tools/xenstore: add documentation for extended watch command

Add documentation for an extension of the WATCH command used to limit
the scope of watched paths. Additionally it enables to receive more
information in the events related to special watches (@introduceDomain
or @releaseDomain).

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>

diff --git a/docs/misc/xenstore-ring.txt b/docs/misc/xenstore-ring.txt
index aa71c56e4c3aca6d6e403ca2524ffc572b85ea87..a1e6c7bb3a973b890d00336dd2eb0d23aa820bd4 100644 (file)
--- a/docs/misc/xenstore-ring.txt
+++ b/docs/misc/xenstore-ring.txt
@@ -71,6 +71,7 @@ Bit     Description
 1       Connection error indicator (see connection error feature below)
 2       GET_FEATURE and SET_FEATURE Xenstore wire commands are available
 3       GET_QUOTA and SET_QUOTA Xenstore wire commands are available
+4       WATCH can take a third parameter limiting its scope
 
 The "Connection state" field is used to request a ring close and reconnect.
 The "Connection state" field only contains valid data if the server has

diff --git a/docs/misc/xenstore.txt b/docs/misc/xenstore.txt
index 629f962bb579f30e7594f11d10bf17227e2f9b87..ee0b51394f794a7ed0d87dd425f2a19ab73b5133 100644 (file)
--- a/docs/misc/xenstore.txt
+++ b/docs/misc/xenstore.txt
@@ -176,7 +176,7 @@ SET_PERMS           <path>|<perm-as-string>|+?
 
 ---------- Watches ----------
 
-WATCH                  <wpath>|<token>|?
+WATCH                  <wpath>|<token>|[<depth>|]?
        Adds a watch.
 
        When a <path> is modified (including path creation, removal,
@@ -187,7 +187,11 @@ WATCH                      <wpath>|<token>|?
        matching watch results in a WATCH_EVENT message (see below).
 
        The event's path matches the watch's <wpath> if it is an child
-       of <wpath>.
+       of <wpath>. This match can be limited by specifying <depth> (a
+       decimal value of 0 or larger): it denotes the directory levels
+       below <wpath> to consider for a match ("0" would not match for
+       a child of <wpath>, "1" would match only for a direct child,
+       etc.).
 
        <wpath> can be a <path> to watch or @<wspecial>.  In the
        latter case <wspecial> may have any syntax but it matches
@@ -198,7 +202,13 @@ WATCH                      <wpath>|<token>|?
                                shutdown, and also on RELEASE
                                and domain destruction
        <wspecial> events are sent to privileged callers or explicitly
-       via SET_PERMS enabled domains only.
+       via SET_PERMS enabled domains only. The semantics for a
+       specification of <depth> differ for generating <wspecial>
+       events: specifying "1" will report the related domid by using
+       @<wspecial>/<domid> for the reported path. Other <depth>
+       values are not supported.
+       For @releaseDomain it is possible to watch only for a specific
+       domain by specifying @releaseDomain/<domid> for the path.
 
        When a watch is first set up it is triggered once straight
        away, with <path> equal to <wpath>.  Watches may be triggered