diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0af5250d914fd7b52d01873571dd6facb7bba8d4..8453fe1342eaf137bcf2c707bc93ac4717ee27db 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1585,6 +1585,20 @@ config EFI_STUB
 
 	  See Documentation/efi-stub.txt for more information.
 
+config EFI_MIXED
+	bool "EFI mixed-mode support"
+	depends on EFI_STUB && X86_64
+	---help---
+	   Enabling this feature allows a 64-bit kernel to be booted
+	   on a 32-bit firmware, provided that your CPU supports 64-bit
+	   mode.
+
+	   Note that it is not possible to boot a mixed-mode enabled
+	   kernel via the EFI boot stub - a bootloader that supports
+	   the EFI handover protocol must be used.
+
+	   If unsure, say N.
+
 config SECCOMP
 	def_bool y
 	prompt "Enable seccomp to safely compute untrusted bytecode"
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index d69d96653325818ff8f37ca18360b96c7b3b6703..256388260c8869c0a018dc39a7e2a78520838481 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -283,7 +283,7 @@ _start:
 	# Part 2 of the header, from the old setup.S
 
 		.ascii	"HdrS"		# header signature
-		.word	0x020c		# header version number (>= 0x0105)
+		.word	0x020d		# header version number (>= 0x0105)
 					# or else old loadlin-1.5 will fail)
 		.globl realmode_swtch
 realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG
@@ -375,7 +375,8 @@ xloadflags:
 # define XLF0 0
 #endif
 
-#if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64)
+#if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64) && \
+	!defined(CONFIG_EFI_MIXED)
    /* kernel/boot_param/ramdisk could be loaded above 4g */
 # define XLF1 XLF_CAN_BE_LOADED_ABOVE_4G
 #else
@@ -383,10 +384,14 @@ xloadflags:
 #endif
 
 #ifdef CONFIG_EFI_STUB
-# ifdef CONFIG_X86_64
-#  define XLF23 XLF_EFI_HANDOVER_64		/* 64-bit EFI handover ok */
+# ifdef CONFIG_EFI_MIXED
+#  define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64)
 # else
-#  define XLF23 XLF_EFI_HANDOVER_32		/* 32-bit EFI handover ok */
+#  ifdef CONFIG_X86_64
+#   define XLF23 XLF_EFI_HANDOVER_64		/* 64-bit EFI handover ok */
+#  else
+#   define XLF23 XLF_EFI_HANDOVER_32		/* 32-bit EFI handover ok */
+#  endif
 # endif
 #else
 # define XLF23 0
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 85935e6f69f3c530ad1fc2cacd17f19d9b5db104..a3837254e3202137ed97d5ecc8d9fa0b0591dc24 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -152,6 +152,17 @@ static inline bool efi_is_native(void)
 	return IS_ENABLED(CONFIG_X86_64) == efi_enabled(EFI_64BIT);
 }
 
+static inline bool efi_runtime_supported(void)
+{
+	if (efi_is_native())
+		return true;
+
+	if (IS_ENABLED(CONFIG_EFI_MIXED) && !efi_enabled(EFI_OLD_MEMMAP))
+		return true;
+
+	return false;
+}
+
 extern struct console early_efi_console;
 extern void parse_efi_setup(u64 phys_addr, u32 data_len);
 
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 06853e6703541f8349106e17330f86621fa984db..ff9b3a62a05cfd75b9891ba73e0d7d52a84828d5 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1243,7 +1243,7 @@ void __init setup_arch(char **cmdline_p)
 	 * mismatched firmware/kernel archtectures since there is no
 	 * support for runtime services.
 	 */
-	if (efi_enabled(EFI_BOOT) && !efi_is_native()) {
+	if (efi_enabled(EFI_BOOT) && !efi_runtime_supported()) {
 		pr_info("efi: Setup done, disabling due to 32/64-bit mismatch\n");
 		efi_unmap_memmap();
 	}
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 39f5b7bba695b67fc17ce099dc4dc5b8f25aa037..395decedfa2bf4f9167c6012a8a1157e8e4d8253 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -802,7 +802,7 @@ void __init efi_init(void)
 	 * that doesn't match the kernel 32/64-bit mode.
 	 */
 
-	if (!efi_is_native())
+	if (!efi_runtime_supported())
 		pr_info("No EFI runtime due to 32/64-bit mismatch with kernel\n");
 	else {
 		if (disable_runtime || efi_runtime_init())