– Download the driver source from here
– Extract it, run ./configure and install all needed *-dev packages
– Install x11proto-gl-dev and mesa-common-dev
– Run make, if it stops with an error, open the corresponding .c file and uncomment the line which gave an error (for example it tries to include mibank.h, but it’s no longer available and even it doesn’t needed for compilation). There are about 3-4 lines to uncomment.
– After the process finished, look for src/.libs/sis671_drv.so. Copy it to /usr/lib/xorg/modules/drivers.
– Run Xorg :1 -configure, move xorg.conf.new from your home dir to /etc/X11, and replace fbdev and vesa to sis671 in the lines starting with Device
– Execute sudo service lightdm restart and now the resolution should be 1280×800
– To fix the console: add blacklist vga16fb to /etc/modprobe.d/blacklist-framebuffer.conf
– If you still have problems, check /var/log/Xorg.0.log