xen/arm: Document the behavior of XENMAPSPACE_dev_mmio

Currently, XENMAPSPACE_dev_mmio maps MMIO regions using one of the most
restrictive memory attribute (Device-nGnRE).

Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index 5f7e0d2c5418e0810a01b105bf497be494d651fc..29ec571d892e722affeeac4f3ead5699ca6c1a60 100644 (file)
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -220,7 +220,11 @@ DEFINE_XEN_GUEST_HANDLE(xen_machphys_mapping_t);
 #define XENMAPSPACE_gmfn_range   3 /* GMFN range, XENMEM_add_to_physmap only. */
 #define XENMAPSPACE_gmfn_foreign 4 /* GMFN from another dom,
                                     * XENMEM_add_to_physmap_batch only. */
-#define XENMAPSPACE_dev_mmio     5 /* device mmio region */
+#define XENMAPSPACE_dev_mmio     5 /* device mmio region
+                                      ARM only; the region is mapped in
+                                      Stage-2 using the memory attribute
+                                      "Device-nGnRE" (previously named
+                                      "Device" on ARMv7) */
 /* ` } */
 
 /*