[U-Boot-Users] Question about CFG_ENV_ADDR during RAMBOOT

[Ulf Samuelsson <ulf@atmel.com>]

----- Original Message ----- 
From: "Wolfgang Denk" <wd@denx.de>
To: "Ladislav Michl" <ladis@linux-mips.org>
Cc: "Ulf Samuelsson" <ulf@atmel.com>; "uboot" <u-boot-users@lists.sourceforge.net>
Sent: Wednesday, May 30, 2007 3:43 PM
Subject: Re: [U-Boot-Users] Question about CFG_ENV_ADDR during RAMBOOT


> In message <20070530105256.GA7649@michl.2n.cz> you wrote:
>>
>> > If you fix anything, then please by making  it  compatible  with  the
>> > poublic  U-Boot  source  tree,i. e. by using the mtdparts command for
>> > this purpose.
>> 
>> Here it might be usefull to avoid modifications of certain partition
>> sizes. For example partition containing environment shouldn't be
>> modified, because code which read it from U-Boot has size and offset
>> hardcoded, therefore modifying it will result to bad surprise...
> 
> The user might prepare for the  installation  of  a  new  version  of
> U-Boot  where the environment is in new sectors (for example, because
> U-Boot has grown after adding new features - been there  before),  or
> for switching from single to redundant environment, or ...
> 
> So actually the user might want to do some clever thing. Please don;t
> prevent him from doing that.
> 

Since everything I work on is dataflash based, U-Boot executes from SDRAM.
While certain partitions are write protected, you an easily unprotect any or all
of the dataflash pages.
From U-Boot you then can download the new U-Boot image to SDRAM using tftp
and then cp.b (at least for now :-) to dataflash and then reboot.

The new image has defined it own partitions, and the environment area
(defined by the new image) is initialized according to compile time values
of the new image

While the named partitions will initialize some environment variables, there
is nothing that forces the user to actually use these in the bootargs or anywhere else.
I want the novice user to have a straightforward path to boot Linux without hassle. 
This does not block anyone else from shooting themselves in the foot.



> Best regards,
> 
> Wolfgang Denk
> 
> -- 


Best Regards
Ulf Samuelsson                ulf at atmel.com
Atmel Nordic AB
Mail:  Box 2033, 174 02 Sundbyberg, Sweden
Visit:  Kavalleriv?gen 24, 174 58 Sundbyberg, Sweden
Phone +46 (8) 441 54 22     Fax +46 (8) 441 54 29
GSM    +46 (706) 22 44 57

Technical support when I am not available:
AT90 AVR Applications Group: mailto:avr at atmel.com
AT91 ARM Applications Group: mailto:at91support at atmel.com
AVR32 Applications Group        mailto:avr32 at atmel.com
http://www.avrfreaks.net/;            http://avr32linux.org/
http://www.at91.com/ ;                ftp://at91dist:distrib at 81.80.104.162/