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Re: boot_table

From: Andrew Lunn <andrew at lunn dot ch>
To: Pazos Escudero Nuria <Nuria dot PazosEscudero at he-arc dot ch>
Cc: eCos Disuss <ecos-discuss at ecos dot sourceware dot org>
Date: Thu, 16 Oct 2008 11:37:15 +0200
Subject: Re: [ECOS] boot_table
References: <F7620004260C5D4DB836EDBF8CC6872D03B0084D@neptune.intra.eiaj.ch> <20081016092616.GC388@lunn.ch> <F7620004260C5D4DB836EDBF8CC6872D03B00858@neptune.intra.eiaj.ch>

On Thu, Oct 16, 2008 at 11:32:04AM +0200, Pazos Escudero Nuria wrote:
> Yes, the flash is mapped to the address 0x0 at boot time (I even checked with the oscilloscope that the chip select of the flash is activated).
> 

> Why does not execute the ARM the instructions stored in the flash?
> Can it be due to an error in the memory configuration or in the
> memory linker scripts?

What normally happens is that the first few instructions remap the
FLASH to a higher address and then RAM is mapped to address 0x0. The
ROM image needs to be linked for execution at this high address, not
for 0x0. The first few instructions are written to the position
independent so will work anywhere.

You probably need to use a JTAG debugger to single step the startup
code and see what is happening. Does it make this transition correctly
etc. If you don't have a JTAG debugger you are limited to LED
patterns.

        Andrew

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References:
- boot_table
  - From: Pazos Escudero Nuria
- Re: boot_table
  - From: Andrew Lunn

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