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: Julien Grall <jgrall@amazon.com>

diff --git a/docs/misc/xenstore-ring.txt b/docs/misc/xenstore-ring.txt
index 2792d1353012df9f293ad37f904f8b3834bf8a3e..dbc7335e24b8a3563f6916c8f2cbad38e71cb79b 100644 (file)
--- a/docs/misc/xenstore-ring.txt
+++ b/docs/misc/xenstore-ring.txt
@@ -69,6 +69,7 @@ Bit     Description
 -----------------------------------------------------------------
 0       Ring reconnection (see the ring reconnection feature below)
 1       Connection error indicator (see connection error feature below)
+2       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 d49a07db21362b50abe4713c2dc68919b1500bd6..4bc262fd5db1c07ef8222856492e586b635a6fed 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