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util-linux build system
=======================
- the build system is non-recursive, individual subdirectories use
Makemodule.am files. These files are merged together by automake
into one global Makefile in the top-level directory
- all final build results (binaries, libtool scripts) are stored in top-level
source directory
- all Makemodule.am files have to be designed as top-level makefiles, it
means with full paths (e.g. foo_SOURCES = subdir/foo.c)
- always use '+=' operator for global variables (e.g. bin_PROGRAMS += foo)
- use libcommon.la (without path!) for lib/ stuff (e.g. foo_LDADD = libcommon.la)
- for libblkid, libuuid and libmount use lib<name>.la in _LDADD and
-I$(ul_lib<name>_incdir) in _CFLAGS, for example
foo_LDADD = libmount.la
foo_CFLAGS = -I$(ul_libmount_incdir)
- always use suffixes for hooks, for example
install-exec-hook-foo:
ln -sf foo foooo
INSTALL_EXEC_HOOKS += install-exec-hook-foo
- all util-linux specific autoconf macros use UL_ prefix
- utils in Makefile.am files are enabled/disabled according to BUILD_<NAME>
conditions (AM_CONDITIONAL), for example:
if BUILD_HWCLOCK
...
endif
- "if BUILD_<NAME>" blocks are never nested within another "if BUILD_<NAME>",
all dependencies have to be resolved in configure.ac (see UL_REQUIRES_BUILD())
- all BUILD_<NAME> in configure.am are always based on build_<name> variables,
for example:
AM_CONDITIONAL([BUILD_HWCLOCK], test "x$build_hwclock" = xyes)
the $build_<name> should be available in whole configure script
- AC_ARG_ENABLE() status is always stored in $enable_<name> variable, possible
setting:
"check" - util/feature is optional, if any subcomponent (function, lib,
...) is missing a warning is printed and the util/feature is
disabled
"yes" - util/feature is required, if any subcomponent (function, lib,
...) is missing an error is printed and ./configure aborted
"no" - the util/feature is unwanted
The default status is always defined by UL_DEFAULT_ENABLE() and it might be
globally modified by $ul_default_estate (see AC_ARG_ENABLE([all-programs])).
- it's possible to disable all programs, but enable just one (or more)
explicitly specified, for example:
./configure --disable-all-programs --enable-hwclock
- some basic scenarios for the ./configure script are defined in the
tools/config-gen.d/ directory. If you want to use these predefined scenarios
then call
./tools/config-gen [<scenario> ...]
for example
./tools/config-gen all selinux
will build all utils with enabled selinux support. You can also define some
CFLAGS, for example:
CFLAGS=$(rpm --eval '%optflags') ./tools/config-gen all
will use the default distro flags.
WARNING: config-gen is not designed for end-user or downstream distributions!
It's for development purpose only. All end-users and downstream have
to use standard ./configure script only.
- the tools/config-gen script is also used for build system regression tests,
the test is not enabled by default, you have to use
tests/run.sh build-sys --force
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