Re: [ECOS] redboot RAM and it's memory address

[Jonathan Larmour <jifl at eCosCentric dot com>]

Holger Schurig wrote:
> So, speaking of Linux: when I arm-elf-objdump vmlinux (that is what the 
> current bootloader gets, in some WinCE NK.BIN format), then I see
>
> c0008000 <stext>:
> c0008000:       e1a0c000        mov     r12, r0
> c0008004:       e3a000d3        mov     r0, #211        ; 0xd3
> c0008008:       e121f000        msr     CPSR_c, r0
>
> but when I arm-elf-objdump install/bin/redboot.elf, then I see
>
> 00020000 <__exception_handlers>:
>    20000:       e59ff018        ldr     pc, [pc, #18]   ; 20020 <vectors>
>    20004:       e59ff018        ldr     pc, [pc, #18]   ; 20024 
> <.undefined_instruction>
> ...
> 00020020 <vectors>:
>    20020:       00020040        andeq   r0, r2, r0, asr #32
> ...
> 00020040 <reset_vector>:
>    20040:       e3a00000        mov     r0, #0  ; 0x0
>    20044:       e59f1388        ldr     r1, [pc, #388]  ; 203d4 
> <_eCos_id+0x14>
Doesn't necessarily matter. execution starts at the start address defined 
in the ELF header, not just the beginning of the file. These may be different.

> My question:
>
> I guess I have to simple edit 
> ecos/packages/hal/arm/xscale/idppxa/current/include/pkgconf/mlt_arm_xscale_idppxa_ram.h 
> and mlt_arm_xscale_idppxa_ram.ldi so that it uses 0xc0008000, too? 
If that's where the board manual says the RAM is, then that would 
ordinarily be better, *but* there is a known limitation in the ARM eCos 
port, which means RAM must be mapped to 0x0. That can be done by the 
startup code tweaking the MMU mappings though. You may have to write this. 
That idppxa port is nothing to do with us - I haven't seen it, and so 
can't help. Complain to Intel (assuming they did it, as the Lubbock port 
is in the same boat) that they should submit it for inclusion in the 
public eCos.

Jifl
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