[U-Boot-Users] Question about CFG_ENV_ADDR during RAMBOOT
Jerry Van Baren
gerald.vanbaren at smiths-aerospace.com
Tue May 22 22:53:57 CEST 2007
Timur Tabi wrote:
> Doesn't anyone have an answer to this question?
> Timur Tabi wrote:
>> On a lot of boards, if CFG_RAMBOOT is defined, the following code is compiled:
>> #define CFG_ENV_ADDR (CFG_MONITOR_BASE - 0x1000)
>> #define CFG_ENV_SIZE 0x2000
>> This means that the environment is stored 0x1000 bytes before the start of u-boot.bin.
>> Doesn't that mean that if the environment is larger than 0x1000 bytes, that it will
>> overwrite the beginning of u-boot.bin whenever someone does a saveenv?
Looks like it to me. Looks like somebody increased the size without
fixing the address offset to match.
Looks to me like it would be better defined:
#define CFG_ENV_SIZE 0x2000
#define CFG_ENV_ADDR (CFG_MONITOR_BASE - CFG_ENV_SIZE)
The saving grace here is probably:
* For a RAMBOOT image, there isn't any incentive to save lots of stuff
in the env since it (generally) disappears on a reboot and definitely
disappears on a power cycle.
* On the PowerPC, at least, the first 12K of u-boot.bin is the HRCW and
vectors which aren't used by a RAMBOOT image so overwriting them is a
* 4K is fairly large for an env, so people probably don't run into the
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