On Thu, Aug 25, 2011 at 03:51, Joshua Juran <[email protected]> wrote:
> On Aug 24, 2011, at 12:47 PM, Matthias Reis wrote:
>
>>> On Sun, Aug 7, 2011 at 23:09, Geert Uytterhoeven <[email protected]>
>>> 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.
>>
>> 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.
>
> It's not out of the question. Although you wouldn't write 192 little
> functions by hand -- just have stubs that push the vector number or offset
> onto the stack and branch to another function, and generate the stub code at
> runtime.
And you only have to do it for the user interrupts you actually need/use.
I.e. m68k_setup_user_interrupt() could allocate the needed memory and fill
it with the generated interrupt handlers.
For Atari that's doable, for VME it would still generate all 192 of them.
Alternatively, let m68k_irq_startup() handle it when it's called the
first time for
that specific interrupt.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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