Add an elf not so kgdb detects the kernel as a FreeBSD elf file. The

ELFNOTE macro is based on one from the FreeBSD/ARM Xen tree [1].

Obtained from:	Julien Grall <julien.grall AT linaro.org> [1]

sys/arm/arm/elf_note.S

@@ -0,0 +1,36 @@
+/*-
+ * Copyright (c) 2014 Andrew Turner <andrew@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ */
+
+#include <machine/asm.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <machine/asmacros.h>
+
+/* An ELF note so GDB detects this as a FreeBSD elf file */
+ELFNOTE(.note.tag, 1, "FreeBSD", .long, __FreeBSD_version);
+

sys/arm/include/asmacros.h

@@ -45,6 +45,18 @@
 	ldr	tmp, [tmp, #PC_CURTHREAD]
 #endif
 
+#define	ELFNOTE(section, type, vendor, desctype, descdata...)	  \
+	.pushsection section					; \
+	    .balign 4						; \
+	    .long 2f - 1f		/* namesz */		; \
+	    .long 4f - 3f		/* descsz */		; \
+	    .long type			/* type */		; \
+	    1: .asciz vendor		/* vendor name */	; \
+	    2: .balign 4					; \
+	    3:  desctype descdata	/* node */		; \
+	    4: .balign 4					; \
+	.popsection
+
 #endif /* LOCORE */
 
 #endif /* _KERNEL */

sys/conf/files.arm

@@ -18,6 +18,7 @@ arm/arm/devmap.c		standard
 arm/arm/disassem.c		optional	ddb
 arm/arm/dump_machdep.c		standard
 arm/arm/elf_machdep.c		standard
+arm/arm/elf_note.S		standard
 arm/arm/exception.S		standard
 arm/arm/fiq.c			standard
 arm/arm/fiq_subr.S		standard