不使用microlib, 程序中使用printf(), 一直没有成功，调试过程如下;
如果不定义_sys_open()，报如下错误：
test\test.axf: Error: L6915E: Library reports error: __use_no_semihosting was requested, but _sys_open was referenced
Not enough information to list load addresses in the image map.
Finished: 1 information, 0 warning and 1 error messages.
如果定义_sys_open()，报如下错误：
test\test.axf: Error: L6200E: Symbol _sys_open multiply defined (by sys_io.o and main.o).
Not enough information to list image symbols.
Not enough information to list load addresses in the image map.
定不定义sys_open(),都不会编译成功。
楼主
