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

["Yuvraj Agarwal" <yuvraj@xxxxxxxxxxx>]

Hi Ian and Vincent,

Thank you for your responses - There are several possible issues it seems:

** I actually have both /dev/xen/eventchn and /dev/xen/evtchn but no 
/dev/xen/gntdev currently?

root@EM:/home/yuvraj# ll /dev/xen/
total 0
drwxr-xr-x  2 root root     80 2011-02-10 09:18 ./
drwxr-xr-x 17 root root   6120 2011-02-10 09:18 ../
crw-r-----  1 root root 10, 63 2011-02-10 09:18 eventchn
crw-rw----  1 root root 10, 60 2011-02-10 09:18 evtchn
root@EM:/home/yuvraj#

** It also looks like the minor numbers are mixed up, for example /proc/misc 
shows minor number 63 also for vga_arbitrer? Not sure if that matters.

root@EM:/home/yuvraj# cat /proc/misc
< snip >
59 gntdev
60 evtchn
< snip >
63 vga_arbiter
root@EM:/home/yuvraj#

** I also tried to start xenstored without the daemonize flag as Vincent 
mentioned, and posted the results in a separate email, (re-posting it here).

root@EM:/home/yuvraj# strace -f /usr/bin/xenstored --no-fork

<snip>
open("/dev/xen/eventchn", O_RDWR)       = 6
open("/proc/xen/xsd_port", O_RDONLY)    = 7
read(7, "145", 20)                      = 3
close(7)                                = 0
open("/proc/xen/xsd_kva", O_RDWR)       = 7
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, 7, 0) = 0x7f5bbd2ef000
close(7)                                = 0
ioctl(6, EVIOCGVERSION, 0x7fffd0cd3e30) = -1 ENOTTY (Inappropriate ioctl for 
device)
write(2, "Fatal error: exception Failure(\""..., 64Fatal error: exception 
Failure("ioctl bind_interdomain failed")
) = 64
exit_group(2)                           = ?

Is there a way I can fix (e.g. a patch I can apply) this on my end?  I can 
try it out and post the results back so that this makes it into the tree, 
and helps anyone else using the OCAML version of xenstored.

Thanks!
Yuvraj


-----Original Message-----
From: Ian Campbell [mailto:Ian.Campbell@xxxxxxxxxx]
Sent: Thursday, February 10, 2011 12:43 AM
To: Vincent Hanquez
Cc: Yuvraj Agarwal; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] XEN 4.0.2-rc2 - using OCAML xenstored -- xend not 
starting?

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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