Chapter 10. Files

78

the default). Some programs might fail to build or run at this level of optimization; it may

be necessary to use

 O1

, for example.

nostrip This string means that the debugging symbols should not be stripped from the binary

during installation, so that debugging information may be included in the package.

The following makefile snippet is an example of how one may implement the build options;

you will probably have to massage this example in order to make it work for your package.

CFLAGS =  Wall  g

INSTALL = install

INSTALL_FILE

= $(INSTALL)  p

 o root  g root

 m

644

INSTALL_PROGRAM = $(INSTALL)  p

 o root  g root

 m

755

INSTALL_SCRIPT

= $(INSTALL)  p

 o root  g root

 m

755

INSTALL_DIR

= $(INSTALL)  p  d  o root  g root

 m

755

ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))

CFLAGS +=  O0

else

CFLAGS +=  O2

endif

ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))

INSTALL_PROGRAM +=  s

endif

It is up to the package maintainer to decide what compilation options are best for the package.

Certain binaries (such as computationally intensive programs) will function better with certain

flags (

 O3

, for example); feel free to use them. Please use good judgment here. Don't use flags

for the sake of it; only use them if there is good reason to do so. Feel free to override the up 

stream author's ideas about which compilation options are best: they are often inappropriate

for our environment.

10.2 Libraries

The shared version of a library must be compiled with

 fPIC

, and the static version must not

be. In other words, each source unit (

*.c

, for example, for C files) will need to be compiled

twice.

You must specify the gcc option

 D_REENTRANT

when building a library (either static or

shared) to make the library compatible with LinuxThreads.

Although not enforced by the build tools, shared libraries must be linked against all libraries

that they use symbols from in the same way that binaries are. This ensures the correct function 

ing of the shlibs system and guarantees that all libraries can be safely opened with

dlopen()

.

Packagers may wish to use the gcc option

 Wl, z,defs

when building a shared library. Since