[U-Boot] [PATCH 2/2] am335x_evm: Add CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG support

[Tom Rini]

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On 10/24/12 12:21, Stephen Warren wrote:
> On 10/24/2012 11:28 AM, Tom Rini wrote:
>> We add CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG, 
>> CONFIG_BOARD_LATE_INIT to set the variables and then fdtfile and
>>  findfdt to make us of this.  It is now possible to do 'run 
>> findfdt' to have fdtfile be set to the value of the dtb file to 
>> load for the board we are running on.
> 
>> diff --git a/arch/arm/cpu/armv7/am33xx/board.c 
>> b/arch/arm/cpu/armv7/am33xx/board.c
> 
>> +#ifdef CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG +	char 
>> safe_string[HDR_NAME_LEN + 1]; + +	/* Now set variables based on
>>  the header. */ +	strncpy(safe_string, (char *)header.name, 
>> sizeof(header.name)); +	safe_string[sizeof(header.name)] = 0; + 
>> setenv("board_name", safe_string); + +	strncpy(safe_string, (char
>> *)header.version, sizeof(header.version)); + 
>> safe_string[sizeof(header.version)] = 0; +	setenv("board_rev", 
>> safe_string); +#endif
> 
> By the way, is there any way to flag these variables as not being 
> saved in the environment by saveenv? With the code above, the 
> values will get over-written every time, so it's not such a big 
> deal; the only issue is that the value needlessly gets saved into 
> flash or uEnv.txt.
> 
> But what about a runtime-calculated variable that is only sometimes
> set? I suppose the answer there is to explicitly clear it if you
> aren't setting it.

Joe?  Am I thinking right that your env work leads us down the path of
being able to do this?

> Or what about if the environment gets saved to uEnv.txt on an SD 
> card which gets moved to a compatible but different board or board
>  revision, running an older U-Boot that doesn't have this patch; 
> then, the values stick around even though they're stale.

Yes, there's potential problems, but I think we can work around it or
live with it.  And FYI, uEnv.txt is (more or less) an un-mkimage'd
boot.scr file :)

- -- 
Tom
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