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RE: A question about mirage



Oh yes the VIRQ handler too – I’d forgotten about that one. So I think you need:

1.       The right to install a DOM_EXC VIRQ handler: xen will signal this event channel whenever a domain shuts down; and

2.       The right to call domain_getinfo: xenstored will need this to figure out *which* domain has shutdown.


If you figure out the correct runes to set this up then please let me know, it would save me some time later! J In my testing I just tolerated the bugs triggered by this.


I think your analysis is correct. If xenstore can’t detect a domain shutdown then:

1.       It won’t free the ring, which will prevent the domain being fully cleaned up (it will remain in ‘Dying’ forever)

2.       It won’t emit the @releaseDomain watch, which is how a toolstack notices a domain has shutdown

So I think the guest will shut itself down internally ok, but the cleanup will block, which will confuse toolstacks like xl.





From: cl-mirage-bounces@xxxxxxxxxxxxxxx [mailto:cl-mirage-bounces@xxxxxxxxxxxxxxx] On Behalf Of tech mailinglists
Sent: 06 February 2013 8:35 AM
To: Dave Scott
Cc: cl-mirage List; Anil Madhavapeddy
Subject: Re: A question about mirage


Hello Dave,

thanks for your reply.

When I understood you right, this rule is not needed:

# Xenstore requires the global VIRQ for domain destroy operations
allow dom0_t xenstore_t:domain set_virq_handler;

So it would be possible to shutdown a guest from within the guest but not via for example xl shutdown and xl destroy am I right?

Best Regards


2013/2/6 Dave Scott <Dave.Scott@xxxxxxxxxxxxx>


I've not tried configuring XSM/FLASK yet but I do know it's only necessary for the domain getinfo hyper call, which is only necessary to detect domain shutdown (and that a ring should be shutdown). Without it everything will work but you'll slowly leak memory.

Dave Scott
XenServer System Architect

On Feb 4, 2013, at 12:17 PM, "Anil Madhavapeddy" <anil@xxxxxxxxxx> wrote:

> I have no idea  about the state of XSM/FLASK I'm afraid.  Dave Scott is probably the person most qualified to answer this one, as he's built oxenstored as a stub domain already.
> -a
> On 4 Feb 2013, at 12:11, tech mailinglists <mailinglists.tech@xxxxxxxxx> wrote:
>> Hello Anil,
>> thanks for your reply. This sounds very good to me. I think that Mirage is a great project, I think that the building of specialized appliances will be the future.
>> I have another question about a special Mirage usecase: I builded a oxenstored mirage appliance which worked without problems. Now I would like to run it on a Xen 4.2.1 with Linux 3.7.4. I talked already with some persons and they say that there are problems with XSM/FLASK. Daniel de Graaf wrote an XSM/FLASK ruleset which should work with 4.3 unstable in this mailinglist post: http://lists.xen.org/archives/html/xen-devel/2013-01/msg00956.html
>> Do you know whether it's possible to modify this ruleset so that oxenstored could work on 4.2.1 and the given XSM/FLASK features in this version?
>> Best Regards
>> 2013/2/4 Anil Madhavapeddy <anil@xxxxxxxxxx>
>> Not yet; you have to use the Mirage base module which provides the OS abstraction. However, some software is already written to be functorised across an OS module for portability, such as the Arakoon database engine (arakoon.org).  These were quite easy to port to Mirage.  Others, such as MLDonkey, use the Unix module extensively and are harder.
>> Raphael Proust is looking into a Mirage/UNIX compatibility layer, so this is something we'll expand on more later on in the year once a stable first version has been released.
>> -anil
>> On 4 Feb 2013, at 10:29, tech mailinglists <mailinglists.tech@xxxxxxxxx> wrote:
>>> Hello all,
>>> I have a question about the mirage OS. Is it possible to run every OCaml Source Code in mirage? So would it be possible to run for example a webserver written in OCaml or MLDonkey in mirage?
>>> Best Regards




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