Adding User Applications to the uClinux Distribution
----------------------------------------------------

D. P. Siddons
9th Dec. 2001


This document gives simple instructions for adding a user-written application to
the uClinux configuration system. Entries must be added to three files, and an
apropriate Makefile must exist in the user application source directory, which
must be put in user (all directory names here are given relative to the uClinux
top directory. In my system this is /home/peter/uClinux-dist).  

Files to edit:

user/Makefile
   Add a line to the file like
   
   dir_$(CONFIG_USER_FOO_FOO)            += foo
   
   This adds the directory 'foo' to the list of directories to be built. I added
   mine in alphabetical order. The order doesn't seem to matter.
  
config/Configure.help
   This file contains the text which is presented on request during the
config.
   Add a block like
   
   CONFIG_USER_FOO_FOO
     This program does fooey things to your bars.
   
   The text must be indented two spaces, and there must be no empty lines. Lines
   should be <70 chars long.

config/config.in:
   Add a line in the apropriate menu section (i.e. in the program group you want
   your app to show up in during 'make config'; I used 'misc'), like 
   
   bool 'foo'           CONFIG_USER_FOO_FOO
   
   The repetition of FOO allows for directories which contain multiple
   executables. Thus, if the user directory 'foo' contained code to make 'foo'
   and 'bar', each gets its own config line if an additional entry is made like
   
   bool 'bar'           CONFIG_USER_FOO_BAR  
   

Next, there needs to be a proper /user/foo/Makefile. The Makefile should follow
the following template:

   --------------------------------------------   
   EXEC = foo
   OBJS = foo.o

   all: $(EXEC)

   $(EXEC): $(OBJS)
        $(CC) $(LDFLAGS) -o $@ $(OBJS) $(LDLIBS)

   romfs:
        $(ROMFSINST)    /bin/$(EXEC)

   clean:
        -rm -f $(EXEC) *.elf *.gdb *.o
   ---------------------------------------------
   
   If more than one executable is built in the foo directory, as above, then the
   Makefile should look like
   
   ------------------------------------------------------------
   EXECS = foo bar
   OBJS = foo.o bar.o

   all: $(EXECS)

   $(EXECS): $(OBJS)
        $(CC) $(LDFLAGS) -o $@ $@.o $(LDLIBS)

   romfs:
        $(ROMFSINST) -e CONFIG_USER_FOO_FOO             /bin/foo
        $(ROMFSINST) -e CONFIG_USER_FOO_BAR             /bin/bar
   --------------------------------------------------------------
   
   More complex makefiles are of course possible. The reader is encouraged to
   browse the user tree for examples.
   
   When all this is set up, doing the standard 'make xconfig; make dep; make'
   should build the app and install it in romfs and hence in the target system
   image.bin.

