title: Providing assignments to variables from makefiles/kconfig
body: <p>I have an unsigned long which needs to get a platform specific variable.<br/> </p>
  
  <p>I do not wish to use boot parameters as this driver will go into products and vendors are reluctant to change boot parameters. <br/></p>
  
  <p>I would like to know if this variable can be initialized from Makefile or from Kconfig.<br/></p>
  
  <p>I remember that the serial port address for early printk is provided in the Kconfig when I used the menuconfig long back to set it. But I never understood how that worked.</p>