Insufficient initialization in Serial1.begin()

[thorv]

Board: Arduino Due,
Board library: Arduino SAM Boards 1.6.12

'Hello' does not appear in the output of Serial1(TX1) in the following program.
Uncomment 'PA11 DISABLE' line, then it works.

void setup(){
  Serial1.begin(115200);
  Serial1.end();
  pinMode(18,OUTPUT); //TX1 override
  //*(uint32_t*)0x400e0e04=0x0800;//PA11 DISABLE (PIO Controller PIO Disable Register (PA) )
  Serial1.begin(115200);
  Serial1.println("Hello.");
}
void loop(){}

I don't think this is a usage that is often used, but I think that the pin configuration should be done every time.

regards,