[xen staging] tools/xenstore: add documentation for new set/get-feature commands

[patchbot@xxxxxxx]

commit 1a564e4b3b4fcb9a49fa09ade689ba38c0a890e8
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Mon Jul 18 17:46:47 2022 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Jul 18 17:46:47 2022 +0200

    tools/xenstore: add documentation for new set/get-feature commands
    
    Add documentation for two new Xenstore wire commands SET_FEATURE and
    GET_FEATURE used to set or query the Xenstore features visible in the
    ring page of a given domain.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
 docs/misc/xenstore-ring.txt |  1 +
 docs/misc/xenstore.txt      | 12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/docs/misc/xenstore-ring.txt b/docs/misc/xenstore-ring.txt
index 2792d13530..fe06af32fe 100644
--- 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       GET_FEATURE and SET_FEATURE Xenstore wire commands are available
 
 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 334dc8b6fd..5f4c5c6a55 100644
--- a/docs/misc/xenstore.txt
+++ b/docs/misc/xenstore.txt
@@ -320,6 +320,18 @@ SET_TARGET         <domid>|<tdomid>|
 
        xenstored prevents the use of SET_TARGET other than by dom0.
 
+GET_FEATURE            <domid>|                <value>|
+SET_FEATURE            <domid>|<value>|
+       Returns or sets the contents of the "feature" field located at
+       offset 2064 of the Xenstore ring page of the domain specified by
+       <domid>. <value> is a decimal number being a logical or of the
+       feature bits as defined in docs/misc/xenstore-ring.txt. Trying
+       to set a bit for a feature not being supported by the running
+       Xenstore will be denied.
+
+       xenstored prevents the use of GET_FEATURE and SET_FEATURE other
+       than by dom0.
+
 ---------- Miscellaneous ----------
 
 CONTROL                        <command>|[<parameters>|]
--
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