The result in my side is:
[root@vt_wb_jimmy xen-unstable]#
xenstore-watch -s /local/domain/0/a/b | while read w ; do echo "watch
fired on $w"; echo "value" $(xenstore-read $w); echo; done
watch fired on /local/domain/0/a/b
value
watch fired on
/local/domain/0/a/b/c/defe
value 44
watch fired on
/local/domain/0/a/b/c/defe
value 45
[root@vt_wb_jimmy xen-unstable]#
xenstore-watch /local/domain/0/a/b | while read w ; do echo "watch fired
on $w"; echo "value" $(xenstore-read $w); echo; doneÂ
xenstore-watch: Unable to add watch on /local/domain/0/a/b
One thing need notice is, the first time
when I use xenstore-watch without -s, it will not fail with "Unable to add
watch on ....", instead, it will simply not print anything when I change
the a/b/c/defe value, then I ctrl-c to kill it. Next time it will fail with
"Unable to add watch on ...", as log below. Hope this will be
helpful. BTW, what's your dom0 version?
[root@vt_wb_jimmy xen-unstable]#
xenstore-watch /local/domain/0/a/b | while read w ; do echo "watch fired on
$w"; echo "value" $(xenstore-read $w); echo; done
watch fired on /local/domain/0/a/b
value
^CÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ >>>>>>>>>>>>>>>>>>I
press ctrl-c here because it does not print anythine while I change the
a/b/c/defe in another console.
[root@vt_wb_jimmy xen-unstable]#
xenstore-watch /local/domain/0/a/b | while read w ; do echo "watch fired
on $w"; echo "value" $(xenstore-read $w); echo; done
xenstore-watch: Unable to add watch on
/local/domain/0/a/b
Thanks
--jyh
>-----Original Message-----
>From: Ian Campbell [mailto:Ian.Campbell@xxxxxxxxxx]
>Sent: Wednesday, October 13, 2010
9:48 PM
>To: Jiang, Yunhong
>Cc: xen-devel@xxxxxxxxxxxxxxxxxxx;
gm281@xxxxxxxxx
>Subject: Re: [Xen-devel] Why
xs_domain_open() in fs_backend
>
>On Wed, 2010-10-13 at 14:18 +0100,
Ian Campbell wrote:
>> On Wed, 2010-10-13 at 13:57
+0100, Ian Campbell wrote:
>> >
>> > I don't know how useful it
is generally but it can be used to shows
>> > that "xenstore-watch
-s x" (i.e. xs_daemon_open) does appear to be
>> > broken.
>>
>> Actually this is backwards and
I seem to be seeing the exact opposite to
>> you. IOW for me:
>>
>> "xenstore-watch x"ÂÂÂ ->
xs_domain_open()ÂÂÂÂÂÂ -- works
>> "xenstore-watch -s x"ÂÂÂÂÂÂÂÂ ->
xs_daemon_open()ÂÂÂÂÂ -- does not work, XS_ERROR reply
>from daemon
>>
>> Can you confirm which version
fails for you?
>>
>> It also seems to be specific to
the C xenstored, the ocaml oxenstored
>> works fine.
>>
>> Lastly it seems to be a problem
with relative paths only, absolute paths
>> seem to be ok.
>
>This appears to be deliberate.
xenstore clients connecting via the
>socket interface have no implicit
/local/domain/<domid> home directory.
>(see xenstored_core.c:canonicalize
and its use from
>xenstored_watch.c:do_watch) and
therefore must use absolute paths. The
>ocaml xenstored works around this by
assuming that socket connections
>originate in domain 0, which is a
little dubious if oxenstored is
>running in a stub domain but in that
case there is no userspace and
>hence no clients using the socket
interface, so it is fine.
>
>The only problem I see is that it
uses whatever random errno happens to
>be current in the error message.
>
>Ian.
>
># HG changeset patch
># User Ian Campbell
<ian.campbell@xxxxxxxxxx>
># Date 1286977342 -3600
># Node ID
78f2c9b4d902fa04f7055012c63d6dd24e823da0
># ParentÂ
9a5a576bcc8ae17f19c9f89b73a026a0acfb5cf1
>xenstored: return EINVAL for attempt
to watch invalid path
>
>errno is essentially random at this
point.
>
>Signed-off-by: Ian Campbell
<ian.campbell@xxxxxxxxxx>
>
>diff -r 9a5a576bcc8a -r 78f2c9b4d902
tools/xenstore/xenstored_watch.c
>---
a/tools/xenstore/xenstored_watch.cÂÂÂÂÂÂ Wed Oct 13 13:56:12 2010 +0100
>+++
b/tools/xenstore/xenstored_watch.cÂÂÂ Wed Oct 13 14:42:22 2010 +0100
>@@ -134,7 +134,7 @@ void
do_watch(struct connection *conn, s
> ÂÂÂÂÂÂÂÂÂÂÂÂÂ relative =
!strstarts(vec[0], "/");
> ÂÂÂÂÂÂÂÂÂÂÂÂÂ vec[0] =
canonicalize(conn, vec[0]);
> ÂÂÂÂÂÂÂÂÂÂÂÂÂ if
(!is_valid_nodename(vec[0])) {
>-ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ send_error(conn,
errno);
>+ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ send_error(conn,
EINVAL);
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ return;
> ÂÂÂÂÂÂÂÂÂÂÂÂÂ }
> ÂÂÂÂ }
>
