The functions in this section manipulate the watchdog hardware. These macros are defined in wdt.h.
The startup code is able to initialize the watchdog hardware. By default, the control register, wdctr, is zeroed out. If you want it to be set to another value, you need to specify it on the linker command line. The symbol used is __init_wdtcr__. For instance, to set wdctr to 0x1f, you would have a command line like this:
% avr-ld --defsym __init_wdctr__=0x1f ...