4. PTXdist Developer’s Manual

This chapter shows all (or most) of the details of how PTXdist works.

  • where are the files stored that PTXdist uses when building packages
  • how patching works
  • where is PTXdist fetching a package’s run-time configuration files from
  • how to control a package’s build stages
  • how to add new packages

4.1. PTXdist’s directory hierarchy

Note

Referenced directories are meant relative to the PTXdist main installation location (if not otherwise stated). If not configured differently, this main path is /usr/local/lib/ptxdist-2017.12.0

Rule Files

When building a single package, PTXdist needs the information on how to handle the package, i.e. on how to get it from the source up to what the target needs at run-time. This information is provided by a rule file per package.

PTXdist collects all rule files in its rules/ directory. Whenever PTXdist builds something, all these rule files are scanned at once. These rule files are global rule files, valid for all projects. PTXdist uses a mechanism to be able to add or replace specific rule files on a per project base. If a rules/ directory exists in the current project, its content is scanned too. These project local rule files are used in addition to the global rule files or – if they are using the same name as a global rule file – replacing the global rule file.

The replacing mechanism can be used to extend or adapt packages for specific project requirements. Or it can be used for bug fixing by backporting rule files from more recent PTXdist revisions to projects that are stuck to an older PTXdist revision for maintenance only.

Patch Series

There are many packages in the wild that are not cross build aware. They fail compiling some files, use wrong include paths or try to link against host libraries. To be successful in the embedded world, these types of failures must be fixed. If required, PTXdist provides such fixes per package. They are organized in patch series and can be found in the patches/ directory within a subdirectory using the same name as the package itself.

PTXdist uses the utility patch or quilt (or git on demand) to apply an existing patch series after extracting the archive. So, every patch series contains a set of patches and one series file to define the order in which the patches must be applied.

Note

Patches can be compressed.

Besides the patches/ directory at the main installation location, PTXdist searches two additional locations for a patch series for the package in question.

One location is the project’s currently used platform directory. If the currently used platform is located in configs/, PTXdist searches in ./configs/platform-versatilepb/patches/<package name>

If no patch series was found in the platform directory, the next location PTXdist it searches for a patch series is the main project directory in ./patches/<package name>.

If both project local locations do not provide a patch series for the specific package, PTXdist falls back to the patches/ directory at its main installation location.

This search order can be used to use specific patch series for specific cases.

  • platfom specific
  • project specific
  • common case
  • bug fixing

The bug fixing case is used in accordance to a replacement of a rule file. If this was done due to a backport, and the more recent PTXdist revision does not only exchange the rule file but also the patch series, this mechanism ensures that both relevant parts can be updated in the project.

Runtime Configuration

Many packages are using run-time configuration files along with their executables and libraries. PTXdist provides default configuration files for the most common cases. These files can be found in the projectroot/etc directory and they are using the same names as the ones at run-time (and their install directory on the target side will also be /etc).

But some of these default configuration files are empty, due to the absence of a common case. The project must provide replacements of these files with a more useful content in every case where the (empty) default one does not meet the target’s requirements.

PTXdist first searches in the local project directory for a specific configuration file and falls back to use the default one if none exists locally. Refer section install_alternative for further details in which order and locations PTXdist searches for these kind of files.

A popular example is the configuration file /etc/fstab. The default one coming with PTXdist works for the most common cases. But if our project requires a special setup, we can just copy the default one to the local ./projectroot/etc/fstab, modify it and we are done. The next time PTXdist builds the root filesystem it will use the local fstab instead of the global (default) one.

4.2. Adding new Packages

PTXdist provides a huge amount of applications sufficient for the most embedded use cases. But there is still need for some fancy new packages. This section describes the steps and the background on how to integrate new packages into the project.

At first a summary about possible application types which PTXdist can handle:

  • host type: This kind of package is built to run on the build host. Most of the time such a package is needed if another target-relevant package needs to generate some data. For example the glib package depends on its own to create some data. But if it is compiled for the target, it can’t do so. That’s why a host glib package is required to provide these utilities runnable on the build host. It sounds strange to build a host package, even if on the build host such utilities are already installed. But this way ensures that there are no dependencies regarding the build host system.
  • target type: This kind of package is built for the target.
  • cross type: This kind of package is built for the build host, but creates architecture specific data for the target.
  • klibc type: This kind of package is built against klibc to be part of an initramfs for the target.
  • src-autoconf-prog: This kind of package is built for the target. It is intended for development, as it does not handle a released archive but a plain source project instead. Creating such a package will also create a small autotools based source template project on demand to give the developer an easy point to start. This template is prepared to build a single executable program. For further details refer section Creating an Executable Template.
  • src-autoconf-lib: This kind of package is built for the target. It is intended for development, as it does not handle a released archive but a plain source project instead. Creating such a package will also create a small autotools/libtool based source template project on demand to give the developer an easy point to start. This template is prepared to build a single shared library. For further details refer section Creating a Library Template.
  • src-autoconf-proglib: This kind of package is built for the target. It is intended for development, as it does not handle a released archive but a plain source project instead. Creating such a package will also create a small autotools/libtool based template project on demand to give the developer an easy point to start. This template is prepared to build a single shared library and a single executable program. The program will be linked against the shared library. For further details refer section Creating an Executable with a Library Template.
  • file: This kind of package is intended to add a few simple files into the build process. We assume these files do not need any processing, they are ready to use and must only be present in the build process or at run-time (HTML files for example). Refer to the section Adding binary only Files for further details on how to use it.
  • src-make-prog: This kind of package is built for the target. It’s intended for development, as it does not handle a released archive but a plain source project instead. Creating such a package will also create a simple makefile-based template project the developer can use as a starting point for development.
  • src-cmake-prog: This kind of package is built for the target. It’s intended for developments based on the cmake buildsystem. Various projects are using cmake instead of make and can be built with this package type. PTXdist will prepare it to compile sources in accordance to the target libraries and their settings. Creating such a package will also create a simple template project to be used as a starting point for development.
  • src-qmake-prog: This kind of package is built for the target. It’s intended for developments based on the qmake buildsystem. If the developer is going to develop a QT based application, this rule is prepared to compile sources in accordance to the target libraries and their settings. Creating such a package will also create a simple template project to be used as a starting point for development.
  • font: This package is a helper to add X font files to the root filesystem. This package does not create an additional IPKG, instead it adds the font to the existing font IPKG. This includes the generation of the directory index files, required by the Xorg framework to recognize the font file.
  • src-linux-driver: This kind of package builds an out of tree kernel driver. It also creates a driver template to give the developer an easy point to start.
  • kernel: PTXdist comes with the ability to handle one kernel in its platform. This type of package enables us to handle more than one kernel in the project.
  • barebox: PTXdist comes with the ability to handle one bootloader in its platform. This type of package enables us to handle more than one bootloader in the project.
  • image-tgz: This kind of package creates a tar ball from a list of packages. It is often uses as an input for other image packages.
  • image-genimage: This kind of package can handle all kind of image generation for almost every target independent of its complexity.
  • blspec-entry: PTXdist comes with the ability to handle one bootspec in its platform. This type of package enables us to handle more than one bootspec in the project.

Rule File Creation

To create such a new package, we create a project local rules/ directory first. Then we run

$ ptxdist newpackage <package type>

If we omit the <package type>, PTXdist will list all available package types.

In our first example, we want to add a new target type archive package. When running the

$ ptxdist newpackage target

command, PTXdist asks a few questions about this package. This information is the basic data PTXdist must know about the package.

ptxdist: creating a new 'target' package:

ptxdist: enter package name.......: foo
ptxdist: enter version number.....: 1.1.0
ptxdist: enter URL of basedir.....: http://www.foo.com/download/src
ptxdist: enter suffix.............: tar.gz
ptxdist: enter package author.....: My Name <me@my-org.com>
ptxdist: enter package section....: project_specific

What we have to answer:

  • package name: As this kind of package handles a source archive, the correct answer here is the basename of the archive’s file name. If its full name is foo-1.1.0.tar.gz, then foo is the basename to enter here.
  • version number: Most source archives are using a release or version number in their file name. If its full name is foo-1.1.0.tar.gz, then 1.1.0 is the version number to enter here.
  • URL of basedir: This URL tells PTXdist where to download the source archive from the web (if not already done). If the full URL to download the archive is http://www.foo.com/download/src/foo-1.1.0.tar.gz, the basedir part http://www.foo.com/download/src is to be entered here.
  • suffix: Archives are using various formats for distribution. PTXdist uses the suffix entry to select the matching extraction tool. If the archive’s full name is foo-1.1.0.tar.gz, then tar.gz is the suffix to enter here.
  • package author: If we intend to contribute this new package to PTXdist mainline, we should add our name here. This name will be used in the copyright note of the rule file and will also be added to the generated ipkg. When you run ptxdist setup prior to this call, you can enter your name and your email address, so PTXdist will use it as the default (very handy if you intend to add many new packages).
  • package section: We can enter here the menu section name where our new package menu entry should be listed. In the first step we can leave the default name unchanged. It’s a string in the menu file only, so changing it later on is still possible.

Make it Work

Generating the rule file is only one of the required steps to get a new package. The next steps to make it work are to check if all stages are working as expected and to select the required parts to get them installed in the target root filesystem. Also we must find a reasonable location where to add our new menu entry to configure the package.

The generated skeleton starts to add the new menu entry in the main configure menu (if we left the section name unchanged). Running ptxdist menuconfig will show it on top of all other menus entries.

Important

To be able to implement and test all the other required steps for adding a new package, we first must enable the package for building. (Fine tuning the menu can happen later on.)

The rule file skeleton still lacks some important information. Let’s take a look into some of the top lines of the generated rule file ./rules/foo.make:

FOO_VERSION := 1.1.0
FOO_MD5     :=
FOO         := foo-$(FOO_VERSION)
FOO_SUFFIX  := tar.gz
FOO_URL     := http://www.foo.com/download/src/$(FOO).$(FOO_SUFFIX)
FOO_SOURCE  := $(SRCDIR)/$(FOO).$(FOO_SUFFIX)
FOO_DIR     := $(BUILDDIR)/$(FOO)
FOO_LICENSE := unknown

We can find these lines with different content in most or all of the other rule files PTXdist comes with. Up to the underline character is always the package name and after the underline character is always PTXdist specific. What does it mean:

  • *_VERSION brings in the version number of the release and is used for the download and IPKG/OPKG package generation.
  • *_MD5 to be sure the correct package has been downloaded, PTXdist checks the given MD5 sum against the archive content. If both sums do not match, PTXdist rejects the archive and fails the currently running build.
  • *_SUFFIX defines the archive type, to make PTXdist choosing the correct extracting tool.
  • *_URL defines the full qualified URL into the web for download. If alternative download locations are known, they can be listed in this variable, delimiter character is the space.
  • *_DIR points to the directory this package will be build later on by PTXdist
  • *_LICENSE enables the user to get a list of licenses she/he is using in her/his project (licenses of the enabled packages).

After enabling the menu entry, we can start to check the get and extract stages, calling them manually one after another.

Note

The shown commands below expect that PTXdist downloads the archives to a global directory named global_src. This is not the default setting, but we recommend to use a global directory to share all archives between PTXdist based projects. Advantage is every download happens only once. Refer to the setup command PTXdist provides.

$ ptxdist get foo

---------------------------
target: foo-1.1.0.tar.gz
---------------------------

--2009-12-21 10:54:45--  http://www.foo.com/download/src/foo-1.1.0.tar.gz
Length: 291190 (284K) [application/x-gzip]
Saving to: `/global_src/foo-1.1.0.tar.gz.XXXXOGncZA'

100%[======================================>] 291,190      170K/s   in 1.7s

2009-12-21 10:54:48 (170 KB/s) - `/global_src/foo-1.1.0.tar.gz' saved [291190/291190]

This command should start to download the source archive. If it fails, we should check our network connection, proxy setup or if the given URL in use is correct.

Note

Sometimes we do not know the content of all the other variables in the rule file. To get an idea what content a variable has, we can ask PTXdist about it:

$ ptxdist print FOO_URL
http://www.foo.com/download/src/foo-1.1.0.tar.gz

The next step would be to extract the archive. But as PTXdist checks the MD5 sum in this case, this step will fail, because the FOO_MD5 variable is still empty. Let’s fill it:

$ md5sum /global_src/foo-1.1.0.tar.gz
9a09840ab775a139ebb00f57a587b447

This string must be assigned to the FOO_MD5 in our new foo.make rule file:

FOO_MD5             := 9a09840ab775a139ebb00f57a587b447

We are now prepared for the next step:

$ ptxdist extract foo

-----------------------
target: foo.extract
-----------------------

extract: archive=/global_src/foo-1.1.0.tar.gz
extract: dest=/home/jbe/my_new_prj/build-target
PATCHIN: packet=foo-1.1.0
PATCHIN: dir=/home/jbe/my_new_prj/build-target/foo-1.1.0
PATCHIN: no patches for foo-1.1.0 available
Fixing up /home/jbe/my_new_prj/build-target/foo-1.1.0/configure
finished target foo.extract

In this example we expect an autotoolized source package. E.g. to prepare the build, the archive comes with a configure script. This is the default case for PTXdist. So, there is no need to modify the rule file and we can simply run:

$ ptxdist prepare foo

-----------------------
target: foo.prepare
-----------------------

[...]

checking build system type... i686-host-linux-gnu
checking host system type... arm-v5te-linux-gnueabi
checking whether to enable maintainer-specific portions of Makefiles... no
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking for arm-v5te-linux-gnueabi-strip... arm-v5te-linux-gnueabi-strip
checking for arm-v5te-linux-gnueabi-gcc... arm-v5te-linux-gnueabi-gcc
checking for C compiler default output file name... a.out

[...]

configure: creating ./config.status
config.status: creating Makefile
config.status: creating ppa_protocol/Makefile
config.status: creating config.h
config.status: executing depfiles commands
finished target foo.prepare

At this stage things can fail:

  • A wrong or no MD5 sum was given
  • The configure script is not cross compile aware
  • The package depends on external components (libraries for example)

If the configure script is not cross compile aware, we are out of luck. We must patch the source archive in this case to make it work. Refer to section Modifying Autotoolized Packages on how to use PTXdist’s features to simplify this task. If the package depends on external components, these components might be already part of PTXdist. In this case we just have to add this dependency into the menu file and we are done. But if PTXdist cannot fulfill this dependency, we also must add it as a separate package first.

If the prepare stage has finished successfully, the next step is to compile the package.

$ ptxdist compile foo

-----------------------
target: foo.compile
-----------------------

make[1]: Entering directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
make  all-recursive
make[2]: Entering directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
make[3]: Entering directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'

[...]

make[3]: Leaving directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
make[2]: Leaving directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
make[1]: Leaving directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
finished target foo.compile

At this stage things can fail:

  • The build system is not cross compile aware (it tries to execute just created target binaries for example)
  • The package depends on external components (libraries for example) not detected by configure
  • Sources are ignoring the endianness of some architectures or using header files from the build host system (from /usr/include for example)
  • The linker uses libraries from the build host system (from /usr/lib for example) by accident

In all of these cases we must patch the sources to make them work. Refer to section Patching Packages on how to use PTXdist’s features to simplify this task.

In this example we expect the best case: everything went fine, even for cross compiling. So, we can continue with the next stage: install

$ ptxdist install foo

-----------------------
target: foo.install
-----------------------

make[1]: Entering directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
make[2]: Entering directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
make[3]: Entering directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
test -z "/usr/bin" || /bin/mkdir -p "/home/jbe/my_new_prj/build-target/foo-1.1.0/usr/bin"
  /usr/bin/install -c 'foo' '/home/jbe/my_new_prj/build-target/foo-1.1.0/usr/bin/foo'
make[3]: Leaving directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
make[2]: Leaving directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
make[1]: Leaving directory `/home/jbe/my_new_prj/build-target/foo-1.1.0'
finished target foo.install

----------------------------
target: foo.install.post
----------------------------

finished target foo.install.post

This install stage does not install anything to the target root filesystem. It is mostly intended to install libraries and header files other programs should link against later on.

The last stage – targetinstall – is the one that defines the package’s components to be forwarded to the target’s root filesystem. Due to the absence of a generic way, this is the task of the developer. So, at this point of time we must run our favourite editor again and modify our new rule file ./rules/foo.make.

The skeleton for the targetinstall stage looks like this:

# ----------------------------------------------------------------------------
# Target-Install
# ----------------------------------------------------------------------------

$(STATEDIR)/foo.targetinstall:
    @$(call targetinfo)

    @$(call install_init,  foo)
    @$(call install_fixup, foo,PACKAGE,foo)
    @$(call install_fixup, foo,PRIORITY,optional)
    @$(call install_fixup, foo,VERSION,$(FOO_VERSION))
    @$(call install_fixup, foo,SECTION,base)
    @$(call install_fixup, foo,AUTHOR,"My Name <me@my-org.com>")
    @$(call install_fixup, foo,DEPENDS,)
    @$(call install_fixup, foo,DESCRIPTION,missing)

    @$(call install_copy, foo, 0, 0, 0755, $(FOO_DIR)/foobar, /dev/null)

    @$(call install_finish, foo)
    @$(call touch)

The “header” of this stage defines some information IPKG needs. The important part that we must modify is the call to the install_copy macro (refer to section Rule File Macro Reference for more details about this kind of macros). This call instructs PTXdist to include the given file (with PID, UID and permissions) into the IPKG, which means to install this file to the target’s root filesystem.

From the previous install stage we know this package installs an executable called foo to location /usr/bin. We can do the same for our target by changing the install_copy line to:

@$(call install_copy, foo, 0, 0, 0755, $(FOO_DIR)/foo, /usr/bin/foo)

To check it, we just run:

$ ptxdist targetinstall foo

-----------------------------
target: foo.targetinstall
-----------------------------

install_init:   preparing for image creation...
install_init:   @ARCH@ -> i386 ... done
install_init:   preinst not available
install_init:   postinst not available
install_init:   prerm not available
install_init:   postrm not available
install_fixup:  @PACKAGE@ -> foo ... done.
install_fixup:  @PRIORITY@ -> optional ... done.
install_fixup:  @VERSION@ -> 1.1.0 ... done.
install_fixup:  @SECTION@ -> base ... done.
install_fixup:  @AUTHOR@ -> "My Name <me\@my-org.com>" ... done.
install_fixup:  @DESCRIPTION@ -> missing ... done.
install_copy:
  src=/home/jbe/my_new_prj/build-target/foo-1.1.0/foo
  dst=/usr/bin/foo
  owner=0
  group=0
  permissions=0755
xpkg_finish:    collecting license (unknown) ... done.
xpkg_finish:    creating ipkg package ... done.
finished target foo.targetinstall

----------------------------------
target: foo.targetinstall.post
----------------------------------

finished target foo.targetinstall.post

After this command, the target’s root filesystem contains a file called /usr/bin/foo owned by root, its group is also root and everyone has execution permissions, but only the user root has write permissions.

One last task of this port is still open: A reasonable location for the new menu entry in PTXdist’s menu hierarchy. PTXdist arranges its menus on the meaning of each package. Is it a network related tool? Or a scripting language? Or a graphical application? Each of these global meanings have their own submenu, where we can add our new entry to. We just have to edit the head of our new menu file ./rules/foo.in to add it to a specific global menu. If our new package is a network related tool, the head of the menu file should look like:

## SECTION=networking

We can grep through the other menu files from the PTXdist main installation rules/ directory to get an idea what section names are available:

rules/ $ find . -name \*.in | xargs grep "## SECTION"
./acpid.in:## SECTION=shell_and_console
./alsa-lib.in:## SECTION=system_libraries
./alsa-utils.in:## SECTION=multimedia_sound
./apache2.in:## SECTION=networking
./apache2_mod_python.in:## SECTION=networking
[...]
./klibc-module-init-tools.in:## SECTION=initramfs
./xkeyboard-config.in:## SECTION=multimedia_xorg_data
./xorg-app-xev.in:## SECTION=multimedia_xorg_app
./xorg-app-xrandr.in:## SECTION=multimedia_xorg_app
./host-eggdbus.in:## SECTION=hosttools_noprompt
./libssh2.in:## SECTION=networking

Porting a new package to PTXdist is (almost) finished now.

To check it right away, we simply run these two commands:

$ ptxdist clean foo
rm -rf /home/jbe/my_new_prj/state/foo.*
rm -rf /home/jbe/my_new_prj/packages/foo_*
rm -rf /home/jbe/my_new_prj/build-target/foo-1.1.0
$ ptxdist targetinstall foo

[...]

Important

Discover somehow hidden dependencies with one more last check!

Up to this point all the development of the new package was done in an already built BSP. Doing so sometimes somehow hidden dependencies cannot be seen: everything seems fine, the new package builds always successfully and the results are working on the target.

So to check for this kind of dependencies there is still one more final check to do (even if its boring and takes time):

$ ptxdist clean
[...]
$ ptxdist targetinstall foo
[...]

This will re-start with a clean BSP and builds exactly the new package and its (known) dependencies. If this builds successfully as well we are really done with the new package.

Some Notes about Licenses

The already mentioned rule variable *_LICENSE (e.g. FOO_LICENSE in our example) is very important and must be filled by the developer of the package. Many licenses bring in obligations using the corresponding package (attribution for example). To make life easier for everybody the license for a package must be provided. SPDX license identifiers unify the license names and are used in PTXdist to identify license types and obligations.

If a package comes with more than one license, alls of their SPDX identifiers must be listed and connected with the keyword AND. If your package comes with GPL-2.0 and LGPL-2.1 licenses, the definition should look like this:

FOO_LICENSE := GPL-2.0 AND LGPL-2.1

One specific obligation cannot be detected examining the SPDX license identifiers by PTXdist: the license choice. In this case all licenses of choice must be listed and connected by the keyword OR.

If, for example, your obligation is to select one of the licenses GPL-2.0 or GPL-3.0, the *_LICENSE variable should look like this:

FOO_LICENSE := GPL-2.0 OR GPL-3.0

SPDX License Identifiers

A list of SPDX license identifiers can be found here:

Help to Detect the Correct License

License identification isn’t trivial. A help in doing so can be the following repository and its content. It contains a list of known licenses based on their SPDX identifier. The content is without formatting to simplify text search.

Advanced Rule Files

The previous example on how to create a rule file sometimes works as shown above. But most of the time source archives are not that simple. In this section we want to give the user a more detailed selection how the package will be built.

Adding Static Configure Parameters

The configure scripts of various source archives provide additional parameters to enable or disable features, or to configure them in a specific way.

We assume the configure script of our foo example (refer to section Rule File Creation) supports two additional parameters:

  • –enable-debug: Make the program more noisy. It’s disabled by default.
  • –with-bar: Also build the special executable bar. Building this executable is also disabled by default.

We now want to forward these options to the configure script when it runs in the prepare stage. To do so, we must again open the rule file with our favourite editor and navigate to the prepare stage entry.

PTXdist uses the variable FOO_CONF_OPT as the list of parameters to be given to configure.

Currently this variable is commented out and defined to:

# FOO_CONF_OPT := $(CROSS_AUTOCONF_USR)

The variable CROSS_AUTOCONF_USR is predefined by PTXdist and contains all basic parameters to instruct configure to prepare for a cross compile environment.

To use the two additional mentioned configure parameters, we comment in this line and supplement this expression as follows:

FOO_CONF_OPT := $(CROSS_AUTOCONF_USR) \
    --enable-debug \
    --with-bar

Note

We recommend to use this format with each parameter on a line of its own. This format is easier to read and a diff shows more exactly any change.

To do a fast check if this addition was successful, we run:

$ ptxdist print FOO_CONF_OPT
--prefix=/usr --sysconfdir=/etc --host=arm-v5te-linux-gnueabi --build=i686-host-linux-gnu --enable-debug --with-bar

Note

It depends on the currently selected platform and its architecture what content this variable will have. The content shown above is an example for an target.

Or re-build the package with the new settings:

$ ptxdist drop foo prepare
$ ptxdist targetinstall foo

Adding Dynamic Configure Parameters

Sometimes it makes sense to add this kind of parameters on demand only; especially a parameter like --enable-debug. To let the user decide if this parameter is to be used or not, we must add a menu entry. So, let’s expand our menu. Here is its current content:

## SECTION=project_specific

config FOO
        tristate
        prompt "foo"
        help
          FIXME

We’ll add two menu entries, one for each optional parameter we want to add on demand to the configure parameters:

## SECTION=project_specific

config FOO
       tristate
       prompt "foo"
       help
         FIXME

if FOO
config FOO_DEBUG
       bool
       prompt "add debug noise"

config FOO_BAR
       bool
       prompt "build bar"

endif

Note

To extend the base name by a suboption name as a trailing component gives PTXdist the ability to detect a change in the package’s settings to force its rebuild.

To make usage of the new menu entries, we must check them in the rule file and add the correct parameters:

#
# autoconf
#
FOO_CONF_OPT := $(CROSS_AUTOCONF_USR)

ifdef PTXCONF_FOO_DEBUG
FOO_CONF_OPT += --enable-debug
else
FOO_CONF_OPT += --disable-debug
endif

ifdef PTXCONF_FOO_BAR
FOO_CONF_OPT += --with-bar
else
FOO_CONF_OPT += --without-bar
endif

Important

Please note the trailing PTXCONF_ for each define. While Kconfig is using FOO_BAR, the rule file must use PTXCONF_FOO_BAR instead.

It is a good practice to add both settings, e.g. --disable-debug even if this is the default case. Sometimes configure tries to guess something and the binary result might differ depending on the build order. For example some kind of package would also build some X related tools, if X libraries are found. In this case it depends on the build order, if the X related tools are built or not. All the autocheck features are problematic here. So, if we do not want configure to guess its settings we must disable everything we do not want.

To support this process, PTXdist supplies a helper script, located at /path/to/ptxdist/scripts/configure-helper.py that compares the configure output with the settings from FOO_CONF_OPT:

$ /opt/ptxdist-2017.06.0/scripts/configure-helper.py -p libsigrok
--- rules/libsigrok.make
+++ libsigrok-0.5.0
@@ -4,3 +4,74 @@
    --libdir=/usr/lib
    --build=x86_64-host-linux-gnu
    --host=arm-v7a-linux-gnueabihf
+   --enable-warnings=min|max|fatal|no
+   --disable-largefile
+   --enable-all-drivers
+   --enable-agilent-dmm
[...]
+   --enable-ruby
+   --enable-java
+   --without-libserialport
+   --without-libftdi
+   --without-libusb
+   --without-librevisa
+   --without-libgpib
+   --without-libieee1284
+   --with-jni-include-path=DIR-LIST

In this example, many configure options from libsigrok (marked with +) are not yet present in LIBSIGROK_CONF_OPT and must be added, possibly also by providing more dynamic options in the package definition.

Since every optional parameter adds four lines of code to the rule files, PTXdist provides some shortcuts to handle it. Refer to section ptx/endis for further details.

With these special macros in use, the file content shown above looks much simpler:

#
# autoconf
#
FOO_CONF_OPT := $(CROSS_AUTOCONF_USR) \
    $(call ptx/endis, PTXCONF_FOO_DEBUG)-debug \
    $(call ptx/wwo, PTXCONF_FOO_BAR)-bar

If some parts of a package are built on demand only, they must also be installed on demand only. Besides the prepare stage, we also must modify our targetinstall stage:

    @$(call install_copy, foo, 0, 0, 0755, $(FOO_DIR)/foo, /usr/bin/foo)

ifdef PTXCONF_FOO_BAR
    @$(call install_copy, foo, 0, 0, 0755, $(FOO_DIR)/bar, /usr/bin/bar)
endif

    @$(call install_finish, foo)
    @$(call touch)

Now we can play with our new menu entries and check if they are working as expected:

$ ptxdist menuconfig
$ ptxdist targetinstall foo

Whenever we change a FOO related menu entry, PTXdist should detect it and re-build the package when a new build is started.

Managing External Compile Time Dependencies

While running the prepare stage, it could happen that it fails due to a missing external dependency.

For example:

checking whether zlib exists....failed

In this example, our new package depends on the compression library zlib. PTXdist comes with a target zlib. All we need to do in this case is to declare that our new package foo depends on zlib. This kind of dependency is managed in the menu file of our new package by simply adding the select ZLIB line. After this addition our menu file looks like:

## SECTION=project_specific

config FOO
       tristate
       select ZLIB
       prompt "foo"
       help
         FIXME

if FOO
config FOO_DEBUG
       bool
       prompt "add debug noise"

config FOO_BAR
       bool
       prompt "build bar"

endif

PTXdist now builds the zlib first and our new package thereafter.

Managing External Compile Time Dependencies on Demand

It is good practice to add only those dependencies that are really required for the current configuration of the package. If the package provides the features foo and bar and its configure provides switches to enable/disable them independently, we can also add dependencies on demand. Let’s assume feature foo needs the compression library libz and bar needs the XML2 library libxml2. These libraries are only required at run-time if the corresponding feature is enabled. To add these dependencies on demand, the menu file looks like:

## SECTION=project_specific

config FOO
       tristate
       select ZLIB if FOO_FOO
       select LIBXML2 if FOO_BAR
       prompt "foo"
       help
         FIXME

if FOO
config FOO_DEBUG
       bool
       prompt "add debug noise"

config FOO_FOO
       bool
       prompt "build foo"

config FOO_BAR
       bool
       prompt "build bar"

endif

Important

Do not add these select statements to the correspondig menu entry. They must belong to the main menu entry of the package to ensure that the calculation of the dependencies between the packages is done in a correct manner.

Managing External Runtime Dependencies

Some packages are building all of their components and also installing them into the target’s sysroot. But only their targetinstall stage decides which parts are copied to the root filesystem. So, compiling and linking of our package will work, because everything required is found in the target’s sysroot.

In our example there is a hidden dependency to the math library libm. Our new package was built successfully, because the linker was able to link our binaries against the libm from the toolchain. But in this case the libm must also be available in the target’s root filesystem to fulfil the run-time dependency: We have to force PTXdist to install libm. libm is part of the glibc package, but is not installed by default (to keep the root filesystem small). So, it does not help to select the GLIBC symbol, to get a libm at run-time.

The correct solution here is to add a select LIBC_M to our menu file. With all the additions above it now looks like:

## SECTION=project_specific

config FOO
       tristate
       select ZLIB if FOO_FOO
       select LIBXML2 if FOO_BAR
       select LIBC_M
       prompt "foo"
       help
         FIXME

if FOO
config FOO_DEBUG
       bool
       prompt "add debug noise"

config FOO_FOO
       bool
       prompt "build foo"

config FOO_BAR
       bool
       prompt "build bar"

endif

Note

There are other packages around, that do not install everything by default. If our new package needs something special, we must take a look into the menu of the other package how to force the required components to be installed and add the corresponding selects to our own menu file. In this case it does not help to enable the required parts in our project configuration, because this has no effect on the build order!

Managing Plain Makefile Packages

Many packages are still coming with a plain Makefile. The user has to adapt it to make it work in a cross compile environment as well. PTXdist can also handle this kind of packages. We only have to specify a special prepare and compile stage.

Such packages often have no special need for any kind of preparation. In this we must instruct PTXdist to do nothing in the prepare stage:

FOO_CONF_TOOL := NO

To compile the package, we can use make’s feature to overwrite variables used in the Makefile. With this feature we can still use the original Makefile but with our own (cross compile) settings.

Most of the time the generic compile rule can be used, only a few settings are required. For a well defined Makefile it is sufficient to set up the correct cross compile environment for the compile stage:

FOO_MAKE_ENV := $(CROSS_ENV)

make will be called in this case with:

$(FOO_MAKE_ENV) $(MAKE) -C $(FOO_DIR) $(FOO_MAKE_OPT)

So, in the rule file only the two variables FOO_MAKE_ENV and FOO_MAKE_OPT must be set, to forward the required settings to the package’s buildsystem. If the package cannot be built in parallel, we can also add the FOO_MAKE_PAR := NO. YES is the default.

Managing CMake / QMake Packages

Building packages that use cmake or qmake is much like building packages with an autotools based buildsystem. We need to specify the configuration tool:

FOO_CONF_TOOL := cmake

or

FOO_CONF_TOOL := qmake

And provide the correct configuration options. The syntax is different so PTXdist provides additional macros to simplify configurable features. For cmake the configuration options typically look like this:

FOO_CONF_OPT := \
    $(CROSS_CMAKE_USR) \
    -DBUILD_TESTS:BOOL=OFF \
    -DENABLE_BAR:BOOL=$(call ptx/onoff, PTXCONF_FOO_BAR)

For qmake the configuration options typically look like this:

FOO_CONF_OPT := \
    $(CROSS_QMAKE_OPT) \
    PREFIX=/usr

Please note that currently only host and target cmake packages and only target qmake packages are supported.

Managing Python Packages

As with any other package, the correct configuration tool must be selected for Python packages:

FOO_CONF_TOOL := python

Note

For Python3 packages the value must be python3.

No Makefiles are used when building Python packages so the usual make and make install for the compile and install stages cannot be used. PTXdist will call python setup.py build and python setup.py install instead.

Note

FOO is still the name of our example package. It must be replaced by the real package name.

Patching Packages

There can be various reasons why a package must be patched:

  • Package is broken for cross compile environments
  • Package is broken within a specific feature
  • Package is vulnerable and needs some fixes
  • or anything else (this case is the most common one)

PTXdist handles patching automatically. After extracting the archive, PTXdist checks for the existence of a patch directory with the same name as the package. If our package’s name is foo-1.1.0, PTXdist searches for patches in:

  1. project (./patches/foo-1.1.0)
  2. platform (./configs/platform-versatilepb/patches/foo-1.1.0)
  3. ptxdist (<ptxdist/installation/path>/patches/foo-1.1.0)

The patches from the first location found are used. Note: Due to this search order, a PTXdist project can replace global patches from the PTXdist installation. This can be useful if a project sticks to a specific PTXdist revision but fixes from a more recent revision of PTXdist should be used.

Creating Patches for a Package

PTXdist uses the utilities git, patch or quilt to work with patches or patch series. We recommend git, as it can manage patch series in a very easy way.

Creating a Patch Series for a Package

To create a patch series for the first time, we can run the following steps. We are still using our foo-1.1.0 example package here:

Using quilt

We create a special directory for the patch series in the local project directory:

$ mkdir -p patches/foo-1.1.0

PTXdist expects a series file in the patch directory and at least one patch. Otherwise it fails. Due to the fact that we do not have any patch content yet, we’ll start with a dummy entry in the series file and an empty patch file.

$ touch patches/foo-1.1.0/dummy
$ echo dummy > patches/foo-1.1.0/series

Next is to extract the package (if already done, we must remove it first):

$ ptxdist extract foo

This will extract the archive and create a symbolic link in the build directory pointing to our local patch directory. Working this way will ensure that we do not lose our created patches if we enter ptxdist clean foo by accident. In our case the patches are still present in patches/foo-1.1.0 and can be used the next time we extract the package again.

All we have to do now is to do the modification we need to make the package work. We change into the build directory and use quilt to create new patches, add files to respective patches, modify these files and refresh the patches to save our changes. See the quilt documentation (man 1 quilt) for more information.

Using Git

Create the patch directory like above for quilt, but only add an empty series file

$ mkdir -p patches/foo-1.1.0
$ touch patches/foo-1.1.0/series

Then extract the package with an additional command line switch:

$ ptxdist --git extract foo

The empty series file makes PTXdist create a Git repository in the respective package build directory, and import the package source as the first commit.

Note

Optionally, you can enable the setting Developer Options → use git to apply patches in ptxdist setup to get this behaviour as a default for every package. However, note that this setting is still experimental and can lead to failures for some packages.

Then you can change into the package build directory (platform-<name>/build-target/foo-1.1.0), patch the required source files, and make Git commits on the way. The Git history should now look something like this:

$ git log --oneline --decorate
* df343e821851 (HEAD -> master) Makefile: don't build the tests
* 65a360c2bd60 strfry.c: frobnicate the excusator
* fdc315f6844c (tag: foobar-1.1.0, tag: base) initial commit

Finally, call git ptx-patches to regenerate the patch series in the patches/foo-1.1.0 folder. This way they don’t get lost when cleaning the package.

Note

PTXdist will only create a Git repository for packages with patches. To use Git to generate the first patch, create an empty series file patches/foobar-1.1.0/series before extracting the packages. This will tell PTXdist to use Git anyways and git ptx-patches will put the patches there.

Both approaches (Git and quilt) are not suitable for modifying files that are autogenerated in autotools-based buildsystems. Refer to section Modifying Autotoolized Packages on how PTXdist can handle this special task.

Adding more Patches to a Package

If we want to add more patches to an already patched package, we can use nearly the same way as creating patches for the first time. But if the patch series comes from the PTXdist main installation, we do not have write permissions to these directories (do NEVER work on the main installation directories, NEVER, NEVER, NEVER). Due to the search order in which PTXdist searches for patches for a specific package, we can copy the global patch series to our local project directory. Now we have the permissions to add more patches or modify the existing ones. Also quilt is our friend here to manage the patch series.

If we think that our new patches are valuable also for others, or they fix an error, it could be a good idea to send these patches to PTXdist mainline.

Modifying Autotoolized Packages

Autotoolized packages are very picky when automatically generated files get patched. The patch order is very important in this case and sometimes it even fails and nobody knows why.

To improve a package’s autotools-based build system, PTXdist comes with its own project local autotools to regenerate the autotools template files, instead of patching them. With this feature, only the template files must be patched, the required configure script and the Makefile.in files are regenerated in the final stages of the prepare step.

This feature works like the regular patching mechanism. The only difference is the additional autogen.sh file in the patch directory. If it exists and has execution permissions, it will be called after the package was patched (while the extract stage is running).

Its content depends on developer needs; for the most simple case the content can be:

#!/bin/bash

aclocal $ACLOCAL_FLAGS

libtoolize \
        --force \
        --copy

autoreconf \
        --force \
        --install \
        --warnings=cross \
        --warnings=syntax \
        --warnings=obsolete \
        --warnings=unsupported

Note

In this way not yet autotoolized package can be autotoolized. We just have to add the common autotool template files (configure.ac and Makefile.am for example) via a patch series to the package source and the autogen.sh to the patch directory.

4.3. Adding binary only Files

Sometimes a few binary files have to be added into the root filesystem. Or - to be more precise - some files, that do not need to be built in any way.

On the other hand, sometimes files should be included that are not covered by any open source license and so, should not be shipped in the source code format.

Add binary Files File by File

Doing to on a file by file base can happen by just using the install_copy macro in the targetinstall stage in our own customized rules file.

@$(call install_copy, binary_example, 0, 0, 0644, \
   </path/to/some/file/>ptx_logo.png, \
   /example/ptx_logo.png)

It copies the file ptx_logo.png from some location to target’s root filesystem. Refer install_copy for further information about using the install_copy macro.

The disadvantage of this method is: if we want to install more than one file, we need one call to the install_copy macro per file. This is even harder if not only a set of files is to be installed, but a whole directory tree with files instead.

Add binary Files via an Archive

If a whole tree of files is to be installed, working with a tar based archive could make life easier. In this case the archive itself provides all the required information the files are needing to be installed in a correct manner:

  • the file itself and its name
  • the directory structure and the final location of every file in this structure
  • user and group ID on a per file base
@$(call install_archive, binary_example, -, -, \
   </path/to/an/>archive.tgz, /)

Refer install_archive for further information about using the install_archive macro.

Using an archive can be useful to install parts of the root filesystem that are not covered by any open source license. Its possible to ship the binaries within the regular BSP, without the need for their sources. However it is possible for the customer to re-create everything required from the BSP to get their target up and running again.

Another use case for the archive method could be the support for different development teams. One team provides a software component in the archive format, the other team does not need to build it but can use it in the same way than every other software component.

Creating a Rules File

Let PTXdist create one for us.

$ ptxdist newpackage file

ptxdist: creating a new 'file' package:

ptxdist: enter package name.......: my_binfiles
ptxdist: enter version number.....: 1
ptxdist: enter package author.....: My Name <me@my-org.com>
ptxdist: enter package section....: rootfs

Now two new files are present in the BSP:

  1. rules/my_binfiles.in The template for the menu
  2. rules/my_binfiles.make The rules template

Both files now must be customized to meet our requirements. Due to the answer rootfs to the “enter package section” question, we will find the new menu entry in:

Root Filesystem --->
    < > my_binfiles (NEW)

Enabling this new entry will also run our stages in rules/my_binfiles.make the next time we enter:

$ ptxdist go