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<?xml version="1.0" encoding="UTF-8"?>
<section>
<title>autotools class</title>
<para>Autotools is one of the most commonly seen configuration methods for
applications. Anything that uses the standard <command>./configure; make;
make install</command> sequence is using autotools. Usually the configure
script will support a large number of options to specify various
installation directories, to disable and/or enable various features and
options to specify search paths for headers and libraries.</para>
<para>The autotools class takes care of all of the details for you. It
defines appropriate tasks for <command>do_configure</command>,
<command>do_compile</command>, <command>do_stage</command> and
<command>do_install</command>. At it's simplest adding an inherit for the
autotools class is all that is required. The netcat recipe for example
is:<screen>DESCRIPTION = "GNU Netcat"
HOMEPAGE = "http://netcat.sourceforge.net"
LICENSE = "GPLv2"
MAINTAINER = "Your name <yname@example.com>"
SECTION = "console/networking"
PR = "r1"
SRC_URI = "${SOURCEFORGE_MIRROR}/netcat/netcat-${PV}.tar.bz2"
inherit autotools</screen>The header is defined, the location of the source
code and then inherit. For the simplest cases that is all that is required.
If you need to pass addition parameters to the configure script, such as for
enabling and/or disabling options, then they can be specified via the
<command>EXTRA_OECONF</command> variable. This example from the lftp recipe
shows several extra options being passed to the configure script:<screen>EXTRA_OECONF = "--disable-largefile --disable-rpath --with-included-readline=no"</screen>If
you define your own tasks for <command>do_configure</command>,
<command>do_compile</command>, <command>do_stage</command> or
<command>do_install</command> then they will override the methods generated
by the autotools class. If you need to perform additional operations (rather
than replacing the generated operations) you can use the
<command>do_<task>_append</command> or
<command>do_<task>_prepend</command> methods. The following example
from the conserver recipe shows some additional items being
installed:<screen># Include the init script and default settings in the package
do_install_append () {
install -m 0755 -d ${D}${sysconfdir}/default ${D}${sysconfdir}/init.d
install -m 0644 ${WORKDIR}/conserver.default ${D}${sysconfdir}/default/conserver
install -m 0755 ${WORKDIR}/conserver.init ${D}${sysconfdir}/init.d/conserver
}</screen></para>
<section>
<title>oe_runconf / autotools_do_configure</title>
<para>Autotools generates a configuration method called
<command>oe_runconf</command> which runs the actual configure script, and
a method called <command>autotools_do_configure</command> which generates
the configure file (runs automake and autoconf) and then calls
<command>oe_runconf</command>. The generated
<command>do_configure</command> task just calls
autotools_do_configure.</para>
<para>It is sometimes desirable to implement your own
<command>do_configure</command> method, where additional configuration is
required or where you wish to inhibit the running of automake and
autoconf, and then manually call <command>oe_runconf</command>.</para>
<para>The following example from the ipacct recipe shows an example of
avoiding the use of automake/autoconf:<screen>do_configure() {
oe_runconf
}</screen>Sometimes manual manipulations of the autotools files is required
prior to calling autoconf/automake. In this case you can defined your own
do_configure which performs the required actions and then calls
<command>autotools_do_configure</command>.</para>
</section>
<section>
<title>Presetting autoconf variables (the site file)</title>
<para>The autotools configuration method has support for caching the
results of tests. In the cross-compilation case it is sometimes necessary
to prime the cache with pre-calculated results (since tests designed to
run on the target cannot be run when cross-compiling). These are defined
via the site file for the architecture you are using which is found in
<command>org.openembedded.dev/site/<arch>-<target-os></command>.</para>
<para>There are some things that you should keep in mind about the caching
of configure tests:</para>
<orderedlist>
<listitem>
<para>Check the other site files to see if there any entries for the
application you are attempting to build.</para>
<para>Sometimes entries are only updated for the target that the
developer has access to. If they exist for another target then it may
provide a good idea of what needs to be defined.</para>
</listitem>
<listitem>
<para>Sometimes the same cache value is used by multiple
applications.</para>
<para>This can have the side effect where a value added for one
application breaks the build of another. It is a very good idea to
empty the site file of all other values if you are having build
problems to ensure that none of the existing values are causing
problems. </para>
</listitem>
<listitem>
<para>Not all values can be stored in the cache</para>
<para>Caching of variables is defined by the author of the configure
script, so sometimes not all variables can be set via the cache. In
this case it often means resorting to patching the original configure
scripts to achieve the desired result.</para>
</listitem>
</orderedlist>
<para>Sometimes it's useful to manually check values from the site file.
This can prove useful in situations where autotools is not used but you
still need some of the same information that an autotools configure script
would require. The following from the net-snmp recipe shows an example of
using the existing site file entries for endianess to pass the required
endianess option to the configure script:<screen>do_configure() {
# endianness fun.. inspired by openssl.inc
. ${CONFIG_SITE}
if test "x$ac_cv_c_bigendian" = "xyes"; then
ENDIANESS=" --with-endianness=big"
elif test "x$ac_cv_c_littleendian" = "xyes"; then
ENDIANESS=" --with-endianness=little"
else
oefatal do_configure cannot determine endianess
fi
oe_runconf $ENDIANESS
}</screen>It is also possible to disable the use of the cached values from the
site file by clearing the definition of <command>CONFIG_SITE</command>
prior to running the configure script. Doing this disables the use of the
site file entirely. This however should be used as a last resort. The
following example from the db recipe shows an example of this:<screen># Cancel the site stuff - it's set for db3 and destroys the
# configure.
CONFIG_SITE = ""
do_configure() {
oe_runconf
}</screen></para>
</section>
</section>
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