IO_ICU2
outb(IO_ICU2 + ICU_IMR_OFFSET, 0xff); /* leave interrupts masked */
outb(IO_ICU2, 0x0a); /* default to IRR on read */
outb(IO_ICU2 + ICU_IMR_OFFSET, 0xff);
irr2 = inb(IO_ICU2);
outb(IO_ICU2 + ICU_IMR_OFFSET, 0xff);
outb(IO_ICU2, 0x11); /* reset; program device, four bytes */
outb(IO_ICU2 + ICU_IMR_OFFSET, IDT_OFFSET + 8);
outb(IO_ICU2 + ICU_IMR_OFFSET, ICU_IRQ_SLAVE);
outb(IO_ICU2 + ICU_IMR_OFFSET, 2 | 1); /* auto EOI, 8086 mode */
outb(IO_ICU2 + ICU_IMR_OFFSET, 1); /* 8086 mode */