On Mon, 2005-03-21 at 22:05, Jan Kiszka wrote:
> Michael Neuhauser schrieb:
> > On Mon, 2005-03-21 at 17:54, Jan Kiszka wrote:
> >
> >>rtai_oldnames.h in magma-CVS is broken. This patch fixes it for x86,
> >>other architectures may require a check as well.
> >>
> >>With this patch applied, RTnet at least loads on top of magma now.
> >>
> >>Jan
> >>[...]
> >>-- rtai_oldnames.h 5 Jan 2005 16:48:31 -0000 1.4
> >>+++ rtai_oldnames.h 21 Mar 2005 16:36:29 -0000
> >>@@ -37,9 +37,9 @@
> >> #define IFLAG RTAI_IFLAG
> >> #define hard_cli() rtai_cli()
> >> #define hard_sti() rtai_sti()
> >>-#define hard_save_flags_and_cli(x) rtai_local_irq_save(x)
> >>-#define hard_restore_flags(x) rtai_local_irq_restore(x)
> >>-#define hard_save_flags(x) rtai_local_irq_flags(x)
> >>+#define hard_save_flags_and_cli(x) rtai_save_flags_and_cli(x)
> >>+#define hard_restore_flags(x) rtai_restore_flags(x)
> >>+#define hard_save_flags(x) rtai_save_flags(x)
> >> #define hard_cpu_id adeos_processor_id
> >>
> >> #endif /* __KERNEL__ */
> >
> >
> > Hm, there is definitely something wrong here (rtai_local_irq_*() are not
> > defined for i386). But I'm not sure if your patch is correct either.
> >
>
> It lets RTnet compile, isn't this enough? ;)
It's a start :-)
> Seriously:
>
> > What is expected from the hard_*() macros? (I'm not so familiar with
> > "historical" RTAI but would like to get it right for ARM.) If they
> > should disable the CPU's interrupt enabled flag (as their name suggests)
> > then it should be
> >
> > #define hard_cli() rtai_hw_cli()
> > #define hard_sti() rtai_hw_sti()
> > #define hard_save_flags_and_cli() rtai_hw_save_flags_and_cli()
> > ...
>
> I think hard_* were originally (rthal) intended to touch the hardware
> directly. With adeos, it's sufficient (I think it's actually the only
> correct way) to stall the pipeline in front of RTAI.
If you know what you are doing it is perfectly OK to hard disable IRQs
(at least I see it that way).
> In fact, that's ok for the use case RTnet.
>
> > Your patch is only correct if the hard_*() macros are expected to
> > prevent interrupts to be delivered to RTAI, but nothing more, i.e. you
> > can't use them to protect time-critical hardware operations (if only the
> > RTAI pipeline is stalled, interrupts are still handled by Adeos, they
> > are just not dispatched to RTAI).
>
> So, let's walk the #define chain of x86-vesuvio (assuming it is correct):
Wait a minute, are we talking about vesuvio or magma/vulcano now?
> hard_cli() -> rtai_cli() -> adeos_stall_pipeline_from(&rtai_domain)
>
> That's what I did to fiddle out the hopefully correct meaning for my patch.
The define chain is not the problem. The problem seems to me, that it
seems unclear what the hard_*() macros should provide:
* protection against IRQ-delivery to RTAI
or
* protection against IRQs happening at all
I don't expect you to answer this, but maybe someone with a big picture
view (Paolo, are you listening?) might shed some light on it.
Mike
--
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