How-to add a user space application to uClinux

First as root user goto the uClinux-dist directory.

The examples below are all for an hellowworld applications. Replace helloworld with the wanted application name.

Edit user/Makefile and add the line with "helloworld" exactly as shown below.

dir_  =
 
dir_$(CONFIG_USER_HELLOWORLD_HELLOWORLD)    += helloworld
 
dir_$(CONFIG_JFFS_FS)                       += mtd-utils
dir_$(CONFIG_JFFS2_FS)                      += mtd-utils

Create a directory for the application

$ mkdir user/helloworld

Next add support in the config help file. Edit config/Configure.help and add the helloworld part as shown below. NOTE: there must be two spaces before text in the comments, which cannot be more than seventy characters long.

CONFIG_USER_APPWEB_DYNAMIC
  Build AppWeb with the ability to dynamically load AppWeb modules.
  AppWeb modules are a convenient way to add your application code
  to AppWeb.
 
CONFIG_USER_HELLOWORLD_HELLOWORLD
  A user space application saying hello to the world.
 
CONFIG_USER_AGETTY_AGETTY
  Install "agetty" in /bin
  Approx. binary size: 19k

Edit the fine config/config.in. Add a line as shown below:

bool '  only allow root login'  CONFIG_USER_ONLY_ROOT
bool 'helloworld'               CONFIG_USER_HELLOWORLD_HELLOWORLD
bool 'agetty'                   CONFIG_USER_AGETTY_AGETTY

If the directory contains several binaries another line can be added, where the last "HELLOWORLD" is the name of the binary file to be included.

Next a proper Makefile must be established in user/helloworld.

   EXEC = helloworld
   OBJS = helloworld.o
 
   all: $(EXEC)
 
   $(EXEC): $(OBJS)
        $(CC) $(LDFLAGS) -o $@ $(OBJS) $(LDLIBS)
 
   romfs:
        $(ROMFSINST)    /bin/$(EXEC)
 
   clean:
        -rm -f $(EXEC) *.elf *.gdb *.o

If there are more binaries to be produced use the skeleton to create a Makefile

   EXECS = helloworld goodbyeworld
   OBJS =  helloworld.o goodbyeworld.o
 
   all: $(EXECS)
 
   $(EXECS): $(OBJS)
        $(CC) $(LDFLAGS) -o $@ $@.o $(LDLIBS)
 
   romfs:
        $(ROMFSINST) -e CONFIG_USER_HELLOWORLD_HELLOWORLD             /bin/helloworld
        $(ROMFSINST) -e CONFIG_USER_HELLOWORLD_GOODBYEWORLD           /bin/goodbyeworld

Finally create the program.

Now when all this are in place run

$ make menuconfig