Ticker problem on ppc405 - FIXED

[Ralf Corsepius]

On Tue, 2004-10-19 at 19:20, Smith, Gene wrote:
> Joel Sherrill <joel at OARcorp.com> wrote, On 10/19/2004 7:08 AM:
> 
> > Smith, Gene wrote:
> > 
> >>Figure out what the problem is but not why or how to correctly fix it. 
> >>The problem was due statements like this for selecting code:
> >>
> >>#if (PPC_USE_SPRG)
> >>    do this way
> >>#else
> >>    do that way
> >>#end
> >>
> >>In file old_exception_processing/cpu.c "do that way" is selected, while
> >>in old_exception_processing/irq_stub.S "do this way" is selected. The 
> >>conflict resulted in some bad memory accesses.  I don't see anywhere 
> >>that PPC_USE_SPRG is explicitly defined in the code except under 
> >>build-rtems there is a automatically generated file bspopts.h that contains
> >>#define PPC_USE_SPRG 1
> >>But the file that (I think) controls this, bspopts.h.in, contains
> >>#undef PPC_USE_SPRG
> >>
> >>The kluge fix was to just add
> >>#define PPC_USE_SPRG 0
> >>in irq_stub.S so both files generate "do that way" code.
> >>
> >>Anyhow, ticker now runs.
> > 
> > 
> > Ralf.. how is this happening?  This is one of those
> > macros from the BSP's configure.ac.  bspopts.h should
> > have it as a 1 if I am reading the configure code correctly.
Seems like a bug having persisted for a very long time to me.

PPC_USE_SPRG is a per-bsp option being used by
old_exception_processing/cpu.c. All bsp options are supposed to be
propagated through bspopts.h, but old_exception_processing/cpu.c does
not include bspopts.h nor bsp.h.

So, one fix would be to let cpu.c include bsp.h.

AFAIS, only the helas405 and the gen405 BSPs are affected.

> > Gene.. the installed bspopts.h has it undef'ed?
> > Where does the cpu.c get its define?
> 
> cpu.c is seeing it undefined (or zero?) as I would have expected. 
> irq_stub.S see it defined (non-zero?). (FWIW, the selectors are "#if x" 
> not "#ifdef x".)

> As a non-kluge solution I just went ahead and defined PPC_USE_SPGR as 1 in
> cpukit/score/cpu/powerpc/rtems/score/ppc.h

This is incorrect. PPC_USE_SPRG is a per-BSP define that is not supposed
to be present nor accessed in cpukit. It is supposed to be defined in
your BSP's bspopts.h and at no other place.

To let bspopts.h contain it, you have to add the corresponding
configure-script magic to your BSP's configure.ac
(cf. c/src/lib/libbsp/powerpc/helas403/configure.ac) and then to run
autoheader (cd <rtems-4.6.2/c/src/lib/libbsp/powerpc/<BSP>; autoreconf)

Ralf