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Re: Which is correct start address with romram mode withpowerpc 8245 ?? 0x0 or 0xfff00100??


On Wed, 2005-08-10 at 19:06 +0800, Steven_cheng wrote:
> Hi All,
> 
>     Does anyone use the ROMRAM startup mode with powerpc 8245 ??
> 
> In my platform (CPU : powerpc 8245 / RAM:256MB)
> I use the Cogent csb281 as the sample then port my platform.
> But I find that the binary code start in the address 0x100 when romram mode,
> I'm confused the start address 0x0 with 0xfff00100 with romram mode.
> 
> Which is correct start address with romram mode with powerpc 8245 ??  0x0 or
> 0xfff00100??
> And I find that the rom code has been copyed to ram,  but it does not jump
> to ram then run.
> Is it correct ??

It depends on how you have your hardware "strapped".  The PowerPC
starts execution at the RESET vector, which is 0x100 offset from
the vector base.  You have a choice, determined by the hardware
settings at boot/reset time, whether the vector space lives at
0x00000000 or 0xFFF00000.  Note: this value can (and normally
does) change once eCos runs to always be at 0x00000000.

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------


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