!!! This version of YAGARTO was built to support newlib with reentrant stubs !!! Therefore it is possible that you will get some undefined references from the linker in case you use the printf function for example. The undefined references could be: _sbrk_r, _fstat_r, _isatty_r, _close_r, _lseek_r, _write_r, _read_r To use functions from stdio (like printf) in own projects, the interface functions for the newlib have to be provided. For more information take a look in chapter 13 from the "Red Hat newlib C Library" documentation. (ftp://sources.redhat.com/pub/newlib/index.html) You can find a good source about "Porting and Using Newlib in Embedded Systems" on the page from Bill Gatliff (http://neptune.billgatliff.com/newlib.html). The YAGARTO version of newlib was built with the following options: -DREENTRANT_SYSCALLS_PROVIDED --disable-newlib-supplied-syscalls To make your life easier, an example "syscalls.c" can be find here: http://www.yagarto.de/download/yagarto/syscalls.c (29.03.2009, mifi)