From ed459780f4d21ff6c691ec1f0fb64be5ad9671a1 Mon Sep 17 00:00:00 2001 From: Mike Frysinger Date: Thu, 24 Feb 2022 23:43:06 -0500 Subject: libgloss: add a little build system generation documentation This is a bit of an abbreviated form of what's in the Newlib subdir, but with emphasis on Libgloss-specific parts, and anything unique to it. I haven't put too much effort in. --- libgloss/doc/porting.texi | 50 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 49 insertions(+), 1 deletion(-) (limited to 'libgloss/doc') diff --git a/libgloss/doc/porting.texi b/libgloss/doc/porting.texi index 21b2f565a..5325fb2ed 100644 --- a/libgloss/doc/porting.texi +++ b/libgloss/doc/porting.texi @@ -14,6 +14,10 @@ @global@parindent=0pt @end iftex +@set autoconf @ref{Top,,GNU Autoconf,autoconf} +@set automake @ref{Top,,GNU Automake,automake} +@set libtool @ref{Top,,GNU Libtool,libtool} + @titlepage @title Embed With GNU @subtitle Porting The GNU Tools To Embedded Systems @@ -242,7 +246,7 @@ mostly for Unix based systems. @section Configuring and building libgloss. Libgloss uses an autoconf based script to configure. Autoconf scripts -are portable shell scripts that are generated from a configure.in file. +are portable shell scripts that are generated from a configure.ac file. Configure input scripts are based themselves on m4. Most configure scripts run a series of tests to determine features the various supported features of the target. For features that can't be determined @@ -353,6 +357,50 @@ the dependencies for the @code{all} target and add target. Now, when libgloss is built and installed, support for your BSP will be installed as well. +@node Build System Internals +@section Build System Internals + +As noted previously, Libgloss uses GNU Autotools (@value{autoconf} & +@value{automake}) to build. @value{libtool} is not used as Libgloss only +produces objects and static archives, and @value{automake} is capable of +handling that. + +If you're editing any of these files and want to regenerate them, simply run +@code{autoreconf}. It will take care of the rest. + +Tool versions are strictly controlled. You must use GNU Autoconf 2.69 and GNU +Automake 1.15.1 to generate the build files. If your system does not include +them, you can manually download and install them into your home directory. + +All of the common configure logic lives in @file{configure.ac}. It checks for +supported targets and creates the makefiles. Any architecture that wishes to +run custom configure tests should store them in @file{acinclude.m4} in their +respective subdirectory and then use @code{m4_include} in @file{configure.ac}. +Make sure to avoid running excessive tests for all targets, and avoid using +generic names that can collide with other architectures -- the build uses a +flat namespace that is shared among everyone. + +Libgloss has partially converted to @value{automake}. The top-level directory +uses it with @file{Makefile.am}, as do a few subdirectories with their +@file{Makefile.inc} fragments. The other subdirectories still use hand written +@file{Makefile.in} files. One day, they should get converted over too. +Patches welcome! + +For directories that have converted to @value{automake}, a non-recursive build +is used. That means only a single Makefile is created in the top-level, and no +Makefiles are created in subdirectories. Make must be run in the top-level at +all times. + +The @file{config/*.mh} and @file{config/*.mt} files are only used by the non- +Automake files (i.e., the @file{Makefile.in} files). They can be ignored for +any target that has migrated to @value{automake}. + +Libgloss automatically builds itself for all multilib configurations that the +active toolchain supports. This logic is provided by common code from the +combined toolchain source tree. This should @strong{not} be confused with the +Libgloss-specific @file{multi-build.in} file. That is used by a few ports to +further produce multiple targets. + @node GCC, Libraries, Libgloss, Top @chapter Porting GCC -- cgit v1.2.3