From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Matthias Reis" <matthias.reis@physik.tu-berlin.de>
Subject: Re: Autovector exceptions on Atari ST
Date: Wed, 24 Aug 2011 21:47:37 +0200
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To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Matthias Reis <matthias.reis@physik.tu-berlin.de>, linux-m68k@vger.kernel.org

> On Sun, Aug 7, 2011 at 23:09, Geert Uytterhoeven <geert@linux-m68k.org>
> wrote:
>
> MFP interrupts are not autovector interrupts, but user vector interrupts.
>
> Sorry, I forgot about this: it may be a stack frame format issue,
> which causes the kernel to
> incorrectly identify the interrupt number.
>
> user_inthandler() in arch/m68k/kernel/entry_mm.S looks at the
> PT_OFF_FORMATVEC
> field in the stack frame to identify the interrupt source. I don't
> know from memory
> if the plain 68000 stores it there. For autovector interrupts, it
> doesn't, that's why
> I created inidividual auto*_inthandler() functions that put an hardcoded
> number
> on the stack instead of looking at the stack frame.
>

Hi Geert,

thanks for your kind reply. As far as I understand the 68000 manual
(http://www.freescale.com/files/archives/doc/ref_manual/M68000PRM.pdf,
section b.2), the CPU does not store the vector number on the exception
stack. This is also what I've seen in the debugger: some seemingly bogus
irq number is passed to m68k_handle_int. Any suggestions how to solve
this? I guess it is not a good idea to write an individual
user*_inthandler for each of the 255-64=191 possible user interrupts.

Best regards,
Matthias