[U-Boot-Users] Running U-boot on RAM

Ulf Samuelsson ulf at atmel.com
Tue Dec 19 20:28:36 CET 2006

----- Original Message ----- 
From: "sathesh babu" <sathesh_edara2003 at yahoo.co.in>
To: "Wolfgang Denk" <wd at denx.de>
Cc: <u-boot-users at lists.sourceforge.net>
Sent: Tuesday, December 19, 2006 7:10 PM
Subject: Re: [U-Boot-Users] Running U-boot on RAM

> Hi Denk,
>   Could you clarify the following.
>    - If we want use u-boot in embedded system, The initial part of u-boot runs from the Flash.So Flash is mandatory.
>  My goal is :
>     On my embedded platform, the flash is not yet ready.So i wanted to load u-boot on DDRAM/SRAM by changing the TEXT address and set PC to start of start () using JTAG debugger.

The AT91RM9200 works this way when you boot from an SPI dataflash.
The internal BootROM will load the dataflashboot.bin application from 
the first couple of pages of the SPI dataflash into internal SRAM.
Once loaded, the bootROM will jump to the beginning of the dataflashboot.bin
Dataflashboot.bin will copy the u-boot from a fixed address in the SPI
dataflash to the SDRAM and jump to the beginning of U-boot.

Wolfgang kept rejecting ideas, sometimes for good reasons,so I got fed up. 
May try to do something about it later.
You can find my stuff at ftp://at91dist:distrib@ -> third party linux -> u-boot

>  could you please clarify Is it possible to boot from RAM as i mentioned above.
>  Any environment variables are access from the Flash during u-boot bootup time.
>  Regards,
>  Sathesh

Best Regards
Ulf Samuelsson                ulf at atmel.com
Atmel Nordic AB
Mail:  Box 2033, 174 02 Sundbyberg, Sweden
Visit:  Kavallerivägen 24, 174 58 Sundbyberg, Sweden
Phone +46 (8) 441 54 22     Fax +46 (8) 441 54 29
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Technical support when I am not available:
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AT90 AVR Applications Group: mailto:avr at atmel.com
AT91 ARM Applications Group: mailto:at91support at atmel.com
FPSLIC Application Group: mailto:fpslic at atmel.com
Best AVR  link: www.avrfreaks.net

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