docs/manual: add documentation for the golang infrastructure

This patch adds the documentation for the golang infrastructure.

Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
This commit is contained in:
Angelo Compagnucci 2018-03-31 15:27:31 +02:00 committed by Arnout Vandecappelle (Essensium/Mind)
parent 048b06ed3e
commit 12ae882bf6
2 changed files with 110 additions and 0 deletions

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@ -0,0 +1,108 @@
// -*- mode:doc; -*-
// vim: set syntax=asciidoc:
=== Infrastructure for Go packages
This infrastructure applies to Go packages that use the standard
build system and use bundled dependencies.
[[golang-package-tutorial]]
==== +golang-package+ tutorial
First, let's see how to write a +.mk+ file for a go package,
with an example :
------------------------
01: ################################################################################
02: #
03: # foo
04: #
05: ################################################################################
06:
07: FOO_VERSION = 1.0
08: FOO_SITE = $(call github,bar,foo,$(FOO_VERSION))
09: FOO_LICENSE = BSD-3-Clause
10: FOO_LICENSE_FILES = LICENSE
11:
12: $(eval $(golang-package))
------------------------
On line 7, we declare the version of the package.
On line 8, we declare the upstream location of the package, here
fetched from Github, since a large number of Go packages are hosted on
Github.
On line 9 and 10, we give licensing details about the package.
Finally, on line 12, we invoke the +golang-package+ macro that
generates all the Makefile rules that actually allow the package to be
built.
[[golang-package-reference]]
==== +golang-package+ reference
In their +Config.in+ file, packages using the +golang-package+
infrastructure should depend on +BR2_PACKAGE_HOST_GO_ARCH_SUPPORTS+
and +BR2_PACKAGE_HOST_GO_CGO_LINKING_SUPPORTS+ because Buildroot will
automatically add a dependency on +host-go+ to such packages.
The main macro of the Go package infrastructure is
+golang-package+. It is similar to the +generic-package+ macro. Only
target packages are supported with +golang-package+.
Just like the generic infrastructure, the Go infrastructure works
by defining a number of variables before calling the +golang-package+.
All the package metadata information variables that exist in the
xref:generic-package-reference[generic package infrastructure] also
exist in the Go infrastructure: +FOO_VERSION+, +FOO_SOURCE+,
+FOO_PATCH+, +FOO_SITE+, +FOO_SUBDIR+, +FOO_DEPENDENCIES+,
+FOO_LICENSE+, +FOO_LICENSE_FILES+, +FOO_INSTALL_STAGING+, etc.
Note that it is not necessary to add +host-go+ in the
+FOO_DEPENDENCIES+ variable of a package, since this basic dependency
is automatically added as needed by the Go package infrastructure.
A few additional variables, specific to the Go infrastructure, can
optionally be defined, depending on the package's needs. Many of them
are only useful in very specific cases, typical packages will
therefore only use a few of them, or none.
* If your package need a custom +GOPATH+ to be compiled in, you can
use the +FOO_WORKSPACE+ variable. The +GOPATH+ being used will be
+<package-srcdir>/<FOO_WORKSPACE>+. If +FOO_WORKSPACE+ is not
specified, it defaults to +_gopath+.
* +FOO_SRC_SUBDIR+ is the sub-directory where your source will be
compiled relatively to the +GOPATH+. An example value is
+github.com/bar/foo+. If +FOO_SRC_SUBDIR+ is not specified, it
defaults to a value infered from the +FOO_SITE+ variable.
* +FOO_LDFLAGS+ and +FOO_TAGS+ can be used to pass respectively the
+LDFLAGS+ or the +TAGS+ to the +go+ build command.
* +FOO_BUILD_TARGETS+ can be used to pass the list of targets that
should be built. If +FOO_BUILD_TARGETS+ is not specified, it
defaults to +.+.
* +FOO_INSTALL_BINS+ can be used to pass the list of binaries that
should be installed in +/usr/bin+ on the target. If
+FOO_INSTALL_BINS+ is not specified, it defaults to the lower-case
name of package.
With the Go infrastructure, all the steps required to build and
install the packages are already defined, and they generally work well
for most Go-based packages. However, when required, it is still
possible to customize what is done in any particular step:
* By adding a post-operation hook (after extract, patch, configure,
build or install). See xref:hooks[] for details.
* By overriding one of the steps. For example, even if the Go
infrastructure is used, if the package +.mk+ file defines its own
+FOO_BUILD_CMDS+ variable, it will be used instead of the default Go
one. However, using this method should be restricted to very
specific cases. Do not use it in the general case.

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@ -38,6 +38,8 @@ include::adding-packages-meson.txt[]
include::adding-packages-cargo.txt[]
include::adding-packages-golang.txt[]
include::adding-packages-kernel-module.txt[]
include::adding-packages-asciidoc.txt[]