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SubjectRe: interrupt magic
Anton Altaparmakov wrote:
> I can't remember anything about protected mode interrupt handlers nor have
> I ever looked at Linux interrupt handling but at least in real mode from my
> good old PC/DOS programming days I seem to remember that if you are hooking
> a hardware interrupt vector then you have to issue a end of interrupt (EOI)
> to the 8259A interrupt controller (PIC) before doing the iret, for example
> like so:
> ; Note: this uses "dst, src" operand ordering not the
> ; "reversed" ordering used by gcc asm.
> push ax
> mov al,20h ; Nonspecific EOI
> out 20h,al ; Write PIC output control word OCW2
> pop ax
> iret
> Might this be the problem (or whatever the equivalent specific is in Linux
> / pmode)?

Oh yes, nothing has changed, this is still required, and don't forget to
signal the slave PIC as well if your IRQ is 8 or higher. Lovely stuff.

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