2. Getting a working Environment¶
2.1. Download Software Components¶
In order to follow this manual, some software archives are needed. There are several possibilities how to get these: either as part of an evaluation board package or by downloading them from the Pengutronix web site.
The central place for OSELAS related documentation is http://www.oselas.com and http://www.ptxdist.org. These websites provide all required packages and documentation (at least for software components which are available to the public).
In order to build OSELAS.BSP-Pengutronix-Example, the following source archives have to be available on the development host:
- OSELAS.BSP-Pengutronix-Example.tar.bz2 (or a similar source)
Main Parts of PTXdist¶
The most important software component which is necessary to build an
OSELAS.BSP( ) board support package is the
ptxdist tool. So before
starting any work we’ll have to install PTXdist on the development host.
PTXdist consists of the following parts:
ptxdistis installed on the development host during the installation process.
ptxdistis called to trigger any action, like building a software packet, cleaning up the tree etc. Usually the
ptxdistprogram is used in a workspace directory, which contains all project relevant files.
- A Configuration System:
- The config system is used to customize a configuration, which contains information about which packages have to be built and which options are selected.
- Due to the fact that some upstream packages are not bug free – especially with regard to cross compilation – it is often necessary to patch the original software. PTXdist contains a mechanism to automatically apply patches to packages. The patches are bundled into a separate archive. Nevertheless, they are necessary to build a working system.
- Package Descriptions:
- For each software component there is a “recipe” file, specifying which actions have to be done to prepare and compile the software. Additionally, packages contain their configuration sniplet for the config system.
PTXdist does not come with a pre-built binary toolchain. Nevertheless, PTXdist itself is able to build toolchains, which are provided by the OSELAS.Toolchain() project. The different OSELAS toolchains can be found at https://www.pengutronix.de/en/software/toolchain.html.
Building a toolchain is not part of this manual, refer for application note “Building Toolchains” instead.
- Board Support Package
- This is an optional component, mostly shipped aside with a piece of hardware. There are various BSP available, some are generic, some are intended for a specific hardware.
Extracting the Sources¶
Do the following steps at best in your own home directory ($HOME).
You need root permissions only in the
make install step, and nowhere
To install PTXdist, the archive Pengutronix provides has to be extracted:
- The PTXdist software itself
The PTXdist archive has to be extracted into some temporary directory in
order to be built before the installation, for example the
directory in the user’s home. If this directory does not exist, we have
to create it and change into it:
$ cd $ mkdir local $ cd local
Next step is to extract the archive:
$ tar -xjf ptxdist-2018.08.0.tar.bz2
If everything goes well, we now have a
directory, so we can change into it:
$ cd ptxdist-2018.08.0 $ ls -lF total 396 -rw-r--r-- 1 jbe ptx 18446 Apr 29 09:36 COPYING -rw-r--r-- 1 jbe ptx 3933 Apr 29 09:36 CREDITS -rw-r--r-- 1 jbe ptx 57 Apr 29 09:36 INSTALL -rw-r--r-- 1 jbe ptx 4483 Apr 29 09:36 Makefile.in -rw-r--r-- 1 jbe ptx 3501 Apr 29 09:36 README -rw-r--r-- 1 jbe ptx 2324 Apr 29 09:36 README.devel -rwxr-xr-x 1 jbe ptx 28 Apr 29 09:36 autogen.sh* drwxr-xr-x 2 jbe ptx 4096 Apr 29 09:36 bin/ drwxr-xr-x 16 jbe ptx 4096 Apr 29 09:36 config/ -rwxr-xr-x 1 jbe ptx 214583 Apr 29 15:55 configure* -rw-r--r-- 1 jbe ptx 12570 Apr 29 09:36 configure.ac drwxr-xr-x 4 jbe ptx 4096 Apr 29 09:36 doc/ drwxr-xr-x 2 jbe ptx 4096 Jun 21 09:52 man/ drwxr-xr-x 263 jbe ptx 12288 Apr 29 09:36 patches/ drwxr-xr-x 2 jbe ptx 4096 Apr 29 09:36 platforms/ drwxr-xr-x 4 jbe ptx 4096 Apr 29 09:36 plugins/ drwxr-xr-x 11 jbe ptx 4096 Apr 29 09:36 projectroot/ drwxr-xr-x 6 jbe ptx 69632 Apr 29 09:36 rules/ drwxr-xr-x 9 jbe ptx 4096 Apr 29 09:36 scripts/ drwxr-xr-x 2 jbe ptx 4096 Apr 29 09:36 tests/
Before PTXdist can be installed it has to check if all necessary
programs are installed on the development host (e.g. external dependencies).
configure script will stop if it discovers that something is missing.
The PTXdist installation is based on GNU autotools, so the first thing to be done now is to configure the package:
This will check your system for required components PTXdist relies on. If all required components are found the output ends with:
[...] checking whether Python development files are present... yes checking for patch... /usr/bin/patch checking whether /usr/bin/patch will work... yes configure: creating ./config.status config.status: creating Makefile ptxdist version 2018.08.0 configured. Using '/usr/local' for installation prefix. Report bugs to firstname.lastname@example.org
Without further arguments PTXdist is configured to be installed into
/usr/local, which is the standard location for user installed
programs. To change the installation path to anything non-standard, we
--prefix argument to the
configure script. The
--help option offers more information about what else can be changed
for the installation process.
The installation paths are configured in a way that several PTXdist versions can be installed in parallel. So if an old version of PTXdist is already installed, there is no need to remove it.
One of the most important tasks for the
configure script is to find
out if all the programs PTXdist depends on are already present on the
development host. The script will stop with an error message in case
something is missing. If this happens, the missing tools have to be
installed from the distribution befor re-running the
configure script is finished successfully, we can now run
All program parts are being compiled, and if there are no errors we can
now install PTXdist into it’s final location. In order to write to
/usr/local, this step has to be performed as user root:
$ sudo make install [enter password] [...]
If we don’t have root access to the machine it is also possible to
install PTXdist into some different directory with the
We need to take care that the
bin/ directory below the new
installation dir is added to our
$PATH environment variable (for
example by exporting it in
The installation is now done, so the temporary folder may now be removed:
$ cd ../../ $ rm -fr local
When using PTXdist for the first time, some setup properties have to be configured. Two settings are the most important ones: where to store the source archives and if a proxy must be used to gain access to the world wide web.
Run PTXdist’s setup:
$ ptxdist setup
Due to the fact that PTXdist is working with sources only, it needs
various source archives from the world wide web. If these archives are
not present on our host, PTXdist starts the
wget command to download
them on demand.
To do so, an internet access is required. If this access is managed by a
wget command must be advised to use it. PTXdist can be
configured to advise the
wget command automatically: navigate to
entry Proxies and enter the required addresses and ports to access the
proxy in the form:
Source Archive Location¶
Whenever PTXdist downloads source archives it stores these archives in a project local manner. This is the default behaviour. If we are working with more than one PTXdist based project, every project would download its own required archives in this case. To share all source archives between all projects, PTXdist can be configured to share only one archive directory for all projects it handles: navigate to menu entry Source Directory and enter the path to the directory where PTXdist should store archives to share between its projects.
Before we can start building our first userland we need a cross
toolchain. On Linux, toolchains are no monolithic beasts. Most parts of
what we need to cross compile code for the embedded target comes from
the GNU Compiler Collection,
gcc. The gcc packet includes the
gcc, plus several backend tools (cc1, g++, ld
etc.) which actually perform the different stages of the compile
gcc does not contain the assembler, so we also need the
GNU Binutils package which provides lowlevel stuff.
Cross compilers and tools are usually named like the corresponding host tool, but with a prefix – the GNU target. For example, the cross compilers for ARM and powerpc may look like
With these compiler frontends we can convert e.g. a C program into binary code for specific machines. So for example if a C program is to be compiled natively, it works like this:
$ gcc test.c -o test
To build the same binary for the ARM architecture we have to use the cross compiler instead of the native one:
$ arm-softfloat-linux-gnu-gcc test.c -o test
Also part of what we consider to be the “toolchain” is the run-time library (libc, dynamic linker). All programs running on the embedded system are linked against the libc, which also offers the interface from user space functions to the kernel.
The compiler and libc are very tightly coupled components: the second stage compiler, which is used to build normal user space code, is being built against the libc itself. For example, if the target does not contain a hardware floating point unit, but the toolchain generates floating point code, it will fail. This is also the case when the toolchain builds code for i686 CPUs, whereas the target is i586.
So in order to make things working consistently it is necessary that the run-time libc is identical with the libc the compiler was built against.
PTXdist doesn’t contain a pre-built binary toolchain. Remember that it’s not a distribution but a development tool. But it can be used to build a toolchain for our target. Building the toolchain usually has only to be done once. It may be a good idea to do that over night, because it may take several hours, depending on the target architecture and development host power.
Using existing Toolchains from different Vendors¶
If a toolchain from a different vendor than OSELAS is already installed which is known to be working, the toolchain building step with PTXdist may be omitted.
The OSELAS.BoardSupport() Packages shipped for PTXdist have been tested with the OSELAS.Toolchains() built with the same PTXdist version. So if an external toolchain is being used which isn’t known to be stable, a target may fail. Note that not all compiler versions and combinations work properly in a cross environment.
Every OSELAS.BoardSupport() Package checks for its OSELAS.Toolchain it’s tested against, so using a toolchain from a different vendor than OSELAS requires an additional step:
Open the OSELAS.BoardSupport() Package menu with:
$ ptxdist platformconfig
and navigate to
architecture ---> toolchain and
check for specific toolchain vendor. Clear this entry to disable the
toolchain vendor check.
Preconditions a toolchain from a different vendor than OSELAS must meet:
- it shall be built with the configure option
--with-sysrootpointing to its own C libraries.
- it should not support the multilib feature as this may confuse PTXdist which libraries are to select for the root filesystem
If we want to check if our toolchain was built with the
--with-sysroot option, we just run this simple command:
$ mytoolchain-gcc -v 2>&1 | grep with-sysroot
If this command does not output anything, this toolchain was not
built with the
--with-sysroot option and cannot be used with
Omitting building a Toolchain¶
Pengutronix also provides ’ready to use’ toolchains in a binary manner. These toolchains are built from the OSELAS.Toolchain bundle, so they comply with all of Pengutronix’s board support packages and we can use them instead of building our own one.
The binary OSELAS toolchains are provided as Debian Distribution Packages. Also most non-Debian distributions can handle such packages.
In order to install the OSELAS binary toolchains on a Debian based system the following steps are required:
Add the OSELAS Server as a Package Source¶
To register the OSELAS package server to the list of known package
servers, we add a new file with the name
pengutronix.list into the
/etc/apt/sources.list.d/. The basename of this file isn’t
important, while the extension
The contents of this new file describe the Pengutronix server as an available package source. It is defined via one text line:
deb http://debian.pengutronix.de/debian/ sid main contrib non-free
Note: if the directory
/etc/apt/sources.list.d/ does not exist, the
text line mentioned above must be added to the file
Make the OSELAS Server Content available¶
The package manager now must update its packages list with the following command:
$ apt-get update
Install the Archive Keyring¶
To avoid warnings about untrusted package sources we can install the OSELAS archive keyring with the following command:
$ apt-get install pengutronix-archive-keyring
Install the binary OSELAS Toolchain¶
Now everything is in place to install the binary OSELAS toolchain for the board support package:
$ apt-get install oselas.toolchain-2016.06.1-arm-v5te-linux-gnueabi-<ptxdistCompilerVersion>
These package names are very long and hard to type without making typos. An easier way is to ask the package manager for available toolchains and just use the name by copy and paste it.
$ apt-cache search "oselas.toolchain-.*-arm.*v5te.*" oselas.toolchain-2016.06.1-arm-v5te-linux-gnueabi-<ptxdistCompilerVersion>
The binary OSELAS Toolchain Package for non-Debian Distributions¶
The Debian Distribution Packages can be found on our server at http://debian.pengutronix.de/debian/pool/main/o/
The related OSELAS toolchain package can be found here:
Package filename is:
Package filenames for 32 bit host machines are ending on
and for 64 bit host machines on
Building a Toolchain¶
If there is no different toolchain available yet, the next step is to build one at least for the desired target architecture.
PTXdist handles toolchain building as a simple project, like all other projects, too. So we can download the OSELAS.Toolchain bundle and build the required toolchain for the OSELAS.BoardSupport() Package.
Building any toolchain of the OSELAS.Toolchain-2016.06.1 is tested with PTXdist-2016.06.0. Pengutronix recommends to use this specific PTXdist to build the toolchain. So, it might be essential to install more than one PTXdist revision to build the toolchain and later on the Board Support Package if the latter one is made for a different PTXdist revision.
A PTXdist project generally allows to build into some project defined directory; all OSELAS.Toolchain projects that come with PTXdist are configured to use the standard installation paths mentioned below.
All OSELAS.Toolchain projects install their result into /opt/OSELAS.Toolchain-2016.06.1/.
/opt directory is not world writeable. So in order to
build our OSELAS.Toolchain into that directory we need to use a root
account to change the permissions. PTXdist detects this case and asks
if we want to run
sudo to do the job for us. Alternatively we can
$ mkdir /opt/OSELAS.Toolchain-2016.06.1 $ chown <username> /opt/OSELAS.Toolchain-2016.06.1 $ chmod a+rwx /opt/OSELAS.Toolchain-2016.06.1
We recommend to keep this installation path as PTXdist expects the
/opt. Whenever we go to select a platform in a
project, PTXdist tries to find the right toolchain from data read from
the platform configuration settings and a toolchain at
matches to these settings. But that’s for our convenience only. If we
decide to install the toolchains at a different location, we still can
use the toolchain parameter to define the toolchain to be used on a
per project base.
Building the OSELAS.Toolchain for OSELAS.BSP-Pengutronix-Example¶
Do the following steps in your own home directory ($HOME). The final
OSELAS.Toolchain gets installed to
/opt, but must never be
compiled in the
/opt directory. You will get many funny error
messages, if you try to compile the OSELAS-Toolchain in
To compile and install an OSELAS.Toolchain we have to extract the OSELAS.Toolchain archive, change into the new folder, configure the compiler in question and start the build.
The required compiler to build the board support package is
Please ensure the ’current directory’ (the
. entry) is not part of
your PATH environment variable. PTXdist tries to sort out this entry,
but might not be successful in doing so. Check by running
ptxdist print PATH if the output still contains any kind of ’current
directory’ as a component. If yes, remove it first.
So the steps to build this toolchain are:
$ tar xf OSELAS.Toolchain-2016.06.1.tar.bz2 $ cd OSELAS.Toolchain-2016.06.1 $ ptxdist-2016.06.0 select ptxconfigs/arm-v5te-linux-gnueabi_gcc-5.4.0_glibc-2.23_binutils-2.26_kernel-4.6-sanitized.ptxconfig $ ptxdist-2016.06.0 go
At this stage we have to go to our boss and tell him that it’s probably time to go home for the day. Even on reasonably fast machines the time to build an OSELAS.Toolchain is something like around 30 minutes up to a few hours.
Measured times on different machines:
- Single Pentium 2.5 GHz, 2 GiB RAM: about 2 hours
- Turion ML-34, 2 GiB RAM: about 1 hour 30 minutes
- Dual Athlon 2.1 GHz, 2 GiB RAM: about 1 hour 20 minutes
- Dual Quad-Core-Pentium 1.8 GHz, 8 GiB RAM: about 25 minutes
- 24 Xeon cores 2.54 GHz, 96 GiB RAM: about 22 minutes
Another possibility is to read the next chapters of this manual, to find out how to start a new project.
When the OSELAS.Toolchain project build is finished, PTXdist is ready for prime time and we can continue with our first project.
Protecting the Toolchain¶
All toolchain components are built with regular user permissions. In order to avoid accidential changes in the toolchain, the files should be set to read-only permissions after the installation has finished successfully. It is also possible to set the file ownership to root. This is an important step for reliability, so it is highly recommended.
Building additional Toolchains¶
The OSELAS.Toolchain- bundle comes with various predefined toolchains.
ptxconfigs/ folder for other definitions. To build
additional toolchains we only have to clean our current toolchain
project, removing the current
selected_ptxconfig link and creating a
$ ptxdist clean $ rm selected_ptxconfig $ ptxdist select ptxconfigs/any_other_toolchain_def.ptxconfig $ ptxdist go
All toolchains will be installed side by side architecture dependent into directory
Different toolchains for the same architecture will be installed side by side version dependent into directory