Add interfaces to dynamically change symbol tables used by posix_spawn, execv, and execl. This is needed for testing.

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5506 42af7a65-404d-4744-a932-0658087f49c3

3 files changed, 85 insertions, 7 deletions

diff --git a/apps/examples/Make.defs b/apps/examples/Make.defs
index de2b8939f..68d4d4340 100644
--- a/apps/examples/Make.defs
+++ b/apps/examples/Make.defs
@@ -182,6 +182,10 @@ ifeq ($(CONFIG_EXAMPLES_PWM),y)
 CONFIGURED_APPS += examples/pwm
 endif
 
+ifeq ($(CONFIG_EXAMPLES_POSIXSPAWN),y)
+CONFIGURED_APPS += examples/posix_spawn
+endif
+
 ifeq ($(CONFIG_EXAMPLES_QENCODER),y)
 CONFIGURED_APPS += examples/qencoder
 endif
diff --git a/apps/examples/Makefile b/apps/examples/Makefile
index 99312af7a..a11dbf240 100644
--- a/apps/examples/Makefile
+++ b/apps/examples/Makefile
@@ -40,8 +40,8 @@
 SUBDIRS  = adc buttons can cdcacm composite cxxtest dhcpd discover elf ftpc
 SUBDIRS += ftpd hello helloxx hidkbd igmp json keypadtest lcdrw mm modbus mount
 SUBDIRS += nettest nsh null nx nxconsole nxffs nxflat nxhello nximage
-SUBDIRS += nxlines nxtext ostest  pashello pipe poll pwm qencoder relays
-SUBDIRS += rgmp romfs serloop telnetd thttpd tiff touchscreen udp uip
+SUBDIRS += nxlines nxtext ostest  pashello pipe poll pwm posix_spawn qencoder
+SUBDIRS += relays rgmp romfs serloop telnetd thttpd tiff touchscreen udp uip
 SUBDIRS += usbserial sendmail usbstorage usbterm watchdog wget wgetjson
 
 # Sub-directories that might need context setup.  Directories may need
diff --git a/apps/examples/README.txt b/apps/examples/README.txt
index 7bfba721a..5c6332ee3 100644
--- a/apps/examples/README.txt
+++ b/apps/examples/README.txt
@@ -329,10 +329,10 @@ examples/elf
   each program in the ROMFS file system is executed.  Requires CONFIG_ELF.
   Other configuration options:
 
-    CONFIG_EXAMPLES_ELF_DEVMINOR - The minor device number of the ROMFS block.
-      For example, the N in /dev/ramN. Used for registering the RAM block driver
-      that will hold the ROMFS file system containing the ELF executables to be
-      tested.  Default: 0
+    CONFIG_EXAMPLES_ELF_DEVMINOR - The minor device number of the ROMFS block
+      driver. For example, the N in /dev/ramN. Used for registering the RAM
+      block driver that will hold the ROMFS file system containing the ELF
+      executables to be tested.  Default: 0
 
     CONFIG_EXAMPLES_ELF_DEVPATH - The path to the ROMFS block driver device.  This
       must match EXAMPLES_ELF_DEVMINOR. Used for registering the RAM block driver
@@ -348,7 +348,7 @@ examples/elf
 
      Similarly for C++ flags which must be provided in CXXELFFLAGS.
 
-  2. Your top-level nuttx/Make.defs file must alos include an approproate definition,
+  2. Your top-level nuttx/Make.defs file must also include an approproate definition,
      LDELFFLAGS, to generate a relocatable ELF object.  With GNU LD, this should
      include '-r' and '-e main' (or _main on some platforms).
 
@@ -1202,6 +1202,80 @@ examples/poll
 
   CONFIGURED_APPS += uiplib
 
+examples/posix_spawn
+^^^^^^^^^^^^^^^^^^^^
+
+  This is a simple test of the posix_spawn() API. The example derives from
+  examples/elf.  As a result, these tests are built using the relocatable
+  ELF format installed in a ROMFS file system.  At run time, the test program
+  in the ROMFS file system is spawned using posix_spawn().
+
+  Requires:
+
+    CONFIG_BINFMT_DISABLE=n           - Don't disable the binary loader
+    CONFIG_ELF=y                      - Enable ELF binary loader
+    CONFIG_LIBC_EXECFUNCS=y           - Enable support for posix_spawn
+    CONFIG_EXECFUNCS_SYMTAB="exports" - The name of the symbol table
+                                        created by the test.
+    CONFIG_EXECFUNCS_NSYMBOLS=10      - Value does not matter, it will be
+                                        corrected at runtime.
+    CONFIG_POSIX_SPAWN_STACKSIZE=768  - This default setting.
+
+  Test-specific configuration options:
+
+    CONFIG_EXAMPLES_POSIXSPAWN_DEVMINOR - The minor device number of the ROMFS
+      block. driver.  For example, the N in /dev/ramN. Used for registering the
+      RAM block driver that will hold the ROMFS file system containing the ELF
+      executables to be tested.  Default: 0
+
+    CONFIG_EXAMPLES_POSIXSPAWN_DEVPATH - The path to the ROMFS block driver
+      device.  This must match EXAMPLES_POSIXSPAWN_DEVMINOR. Used for
+      registering the RAM block driver that will hold the ROMFS file system
+      containing the ELF executables to be tested.  Default: "/dev/ram0"
+
+  NOTES:
+
+  1. CFLAGS should be provided in CELFFLAGS.  RAM and FLASH memory regions
+     may require long allcs.  For ARM, this might be:
+
+       CELFFLAGS = $(CFLAGS) -mlong-calls
+
+     Similarly for C++ flags which must be provided in CXXELFFLAGS.
+
+  2. Your top-level nuttx/Make.defs file must also include an approproate
+     definition, LDELFFLAGS, to generate a relocatable ELF object.  With GNU
+     LD, this should include '-r' and '-e main' (or _main on some platforms).
+
+       LDELFFLAGS = -r -e main
+
+     If you use GCC to link, you make also need to include '-nostdlib' or 
+     '-nostartfiles' and '-nodefaultlibs'.
+
+  3. This example also requires genromfs.  genromfs can be build as part of the
+     nuttx toolchain.  Or can built from the genromfs sources that can be found
+     at misc/tools/genromfs-0.5.2.tar.gz.  In any event, the PATH variable must
+     include the path to the genromfs executable.
+
+  4. ELF size:  The ELF files in this example are, be default, quite large
+     because they include a lot of "build garbage".  You can greatly reduce the
+     size of the ELF binaries are using the 'objcopy --strip-unneeded' command to
+     remove un-necessary information from the ELF files.
+
+  5. Simulator.  You cannot use this example with the the NuttX simulator on
+     Cygwin.  That is because the Cygwin GCC does not generate ELF file but
+     rather some Windows-native binary format.
+
+     If you really want to do this, you can create a NuttX x86 buildroot toolchain
+     and use that be build the ELF executables for the ROMFS file system.
+
+  6. Linker scripts.  You might also want to use a linker scripts to combine
+     sections better.  An example linker script is at nuttx/binfmt/libelf/gnu-elf.ld.
+     That example might have to be tuned for your particular linker output to
+     position additional sections correctly.  The GNU LD LDELFFLAGS then might
+     be:
+
+       LDELFFLAGS = -r -e main -T$(TOPDIR)/binfmt/libelf/gnu-elf.ld
+
 examples/pwm
 ^^^^^^^^^^^^