From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marco Cavallini Date: Thu, 04 Jan 2007 13:20:04 +0100 Subject: [U-Boot-Users] Question about U-Boot in general and the AT91RM9200 in particular In-Reply-To: <200701031949.26084.javierruere@apexar.com> References: <200701031949.26084.javierruere@apexar.com> Message-ID: <459CF0F4.2000406@koansoftware.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de 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