ticker hangs on bf537Stamp
sebastian.huber at embedded-brains.de
Tue Oct 15 13:01:49 UTC 2013
On 2013-10-15 14:44, Kolja Waschk wrote:
>> You can set a break point to _Thread_Delay_ended().
> Ok, thanks, that's a good starting point.
> After the first hit, it runs into _Scheduler_priority_Unblock which sets
> "_Thread_Dispatch_necessary" = true.
This is fine.
> The code following label doDispatch in cpu_asm.S shortly afterwards zeros the
> flag (revealed by a HW watch on the DISPATCH_NEEDED location).
Is this the following code (from cpu_asm.S):
/* do thread dispatch if necessary */
p0.h = DISPATCH_NEEDED;
p0.l = DISPATCH_NEEDED;
r0 = B[p0] (Z);
cc = r0 == 0;
if cc jump noDispatch
r0 = 0;
B[p0] = r0; <-- here _Thread_Dispatch_necessary is set to zero?
This code was introduced with:
2008-08-13 Allan Hessenflow <allanh at kallisti.com>
* cpu.c, cpu_asm.S, irq.c, rtems/score/cpu.h,
rtems/score/cpu_asm.h: reworked interrupt handling to fix
I really wonder if this ever worked. The exception epilogue must not write to
For a start you can remove the lines "r0 = 0;" and "B[p0] = r0;".
There is a comment in this file:
/* the approach here is for the main interrupt handler, when a dispatch is
wanted, to do a "raise 15". when the main interrupt handler does its
"rti", the "raise 15" takes effect and we end up here. we can now
safely call _Thread_Dispatch, and do an "rti" to get back to the
original interrupted function. this does require self-nesting to be
enabled; the maximum nest depth is the number of tasks. */
A maximum nest depth limited by the number of tasks is questionable.
Sebastian Huber, embedded brains GmbH
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