Sometimes you may need to write a program which needs to query some system information (e.g. system uptime). In this case, one may want to call the sysinfo() with struct sysinfo as defined in <sys/sysinfo.h>. Unfortunately, Android NDK does not provide the sysinfo() definition (definition is included since android-9, but I am still having no luck to link it properly). After some searching, I found this thread provides a solution: adding an assembly source (.S). Build it with your project and it works like a charm. The assembly source is attached below for your reference.