This recipe is for building the latest version of libgpiod on a bullseye system (aka .oldstable as of Dec 2023).
-
The tarball is obtained as follows:
$ curl -o libgpiod-2.1.tar.gz 'https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/snapshot/libgpiod-2.1.tar.gz' -
Some tools are needed:
$ sudo apt install tar gzip build-essential autoconf
You may have all of these, but getting them now will avoid errors later on.
- Un-tar the d/l file
$ tar xf libgpiod-2.1.tar.gz- Check out the un-tarred folder & review the README:
$ cd libgpiod-2.1
$ less README- Do some more reading: The Linux Program Library HOWTO.
- Before
make && make install, explore the filesystem where the old/existing (ver 1.6 as I write this) libraries are kept, and make notes:
$ whereis libgpiod
libgpiod: /usr/lib/arm-linux-gnueabihf/libgpiod.a /usr/lib/arm-linux-gnueabihf/libgpiod.so
# now we know where things are kept... let's visit:
$ ls -l /usr/lib/arm-linux-gnueabihf | less
# you may want to copy & paste this to a file for subsequent reference:
$ ls -l /usr/lib/arm-linux-gnueabihf | grep libgpiod
-rw-r--r-- 1 root root 32258 Dec 20 2020 libgpiod.a
-rw-r--r-- 1 root root 139276 Dec 20 2020 libgpiodcxx.a
lrwxrwxrwx 1 root root 20 Dec 20 2020 libgpiodcxx.so -> libgpiodcxx.so.1.1.1
lrwxrwxrwx 1 root root 20 Dec 20 2020 libgpiodcxx.so.1 -> libgpiodcxx.so.1.1.1
-rw-r--r-- 1 root root 66976 Dec 20 2020 libgpiodcxx.so.1.1.1
lrwxrwxrwx 1 root root 17 Dec 20 2020 libgpiod.so -> libgpiod.so.2.2.2
lrwxrwxrwx 1 root root 17 Dec 20 2020 libgpiod.so.2 -> libgpiod.so.2.2.2
-rw-r--r-- 1 root root 25912 Dec 20 2020 libgpiod.so.2.2.2-
DETOUR !! ====> (JUMP TO STEP 10)
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From the
READMEin Step 4. above, review the steps for building the library:
# ./autogen.sh --enable-tools=yes --prefix=<install path>
$ pwd
/home/pi/libgpiod-2.1
$ ./autogen.sh --enable-tools=yes --prefix=/usr/lib/arm-linux-gnueabihf
autoreconf: Entering directory `.'
autoreconf: configure.ac: not using Gettext
autoreconf: running: aclocal --force -I m4
aclocal: warning: couldn't open directory 'm4': No such file or directory
autoreconf: configure.ac: tracing
autoreconf: configure.ac: not using Libtool
autoreconf: running: /usr/bin/autoconf --force
configure.ac:203: error: Unexpanded AX_ macro found. Please install GNU autoconf-archive.
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
autoreconf: /usr/bin/autoconf failed with exit status: 1
# bummer!- Try installing the
install GNU autoconf-archive:
$ sudo apt install autoconf-archive
...
autoreconf: automake failed with exit status: 1
# bummer! Try following advice/suggestions in error message-
END DETOUR
-
As I learned in the DETOUR, there are some steps that must be completed prior to successful compilation. I should have read
/usr/share/doc/libgpiod-dev/README.gzfirst. This is the "RPi Version" of the more genericREADMEfile in./libgpiod-2.1, and it contains important exceptions & additions including this :Recent kernel headers are also required for the GPIO user API definitions. For the exact version of kernel headers required, please refer to the configure.ac contents.
But what are recent kernel headers?
configure.acdoesn't provide any guidance. So, we'll have to rely on guesswork... (actually, install them all).$ zless /usr/share/doc/libgpiod-dev/README.gz $ apt-cache search linux-headers # ... and at the end of that list: raspberrypi-kernel-headers - Header files for the Raspberry Pi Linux kernel # following more trial and error, install the following packages: $ sudo apt install raspberrypi-kernel-headers autoconf-archive libtool help2man # # now ready to go to work $ cd /home/pi/libgpiod-2.1 $ pwd /home/pi/libgpiod-2.1 $ ./autogen.sh --enable-tools=yes --prefix=/usr/lib/arm-linux-gnueabihf --enable-gpioset-interactive # ... config.status: executing libtool commands $ make $ sudo make install
-
There have been a few changes to
/usr/lib/arm-linux-gnueabihf, but the new tools andmanpages have not been moved into place - which means that the freshly-compiled stuff is floating around the filesystem somewhere! Actually this freshly-compiled stuff is in folders under/usr/lib/arm-linux-gnueabihf, but some manual intervention is needed to temporarily upgrade the binaries and themanpages.$ sudo mkdir /usr/bin/old-gpio $ sudo mv /usr/bin/gpio?* /usr/bin/old-gpio #for subsequent restoration if needed $ cd /usr/lib/arm-linux-gnueabihf $ pwd /usr/lib/arm-linux-gnueabihf $ sudo cp -a ./bin/gpio* /usr/bin # cp new gpiod tools where needed: /usr/bin # and we need the new man pages, so ... $ export MANPATH="/usr/lib/arm-linux-gnueabihf/share/man:$(manpath)" # # NOTE: you should probably add the `export MANPATH` definition above into # ~/.profile if you plan on using it for any length of time; i.e. $ echo -e '\nexport MANPATH="/usr/lib/arm-linux-gnueabihf/share/man:$(manpath)"' >> ~/.profile
In addition to the
./binand./sharefolders (above), there were two other folders created under/usr/lib/arm-linux-gnueabihf:./lib, and./include. These folders contain thelibgpiod.sobinary, and thegpiod.hheader file needed to compile apps using the new ver 2.1 library. Let's take care of those now:$ sudo mkdir /usr/lib/arm-linux-gnueabihf/old-libgpiod $ sudo mv /usr/lib/arm-linux-gnueabihf/libgpiod* /usr/lib/arm-linux-gnueabihf/old-libgpiod $ sudo cp ~/libgpiod-2.1/include/gpiod.h /usr/include $ sudo cp -a /usr/lib/arm-linux-gnueabihf/lib/libgpiod.* /usr/lib/arm-linux-gnueabihf $ ls -l /usr/lib/arm-linux-gnueabihf | grep libgpiod.* -rw-r--r-- 1 root root 164256 Dec 20 02:46 libgpiod.a -rwxr-xr-x 1 root root 957 Dec 20 02:46 libgpiod.la lrwxrwxrwx 1 root root 17 Dec 20 02:46 libgpiod.so -> libgpiod.so.3.1.0 lrwxrwxrwx 1 root root 17 Dec 20 02:46 libgpiod.so.3 -> libgpiod.so.3.1.0 -rwxr-xr-x 1 root root 114436 Dec 20 02:46 libgpiod.so.3.1.0 drwxr-xr-x 2 root root 4096 Dec 21 04:06 old-libgpiod
Which looks like everything is accounted for...