#include /* code taken from: ! ! setup.S Copyright (C) 1991, 1992 Linus Torvalds ! ! setup.s is responsible for getting the system data from the BIOS, ! and putting them into the appropriate places in system memory. ! both setup.s and system has been loaded by the bootblock. */ /* we're getting screwed again and again by this problem of the 8259. * so we're going to leave this lying around for inclusion into * crt0.S on an as-needed basis. ! well, that went ok, I hope. Now we have to reprogram the interrupts :-( ! we put them right after the intel-reserved hardware interrupts, at ! int 0x20-0x2F. There they won't mess up anything. Sadly IBM really ! messed this up with the original PC, and they haven't been able to ! rectify it afterwards. Thus the bios puts interrupts at 0x08-0x0f, ! which is used for the internal hardware interrupts as well. We just ! have to reprogram the 8259's, and it isn't fun. */ void setup_i8259(void) { outb(0x11, 0x20); /*! initialization sequence to 8259A-1*/ outb(0x11, 0xA0); /*! and to 8259A-2*/ outb(0x20, 0x21); /*! start of hardware int's (0x20)*/ outb(0x28, 0xA1); /*! start of hardware int's 2 (0x28)*/ outb(0x04, 0x21); /*! 8259-1 is master*/ outb(0x02, 0xA1); /*! 8259-2 is slave*/ outb(0x01, 0x21); /*! 8086 mode for both*/ outb(0x01, 0xA1); outb(0xFF, 0xA1); /*! mask off all interrupts for now*/ outb(0xFB, 0x21); /*! mask all irq's but irq2 which is cascaded*/ } /* * I like the way Linus says it: ! Well, that certainly wasn't fun :-(. Hopefully it works, and we don't ! need no steenking BIOS anyway (except for the initial loading :-). */