[U-Boot-Users] Question about U-Boot in general and the AT91RM9200 in particular

[Marco Cavallini]

Javier Ruere ha scritto:
> Hello everyone,
> 	I have been working with an AT91RM9200-EK board for a couple of months now 
> and we are about to make our own custom board. Lately I started investigating 
> about U-Boot and how it works in this board and, though I have found a lot of 
> bits of information, I am still quite confused.
> 	I would like to ask about U-Boot running from RAM. On the one hand, I have 
> seen links [1] and [2] that say that it should not be done but, on the other 
> hand, from the documentation from Atmel [3] I see it _is_ being run from RAM. 
> I have done this myself with u-boot 1.1.6 defining CONFIG_SKIP_LOWLEVEL_INIT 
> at the top of include/configs/at91rm9200dk.h, otherwise it wouldn't work. I 
> found out about this define here [4]
> 	For what I gather from the instructions from Atmel, there is always a 
> bootloader before U-Boot, loading it from the dataflash, serial port or Flash 
> and this could explain why I must define CONFIG_SKIP_LOWLEVEL_INIT, so that 
> the hardware is not initialized twice.
> 	Would it work to put an uncompressed image of U-Boot at the beginning of the 
> flash memory and let it initialize the board if I don't add the define I 
> mentioned before?
> 	Thank you all for your time and help.
> 
> Regards,
> 		Javier Ruere
> 
> 
> [1] http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/25551/focus=25596
> [2] 
> http://www.denx.de/wiki/view/DULG/CanUBootBeConfiguredSuchThatItCanBeStartedInRAM
> [3] 
> http://www.atmel.com/dyn/resources/prod_documents/UBootFlashProgramming.zip
> [4] 
> http://www.at91.com/www/phpBB2_mirror/viewtopic.php4?t=1300&highlight=at91rm9200ek+uboot

If you have a NOR flash romboot (boot.bin) is no longer necessary,
maybe this link could help as well :-)

  http://www.koansoftware.com/en/art.php?art=80

Ciao
-- 
Marco Cavallini
Koan s.a.s. - Bergamo - Italia
Embedded and Real-Time Software Engineering
  - Atmel Third Party Consultant
  - Intel PCA Developer Network Member
Tel. +39-(0)35-255.235 - Fax +39-178-223.9748
http://www.KoanSoftware.com  -  http://www.KaeilOS.com