#define EFI_LOCATE_BY_REGISTER_NOTIFY 1
#define EFI_LOCATE_BY_PROTOCOL 2
+/*
+ * An efi_boot_memmap is used by efi_get_memory_map() to return the
+ * EFI memory map in a dynamically allocated buffer.
+ *
+ * The buffer allocated for the EFI memory map includes extra room for
+ * a minimum of EFI_MMAP_NR_SLACK_SLOTS additional EFI memory descriptors.
+ * This facilitates the reuse of the EFI memory map buffer when a second
+ * call to ExitBootServices() is needed because of intervening changes to
+ * the EFI memory map. Other related structures, e.g. x86 e820ext, need
+ * to factor in this headroom requirement as well.
+ */
+#define EFI_MMAP_NR_SLACK_SLOTS 8
+
struct efi_boot_memmap {
efi_memory_desc_t **map;
unsigned long *map_size;