diff --git a/include/lib/hob/mmram.h b/include/lib/hob/mmram.h
new file mode 100644
index 0000000..b269c64
--- /dev/null
+++ b/include/lib/hob/mmram.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2024, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#ifndef MMRAM_H
+#define MMRAM_H
+
+#include <lib/hob/efi_types.h>
+
+/**
+ * MMRAM states and capabilities
+ * See UEFI Platform Initialization Specification Version 1.8, IV-5.3.5
+ */
+#define EFI_MMRAM_OPEN                U(0x00000001)
+#define EFI_MMRAM_CLOSED              U(0x00000002)
+#define EFI_MMRAM_LOCKED              U(0x00000004)
+#define EFI_CACHEABLE                 U(0x00000008)
+#define EFI_ALLOCATED                 U(0x00000010)
+#define EFI_NEEDS_TESTING             U(0x00000020)
+#define EFI_NEEDS_ECC_INITIALIZATION  U(0x00000040)
+
+#define EFI_SMRAM_OPEN    EFI_MMRAM_OPEN
+#define EFI_SMRAM_CLOSED  EFI_MMRAM_CLOSED
+#define EFI_SMRAM_LOCKED  EFI_MMRAM_LOCKED
+
+struct efi_mmram_descriptor {
+	efi_physical_address_t physical_start;
+	efi_physical_address_t cpu_start;
+	uint64_t physical_size;
+	uint64_t region_state;
+};
+
+/**
+ * MMRAM block descriptor
+ * This definition comes from
+ *     https://github.com/tianocore/edk2/blob/master/StandaloneMmPkg/Include/Guid/MmramMemoryReserve.h
+ */
+struct efi_mmram_hob_descriptor_block {
+	uint32_t number_of_mm_reserved_regions;
+	struct efi_mmram_descriptor descriptor[];
+};
+
+#endif /* MMRAM_H */