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RE: Trying to run on pid7t board

> On Wed, Aug 21, 2002 at 05:24:50PM +0100, Robert Cragie wrote:
> > [...]
> > I then connect to it using gdb (insight 5.0), and connect
> successfully to
> > the target. I then download the test, and inspect memory at 0x8000, no
> > problem, it's there. However, when I start to run, it hits the
> breakpoint I
> > have set, but I notice all the code has vanished at 0x8000, and it's
> > executing 0x00000000 each time. Any idea what's going on?
> Yes, that is odd.  Can you tell me why you think it's executing 0x0?
> You could show gdb's side of the conversation, either a console script,
> or maybe even include packet traces as per `(gdb) set remote debug 3'.

If I specify --trace-semantics in the sid command line I get the following:

0x8040: LDR_PRE_INC_IMM_OFFSET	gr[0]:=0x8048
0x8044: MOV_REG_IMM_SHIFT	pc:=0x8048
0x8048: LDR_PRE_INC_IMM_OFFSET	gr[0]:=0xb000020
0x804c: STR_PRE_INC_IMM_OFFSET	memory[0xb000020]:=0xb000020

...AND_REG_IMM_SHIFT looks like andeq r0,r0,r0 to me (i.e. NOP). I stepped
through the code and sure enough what happens is that indeed the first three
opcodes run OK, but when the fourth opcode is run, it screws up thereafter -
all the memory gets set to 0.

On the PID board, 'str r0,[r0]', where r0 is 0xb000020, changes the mapping
of the PID board mapping RAM to 0x0000000 instead of ROM - if the REMAP
board link (LK18) is in place. So it looks like the simulation of this is
doing something odd causing it to go wrong - I would expect it to just carry
on, as I would guess the software component of the simulation would have
already remapped (as a debug monitor on a real board would have), and once
this is done, it's done until the next reset.

Robert Cragie, Design Engineer
Jennic Ltd, Furnival Street, Sheffield, S1 4QT,  UK  Tel: +44 (0) 114 281 2655

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