Quick how to for adding program to HelenOS

Following steps are needed in order to add a program to HelenOS (i.e. executable that can be launched from HelenOS userspace shell).

Sources location

Under one of uspace/ directories. Use app/ for standalone applications, srv/ for system services or drv/ for device drivers.

Definitely put it inside its own subdirectory (e.g. uspace/app/hello/).

The main uses standard signature int main(int, char **).

Makefiles & co.

Simplest way is to copy Makefile from other program and change two variables:

• BINARY to specify name of the compiled executable
• SOURCES to list C source files

For a simple Hello World program, the Makefile would look like this (omitting the copyright notice):

USPACE_PREFIX = ../..
BINARY = hello
SOURCES = hello.c
include $(USPACE_PREFIX)/Makefile.common

Compiling

To compile the program, add the directory name (e.g. app/hello) to DIRS variable in uspace/Makefile.

Adding it to the image

Last thing that needs to be done is to add the compiled executable to the image file (e.g. image.iso for IA-32). That is done by adding the executable filename to a variable in boot/Makefile.common. For services use the RD_SRVS_* variable, for application use RD_APPS_*. The suffix is either ESSENTIAL or NON_ESSENTIAL.

C++ support

Since HelenOS 0.7.2, all source files with the extensions .cpp, .cxx and .cc are compiled as C++17 source files with (at the moment) access to most C++14 standard library features.

Complete diff

Below is a diff (with copyrights omitted) for a Hello World.

=== modified file 'boot/Makefile.common'
--- boot/Makefile.common	2011-06-12 15:44:38 +0000
+++ boot/Makefile.common	2011-06-12 20:45:19 +0000
@@ -142,6 +142,7 @@
 	$(USPACE_PATH)/app/dload/dload \
 	$(USPACE_PATH)/app/edit/edit \
 	$(USPACE_PATH)/app/ext2info/ext2info \
+	$(USPACE_PATH)/app/hello/hello \
 	$(USPACE_PATH)/app/kill/kill \
 	$(USPACE_PATH)/app/killall/killall \
 	$(USPACE_PATH)/app/mkfat/mkfat \

=== modified file 'uspace/Makefile'
--- uspace/Makefile	2011-06-12 15:44:38 +0000
+++ uspace/Makefile	2011-06-12 20:44:44 +0000
@@ -39,6 +39,7 @@
 	app/edit \
 	app/ext2info \
 	app/getterm \
+	app/hello \
 	app/init \
 	app/kill \
 	app/killall \

=== added directory 'uspace/app/hello'
=== added file 'uspace/app/hello/Makefile'
--- uspace/app/hello/Makefile	1970-01-01 00:00:00 +0000
+++ uspace/app/hello/Makefile	2011-06-12 20:43:41 +0000
@@ -0,0 +1,12 @@
+#
+# Copyright omitted
+#
+
+USPACE_PREFIX = ../..
+
+BINARY = hello
+SOURCES = \
+	hello.c
+
+include $(USPACE_PREFIX)/Makefile.common
+

=== added file 'uspace/app/hello/hello.c'
--- uspace/app/hello/hello.c	1970-01-01 00:00:00 +0000
+++ uspace/app/hello/hello.c	2011-06-12 20:44:18 +0000
@@ -0,0 +1,9 @@
+/* Copyright omitted */
+
+#include <stdio.h>
+
+int main(int argc, char * argv[]) {
+	printf("Hello World!\n");
+	return 0;
+}
+