This is the mail archive of the
ecos-discuss@sources.redhat.com
mailing list for the eCos project.
Re: Initialization routines take too long?
On Fri, Nov 10, 2000 at 01:19:25PM -0700, Gary Thomas wrote:
> >> I think it's more likely a problem with what happens when the
> >> ARM IRQ is finally enabled. It appears that the system crashes
> >> if there is a pending interrupt when that happens.
> >
> > Strange, that would mean you can't disable and reenable the IRQ without
> > problem...
>
> As far as I know, this is not a problem with any of our internal ports.
I thought probably not. ;)
> This is not to say that a problem does not exist, but we've never seen such.
>
> However, note that the normal case is for interrupts to remain disabled,
> sometimes for long periods, until the scheduler is started from the main
> thread. Is this how your application works [Grant]?
That depends on the meaning of "interrupts remain disabled".
The IRQ mask bit in the ARM CPU register CPSR remains set (IRQ
disabled) until Cyg_Scheduler::start() is called.
However, individual interrupts are unmasked (enabled in the
interrupt controller) during initialization. This means that
there may be an IRQ pending when Cyg_Scheduler::start() is
called.
If that is the case, the first IRQ is serviced before
HAL_THREAD_LOAD_CONTEXT( &next->stack_ptr ) is called at the
bottom of Cyg_Scheduler::start().
I don't know enough about eCos internals to determine if that's
a problem or not.
The only thing I can think of is that current_thread is set to
a value inconsistent with the actual CPU context at that point,
and that's causing a problem somewhere in the timer interrupt
code.
All of my tasks do seem to get started, but things crash in
random ways. If I speed up my init routines (doesn't matter
which one) or delay that first timer interrupt, things are
fine.
--
Grant Edwards
grante@visi.com