SmartBook
Unfortunately, it's not - not anymore, that is. Support for the Efika MX smartbook was added in Linux 2.6.39, and it should work with the linux-image-mx5 kernel in Wheezy - FSVO work, because the GPU only works to its potential with proprietary drivers, as on nearly all ARM-based machines, and I am not sure about other drivers (sound, Wifi…) either.
The bad news is that support for your machine got ripped out again in Linux 3.7, as nobody added device tree support for it, and so the Jessie kernel does not work with it, as mentioned in the release notes[1].
> I don't know how to find out, if the hardware is really supported, nor > how to build a mainline kernel and integrate it with Uboot.
Install the linux-image-mx5 kernel and the flash-kernel package from Wheezy, it should know what to do. If the official Wheezy kernel works, you can upgrade your userland to Jessie (and maybe to Stretch, but note that systemd in Stretch officially requires Linux 3.12). This would give you a few extra years.
Good luck, Sven
ls -l /boot/ total 24881 -rw-r--r-- 1 root root 474 Aug 6 2012 boot.scr -rw-r--r-- 1 root root 452 Aug 6 2012 boot.scr.bak -rw-r--r-- 1 root root 65840 Jul 31 2012 config-2.6.31.14.27-efikamx -rw-r--r-- 1 root root 75779 Mar 9 2016 config-3.2.0-4-mx5 -rw-r--r-- 1 root root 3754408 Jun 15 2015 initrd.img-2.6.31.14.27-efikamx -rw-r--r-- 1 root root 5496593 Feb 16 11:58 initrd.img-3.2.0-4-mx5 drwx------ 2 root root 12288 Jul 28 2012 lost+found -rw-r--r-- 1 root root 893601 Jul 31 2012 System.map-2.6.31.14.27-efikamx -rw-r--r-- 1 root root 1150071 Mar 9 2016 System.map-3.2.0-4-mx5 lrwxrwxrwx 1 root root 27 Jul 28 2012 uImage -> uImage-2.6.31.14.27-efikamx -rw-r--r-- 1 root root 1956776 Aug 6 2012 uImage-2.6.31.14.27-efikamx -rw-r--r-- 1 root root 1956692 Jul 28 2012 uImage-2.6.31.14.27-efikamx.bak lrwxrwxrwx 1 root root 28 Jul 28 2012 uInitrd -> uInitrd-2.6.31.14.27-efikamx -rw-r--r-- 1 root root 3105686 Aug 6 2012 uInitrd-2.6.31.14.27-efikamx -rw-r--r-- 1 root root 2921664 Jul 28 2012 uInitrd-2.6.31.14.27-efikamx.bak -rw-r--r-- 1 root root 1956712 Jul 31 2012 vmlinuz-2.6.31.14.27-efikamx -rw-r--r-- 1 root root 2008520 Mar 9 2016 vmlinuz-3.2.0-4-mx5
# cat /boot/boot.scr
'VQPû]FUbuntu boot scriptsetenv ramdisk uInitrd-2.6.31.14.27-efikamx;
setenv kernel uImage-2.6.31.14.27-efikamx;
setenv bootargs console=tty1 root=/dev/sda2 rootwait rw quiet splash;
${loadcmd} ${ramdiskaddr} ${ramdisk};
if imi ${ramdiskaddr}; then; else
setenv bootargs ${bootargs} noinitrd;
setenv ramdiskaddr "";
fi;
${loadcmd} ${kerneladdr} ${kernel}
if imi ${kerneladdr}; then
bootm ${kerneladdr} ${ramdiskaddr}
fi;1. https://www.debian.org/releases/jessie/armhf/ch02s01.html.en
https://stackoverflow.com/questions/29342821/creating-boot-scr-for-u-boot