Changes

Several "distribution" are available for embedded Linux devices. [[Yocto|https://www.yoctoproject.org]Yocto] and [[Buildroot|https://buildroot.org]Buildroot] are just two examples of the most common. Nevertheless, for some applications the use of a desktop/server distribution might be preferable. Since they are not conceived for embedded platforms, these distributions have to be carefully tailored, in order to match hardware resources.[1]

This application note shows how to run one of such distributions - Debian Jessie - on SBC Lynx. Since it '''It is , assumed that the reader if already familiar with''' [[AXEL_ULite_and_SBC_Lynx_Embedded_Linux_Kit_(XUELK)|'''AXEL ULite and SBC Lynx Embedded Linux Kit (XUELK)''']], as it is the basis of this work.

[1] Non-volatile storage footprint is the typical example. Disk occupation of a desktop distribution is measure measured in GB or tens of GB, while many embedded platforms have less the 1 GB of flash memory.==Initial configuration==For the sake of simplicity, the same approach described [[AXEL_ULite_and_SBC_Lynx_Embedded_Linux_Kit_(XUELK)#Target_setup_and_first_boot|here]] is used. It is quite straightforward to prepare a microSD card containing a Debian minimal root file system that replaces the one delivered along the XUELK. To get such an image, issue the following command on your host machine:[1]<pre class="board-terminal">wget -c https://rcn-ee.com/rootfs/eewiki/barefs/debian-8.7-bare-armhf-2017-01-14.tar.xz</pre>To verify it:<pre class="board-terminal">sha256sum debian-8.7-bare-armhf-2017-01-14.tar.xz159e1a6addc35bbfff03b5eafd5cb741086a8a016d5ab9572ab122ce64d63e5e debian-8.7-bare-armhf-2017-01-14.tar.xz</pre>After inserting the microSD card into the adapter connectd to the host machine, it is possible to decompress the <code>.tar.xz</code> file in the <code>ROOTFS</code> partition:<pre class="board-terminal">unzip debian-8-xfce-wandboard-20150514.zip cd debian-8.7-bare-armhf-2017-01-14/tar xvf armhf-rootfs-debian-jessie.tar -C /media/dvdk/ROOTFS/sudo umount /media/dvdk/BOOT sudo umount /media/llandre/ROOTFS </pre> On target side, these are the messages printed out on the serial console, when this card is used:<pre class="board-terminal">...[ 5.114803] VFS: Mounted root (ext3 filesystem) on device 179:2.[ 5.125035] devtmpfs: mounted[ 5.128943] Freeing unused kernel memory: 408K (80b15000 - 80b7b000)[ 5.751274] systemd[1]: System time before build time, advancing clock.[ 5.783486] systemd[1]: Failed to insert module 'kdbus': Function not imp[ 5.823801] systemd[1]: systemd 230 running in system mode. (+PAM +AUDIT +GNUTLS +ACL +XZ -LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN)[ 5.843563] systemd[1]: Detected architecture arm. Welcome to Debian GNU/Linux 8 (jessie)! [ 5.880235] systemd[1]: Set hostname to <arm>.[ 6.727889] systemd[1]: Listening on udev Control Socket.[ OK ] Listening on udev Control Socket.[ 6.758625] systemd[1]: Listening on Journal Socket (/dev/log).[ OK ] Listening on Journal Socket (/dev/log).[ 6.788119] systemd[1]: Reached target Encrypted Volumes.[ OK ] Reached target Encrypted Volumes.[ 6.818418] systemd[1]: Listening on Syslog Socket.[ OK ] Listening on Syslog Socket.[ 6.839082] systemd[1]: Reached target Remote File Systems (Pre).[ OK ] Reached target Remote File Systems (Pre).[ 6.869354] systemd[1]: Started Forward Password Requests to Wall Directo[ OK ] Started Forward Password Requests to Wall Directory Watch.[ 6.901334] systemd[1]: Set up automount Arbitrary Executable File Format[ OK ] Set up automount Arbitrary Executab...ats File System Automount Poi[ 6.939313] systemd[1]: Listening on /dev/initctl Compatibility Named Pip[ OK ] Listening on /dev/initctl Compatibility Named Pipe.[ 6.968527] systemd[1]: Reached target Remote File Systems.[ OK ] Reached target Remote File Systems.[ 6.999801] systemd[1]: Reached target Swap.[ OK ] Reached target Swap.[ 7.019678] systemd[1]: Created slice System Slice.[ OK ] Created slice System Slice.[ 7.038667] systemd[1]: Reached target Slices.[ OK ] Reached target Slices.[ 7.059455] systemd[1]: Created slice system-serial\x2dgetty.slice.[ OK ] Created slice system-serial\x2dgetty.slice.[ 7.089497] systemd[1]: Created slice system-getty.slice.[ OK ] Created slice system-getty.slice.[ 7.119398] systemd[1]: Listening on Journal Socket.[ OK ] Listening on Journal Socket.[ 7.145290] systemd[1]: Starting Journal Service... Starting Journal Service...[ 7.182154] systemd[1]: Starting Remount Root and Kernel File Systems... Starting Remount Root and Kernel File Systems...[ 7.241987] systemd[1]: Mounting Debug File System... Mounting Debug File System...[ 7.308585] systemd[1]: Starting Load Kernel Modules... Starting Load Kernel Modules...[ 7.364001] systemd[1]: Started Dispatch Password Requests to Console Dir[ OK ] Started Dispatch Password Requests to Console Directory Watch.[ 7.418164] systemd[1]: Reached target Paths.[ OK ] Reached target Paths.[ 7.451915] systemd[1]: Starting Create Static Device Nodes in /dev... Starting Create Static Device Nodes in /dev...[ 7.508441] systemd[1]: Listening on udev Kernel Socket.[ OK ] Listening on udev Kernel Socket.[ 7.528001] systemd[1]: Reached target Sockets.[ OK ] Reached target Sockets.[ 7.558251] systemd[1]: Mounted Debug File System.[ OK ] Mounted Debug File System.[ 7.589958] systemd[1]: Started Remount Root and Kernel File Systems.[ OK ] Started Remount Root and Kernel File Systems.[ 7.651199] systemd[1]: Started Load Kernel Modules.[ OK ] Started Load Kernel Modules.[ 7.680384] systemd[1]: Started Create Static Device Nodes in /dev.[ OK ] Started Create Static Device Nodes in /dev.[ 7.716855] systemd[1]: Starting udev Kernel Device Manager... Starting udev Kernel Device Manager...[ 7.780271] systemd[1]: Starting Apply Kernel Variables... Starting Apply Kernel Variables...[ 7.821035] systemd[1]: Mounting FUSE Control File System... Mounting FUSE Control File System...[ 7.909856] systemd[1]: Starting udev Coldplug all Devices... Starting udev Coldplug all Devices...[ 7.932630] systemd[1]: Reached target Local File Systems (Pre).[ OK ] Reached target Local File Systems (Pre).[ 8.001492] systemd[1]: Starting Load/Save Random Seed... Starting Load/Save Random Seed...[ 8.058300] systemd[1]: Reached target Local File Systems.[ OK ] Reached target Local File Systems.[ 8.114063] systemd[1]: Mounted FUSE Control File System.[ OK ] Mounted FUSE Control File System.[ 8.179693] systemd[1]: Started udev Kernel Device Manager.[ OK ] Started udev Kernel Device Manager.[ 8.210239] systemd[1]: Started Apply Kernel Variables.[ OK ] Started Apply Kernel Variables.[ 8.251215] systemd[1]: Started Load/Save Random Seed.[ OK ] Started Load/Save Random Seed.[ 8.295404] systemd[1]: Starting Raise network interfaces... Starting Raise network interfaces...[ 9.378588] systemd[1]: Started Journal Service.[ OK ] Started Journal Service. Starting Flush Journal to Persistent Storage...[ 10.329376] systemd-journald[134]: Received request to flush runtime jour[ OK ] Started Flush Journal to Persistent Storage. Starting Create Volatile Files and Directories...[ OK ] Started Create Volatile Files and Directories. Starting Network Time Synchronization... Starting Update UTMP about System Boot/Shutdown...[ OK ] Started udev Coldplug all Devices.[ 21.038081] fec 2188000.ethernet eth0: Freescale FEC PHY driver [Micrel K[ 21.188538] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready[ OK ] Started Update UTMP about System Boot/Shutdown.[ OK ] Started Network Time Synchronization.[ OK ] Reached target System Initialization.[ OK ] Reached target Basic System.[ OK ] Started Regular background program processing daemon. Starting Cape Manager Service... Starting System Logging Service... Starting getty on tty2-tty6 if dbus and logind are not available...[ OK ] Started Daily Cleanup of Temporary Directories.[ OK ] Reached target Timers. Starting Generic Board Startup...[ OK ] Reached target System Time Synchronized.[FAILED] Failed to start Cape Manager Service.See 'systemctl status capemgr.service' for details.[FAILED] Failed to start Generic Board Startup.See 'systemctl status generic-board-startup.service' for details.[ OK ] Started System Logging Service.[ 25.038599] libphy: 2188000.ethernet:03 - Link is Up - 100/Full[ 25.044599] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready[ OK ] Started getty on tty2-tty6 if dbus and logind are not available.[ OK ] Found device /dev/ttymxc0.[ OK ] Started Raise network interfaces.[ OK ] Reached target Network. Starting /etc/rc.local Compatibility... Starting Permit User Sessions...[ OK ] Started /etc/rc.local Compatibility.[ OK ] Started Permit User Sessions.[ OK ] Started Getty on tty6.[ OK ] Started Getty on tty3.[ OK ] Started Serial Getty on ttymxc0.[ OK ] Started Getty on tty2.[ OK ] Started Getty on tty1.[ OK ] Started Getty on tty5.[ OK ] Started Getty on tty4.[ OK ] Reached target Login Prompts.[ OK ] Reached target Multi-User System.[ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes...[ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 8 arm ttymxc0 default username:password is [debian:temppwd] arm login: rootPassword:Last login: Sun Jan 15 02:57:41 UTC 2017 on ttymxc0Linux arm 3.14.52-xuelk-1.1.0 #7 SMP PREEMPT Fri Nov 25 17:15:33 CET 2016 ar The programs included with the Debian GNU/Linux system are free software;the exact distribution terms for each program are described in theindividual files in /usr/share/doc/*/copyright. Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extentpermitted by applicable law.root@arm:~#</pre>    [1] These information are retrieved from [https://eewiki.net/display/linuxonarm/Wandboard#Wandboard-RootFileSystem(smallflash) here].==Adding packages==Of course, one of the greatest - if not ''the'' greatest - pros of having a desktop distribution, is the availability of a huge archive of pre-built packages. They can be installed very easily with tools such as [https://wiki.debian.org/Apt <code>apt</code>] and [https://packaging.python.org <code>pip</code>]:<pre class="board-terminal">root@arm:~# apt updateGet:1 http://security.debian.org jessie/updates InRelease [63.1 kB]Get:2 http://repos.rcn-ee.com jessie InRelease [4373 B]Ign http://httpredir.debian.org jessie InReleaseGet:3 http://httpredir.debian.org jessie-updates InRelease [145 kB]Get:4 http://httpredir.debian.org jessie Release.gpg [2373 B]Get:5 http://httpredir.debian.org jessie Release [148 kB]Get:6 http://security.debian.org jessie/updates/main armhf Packages [420 kB]Get:7 http://repos.rcn-ee.com jessie/main armhf Packages [796 kB]Get:8 http://security.debian.org jessie/updates/contrib armhf Packages [994 B]Get:9 http://security.debian.org jessie/updates/non-free armhf Packages [20 B]Get:10 http://httpredir.debian.org jessie-updates/main armhf Packages [17.6 kB]Get:11 http://httpredir.debian.org jessie-updates/contrib armhf Packages [20 B]Get:12 http://httpredir.debian.org jessie-updates/non-free armhf Packages [450 B]Get:13 http://httpredir.debian.org jessie/contrib armhf Packages [44.7 kB]Get:14 http://httpredir.debian.org jessie/non-free armhf Packages [74.9 kB]Get:15 http://httpredir.debian.org jessie/main armhf Packages [8850 kB]Fetched 10.6 MB in 43s (240 kB/s)Reading package lists... DoneBuilding dependency treeReading state information... DoneAll packages are up to date.root@arm:~# apt-get install pythonReading package lists... DoneBuilding dependency treeReading state information... DoneThe following extra packages will be installed: file libexpat1 libmagic1 libpython-stdlib libpython2.7-minimal libpython2.7-stdlib libsqlite3-0 libssl1.0.0 mime-support python-minimal python2.7 python2.7-minimalSuggested packages: python-doc python-tk python2.7-doc binutils binfmt-supportThe following NEW packages will be installed: file libexpat1 libmagic1 libpython-stdlib libpython2.7-minimal libpython2.7-stdlib libsqlite3-0 libssl1.0.0 mime-support python python-minimal python2.7 python2.7-minimal0 upgraded, 13 newly installed, 0 to remove and 0 not upgraded.Need to get 5449 kB of archives.After this operation, 20.5 MB of additional disk space will be used.Do you want to continue? [Y/n]Get:1 http://security.debian.org/ jessie/updates/main libssl1.0.0 armhf 1.0.1t-1+deb8u6 [868 kB]Get:2 http://httpredir.debian.org/debian/ jessie/main libmagic1 armhf 1:5.22+15-2+deb8u3 [245 kB]Get:3 http://httpredir.debian.org/debian/ jessie/main libsqlite3-0 armhf 3.8.7.1-1+deb8u2 [384 kB]Get:4 http://httpredir.debian.org/debian/ jessie/main libpython2.7-minimal armhf 2.7.9-2+deb8u1 [376 kB]Get:5 http://httpredir.debian.org/debian/ jessie/main python2.7-minimal armhf 2.7.9-2+deb8u1 [1152 kB]Get:6 http://httpredir.debian.org/debian/ jessie/main mime-support all 3.58 [36.0 kB]Get:7 http://httpredir.debian.org/debian/ jessie/main python-minimal armhf 2.7.9-1 [40.2 kB]Get:8 http://httpredir.debian.org/debian/ jessie/main libexpat1 armhf 2.1.0-6+deb8u3 [61.8 kB]Get:9 http://httpredir.debian.org/debian/ jessie/main file armhf 1:5.22+15-2+deb8u3 [60.0 kB]Get:10 http://httpredir.debian.org/debian/ jessie/main libpython2.7-stdlib armhf 2.7.9-2+deb8u1 [1805 kB]Get:11 http://httpredir.debian.org/debian/ jessie/main python2.7 armhf 2.7.9-2+deb8u1 [252 kB]Get:12 http://httpredir.debian.org/debian/ jessie/main libpython-stdlib armhf 2.7.9-1 [19.6 kB]Get:13 http://httpredir.debian.org/debian/ jessie/main python armhf 2.7.9-1 [151 kB]Fetched 5449 kB in 4s (1306 kB/s)debconf: unable to initialize frontend: Dialogdebconf: (No usable dialog-like program is installed, so the dialog based frontend cannot be used. at /usr/share/perl5/Debconf/FrontEnd/Dialog.pm line 76, <> line 13.)debconf: falling back to frontend: Readlinedebconf: unable to initialize frontend: Readlinedebconf: (Can't locate Term/ReadLine.pm in @INC (you may need to install the Term::ReadLine module) (@INC contains: /etc/perl /usr/local/lib/arm-linux-gnueabihf/perl/5.20.2 /usr/local/share/perl/5.20.2 /usr/lib/arm-linux-gnueabihf/perl5/5.20 /usr/share/perl5 /usr/lib/arm-linux-gnueabihf/perl/5.20 /usr/share/perl/5.20 /usr/local/lib/site_perl .) at /usr/share/perl5/Debconf/FrontEnd/Readline.pm line 7, <> line 13.)debconf: falling back to frontend: TeletypePreconfiguring packages ...Selecting previously unselected package libssl1.0.0:armhf.(Reading database ... (Reading database ... 5%(Reading database ... 10%(Reading database ... 15%(Reading database ... 20%(Reading database ... 25%(Reading database ... 30%(Reading database ... 35%(Reading database ... 40%(Reading database ... 45%(Reading database ... 50%(Reading database ... 55%(Reading database ... 60%(Reading database ... 65%(Reading database ... 70%(Reading database ... 75%(Reading database ... 80%(Reading database ... 85%(Reading database ... 90%(Reading database ... 95%(Reading database ... 100%(Reading database ... 8710 files and directories currently installed.)Preparing to unpack .../libssl1.0.0_1.0.1t-1+deb8u6_armhf.deb ...Unpacking libssl1.0.0:armhf (1.0.1t-1+deb8u6) ...Selecting previously unselected package libmagic1:armhf.Preparing to unpack .../libmagic1_1%3a5.22+15-2+deb8u3_armhf.deb ...Unpacking libmagic1:armhf (1:5.22+15-2+deb8u3) ...Selecting previously unselected package libsqlite3-0:armhf.Preparing to unpack .../libsqlite3-0_3.8.7.1-1+deb8u2_armhf.deb ...Unpacking libsqlite3-0:armhf (3.8.7.1-1+deb8u2) ...Selecting previously unselected package libpython2.7-minimal:armhf.Preparing to unpack .../libpython2.7-minimal_2.7.9-2+deb8u1_armhf.deb ...Unpacking libpython2.7-minimal:armhf (2.7.9-2+deb8u1) ...Selecting previously unselected package python2.7-minimal.Preparing to unpack .../python2.7-minimal_2.7.9-2+deb8u1_armhf.deb ...Unpacking python2.7-minimal (2.7.9-2+deb8u1) ...Selecting previously unselected package python-minimal.Preparing to unpack .../python-minimal_2.7.9-1_armhf.deb ...Unpacking python-minimal (2.7.9-1) ...Selecting previously unselected package mime-support.Preparing to unpack .../mime-support_3.58_all.deb ...Unpacking mime-support (3.58) ...Selecting previously unselected package libexpat1:armhf.Preparing to unpack .../libexpat1_2.1.0-6+deb8u3_armhf.deb ...Unpacking libexpat1:armhf (2.1.0-6+deb8u3) ...Selecting previously unselected package libpython2.7-stdlib:armhf.Preparing to unpack .../libpython2.7-stdlib_2.7.9-2+deb8u1_armhf.deb ...Unpacking libpython2.7-stdlib:armhf (2.7.9-2+deb8u1) ...Selecting previously unselected package python2.7.Preparing to unpack .../python2.7_2.7.9-2+deb8u1_armhf.deb ...Unpacking python2.7 (2.7.9-2+deb8u1) ...Selecting previously unselected package libpython-stdlib:armhf.Preparing to unpack .../libpython-stdlib_2.7.9-1_armhf.deb ...Unpacking libpython-stdlib:armhf (2.7.9-1) ...Setting up libpython2.7-minimal:armhf (2.7.9-2+deb8u1) ...Setting up python2.7-minimal (2.7.9-2+deb8u1) ...Linking and byte-compiling packages for runtime python2.7...Setting up python-minimal (2.7.9-1) ...Selecting previously unselected package python.(Reading database ... (Reading database ... 5%(Reading database ... 10%(Reading database ... 15%(Reading database ... 20%(Reading database ... 25%(Reading database ... 30%(Reading database ... 35%(Reading database ... 40%(Reading database ... 45%(Reading database ... 50%(Reading database ... 55%(Reading database ... 60%(Reading database ... 65%(Reading database ... 70%(Reading database ... 75%(Reading database ... 80%(Reading database ... 85%(Reading database ... 90%(Reading database ... 95%(Reading database ... 100%(Reading database ... 9539 files and directories currently installed.)Preparing to unpack .../python_2.7.9-1_armhf.deb ...Unpacking python (2.7.9-1) ...Selecting previously unselected package file.Preparing to unpack .../file_1%3a5.22+15-2+deb8u3_armhf.deb ...Unpacking file (1:5.22+15-2+deb8u3) ...Setting up libssl1.0.0:armhf (1.0.1t-1+deb8u6) ...debconf: unable to initialize frontend: Dialogdebconf: (No usable dialog-like program is installed, so the dialog based frontend cannot be used. at /usr/share/perl5/Debconf/FrontEnd/Dialog.pm line 76.)debconf: falling back to frontend: Readlinedebconf: unable to initialize frontend: Readlinedebconf: (Can't locate Term/ReadLine.pm in @INC (you may need to install the Term::ReadLine module) (@INC contains: /etc/perl /usr/local/lib/arm-linux-gnueabihf/perl/5.20.2 /usr/local/share/perl/5.20.2 /usr/lib/arm-linux-gnueabihf/perl5/5.20 /usr/share/perl5 /usr/lib/arm-linux-gnueabihf/perl/5.20 /usr/share/perl/5.20 /usr/local/lib/site_perl .) at /usr/share/perl5/Debconf/FrontEnd/Readline.pm line 7.)debconf: falling back to frontend: TeletypeSetting up libmagic1:armhf (1:5.22+15-2+deb8u3) ...Setting up libsqlite3-0:armhf (3.8.7.1-1+deb8u2) ...Setting up mime-support (3.58) ...Setting up libexpat1:armhf (2.1.0-6+deb8u3) ...Setting up libpython2.7-stdlib:armhf (2.7.9-2+deb8u1) ...Setting up python2.7 (2.7.9-2+deb8u1) ...Setting up libpython-stdlib:armhf (2.7.9-1) ...Setting up python (2.7.9-1) ...Setting up file (1:5.22+15-2+deb8u3) ...Processing triggers for libc-bin (2.19-18+deb8u7) ...root@arm:~# pip install 'autobahn==0.13.0'Downloading/unpacking autobahn==0.13.0 Downloading autobahn-0.13.0.tar.gz (169kB): 169kB downloaded Running setup.py (path:/tmp/pip-build-bHFxQl/autobahn/setup.py) egg_info f  package init file 'twisted/plugins/__init__.py' not found (or not a regu Unhandled Error Traceback (most recent call last): File "<string>", line 17, in <module>  File "/tmp/pip-build-bHFxQl/autobahn/setup.py", line 259, in <module> list(getPlugins(IPlugin)) File "/usr/local/lib/python2.7/dist-packages/twisted/plugin.py", line allDropins = getCache(package) --- <exception caught here> --- File "/usr/local/lib/python2.7/dist-packages/twisted/plugin.py", line provider = pluginModule.load() File "/usr/local/lib/python2.7/dist-packages/twisted/python/modules.py return self.pathEntry.pythonPath.moduleLoader(self.name) File "/usr/local/lib/python2.7/dist-packages/twisted/python/reflect.py topLevelPackage = _importAndCheckStack(trialname) File "/usr/local/lib/python2.7/dist-packages/twisted/python/reflect.py reraise(excValue, excTraceback) File "/tmp/pip-build-bHFxQl/autobahn/twisted/plugins/autobahn_endpoint from autobahn.twisted.websocket import WrappingWebSocketServerFactor File "autobahn/twisted/__init__.py", line 41, in <module> from autobahn.twisted.choosereactor import install_reactor File "autobahn/twisted/choosereactor.py", line 31, in <module> import txaio exceptions.ImportError: No module named txaio  Twisted found (default reactor is <class 'twisted.internet.epollreactor. Twisted dropin.cache regenerated.Downloading/unpacking six>=1.10.0 (from autobahn==0.13.0) Downloading six-1.10.0-py2.py3-none-any.whlDownloading/unpacking txaio>=2.2.2 (from autobahn==0.13.0) Downloading txaio-2.6.0-py2.py3-none-any.whlInstalling collected packages: autobahn, six, txaio Running setup.py install for autobahn package init file 'twisted/plugins/__init__.py' not found (or not a regu  Unhandled Error Traceback (most recent call last): File "<string>", line 1, in <module>  File "/tmp/pip-build-bHFxQl/autobahn/setup.py", line 259, in <module> list(getPlugins(IPlugin)) File "/usr/local/lib/python2.7/dist-packages/twisted/plugin.py", line allDropins = getCache(package) --- <exception caught here> --- File "/usr/local/lib/python2.7/dist-packages/twisted/plugin.py", line provider = pluginModule.load() File "/usr/local/lib/python2.7/dist-packages/twisted/python/modules.py return self.pathEntry.pythonPath.moduleLoader(self.name) File "/usr/local/lib/python2.7/dist-packages/twisted/python/reflect.py topLevelPackage = _importAndCheckStack(trialname) File "/usr/local/lib/python2.7/dist-packages/twisted/python/reflect.py reraise(excValue, excTraceback) File "/usr/local/lib/python2.7/dist-packages/twisted/plugins/autobahn_ from autobahn.twisted.websocket import WrappingWebSocketServerFactor File "autobahn/twisted/__init__.py", line 41, in <module> from autobahn.twisted.choosereactor import install_reactor File "autobahn/twisted/choosereactor.py", line 31, in <module> import txaio exceptions.ImportError: No module named txaio  Twisted found (default reactor is <class 'twisted.internet.epollreactor. Twisted dropin.cache regenerated. Found existing installation: six 1.8.0 Not uninstalling six at /usr/lib/python2.7/dist-packages, owned by OSSuccessfully installed autobahn six txaioCleaning up...</pre>