Squashed commit of the following:

Author: Xiang Xiao <xiaoxiang@xiaomi.com>

     arch/arm/src/armv7-m:  Implement SYSTICK timer driver

   Author: anchao <anchao@pinecone.net>

     configs/sim/loadable:  Add loadable demo for arch sim
     sched/init: Restore previously reverted option to mount block device for INIT_FILEPATH case
     configs/stm3240g-eval/knxwm: Fix build breakage.

   Author: Gregory Nutt <gnutt@nuttx.org>
     configs:  With recent changes to apps/ all configurations that build applications as modules must now also select CONFIG_APPS_LOADABLE.

   Author: anchao <anchao@pinecone.net>
      configs/sim/loadable:  Add loadable demo for arch sim
       Kconfig and tools/Makefile.unix and : add dynamic application loadable support

Kconfig

@@ -161,6 +161,16 @@ config APPS_DIR
 		example, to include makefile fragments (e.g., .config or Make.defs)
 		or to set up include file paths.
 
+config BUILD_LOADABLE
+	bool "NuttX application loadable build"
+	default n if !BUILD_KERNEL
+	default y if BUILD_KERNEL
+	---help---
+		Automatically selected if KERNEL build is selected.
+		This selection only effects the behavior of the 'make export'
+		target and currently has no effect unless you wish to build
+		loadable applications in a FLAT build.
+
 choice
 	prompt "Memory organization"
 	default BUILD_FLAT

configs/lc823450-xgevk/krndis/defconfig

@@ -22,6 +22,7 @@ CONFIG_BINFMT_EXEPATH=y
 CONFIG_BOARDCTL_RESET=y
 CONFIG_BOARDCTL_USBDEVCTRL=y
 CONFIG_BOARD_LOOPSPERMSEC=12061
+CONFIG_BUILD_LOADABLE=y
 CONFIG_BUILD_PROTECTED=y
 CONFIG_C99_BOOL8=y
 CONFIG_CODECS_HASH_MD5=y

configs/lc823450-xgevk/rndis/defconfig

@@ -21,6 +21,7 @@ CONFIG_BINFMT_EXEPATH=y
 CONFIG_BOARDCTL_RESET=y
 CONFIG_BOARDCTL_USBDEVCTRL=y
 CONFIG_BOARD_LOOPSPERMSEC=12061
+CONFIG_BUILD_LOADABLE=y
 CONFIG_BUILTIN=y
 CONFIG_C99_BOOL8=y
 CONFIG_CODECS_HASH_MD5=y

configs/sim/README.txt

@@ -561,6 +561,12 @@ ipforward
   Additional required settings will also be selected when you manually
   select the above via 'make menuconfig'.
 
+loadable
+
+  This configuration provides an example of loadable apps.  It cannot used
+  with any Windows configuration, however, because Windows does not use
+  the ELF format.
+
 minibasic
 
   This configuration was used to test the Mini Basic port at

configs/sim/loadable/defconfig

@@ -1,4 +1,3 @@
-CONFIG_APPS_LOADABLE=y
 CONFIG_ARCH="sim"
 CONFIG_ARCH_BOARD="sim"
 CONFIG_ARCH_BOARD_SIM=y
@@ -6,26 +5,31 @@ CONFIG_ARCH_SIM=y
 CONFIG_BINFMT_EXEPATH=y
 CONFIG_BOARDCTL_APP_SYMTAB=y
 CONFIG_BOARDCTL_POWEROFF=y
+CONFIG_BOARD_INITIALIZE=y
+CONFIG_BUILD_LOADABLE=y
 CONFIG_BUILTIN=y
 CONFIG_CLOCK_MONOTONIC=y
 CONFIG_DEBUG_FEATURES=y
 CONFIG_DEBUG_SYMBOLS=y
 CONFIG_ELF=y
-CONFIG_EXAMPLES_HELLO=y
+CONFIG_EXAMPLES_HELLO=m
 CONFIG_EXAMPLES_HELLO_STACKSIZE=8192
 CONFIG_EXECFUNCS_HAVE_SYMTAB=y
 CONFIG_FS_HOSTFS=y
 CONFIG_FS_PROCFS=y
 CONFIG_IDLETHREAD_STACKSIZE=4096
 CONFIG_INIT_FILEPATH=y
+CONFIG_INIT_MOUNT=y
 CONFIG_INIT_MOUNT_DATA="fs=../apps/exe/system"
 CONFIG_INIT_MOUNT_FLAGS=0x1
 CONFIG_INIT_MOUNT_FSTYPE="hostfs"
+CONFIG_INIT_MOUNT_SOURCE=""
 CONFIG_INIT_MOUNT_TARGET="/system"
 CONFIG_LIBC_EXECFUNCS=y
 CONFIG_MEMSET_OPTSPEED=y
 CONFIG_NSH_ARCHINIT=y
 CONFIG_NSH_BUILTIN_APPS=y
+CONFIG_NSH_FILE_APPS=y
 CONFIG_NSH_LINELEN=128
 CONFIG_NSH_READLINE=y
 CONFIG_PATH_INITIAL="/system/bin"
@@ -40,7 +44,7 @@ CONFIG_SIM_M32=y
 CONFIG_SIM_WALLTIME=y
 CONFIG_START_MONTH=6
 CONFIG_START_YEAR=2008
-CONFIG_SYSTEM_NSH=y
+CONFIG_SYSTEM_NSH=m
 CONFIG_TIME_EXTENDED=y
 CONFIG_USERMAIN_STACKSIZE=4096
 CONFIG_USER_INITPATH="/system/bin/nsh"

configs/sim/src/sim_bringup.c

@@ -44,6 +44,7 @@
 #include <sys/mount.h>
 #include <debug.h>
 
+#include <nuttx/binfmt/elf.h>
 #include <nuttx/board.h>
 #include <nuttx/clock.h>
 #include <nuttx/kmalloc.h>

configs/stm3240g-eval/knxwm/Make.defs

@@ -77,7 +77,7 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
 endif
 
 ARCHCFLAGS = -fno-builtin
-ARCHCXXFLAGS = -fno-builtin -fno-exceptions -fcheck-new -fno-rtti
+ARCHCXXFLAGS = -fno-builtin -fno-exceptions -fcheck-new -fno-rtti -fpermissive
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHDEFINES =

sched/Kconfig

@@ -363,6 +363,40 @@ config INIT_NEXPORTS
 		Any kernel mode symbols tables would not be usable for resolving
 		symbols in user mode executables.
 
+menuconfig INIT_MOUNT
+	bool "Auto-mount init file system"
+	default n
+	depends on !DISABLE_MOUNTPOINT
+	---help---
+		In order to use the the initial startup program when CONFIG_INIT_FILEPATH
+		is provided, it is necessary to mount the initial file system that
+		provides init program.  Normally this mount is done in the board-specific
+		initialization logic.  However, if the mount is very simple, it can be
+		performed by the OS bring-up logic itself by selecting this option.
+
+if INIT_MOUNT
+
+config INIT_MOUNT_SOURCE
+	string "The block device to mount"
+	default "/dev/ram0"
+
+config INIT_MOUNT_TARGET
+	string "Path to the mounted file system"
+	default "/bin"
+
+config INIT_MOUNT_FSTYPE
+	string "The file system type to mount"
+	default "romfs"
+
+config INIT_MOUNT_FLAGS
+	hex "Flags passed to mount"
+	default 0
+
+config INIT_MOUNT_DATA
+	string "Additional data passed to mount"
+	default ""
+
+endif # INIT_MOUNT
 endif # INIT_FILEPATH
 
 config RR_INTERVAL

sched/init/os_bringup.c

@@ -45,7 +45,9 @@
 
 #include <sched.h>
 #include <stdlib.h>
+#include <string.h>
 #include <debug.h>
+#include <sys/mount.h>
 
 #include <nuttx/arch.h>
 #include <nuttx/board.h>
@@ -98,10 +100,6 @@
    * program.
    */
 
-#    ifndef CONFIG_BOARD_INITIALIZE
-#      warning You probably need CONFIG_BOARD_INITIALIZE to mount the file system
-#    endif
-
 #    ifndef CONFIG_USER_INITPATH
   /* Path to the initialization program must have been provided */
 
@@ -287,6 +285,16 @@ static inline void os_do_appstart(void)
   board_initialize();
 #endif
 
+#ifdef CONFIG_INIT_MOUNT
+  /* Mount the file system containing the init program. */
+
+  ret = mount(CONFIG_INIT_MOUNT_SOURCE, CONFIG_INIT_MOUNT_TARGET,
+              CONFIG_INIT_MOUNT_FSTYPE, CONFIG_INIT_MOUNT_FLAGS,
+              CONFIG_INIT_MOUNT_DATA);
+  DEBUGASSERT(ret >= 0);
+  UNUSED(ret);
+#endif
+
   /* Start the application initialization program from a program in a
    * mounted file system.  Presumably the file system was mounted as part
    * of the board_initialize() operation.
@@ -297,6 +305,7 @@ static inline void os_do_appstart(void)
   ret = exec(CONFIG_USER_INITPATH, NULL, CONFIG_INIT_SYMTAB,
              CONFIG_INIT_NEXPORTS);
   ASSERT(ret >= 0);
+  UNUSED(ret);
 }
 
 #elif defined(CONFIG_INIT_NONE)

syscall/syscall_funclookup.c

@@ -86,7 +86,7 @@
 #undef get_errno
 #undef set_errno
 
-#include <nuttx/errno.h>
+#include <errno.h>
 #include <nuttx/clock.h>
 
 /****************************************************************************

tools/Makefile.unix

@@ -166,10 +166,10 @@ MKEXPORT_ARGS = -w$(WINTOOL) -t "$(TOPDIR)"
 
 ifeq ($(CONFIG_BUILD_PROTECTED),y)
 MKEXPORT_ARGS += -u
-else
+else ifeq ($(CONFIG_BUILD_KERNEL),y)
-ifeq ($(CONFIG_BUILD_KERNEL),y)
+MKEXPORT_ARGS += -u
+else ifeq ($(CONFIG_BUILD_LOADABLE),y)
 MKEXPORT_ARGS += -u
-endif
 endif
 
 ifeq ($(V),2)

tools/Makefile.win

@@ -158,11 +158,11 @@ MKEXPORT = tools\mkexport.bat
 MKEXPORT_ARGS = -w$(WINTOOL) -t "$(TOPDIR)"
 
 ifeq ($(CONFIG_BUILD_PROTECTED),y)
-MKEXPORT_ARGS = -u
+MKEXPORT_ARGS += -u
-else
+else ifeq ($(CONFIG_BUILD_KERNEL),y)
-ifeq ($(CONFIG_BUILD_KERNEL),y)
+MKEXPORT_ARGS += -u
-MKEXPORT_ARGS = -u
+else ifeq ($(CONFIG_BUILD_LOADABLE),y)
-endif
+MKEXPORT_ARGS += -u
 endif
 
 ifeq ($(V),2)