[ECOS] Problems with ISR/DSR stacks

Øyvind Harboe oyvind.harboe@zylin.com
Wed Jun 6 09:36:00 GMT 2007

Enabling INFRA_DEBUG crashes my "rocket"...

As far as I can tell the DSR runs run on the thread stack and not the
interrupt stack(from inside interrupt_end).

Also, as long as the interrupt handling in a HAL does not support
interrupt nesting, then there is no point in adding support for an
interrupt stack as a single level ISR probably uses less stack than a
DSR anyway.

DSR's don't nest. However, any DSR that uses a non-trivial amount of
stack is *nasty* as all threads in the system then needs to have
enough stack to accomodate that DSR. This gets even nastier as there
is no way for a DSR to enforce all threads to have this extra amount
of stack.

The thing that I don't understand is why there is no DSR stack....

DSR's can be interrupted by ISR's but not by threads, so presumably
the requirement to be on the interrupted threads stack arises *after*
the DSR's have run?

My system crashes when I enable INFRA_DEBUG because an assert is
triggered during a DSR where diag_printf() is invoked and this blows
the stack. Initially with the DHCP client in the FreeBSD tcp/ip stack
for which I submitted a patch that got accepted a  while ago, but
other thread suffer the same faith.


Øyvind Harboe
http://www.zylin.com - eCos ARM & FPGA  developer kit

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