docs/misc: document PV control/feature keys for laptop/slate mode

Commit 4c8153d9 "add ACPI device for Windows laptop/slate mode switch"
added code to provide an 'laptop/slate mode' ACPI device to guests.

When present this device is used by Microsoft Windows to bind a HID
driver which controls whether the Windows desktop appearance is optimized
for laptop/desktop or slate/tablet PCs. The mechanism for switching
between modes is to open a handle to this driver and write a byte of
arbitrary data.

This patch documents xenstore keys such that a PV agent running in a
Windows guest can advertise the capability to, and receive instruction
from, a toolstack to cause such a mode switch.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

diff --git a/docs/misc/xenstore-paths.markdown b/docs/misc/xenstore-paths.markdown
index 5d89ed8563355eac5d689f9577508c1c61d74de8..6c80a9eb5505af082c3f7a33af504d23f48ec809 100644 (file)
--- a/docs/misc/xenstore-paths.markdown
+++ b/docs/misc/xenstore-paths.markdown
@@ -435,6 +435,21 @@ XS_RESET_WATCHES xenstore message. See
 [xen/include/public/io/xs\_wire.h][XSWIRE] for the XenStore wire
 protocol definition.
 
+#### ~/control/laptop-slate-mode = (""|"laptop"|"slate") [w]
+
+This is the PV laptop/slate mode control node. If the toolstack has
+provisioned a guest with the ACPI laptop/slate mode device then it
+can write the desired mode here to cause the guest to switch modes if
+necessary. The guest acknowledges a request by writing the empty
+string back to the control node.
+
+#### ~/control/feature-laptop-slate-mode = (""|"0"|"1") [w]
+
+This may be initialized to "" by the toolstack and may then be set
+to 0 or 1 by a guest to indicate whether it is capable or incapable,
+respectively, of responding to a mode value written to
+~/control/laptop-slate-mode.
+
 ### Domain Controlled Paths
 
 #### ~/data/* [w]