[ECOS] Redboot-GDB

[Michael Anburaj]

Hi Nick/Mark/All,


>You can test the basic GDB stub entry/exit handling by typing:
>
>   $k#6b
>

I was about to try this with the redboot build from the current cvs source, 
but Redboot was dying while the context was switched to reach trampoline() 
of redboot\current\src\main.c after receiving ‘$’.

After much debugging I found that in hal_thread_load_context at the last 
instruction “movs    pc,lr” the SPSR (with I bit cleared) was moved to the 
CPSR. Thus enabling the IRQs. At this point the ECOS-RTC (tick timer) 
interrupt was pending & because of which the flow never reached 
trampoline(). This may be the reason for my other problem too.

Questions (please let me know, which is right & which is not):
1. Is this ok? Can the flow, while switching to trampoline() be interrupted? 
If this is normal, then I need to debug further to find why it did not 
resume after the ECOS-RTC interrupt was serviced.
2. I believe the ECOS-RTC (tick timer) interrupt got unmasked at 
hal_clock_initialize(). hal_clock_initialize() getting called in Redboot at 
this point; is it normal?
3. hal_clock_initialize() starts the timer & unmasks the interrupt (from 
this point the timer can generate ARM-IRQs, provided the I bit in CPSR is 
low). Is this right? Or should hal_clock_initialize() not unmask the timer 
interrupt.
4. The following lines in hal_thread_load_context of context.s moves 0x13 
(with I & F bits low):
ldr     r0,[fp,#armreg_cpsr]
msr     spsr,r0
Is this right? Or should the I & F bit be high, disabling the IRQs before 
shifting control to trampoline()?


Please comment on these questions, so that I can solve this issue...

Thanks a lot & Cheers,
-Mike

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