[Xen-changelog] [xen master] docs: Introduce xenstore paths for hotplug features

[patchbot@xxxxxxx]

commit e8f98cb2d4112d08add03caecf9d53da7e92b6f3
Author:     Paul Durrant <paul.durrant@xxxxxxxxxx>
AuthorDate: Tue Nov 17 11:32:04 2015 +0000
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Tue Nov 24 16:19:00 2015 +0000

    docs: Introduce xenstore paths for hotplug features
    
    Without some indication from a guest it is not possible for a
    toolstack to know whether instantiation of a new vbd or vif should
    result in a new PV device of the appropriate type being brought online.
    (In other words whether guest PV drivers are present and functioning).
    
    This patch documents two paths which vif and vbd frontend drivers can
    use to advertise their ability to respond to new vif or vbd
    instantiations.
    
    Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
    Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
    Cc: Jan Beulich <jbeulich@xxxxxxxx>
    Cc: Keir Fraser <keir@xxxxxxx>
    Cc: Tim Deegan <tim@xxxxxxx>
    Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
 docs/misc/xenstore-paths.markdown |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/docs/misc/xenstore-paths.markdown 
b/docs/misc/xenstore-paths.markdown
index b8788f2..624b7fd 100644
--- a/docs/misc/xenstore-paths.markdown
+++ b/docs/misc/xenstore-paths.markdown
@@ -409,6 +409,18 @@ A domain writable path. Available for arbitrary domain use.
 A domain may write information about installed PV drivers using
 paths of this form.
 
+#### ~/feature/hotplug/vif = ("0"|"1") [w]
+#### ~/feature/hotplug/vbd = ("0"|"1") [w]
+
+By setting these paths to "1" a guest can indicate to a toolstack
+that it is capable of responding immediately to instantiation of,
+respectively, new vif by bringing online a new PV network device or
+a new vbd by bringing online a new PV block device.
+If the guest sets this path to "0" then it is indicating that it is
+definitely unable to respond immediately and hence the toolstack should
+defer instantiaton to the next VM start. However, if the path is absent
+then the toolstack may attempt the operation.
+
 ### Paths private to the toolstack
 
 #### ~/device-model/$DOMID/state [w]
--
generated by git-patchbot for /home/xen/git/xen.git#master

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