On Mon, 2006-09-11 at 16:22 +0200, Jan Kiszka wrote:
> Philippe Gerum wrote:
> > On Mon, 2006-09-11 at 14:20 +0200, Wolfgang Grandegger wrote:
> >> Matthias Fuchs wrote:
> >>> Hello Philippe,
> >>>
> >>> that helps. I will do some further testing.
> >>>
> >>> Matthias
> >>>
> >>>
> >>> On Monday 11 September 2006 12:20, Philippe Gerum wrote:
> >>>> It's likely an Adeos issue. Could you try this patch? TIA,
> >>>>
> >>>> --- arch/ppc/syslib/ppc4xx_pic.c~ 2005-10-28 02:02:08.000000000
> >>>> +0200
> >>>> +++ arch/ppc/syslib/ppc4xx_pic.c 2006-09-11 12:18:14.000000000 +0200
> >>>> @@ -72,7 +72,8 @@
> >>>> mtdcr(DCRN_UIC_SR(UIC##n), mask);
> >>>> \
> >>>> ACK_UIC##n##_PARENT
> >>>> \
> >>>> }
> >>>> \
> >>>> - if (!(status & (IRQ_DISABLED | IRQ_INPROGRESS))) {
> >>>> \
> >>>> + if (!ipipe_root_domain_p ||
> >>>> \
> >>>> + !(status & (IRQ_DISABLED | IRQ_INPROGRESS))) {
> >>>> \
> >>>> ppc_cached_irq_mask[n] |= mask;
> >>>> \
> >>>> mtdcr(DCRN_UIC_ER(UIC##n), ppc_cached_irq_mask[n]);
> >>>> \
> >>>> }
> >>>> \
> >> Philippe, could you please explain the problem in more detail? And what
> >> are the consequences for other PowerPC ARCs and PICs, also for Linux 2.4?
> >
> > The issue lies in the fact that PICs *_end() routines may be called over
> > the Xenomai domain, and actually are, most of the time, since
> > xnintr_irq_handler() -which invokes xnarch_end_irq()- is always called
> > from the the Xenomai stage in the Adeos pipeline.
> >
> > In such a case, we must not check for the Linux-defined IRQ bits (e.g.
> > IRQ_INPROGRESS), and always send the eoi, since those bits are not
> > relevant to the Xenomai context. The patch above ensures this.
> >
> > And yes, the 2.4 patch has the very same problem, which should be fixed
> > the same way for all supported ppc platforms in the various PIC
> > management code. Oops.
>
> And why didn't this render PPC-over-2.4 useless, i.e. what is special
> about this 405-scenario?
>
A possible explanation is that configurations only using the timer IRQ
are not affected, since the decrementer is not subject to this issue
(the tick handler returns XN_ISR_NOENABLE anyway).
--
Philippe.
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