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Date: Fri, 24 Nov 2000 09:23:55 -0700 (MST)
From: Ronald G Minnich <rminnich@lanl.gov>
To: Joan Bertran <jbertran@cirsa.com>
cc: "'Jon Burgess'" <Jon_Burgess@eur.3com.com>,
        "'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>
Subject: RE: Booting AMD Elan520 without BIOS
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On Fri, 24 Nov 2000, Joan Bertran wrote:

>  I think so, because I've read somewhere the kernel needs interrupts 
> configured, but as kernel configures i8259 I don't know what is necessary,
> the IDT with interrupt service routines ?, sommething special about the chipset ?

I put the following familiar-looking code at the head of linuxbios for
mainboards that need to boot 2.2.x. It should look familiar, except of
course this is 32-bit gas-compatible code. 


#define i8259delay jmp 1f ; 1:

        movb    $0x11,%al               /*! initialization sequence*/
        outb    %al,$0x20               /*! send it to 8259A-1*/
        i8259delay
        outb    %al,$0xA0               /*! and to 8259A-2*/
        i8259delay
        movb    $0x20,%al               /*! start of hardware int's
(0x20)*/
        outb    %al,$0x21
        i8259delay
        movb    $0x28,%al               /*! start of hardware int's 2
(0x28)*/
        outb    %al,$0xA1
        i8259delay
        movb    $0x04,%al               /*! 8259-1 is master*/
        outb    %al,$0x21
        i8259delay
        movb    $0x02,%al               /*! 8259-2 is slave*/
        outb    %al,$0xA1
        i8259delay
        movb    $0x01,%al               /*! 8086 mode for both*/
        outb    %al,$0x21
        i8259delay
        outb    %al,$0xA1
        i8259delay
        movb    $0xFF,%al               /*! mask off all interrupts for
now*/
        outb    %al,$0xA1
        i8259delay
        movb    $0xFB,%al               /*! mask all irq's but irq2
which*/
        outb    %al,$0x21               /*! is cascaded*/



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