diff --git a/xen/arch/x86/io_apic.c b/xen/arch/x86/io_apic.c
index 732b57995c..6517eb5ae9 100644
--- a/xen/arch/x86/io_apic.c
+++ b/xen/arch/x86/io_apic.c
@@ -285,7 +285,7 @@ static void __io_apic_eoi(unsigned int apic, unsigned int vector, unsigned int p
     {
         /* If vector is unknown, read it from the IO-APIC */
         if ( vector == IRQ_VECTOR_UNASSIGNED )
-            vector = __ioapic_read_entry(apic, pin, TRUE).vector;
+            vector = __ioapic_read_entry(apic, pin, true).vector;
 
         *(IO_APIC_BASE(apic)+16) = vector;
     }
@@ -296,28 +296,28 @@ static void __io_apic_eoi(unsigned int apic, unsigned int vector, unsigned int p
         struct IO_APIC_route_entry entry;
         bool need_to_unmask = false;
 
-        entry = __ioapic_read_entry(apic, pin, TRUE);
+        entry = __ioapic_read_entry(apic, pin, true);
 
         if ( ! entry.mask )
         {
             /* If entry is not currently masked, mask it and make
              * a note to unmask it later */
             entry.mask = 1;
-            __ioapic_write_entry(apic, pin, TRUE, entry);
+            __ioapic_write_entry(apic, pin, true, entry);
             need_to_unmask = true;
         }
 
         /* Flip the trigger mode to edge and back */
         entry.trigger = 0;
-        __ioapic_write_entry(apic, pin, TRUE, entry);
+        __ioapic_write_entry(apic, pin, true, entry);
         entry.trigger = 1;
-        __ioapic_write_entry(apic, pin, TRUE, entry);
+        __ioapic_write_entry(apic, pin, true, entry);
 
         if ( need_to_unmask )
         {
             /* Unmask if neccesary */
             entry.mask = 0;
-            __ioapic_write_entry(apic, pin, TRUE, entry);
+            __ioapic_write_entry(apic, pin, true, entry);
         }
     }
 }
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index fa55f3474e..e9d7b80caf 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -1077,7 +1077,7 @@ long do_set_segment_base(unsigned int which, unsigned long base)
 }
 
 
-/* Returns TRUE if given descriptor is valid for GDT or LDT. */
+/* Returns true if given descriptor is valid for GDT or LDT. */
 int check_descriptor(const struct domain *dom, seg_desc_t *d)
 {
     u32 a = d->a, b = d->b;
diff --git a/xen/common/kexec.c b/xen/common/kexec.c
index a262cc5a18..8e7540f605 100644
--- a/xen/common/kexec.c
+++ b/xen/common/kexec.c
@@ -33,7 +33,7 @@
 #include <compat/kexec.h>
 #endif
 
-bool_t kexecing = FALSE;
+bool kexecing = false;
 
 /* Memory regions to store the per cpu register state etc. on a crash. */
 typedef struct { Elf_Note * start; size_t size; } crash_note_range_t;
@@ -379,7 +379,7 @@ void kexec_crash(void)
     if ( !test_bit(KEXEC_IMAGE_CRASH_BASE + pos, &kexec_flags) )
         return;
 
-    kexecing = TRUE;
+    kexecing = true;
 
     if ( kexec_common_shutdown() != 0 )
         return;
@@ -395,7 +395,7 @@ static long kexec_reboot(void *_image)
 {
     struct kexec_image *image = _image;
 
-    kexecing = TRUE;
+    kexecing = true;
 
     kexec_common_shutdown();
     machine_reboot_kexec(image);
diff --git a/xen/common/timer.c b/xen/common/timer.c
index 645206a989..29f8f40f88 100644
--- a/xen/common/timer.c
+++ b/xen/common/timer.c
@@ -100,7 +100,7 @@ static void up_heap(struct timer **heap, unsigned int pos)
 }
 
 
-/* Delete @t from @heap. Return TRUE if new top of heap. */
+/* Delete @t from @heap. Return true if new top of heap. */
 static int remove_from_heap(struct timer **heap, struct timer *t)
 {
     unsigned int sz = heap_metadata(heap)->size;
@@ -127,7 +127,7 @@ static int remove_from_heap(struct timer **heap, struct timer *t)
 }
 
 
-/* Add new entry @t to @heap. Return TRUE if new top of heap. */
+/* Add new entry @t to @heap. Return true if new top of heap. */
 static int add_to_heap(struct timer **heap, struct timer *t)
 {
     unsigned int sz = heap_metadata(heap)->size;
diff --git a/xen/drivers/acpi/tables/tbfadt.c b/xen/drivers/acpi/tables/tbfadt.c
index f11fd5a900..6f30aede9c 100644
--- a/xen/drivers/acpi/tables/tbfadt.c
+++ b/xen/drivers/acpi/tables/tbfadt.c
@@ -250,9 +250,9 @@ void __init acpi_tb_create_local_fadt(struct acpi_table_header *table, u32 lengt
 
 	/* Take a copy of the Hardware Reduced flag */
 
-	acpi_gbl_reduced_hardware = FALSE;
+	acpi_gbl_reduced_hardware = false;
 	if (acpi_gbl_FADT.flags & ACPI_FADT_HW_REDUCED) {
-		acpi_gbl_reduced_hardware = TRUE;
+		acpi_gbl_reduced_hardware = true;
 	}
 
 	/*
diff --git a/xen/drivers/passthrough/vtd/utils.c b/xen/drivers/passthrough/vtd/utils.c
index 7552dd8e0c..4531581846 100644
--- a/xen/drivers/passthrough/vtd/utils.c
+++ b/xen/drivers/passthrough/vtd/utils.c
@@ -281,7 +281,7 @@ void vtd_dump_iommu_info(unsigned char key)
             for ( i = 0; i <= reg_01.bits.entries; i++ )
             {
                 struct IO_APIC_route_entry rte =
-                    __ioapic_read_entry(apic, i, TRUE);
+                    __ioapic_read_entry(apic, i, true);
 
                 remap = (struct IO_APIC_route_remap_entry *) &rte;
                 if ( !remap->format )
diff --git a/xen/include/acpi/acconfig.h b/xen/include/acpi/acconfig.h
index 422f29c06c..f0330fb990 100644
--- a/xen/include/acpi/acconfig.h
+++ b/xen/include/acpi/acconfig.h
@@ -87,7 +87,7 @@
  * Should the subsystem abort the loading of an ACPI table if the
  * table checksum is incorrect?
  */
-#define ACPI_CHECKSUM_ABORT             FALSE
+#define ACPI_CHECKSUM_ABORT             false
 
 /******************************************************************************
  *
diff --git a/xen/include/acpi/actypes.h b/xen/include/acpi/actypes.h
index f3e95abc3a..4aad815f7b 100644
--- a/xen/include/acpi/actypes.h
+++ b/xen/include/acpi/actypes.h
@@ -124,7 +124,7 @@
  *
  ******************************************************************************/
 
-typedef unsigned char BOOLEAN;
+typedef bool BOOLEAN;
 typedef unsigned char UINT8;
 typedef unsigned short UINT16;
 typedef COMPILER_DEPENDENT_UINT64 UINT64;
@@ -260,22 +260,6 @@ typedef acpi_native_uint acpi_size;
  *
  ******************************************************************************/
 
-/* Logical defines and NULL */
-
-#ifdef FALSE
-#undef FALSE
-#endif
-#define FALSE                           (1 == 0)
-
-#ifdef TRUE
-#undef TRUE
-#endif
-#define TRUE                            (1 == 1)
-
-#ifndef NULL
-#define NULL                            (void *) 0
-#endif
-
 /*
  * Mescellaneous types
  */
@@ -503,7 +487,7 @@ typedef u32 acpi_event_type;
  * Event Status - Per event
  * -------------
  * The encoding of acpi_event_status is illustrated below.
- * Note that a set bit (1) indicates the property is TRUE
+ * Note that a set bit (1) indicates the property is true
  * (e.g. if bit 0 is set then the event is enabled).
  * +-------------+-+-+-+
  * |   Bits 31:3 |2|1|0|
diff --git a/xen/include/asm-arm/arm64/efibind.h b/xen/include/asm-arm/arm64/efibind.h
index 2b0bf40bf2..08ab70e668 100644
--- a/xen/include/asm-arm/arm64/efibind.h
+++ b/xen/include/asm-arm/arm64/efibind.h
@@ -107,7 +107,7 @@ typedef uint64_t   UINTN;
 #define POST_CODE(_Data)
 
 
-#define BREAKPOINT()        while (TRUE);    // Make it hang on Bios[Dbg]32
+#define BREAKPOINT()        while (true);    // Make it hang on Bios[Dbg]32
 
 //
 // Pointers must be aligned to these address to function
diff --git a/xen/include/asm-arm/regs.h b/xen/include/asm-arm/regs.h
index 0e3e56b452..f93e1d42b0 100644
--- a/xen/include/asm-arm/regs.h
+++ b/xen/include/asm-arm/regs.h
@@ -53,7 +53,7 @@ static inline bool guest_mode(const struct cpu_user_regs *r)
     ASSERT(diff < STACK_SIZE);
     /* If not a guest frame, it must be a hypervisor frame. */
     ASSERT((diff == 0) || hyp_mode(r));
-    /* Return TRUE if it's a guest frame. */
+    /* Return true if it's a guest frame. */
     return (diff == 0);
 }
 
diff --git a/xen/include/asm-x86/regs.h b/xen/include/asm-x86/regs.h
index 725a664e0a..679c38bb76 100644
--- a/xen/include/asm-x86/regs.h
+++ b/xen/include/asm-x86/regs.h
@@ -11,7 +11,7 @@
     ASSERT(diff < STACK_SIZE);                                                \
     /* If not a guest frame, it must be a hypervisor frame. */                \
     ASSERT((diff == 0) || (r->cs == __HYPERVISOR_CS));                        \
-    /* Return TRUE if it's a guest frame. */                                  \
+    /* Return true if it's a guest frame. */                                  \
     (diff == 0);                                                              \
 })
 
diff --git a/xen/include/asm-x86/x86_64/efibind.h b/xen/include/asm-x86/x86_64/efibind.h
index b013db175d..2b7001f8f4 100644
--- a/xen/include/asm-x86/x86_64/efibind.h
+++ b/xen/include/asm-x86/x86_64/efibind.h
@@ -127,7 +127,7 @@ typedef uint64_t   UINTN;
 #ifdef EFI_NT_EMULATOR
     #define BREAKPOINT()        __asm { int 3 }
 #else
-    #define BREAKPOINT()        while (TRUE);    // Make it hang on Bios[Dbg]32
+    #define BREAKPOINT()        while (true);    // Make it hang on Bios[Dbg]32
 #endif
 
 //
diff --git a/xen/include/efi/efidef.h b/xen/include/efi/efidef.h
index 86a7e111bf..fe1750de51 100644
--- a/xen/include/efi/efidef.h
+++ b/xen/include/efi/efidef.h
@@ -22,16 +22,7 @@ Revision History
 
 typedef UINT16          CHAR16;
 typedef UINT8           CHAR8;
-typedef UINT8           BOOLEAN;
-
-#ifndef TRUE
-    #define TRUE    ((BOOLEAN) 1)
-    #define FALSE   ((BOOLEAN) 0)
-#endif
-
-#ifndef NULL
-    #define NULL    ((VOID *) 0)
-#endif
+typedef bool            BOOLEAN;
 
 typedef UINTN           EFI_STATUS;
 typedef UINT64          EFI_LBA;
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 8d0ddfb60c..2b5ae8cae4 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -607,7 +607,7 @@ int __must_check donate_page(struct domain *d, struct page_info *page,
 #define RAM_TYPE_UNUSABLE     0x00000004
 #define RAM_TYPE_ACPI         0x00000008
 #define RAM_TYPE_UNKNOWN      0x00000010
-/* TRUE if the whole page at @mfn is of the requested RAM type(s) above. */
+/* true if the whole page at @mfn is of the requested RAM type(s) above. */
 int page_is_ram_type(unsigned long mfn, unsigned long mem_type);
 /* Returns the page type(s). */
 unsigned int page_get_ram_type(mfn_t mfn);
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 9f7bc69293..c43d9311aa 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -552,7 +552,7 @@ static inline bool is_system_domain(const struct domain *d)
 
 /*
  * Use this when you don't have an existing reference to @d. It returns
- * FALSE if @d is being destroyed.
+ * false if @d is being destroyed.
  */
 static always_inline int get_domain(struct domain *d)
 {
