clarify SHUTDOWN_suspend additional argument

Clarify the behaviour of SCHEDOP_shutdown: PV x86 guests need to pass a
third argument, that is unused on HVM and ARM guests.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/xen/include/public/sched.h b/xen/include/public/sched.h
index a30b11d96a61559f71359ff824d4dc984fec082e..4000ac99dd5dc362e5b148be1bc3a1810841133d 100644 (file)
--- a/xen/include/public/sched.h
+++ b/xen/include/public/sched.h
@@ -76,9 +76,10 @@
  * Halt execution of this domain (all VCPUs) and notify the system controller.
  * @arg == pointer to sched_shutdown_t structure.
  *
- * If the sched_shutdown_t reason is SHUTDOWN_suspend then this
- * hypercall takes an additional extra argument which should be the
- * MFN of the guest's start_info_t.
+ * If the sched_shutdown_t reason is SHUTDOWN_suspend then
+ * x86 PV guests must also set RDX (EDX for 32-bit guests) to the MFN
+ * of the guest's start info page.  RDX/EDX is the third hypercall
+ * argument.
  *
  * In addition, which reason is SHUTDOWN_suspend this hypercall
  * returns 1 if suspend was cancelled or the domain was merely