my work is based nios2-linux-20120802 from www.nioswiki.com i write a char device driver, if the driver is "compile-in" with the kernel, all things are ok! but if the driver is compile as a loadable module, errors occurs: ERROR: "__ioremap" [drivers/char/test.ko] undefined! ERROR: "__iounmap" [drivers/char/test.ko] undefined! __ioremap is defined in <asm/io.h> , which is# included in my test.c. what's the problem?