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RE: ROMRAM Application on xScale (PXA255)


Mark,
	Got it going!!!  Many thanks!!!  This was actually my first time
using code in CVS.

	The hal_platform_init I was using for the PXA255 was quite a bit
different then the one for the ixdp425.  I implemented your changes in a
slightly different way.  Right after the SDRAM is configured, I copy the
flash image into RAM.  Then when the MMU is started (and ram moves to
0x00000000, execution simply continues from the same address but now in ram.
Seems to work, but I do notice a few seconds delay for the copying of the
image.  Maybe a result of not having the cache running when copying the
image.

	Again, many thanks!!!
 
-Joe Porthouse

-----Original Message-----
From: ecos-discuss-owner@ecos.sourceware.org
[mailto:ecos-discuss-owner@ecos.sourceware.org] On Behalf Of Mark Salter
Sent: Friday, March 24, 2006 3:54 PM
To: jporthouse@toptech.com
Cc: ecos-discuss-return-34516-jporthouse=toptech.com@ecos.sourceware.org;
'eCos Discussion'
Subject: RE: [ECOS] ROMRAM Application on xScale (PXA255)

On Fri, 2006-03-24 at 13:49 -0500, Joe Porthouse wrote:
> Mark/All,
> 
> 	Thanks for the reply.  I did not find any ROMRAM support in the
> IXDP425 (..._ixdp425_romram.ldi or other support files), but I did find
some
> in the uE250 target platform.

Its in CVS...

> 	I believe I have found all the references I needed to update but I
> am still running into problems getting the application to run.
> 
...

> 	With the ROMRAM startup type the "ldr r2,1f" loads r2 with
> 0x00000xxx, the RAM address to continue execution.  Problem is that the
> image is not copied from flash to RAM until later in the startup.
Execution
> is suppose to continue in flash at 0x50000000.

...and the ixdp425 port deals with this issue thusly:

	// value to load into pc to jump to real runtime address
	ldr     r0, =1f
#if defined(CYG_HAL_STARTUP_ROMRAM)
	// R0 holds a RAM address for ROMRAM startup,
	// so convert to a flash address.
	orr	r0, r0, #IXDP_FLASH_BASE
#endif

--Mark



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