+ *
+ *
+ * Warning!
+ *
+ * Changes to the FIFO system should be done with extreme care since
+ * the hardware is full of bugs related to the FIFO. Known issues are:
+ *
+ * - FIFO size field in FSR is always zero.
+ *
+ * - FIFO interrupts tend not to work as they should. Interrupts are
+ * triggered only for full/empty events, not for threshold values.
+ *
+ * - On APIC systems the FIFO empty interrupt is sometimes lost.