Chapter 5. Compiler and linker options

Table of Contents
Compiling a C application
Compiling a C++ application

eCos is built using the GNU C and C++ compilers. The versions of the tools Cygnus has prepared for this release have some enhancements, such as constructor priority ordering and selective linking, which will eventually become part of the standard distribution.

Some GCC options are required for eCos, and others can be useful. This chapter gives a brief description of the required options as well as some recommended eCos-specific options. All other GCC options (described in the GNUPro manuals) are available.

Compiling a C application

The following command lines demonstrate the minimum set of options required to compile and link an eCos program written in C.

Note: Remember that when this manual shows gcc you should type the full name of the cross compiler: mn10300-elf-gcc, mips-tx39-elf-gcc, powerpc-eabi-gcc, sparclite-elf-gcc, or arm-elf-gcc. When compiling for the synthetic Linux target, use the native gcc which must have the features required by eCos.

$ gcc -c  -IINSTALL_DIR/include file.c
$ gcc -o program file.o -LINSTALL_DIR/lib -Ttarget.ld -nostdlib

Note: Certain targets may require extra options, for example the SPARClite architectures require the option -mcpu=sparclite. Examine the BASE_DIR/packages/targets file or BASE_DIR/examples/Makefile to see if any extra options are required, and if so, what they are.

The following command lines use some other options which are recommended because they use the selective linking feature:

$ gcc -c  -IINSTALL_DIR/include -I. -ffunction-sections -fdata-sections -g -O2 file.c
$ gcc -o program file.o -ffunction-sections -fdata-sections -Wl,--gc-sections -g -O2 -LINSTALL_DIR/lib -Ttarget.ld -nostdlib