Index: sys/amd64/amd64/machdep.c
===================================================================
--- sys/amd64/amd64/machdep.c
+++ sys/amd64/amd64/machdep.c
@@ -1176,11 +1176,11 @@
 
 	if (efihdr != NULL) {
 		add_efi_map_entries(efihdr, physmap, physmap_idx);
-		strlcpy(bootmethod, "UEFI", sizeof(bootmethod));
+		firmware_type = FW_UEFI;
 	} else {
 		size = *((u_int32_t *)smap - 1);
 		bios_add_smap_entries(smap, size, physmap, physmap_idx);
-		strlcpy(bootmethod, "BIOS", sizeof(bootmethod));
+		firmware_type = FW_BIOS;
 	}
 }
 
Index: sys/arm64/acpica/acpi_machdep.c
===================================================================
--- sys/arm64/acpica/acpi_machdep.c
+++ sys/arm64/acpica/acpi_machdep.c
@@ -234,7 +234,7 @@
 {
 
 	/* Only parse ACPI tables when booting via ACPI */
-	if (arm64_bus_method != ARM64_BUS_ACPI)
+	if (firmware_type != FW_UEFI)
 		return;
 
 	acpi_pxm_init(MAXCPU, get_physaddr_max());
Index: sys/arm64/arm64/machdep.c
===================================================================
--- sys/arm64/arm64/machdep.c
+++ sys/arm64/arm64/machdep.c
@@ -103,7 +103,7 @@
 static void get_fpcontext(struct thread *td, mcontext_t *mcp);
 static void set_fpcontext(struct thread *td, mcontext_t *mcp);
 
-enum arm64_bus arm64_bus_method = ARM64_BUS_NONE;
+enum firmware_types firmware_type = FW_NONE;
 
 struct pcpu __pcpu[MAXCPU];
 
@@ -1199,13 +1199,13 @@
 			if (has_acpi &&
 			    strncmp(order, "acpi", 4) == 0 &&
 			    (order[4] == ',' || order[4] == '\0')) {
-				arm64_bus_method = ARM64_BUS_ACPI;
+				firmware_type = FW_UEFI;
 				break;
 			}
 			if (has_fdt &&
 			    strncmp(order, "fdt", 3) == 0 &&
 			    (order[3] == ',' || order[3] == '\0')) {
-				arm64_bus_method = ARM64_BUS_FDT;
+				firmware_type = FW_DEVTREE;
 				break;
 			}
 			order = strchr(order, ',');
@@ -1213,15 +1213,15 @@
 		freeenv(env);
 
 		/* If we set the bus method it is valid */
-		if (arm64_bus_method != ARM64_BUS_NONE)
+		if (firmware_type != FW_NONE)
 			return (true);
 	}
 	/* If no order or an invalid order was set use the default */
-	if (arm64_bus_method == ARM64_BUS_NONE) {
+	if (firmware_type == FW_NONE) {
 		if (has_fdt)
-			arm64_bus_method = ARM64_BUS_FDT;
+			firmware_type = FW_DEVTREE;
 		else if (has_acpi)
-			arm64_bus_method = ARM64_BUS_ACPI;
+			firmware_type = FW_UEFI;
 	}
 
 	/*
@@ -1423,7 +1423,7 @@
 		strlcpy(kernelname, env, sizeof(kernelname));
 
 #ifdef FDT
-	if (arm64_bus_method == ARM64_BUS_FDT) {
+	if (firmware_type == FW_DEVTREE) {
 		root = OF_finddevice("/");
 		if (OF_getprop(root, "freebsd,dts-version", dts_version, sizeof(dts_version)) > 0) {
 			if (strcmp(LINUX_DTS_VERSION, dts_version) != 0)
Index: sys/arm64/arm64/mp_machdep.c
===================================================================
--- sys/arm64/arm64/mp_machdep.c
+++ sys/arm64/arm64/mp_machdep.c
@@ -669,15 +669,15 @@
 	CPU_SET(0, &all_cpus);
 	__pcpu[0].pc_mpidr = READ_SPECIALREG(mpidr_el1) & CPU_AFF_MASK;
 
-	switch(arm64_bus_method) {
+	switch(firmware_type) {
 #ifdef DEV_ACPI
-	case ARM64_BUS_ACPI:
+	case FW_UEFI:
 		mp_quirks = MP_QUIRK_CPULIST;
 		cpu_init_acpi();
 		break;
 #endif
 #ifdef FDT
-	case ARM64_BUS_FDT:
+	case FW_DEVTREE:
 		cpu_init_fdt();
 		break;
 #endif
@@ -744,9 +744,9 @@
 	mp_ncpus = 1;
 	mp_maxid = 0;
 
-	switch(arm64_bus_method) {
+	switch(firmware_type) {
 #ifdef DEV_ACPI
-	case ARM64_BUS_ACPI:
+	case FW_UEFI:
 		cores = cpu_count_acpi();
 		if (cores > 0) {
 			cores = MIN(cores, MAXCPU);
@@ -759,7 +759,7 @@
 		break;
 #endif
 #ifdef FDT
-	case ARM64_BUS_FDT:
+	case FW_DEVTREE:
 		cores = ofw_cpu_early_foreach(NULL, false);
 		if (cores > 0) {
 			cores = MIN(cores, MAXCPU);
Index: sys/arm64/arm64/nexus.c
===================================================================
--- sys/arm64/arm64/nexus.c
+++ sys/arm64/arm64/nexus.c
@@ -493,7 +493,7 @@
 nexus_fdt_probe(device_t dev)
 {
 
-	if (arm64_bus_method != ARM64_BUS_FDT)
+	if (firmware_type != FW_DEVTREE)
 		return (ENXIO);
 
 	device_quiet(dev);
@@ -554,7 +554,7 @@
 nexus_acpi_probe(device_t dev)
 {
 
-	if (arm64_bus_method != ARM64_BUS_ACPI || acpi_identify() != 0)
+	if (firmware_type != FW_UEFI || acpi_identify() != 0)
 		return (ENXIO);
 
 	device_quiet(dev);
Index: sys/arm64/include/machdep.h
===================================================================
--- sys/arm64/include/machdep.h
+++ sys/arm64/include/machdep.h
@@ -42,14 +42,6 @@
 	int		pad;
 };
 
-enum arm64_bus {
-	ARM64_BUS_NONE,
-	ARM64_BUS_FDT,
-	ARM64_BUS_ACPI,
-};
-
-extern enum arm64_bus arm64_bus_method;
-
 void dbg_init(void);
 bool has_hyp(void);
 void initarm(struct arm64_bootparams *);
Index: sys/dev/psci/psci.c
===================================================================
--- sys/dev/psci/psci.c
+++ sys/dev/psci/psci.c
@@ -89,8 +89,8 @@
 #define	USE_ACPI	0
 #define	USE_FDT		1
 #elif defined(__aarch64__)
-#define	USE_ACPI	(arm64_bus_method == ARM64_BUS_ACPI)
-#define	USE_FDT		(arm64_bus_method == ARM64_BUS_FDT)
+#define	USE_ACPI	(firmware_type == FW_UEFI)
+#define	USE_FDT		(firmware_type == FW_DEVTREE)
 #else
 #error Unknown architecture
 #endif
Index: sys/dev/uart/uart_dev_pl011.c
===================================================================
--- sys/dev/uart/uart_dev_pl011.c
+++ sys/dev/uart/uart_dev_pl011.c
@@ -59,7 +59,7 @@
 #include <sys/kdb.h>
 
 #ifdef __aarch64__
-#define	IS_FDT	(arm64_bus_method == ARM64_BUS_FDT)
+#define	IS_FDT	(firmware_type == FW_DEVTREE)
 #elif defined(FDT)
 #define	IS_FDT	1
 #else
Index: sys/dev/xen/efi/pvefi.c
===================================================================
--- sys/dev/xen/efi/pvefi.c
+++ sys/dev/xen/efi/pvefi.c
@@ -43,8 +43,6 @@
 
 #include <xen/interface/platform.h>
 
-extern char bootmethod[16];
-
 static int
 rt_ok(void)
 {
@@ -224,7 +222,7 @@
 		rt_disabled = 0;
 		TUNABLE_INT_FETCH("efi.rt.disabled", &rt_disabled);
 
-		if (!xen_initial_domain() || strcmp("UEFI", bootmethod) != 0 ||
+		if (!xen_initial_domain() || firmware_type != FW_UEFI ||
 		    rt_disabled == 1)
 			return (0);
 
Index: sys/i386/i386/machdep.c
===================================================================
--- sys/i386/i386/machdep.c
+++ sys/i386/i386/machdep.c
@@ -2350,7 +2350,7 @@
 	init_param1();
 
 	/* Set bootmethod to BIOS: it's the only supported on i386. */
-	strlcpy(bootmethod, "BIOS", sizeof(bootmethod));
+	firmware_type = FW_BIOS;
 
 	/*
 	 * Make gdt memory segments.  All segments cover the full 4GB
Index: sys/sys/systm.h
===================================================================
--- sys/sys/systm.h
+++ sys/sys/systm.h
@@ -70,6 +70,15 @@
 extern int boothowto;		/* reboot flags, from console subsystem */
 extern int bootverbose;		/* nonzero to print verbose messages */
 
+extern enum firmware_types {
+	FW_NONE = 0,
+	FW_UEFI,
+	FW_DEVTREE,
+	FW_BIOS,
+	FW_HYPER,
+	FW_LAST
+} firmware_type;
+
 extern int maxusers;		/* system tune hint */
 extern int ngroups_max;		/* max # of supplemental groups */
 extern int vm_guest;		/* Running as virtual machine guest? */
Index: sys/x86/include/x86_var.h
===================================================================
--- sys/x86/include/x86_var.h
+++ sys/x86/include/x86_var.h
@@ -95,7 +95,6 @@
 extern	int	cpu_flush_rsb_ctxsw;
 extern	int	x86_rngds_mitg_enable;
 extern	int	cpu_amdc1e_bug;
-extern	char	bootmethod[16];
 
 struct	pcb;
 struct	thread;
Index: sys/x86/x86/cpu_machdep.c
===================================================================
--- sys/x86/x86/cpu_machdep.c
+++ sys/x86/x86/cpu_machdep.c
@@ -113,10 +113,30 @@
 static volatile u_int	cpu_reset_proxy_active;
 #endif
 
-char bootmethod[16];
+static char bootmethod[16];
 SYSCTL_STRING(_machdep, OID_AUTO, bootmethod, CTLFLAG_RD, bootmethod, 0,
     "System firmware boot method");
 
+enum firmware_types firmware_type = FW_NONE;
+
+/*
+ * Set the sysctl bootmethod for compatibility
+ */
+static void set_bootmethod(const void *unused __unused)
+{
+	const char *const types[] = {
+		[FW_UEFI] = "UEFI",
+		[FW_BIOS] = "BIOS",
+	};
+	const char *val = "unknown";
+
+	if (firmware_type < nitems(types) && types[firmware_type] != NULL)
+		val = types[firmware_type];
+
+	strlcpy(bootmethod, val, sizeof(bootmethod));
+}
+C_SYSINIT(set_bootmethod, SI_SUB_LAST, SI_ORDER_SECOND, set_bootmethod, NULL);
+
 struct msr_op_arg {
 	u_int msr;
 	int op;
Index: sys/x86/xen/pv.c
===================================================================
--- sys/x86/xen/pv.c
+++ sys/x86/xen/pv.c
@@ -365,9 +365,9 @@
 		xen_pvh_set_env(envp, reject_option);
 
 		if (MD_FETCH(kmdp, MODINFOMD_EFI_MAP, void *) != NULL)
-		    strlcpy(bootmethod, "UEFI", sizeof(bootmethod));
+			firmware_type = FW_UEFI;
 		else
-		    strlcpy(bootmethod, "BIOS", sizeof(bootmethod));
+			firmware_type = FW_BIOS;
 	} else {
 		/* Parse the extra boot information given by Xen */
 		if (start_info->cmdline_paddr != 0)
@@ -375,7 +375,7 @@
 			    (char *)(start_info->cmdline_paddr + KERNBASE),
 			    ",");
 		kmdp = NULL;
-		strlcpy(bootmethod, "XEN", sizeof(bootmethod));
+		firmware_type = FW_HYPER;
 	}
 
 	boothowto |= boot_env_to_howto();