hw: use generic crt0.s for progs other than core

Use '__initial_sp' instead of '_main_utcb' to receive a main threads
UTCB pointer outside core.

Ref #766

base-hw/lib/mk/arm/startup.mk

@@ -1,10 +0,0 @@
-#
-# \brief  Linked against any program expect LDSO and dynamic binaries
-# \author Martin Stein
-# \date   2012-04-16
-#
-
-include $(BASE_DIR)/lib/mk/startup.inc
-
-vpath crt0.s $(REP_DIR)/src/platform/arm
-

base-hw/src/base/thread_support.cc

@@ -19,7 +19,7 @@
 
 using namespace Genode;
 
-extern Native_utcb * _main_utcb;
+extern Native_utcb * __initial_sp;
 
 namespace Genode { Rm_session  *env_context_area_rm_session(); }
 
@@ -31,7 +31,7 @@ namespace Genode { Rm_session  *env_context_area_rm_session(); }
 Native_utcb * Thread_base::utcb()
 {
 	/* this is a main thread, so CRT0 provides UTCB through '_main_utcb' */
-	if (!this) return _main_utcb;
+	if (!this) return __initial_sp;
 
 	/* otherwise we have a valid thread base */
 	return &_context->utcb;

base-hw/src/platform/arm/crt0.s

@@ -1,53 +0,0 @@
-
-/**
- * \brief   Startup code for Genode programs on Cortex A9
- * \author  Martin Stein
- * \date    2011-10-01
- */
-
-/*
- * Copyright (C) 2012-2013 Genode Labs GmbH
- *
- * This file is part of the Genode OS framework, which is distributed
- * under the terms of the GNU General Public License version 2.
- */
-
-.section .text
-
-	/* ELF entry symbol */
-	.global _start
-	_start:
-
-		/* fetch thread-entry arguments to their destinations in BSS */
-		ldr r0, =_main_utcb
-		str sp, [r0]
-
-		/* call _main routine */
-		ldr sp, =_stack_high
-		.extern _main
-		bl _main
-		1: b 1b
-
-	/* dynamic symbol object handle */
-	.p2align 2
-	.global __dso_handle
-	__dso_handle: .long 0
-
-	.global __initial_sp
-	__initial_sp: .long 0
-
-.section .bss
-
-	/* main-thread stack */
-	.p2align 2
-	.global _stack_low
-	_stack_low:
-	.space 64*1024
-	.global _stack_high
-	_stack_high:
-
-	/* main-thread UTCB-pointer for the Genode thread-API */
-	.p2align 2
-	.global _main_utcb
-	_main_utcb: .long 0
-