INT2_CTL1
outb(INT2_CTL1, 8); /* ICW2 for slave */
outb(INT2_CTL1, CASCADE_IRQ); /* ICW3 is slave nr */
outb(INT2_CTL1, ICW4_AT); /* ICW4 */
outb(INT2_CTL1, (INT2_MASK = ~0)); /* IRQ 8-15 mask */
outb(irc_no ? INT2_CTL1 : INT_CTL1, ~(1 << (irq_no >> (irc_no * 3))));
outb(INT2_CTL1, INT2_MASK);