C6-949B-F6070CE40043@recoil.org%3E
>>
>>  
>> Simon also sent the code out already, here:
>> https://github.com/FurryFuttock/micro-pv
>> For anything about MirageOS: http://openmirage.org/ , https://github.com/mirage/
>>  
>> In case you need something bigger, Julien ported FreeBSD on Xen on ARM
>> (as a DomU). That lives here (Julien, correct me if I'm wrong):
>> http://xenbits.xen.org/gitweb/?p=people/julieng/freebsd.git;a=shortlog;h=refs/heads/xen-arm
>>
>> I expect this to be super-overkill, but perhaps it could help to get an
>> idea of what an actual port (rather than a 'write from scratch') would
>> require.
>>  
>> Last but not least, the hypercall interface official documentation is
>> all in the public header files, in the repository, as well as here:
>> http://xenbits.xen.org/docs/unstable-staging/hypercall/index.html
>> http://xenbits.xen.org/docs/unstable-staging/hypercall/arm/index.html
>>  
>> That is all for now I guess... Ask if there is anything you do not
>> understand that you think this community could help with. :-)
>>  
>> Best Regards,
>> Dario
>>  
>> -- 
>> <<This happens because I choose it to happen!>> (Raistlin Majere)
>> -----------------------------------------------------------------
>> Dario Faggioli, Ph.D, http://about.me/dario.faggioli
>> Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
>>  


-- 
/*
 * Arianna Avanzini
 * avanzini.arianna@gmail.com
 * 73628@studenti.unimore.it
 */

Re: OS porting on Xen on ARM

[Ian Campbell]

On Tue, 2013-12-17 at 12:05 +0100, Dario Faggioli wrote:
> About how a small, and an hopefully easy enough to understand, OS that
> runs as a Xen DomU looks like, check out Mini-OS in the Xen Source tree:
> http://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=extras/mini-os;hb=HEAD
> As I said, it's small, and definitely simpler, for instance, than Linux,
> but it's quite feature complete, which is something you probably won't
> need.

Note however that mini-os has not been ported to ARM. So as an example
of the arch stuff it is not all that useful, but it does contain PV
drivers and the like, which is most of what a Xen on ARM port consists
of given there is no PV MMU stuff to worry about.

The only existing ports are of Linux and of FreeBSD.

Ian.

Re: OS porting on Xen on ARM

[Dario Faggioli]

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On gio, 2013-12-19 at 17:42 +0000, Ian Campbell wrote:
> On Tue, 2013-12-17 at 12:05 +0100, Dario Faggioli wrote:
> > About how a small, and an hopefully easy enough to understand, OS that
> > runs as a Xen DomU looks like, check out Mini-OS in the Xen Source tree:
> > http://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=extras/mini-os;hb=HEAD
> > As I said, it's small, and definitely simpler, for instance, than Linux,
> > but it's quite feature complete, which is something you probably won't
> > need.
> 
> Note however that mini-os has not been ported to ARM. So as an example
> of the arch stuff it is not all that useful, 
>
Yep... Arianna's work will be the first real example of that, and quite
a cool example, at least as far as I can tell, given the nature of the
to be ported guest OS! Challenging, indeed, as well as very
interesting! :-)

> but it does contain PV
> drivers and the like, which is most of what a Xen on ARM port consists
> of given there is no PV MMU stuff to worry about.
> 
Indeed... I hope both mini-os and Simon's work (and perhaps some bits of
MirageOS too) can be a valuable help, at least for understanding at
least that part.

> The only existing ports are of Linux and of FreeBSD.
> 
Exactly. I guess both could be very useful sources of information.
Probably, the FreeBSD one, is a better fit here, as it is, let's say, a
"proper DomU port", while Linux has a lot more stuff in it, e.g.,
related to Dom0 support.

Thanks for replying,
Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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Re: OS porting on Xen on ARM

[Dario Faggioli]

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On gio, 2013-12-19 at 23:50 +0100, Dario Faggioli wrote:
> On gio, 2013-12-19 at 17:42 +0000, Ian Campbell wrote:
> > On Tue, 2013-12-17 at 12:05 +0100, Dario Faggioli wrote:
> > > About how a small, and an hopefully easy enough to understand, OS that
> > > runs as a Xen DomU looks like, check out Mini-OS in the Xen Source tree:
> > > http://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=extras/mini-os;hb=HEAD
> > > As I said, it's small, and definitely simpler, for instance, than Linux,
> > > but it's quite feature complete, which is something you probably won't
> > > need.
> > 
> > Note however that mini-os has not been ported to ARM. So as an example
> > of the arch stuff it is not all that useful, 
> >
> Yep... Arianna's work will be the first real example of that, and quite
> a cool example, at least as far as I can tell, given the nature of the
> to be ported guest OS! Challenging, indeed, as well as very
> interesting! :-)
> 
FYI:

http://www.gossamer-threads.com/lists/xen/devel/312174?do=post_view_flat#312174

I've already asked if the source code for such effort could be made
available somehow, as it can be of great help to similar projects, like,
e.g., this one. :-)

Regards,
Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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