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Re: Which is correct start address with romram mode withpowerpc 8245 ?? 0x0 or 0xfff00100??
- From: Gary Thomas <gary at mlbassoc dot com>
- To: Steven_cheng <05071 at alphanetworks dot com>
- Cc: eCos Discussion <ecos-discuss at ecos dot sourceware dot org>
- Date: Thu, 11 Aug 2005 06:18:10 -0600
- Subject: Re: [ECOS] Which is correct start address with romram mode withpowerpc 8245 ?? 0x0 or 0xfff00100??
- References: <00c501c59d9b$82908c10$01473264@stevencheng>
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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