[ECOS] why jump from hal_cpu_merge_int to hal_null_call() ?

Zi Zhou zzhou@3upsystems.com
Fri May 9 23:41:00 GMT 2003


"Gary D. Thomas" wrote:

> On Fri, 2003-05-09 at 16:33, Zi Zhou wrote:
> > Hi,
> >
> > I am trying to port eCos on to a demo board which uses MPC8245. So I use
> > csb281 as a baseline. I am able to bring up Redboot with minimum hardware
> > initialized (e.g. UART). I am trying to load the simple eCos 'hello world'
> > application but failed. I have a VisualClick EJTAG to help debugging,  and I
> > found that when execute to hal_cpu_merge_int macro, right after the first
> > 'sync',  the program will jump to hal_null_call(), which is at address 0x0.
> > The MSR register is 0x3032 and r0 is 0xb032 right after 'rlwimi' instruction,
> >   and MSR becomes 0 after jumping to hal_null_call(). Since I am not an
> > expert of eCos or PowerPC, I will really need some info about what could go
> > wrong to cause this scenorio. Could someone give me some suggestion?
>
> If you're not using a ROM monitor (like RedBoot), have you initialized
> the interrupt environment?  The default case on the PowerPC for RAM
> applications is to inherit an already initialized environment.  In
> particular, the application will normally not set up interrupt and
> exception handlers.
>

I have a Redboot running in PROM at address 0xfff00000. And I use EJTAG to load
RAM application.

>
> I suspect that this is your problem. Try disabling CYGSEM_HAL_USE_ROM_MONITOR.

I try to disable it, and it failed even before cyg_start(), seems while trying to
invoke C++ constructor, it entered an endless loop  of
cyg_hal_diag_mangler_gdb_flush. BTW, if I don't use a ROM monitor, by disabling
CYGSEM_HAL_USE_ROM_MONITOR,
what should I expect to happen? If I have initialized interrupt environment in RAM
application, I guess everything should be fine,
if not, will I jump to address 0x0? But I don't understand why I would jump to
hal_null_call() before I enable external exception by
writing 0xb032 to MSR? What is actually happening while CPU is executing 'sync' ?

Thanks a lot for any help !

Zi

>
>
> --
> Gary D. Thomas <gary.thomas@mind.be>
>
> --
> Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
> and search the list archive: http://sources.redhat.com/ml/ecos-discuss


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