diff --git a/xen/arch/arm/arm64/mm.c b/xen/arch/arm/arm64/mm.c
index 78b7c7eb00..cb69df0661 100644
--- a/xen/arch/arm/arm64/mm.c
+++ b/xen/arch/arm/arm64/mm.c
@@ -41,7 +41,8 @@ static void __init prepare_boot_identity_mapping(void)
     clear_page(boot_third_id);
 
     if ( id_offsets[0] >= IDENTITY_MAPPING_AREA_NR_L0 )
-        panic("Cannot handle ID mapping above 2TB\n");
+        panic("Cannot handle ID mapping above %uTB\n",
+              IDENTITY_MAPPING_AREA_NR_L0 >> 1);
 
     /* Link first ID table */
     pte = mfn_to_xen_entry(virt_to_mfn(boot_first_id), MT_NORMAL);
@@ -74,7 +75,8 @@ static void __init prepare_runtime_identity_mapping(void)
     DECLARE_OFFSETS(id_offsets, id_addr);
 
     if ( id_offsets[0] >= IDENTITY_MAPPING_AREA_NR_L0 )
-        panic("Cannot handle ID mapping above 2TB\n");
+        panic("Cannot handle ID mapping above %uTB\n",
+              IDENTITY_MAPPING_AREA_NR_L0 >> 1);
 
     /* Link first ID table */
     pte = pte_of_xenaddr((vaddr_t)xen_first_id);
diff --git a/xen/arch/arm/include/asm/mmu/layout.h b/xen/arch/arm/include/asm/mmu/layout.h
index 2cb2382fbf..eac7eef885 100644
--- a/xen/arch/arm/include/asm/mmu/layout.h
+++ b/xen/arch/arm/include/asm/mmu/layout.h
@@ -19,11 +19,11 @@
  *   2G -   4G   Domheap: on-demand-mapped
  *
  * ARM64 layout:
- * 0x0000000000000000 - 0x000001ffffffffff (2TB, L0 slots [0..3])
+ * 0x0000000000000000 - 0x000009ffffffffff (10TB, L0 slots [0..19])
  *
  *  Reserved to identity map Xen
  *
- * 0x0000020000000000 - 0x0000027fffffffff (512GB, L0 slot [4])
+ * 0x00000a0000000000 - 0x00000a7fffffffff (512GB, L0 slot [20])
  *  (Relative offsets)
  *   0  -   2M   Unmapped
  *   2M -  10M   Xen text, data, bss
@@ -35,7 +35,7 @@
  *
  *  32G -  64G   Frametable: 56 bytes per page for 2TB of RAM
  *
- * 0x0000028000000000 - 0x00007fffffffffff (125TB, L0 slots [5..255])
+ * 0x00000a8000000000 - 0x00007fffffffffff (512GB+117TB, L0 slots [21..255])
  *  Unused
  *
  * 0x0000800000000000 - 0x000084ffffffffff (5TB, L0 slots [256..265])
@@ -49,7 +49,7 @@
 #define XEN_VIRT_START          _AT(vaddr_t, MB(2))
 #else
 
-#define IDENTITY_MAPPING_AREA_NR_L0     4
+#define IDENTITY_MAPPING_AREA_NR_L0     20
 #define XEN_VM_MAPPING                  SLOT0(IDENTITY_MAPPING_AREA_NR_L0)
 
 #define SLOT0_ENTRY_BITS  39