----- 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
--
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