diff --git a/sys/i386/i386/genassym.c b/sys/i386/i386/genassym.c
--- a/sys/i386/i386/genassym.c
+++ b/sys/i386/i386/genassym.c
@@ -183,7 +183,6 @@
 ASSYM(BI_VERSION, offsetof(struct bootinfo, bi_version));
 ASSYM(BI_KERNELNAME, offsetof(struct bootinfo, bi_kernelname));
 ASSYM(BI_NFS_DISKLESS, offsetof(struct bootinfo, bi_nfs_diskless));
-ASSYM(BI_ENDCOMMON, offsetof(struct bootinfo, bi_endcommon));
 ASSYM(NFSDISKLESS_SIZE, sizeof(struct nfs_diskless));
 ASSYM(BI_SIZE, offsetof(struct bootinfo, bi_size));
 ASSYM(BI_SYMTAB, offsetof(struct bootinfo, bi_symtab));
diff --git a/sys/i386/i386/locore.s b/sys/i386/i386/locore.s
--- a/sys/i386/i386/locore.s
+++ b/sys/i386/i386/locore.s
@@ -178,6 +178,9 @@
 	 *	 and always passed in as 0]
 	 *	[esym is also known as total in the boot code, and
 	 *	 was never properly supported by the FreeBSD boot code]
+	 *	This code from 1.x/2.x doesn't supply now-required metadata and
+	 *	likely will fail (we test for it to avoid dereferencing stack
+	 *	garbage here).
 	 *
 	 * Old diskless netboot code:
 	 *	(*btext)(0,0,0,0,&nfsdiskless,0,0,0);
@@ -195,9 +198,11 @@
 	 */
 
 	/*
-	 * The old style disk boot blocks fake a frame on the stack and
-	 * did an lret to get here.  The frame on the stack has a return
-	 * address of 0.
+	 * The old style disk boot blocks fake a frame on the stack and did an
+	 * lret to get here.  The frame on the stack has a return address of 0.
+	 * This style of boot (from 1.x / 2.x) almost certainly won't work,
+	 * since the kernel has required metadata since about 7.x or so and none
+	 * are present.
 	 */
 	cmpl	$0,4(%ebp)
 	je	olddiskboot
@@ -212,9 +217,9 @@
 	je	newboot
 
 	/*
-	 * Seems we have been loaded by the old diskless boot code, we
-	 * don't stand a chance of running as the diskless structure
-	 * changed considerably between the two, so just halt.
+	 * Seems we have been loaded by the old 1.x/2.x diskless boot code, we
+	 * don't stand a chance of running as the diskless structure changed
+	 * considerably between the two, so just halt.
 	 */
 	 hlt
 
@@ -228,6 +233,8 @@
 	movl	BI_VERSION(%ebx),%eax
 	cmpl	$1,%eax			/* We only understand version 1 */
 	je	1f
+	testl   $RB_BOOTINFO,8(%ebp)    /* bi_size (and bootinfo) valid? */
+	jne	1f
 	movl	$1,%eax			/* Return status */
 	leave
 	/*
@@ -258,21 +265,12 @@
 2:
 	/*
 	 * Determine the size of the boot loader's copy of the bootinfo
-	 * struct.  This is impossible to do properly because old versions
-	 * of the struct don't contain a size field and there are 2 old
-	 * versions with the same version number.
-	 */
-	movl	$BI_ENDCOMMON,%ecx	/* prepare for sizeless version */
-	testl	$RB_BOOTINFO,8(%ebp)	/* bi_size (and bootinfo) valid? */
-	je	got_bi_size		/* no, sizeless version */
-	movl	BI_SIZE(%ebx),%ecx
-got_bi_size:
-
-	/*
-	 * Copy the common part of the bootinfo struct
+	 * struct. Copy min(our size, loader's size) into our bootinfo.
+	 * Incompatible with really old boot loaders from FreeBSD 1.x and 2.0.
 	 */
 	movl	%ebx,%esi
 	movl	$bootinfo,%edi
+	movl	BI_SIZE(%ebx),%ecx
 	cmpl	$BOOTINFO_SIZE,%ecx
 	jbe	got_common_bi_size
 	movl	$BOOTINFO_SIZE,%ecx
diff --git a/sys/i386/include/bootinfo.h b/sys/i386/include/bootinfo.h
--- a/sys/i386/include/bootinfo.h
+++ b/sys/i386/include/bootinfo.h
@@ -44,15 +44,13 @@
 
 /*
  * A zero bootinfo field often means that there is no info available.
- * Flags are used to indicate the validity of fields where zero is a
- * normal value.
+ * Assumes booting with a boot loader from FreeBSD 2.1 or newer and
+ * that bi_size is always valid when bi_version == 1.
  */
 struct bootinfo {
-	u_int32_t	bi_version;
+	u_int32_t	bi_version;		/* Must be 1 */
 	u_int32_t	bi_kernelname;		/* represents a char * */
 	u_int32_t	bi_nfs_diskless;	/* struct nfs_diskless * */
-				/* End of fields that are always present. */
-#define	bi_endcommon	_was_bi_n_bios_used
 	u_int32_t	_was_bi_n_bios_used;
 	u_int32_t	_was_bi_bios_geom[_WAS_N_BIOS_GEOM];
 	u_int32_t	bi_size;
@@ -67,13 +65,6 @@
 	u_int32_t	bi_kernend;		/* end of kernel space */
 	u_int32_t	bi_envp;		/* environment */
 	u_int32_t	bi_modulep;		/* preloaded modules */
-	uint32_t	_was_bi_memdesc_version;/* EFI memory desc version */
-	uint64_t	_was_bi_memdesc_size;	/* sizeof EFI memory desc */
-	uint64_t	_was_bi_memmap;		/* pa of EFI memory map */
-	uint64_t	_was_bi_memmap_size;	/* size of EFI memory map */
-	uint64_t	_was_bi_hcdp;		/* DIG64 HCDP table */
-	uint64_t	_was_bi_fpswa;		/* FPSWA interface */
-	uint64_t	_was_bi_systab;		/* pa of EFI system table */
 };
 
 #ifdef _KERNEL