text: // trivial test of putk: this is the easiest one, since the uart hardware
  // is pretty tolerant of errors.
  #include "rpi.h"
  #include "sw-uart.h"
  
  void notmain(void) {
      uart_init();
      enable_cache();
  
      // use pin 20 for tx, 21 for rx
      sw_uart_t u = sw_uart_mk(20,21, 115200);
  
      for(int i = 0; i < 10; i++) {
          printk("%d: going to print hello world\n", i);
          sw_uart_printk(&u, "hello world: %d\n", i);
          delay_ms(1000);
      }
  
      clean_reboot();
  }
  