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RE: [Xen-devel] Re: [PATCH] libxl: fix xenstore connection when run in d

To: Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>, Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>, "pjcolp@xxxxxxxxx" <pjcolp@xxxxxxxxx>
Subject: RE: [Xen-devel] Re: [PATCH] libxl: fix xenstore connection when run in domU
From: "Jun Zhu (Intern)" <Jun.Zhu@xxxxxxxxxx>
Date: Tue, 31 Aug 2010 11:32:11 +0100
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Thread-topic: [Xen-devel] Re: [PATCH] libxl: fix xenstore connection when run in domU
If xenstore runs in a seperate domain, it must use xenbus dev to communicate. 
If so, the xenstore commands in Xenbus driver are not complete. For example, it 
does not contain XS_INTRODUCE now. 

Jun Zhu
Citrix Systems UK
From: Tim Deegan
Sent: Tuesday, August 31, 2010 6:28 AM
To: Ian Campbell
Cc: Jun Zhu (Intern); dgdegra@xxxxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] Re: [PATCH] libxl: fix xenstore connection when        
run in domU

At 10:15 +0100 on 31 Aug (1283249719), Ian Campbell wrote:
> On Tue, 2010-08-31 at 10:05 +0100, Jun Zhu (Intern) wrote:
> > Hi
> >
> > There are other places that use the xs_daemon_open in libxl. Is it 
> > necessory to change them as follows?
> >      ctx->xsh = xs_daemon_open();
> > +    if (!ctx->xsh)
> > +        ctx->xsh = xs_domain_open();
> >      if (!ctx->xsh) {
> >          XL_LOG_ERRNOVAL(ctx, XL_LOG_ERROR, errno,
> >                          "cannot connect to xenstore");
> I think we'd be better off introducing "libxl__xs_open" which does the
> right thing and make the users to all use it.
> Is there any harm in always preferring xs_domain_open, even if the
> xenstore daemon happens to be co-located in the same domain?

I don't think so; even the performance probably won't be that much
different.  It certainly used to work when we first put Xenstore in its
own domain and anything that's broken since then is a regression worth


Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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