Re: [Xen-devel] XEN 4.0.2-rc2 - using OCAML xenstored -- xend not starting?

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2011-02-09 at 08:22 +0000, Vincent Hanquez wrote:
> On 08/02/11 17:02, Yuvraj Agarwal wrote:
> > Hi All,
> >
> > I just tried a new installation of Ubuntu 10.04 (64bit) + Xen and am
> > having some trouble starting XEN. I am using the latest mercurial checkout
> > (4.0.2-rc2) and the only change I made was to Config.mk to enable building
> > the OCAML version of xenstored. " CONFIG_OCAML_XENSTORED ?= y". I am using
> > the same kernel I built earlier for a similar Ubuntu 10.04-64bit / Xen
> > 4.0.0 installation (version 2.6.32.12).  I would like to use the OCAML
> > version of xenstored since it is supposed to be much better/faster when
> > starting up a larger number of domUs.
> >
> > The system starts up, and I can see xend started up, but when I do "xm
> > list" or "xm info" I get an error message that xend has not started up?
> >
> > root@EM:/etc# xm list
> > Error: Unable to connect to xend: No such file or directory. Is xend
> > running?
> > root@EM:/etc#
> >
> > root@EM:/etc# ps -efw | grep xen
> > root        88     2  0 Feb07 ?        00:00:00 [xenwatch]
> > root        89     2  0 Feb07 ?        00:00:00 [xenbus]
> > root      6254     1  0 Feb07 ?        00:00:00 /usr/bin/python
> > /usr/sbin/xend start
> > root      6255  6254  0 Feb07 ?        00:00:17 /usr/bin/python
> > /usr/sbin/xend start
> > root      7043  5919  0 08:55 pts/2    00:00:00 grep --color=auto xen
> > root@EM:/etc#
> >
> > root@EM:/etc# uname -a
> > Linux EM 2.6.32.12 #11 SMP Fri Jun 18 20:52:17 PDT 2010 x86_64 GNU/Linux
> > root@EM:/etc#
> >
> > I did check and found two difference with my earlier installation of Xen
> > 4.0.0 with the same kernel (although with the standard xenstored).
> > 1. The xen 4.0 installation does show a "xenstored" process also running
> > in addition to these ones.
> > 2.  "xend" seems to be looking for a directory, " /var/lib/xenstored" that
> > doesn't seem to exist on my system?
> >
> > Any pointers to fix this issue?
> 
> The reason xend died is that xenstored hasn't started (or something 
> happened to it), you need to figure out why.
> 
> You can start xenstored directly on the cmdline with the no daemonize 
> flag, to see if the program stays running, and if not you'll see
> the reason why it dies.

Xen 4.0 appears to use oxenstored from
http://xenbits.xensource.com/ext/xen-ocaml-tools.hg (it only moved
in-tree in the 4.1 dev cycle).

IIRC the ocaml evtchn bindings used to blow away the /dev/evtchn node
and replace it with their own, with hardcoded major:minor or 10:61.
However that "61" is not really a static number and can vary depending
on kernel version / configuration.

Judging from Yuvraj's debugging his evtchn node has ended up at minor
60.

Looks like http://xenbits.xensource.com/xen-unstable.hg?rev/e7b55cc5533a
needs porting to xen-ocaml-tools.hg.

Ian.



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