IDSR_NACK_TO_BUSY
busymask = IDSR_NACK_TO_BUSY(nackmask);
cpus_left = ~(IDSR_NACK_TO_BUSY(curnack) | curbusy) &
busymask = IDSR_NACK_TO_BUSY(nackmask);
cpus_left = ~(IDSR_NACK_TO_BUSY(curnack) | curbusy) &
busymask = IDSR_NACK_TO_BUSY(nackmask);
cpus_left = ~(IDSR_NACK_TO_BUSY(curnack) | curbusy) &
busymask = IDSR_NACK_TO_BUSY(nackmask);