I have no problem using debug printf() in Keil MDK IDE using ARMCC. The same doesn't work with GCC. I do not use GCC except when I have to. Could you please point me to a simple "Hello world" project for Keil MDK with GCC?
Thanks.
Please read my question carefully: the problem was in the compiler internals. All is required to replace weak function _write() with the working ARMCC code. It calls fputc() which does printing job, GCC calls _write(). That is basically it.