[U-Boot-Users] Re: ENV_IS_EMBEDDED functionality

[J. William Campbell <jwilliamcampbell@comcast.net>]

Thanks for the quick response. There are some Blackfin related questions 
on the old list, but the attempt made a couple of years ago to submit 
the patches was rejected for a lot of reasons. I was not involved at 
that time.  I am attempting to determine if this ENV_IS_EMBEDDED 
approach is also going to be rejected so I can find another way. It is 
not clear to me that it is really necessary, but I want to understand 
further the functionality to determine if it is in any way useful. This 
reflects the current state of the Blackfin code, so I am trying to clean 
it up somewhat. I have a further question below.

Wolfgang Denk wrote:

>In message <43C7FF53.7020809@comcast.net> you wrote:
>  
>
>>        I have a question regarding the functionality provided by 
>>ENV_IS_EMBEDDED. Currently, this value is computed only for the case 
>>CFG_ENV_IS_IN_FLASH defined in environment.h, and is based on the flash 
>>    
>>
>
>Yes, because it can only be located in the middle of the U-Boot image
>in flash if the environment is stored itself in flash  -  you  cannot
>have this if the environment is, for example, sotred in a EEPROM.
>
>  
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>>addresses of the environment being defined as inside the executing 
>>addresses of u-boot. This seems to be designed for the case where u-boot 
>>is executed out of flash and not copied into ram for execution. There is 
>>    
>>
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>Wrong. This has nothing to do with execution, just with storage.
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The source of my confusion is that ENV_IS_EMBEDDED is defined as follows 
in environment.h
#if (CFG_ENV_ADDR >= CFG_MONITOR_BASE) && \
      (CFG_ENV_ADDR+CFG_ENV_SIZE) <= (CFG_MONITOR_BASE+CFG_MONITOR_LEN)
#define ENV_IS_EMBEDDED 1
#endif
Isn't CFG_MONITOR_BASE the address where u-boot resides for execution? 
It is defined that way on the Blackfin code
because CFG_MONITOR_BASE is defined as TEXT_BASE and TEXT_BASE is 
defined as 0x07FC0000. The flash
memory is located at CFG_FLASH_BASE (defined as 0x20000000) and 
CFG_ENV_ADDR is 0x20004000. U-boot is loaded into flash@0x20000000, 
so the environment data does reside in flash even though the 
ENV_IS_EMBEDDED test fails. The code gets around this by just defining 
it directly. So is CFG_MONITOR_BASE incorrectly defined and it should be 
a flash address?? BTW the u-boot code is not compiled PIC, so the 
execution address must matc the link address.

>  
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>>an old configuration variable, CFG_ENV_IS_EMBEDDED, that appears to be 
>>non-functional and deprecated. I am working with u-boot for the Analog 
>>Devices Blackfin chip, which has not yet been submitted to mainstream 
>>    
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>
>I think I remember to have seen patches here on the list - search the
>archives, please.
>
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>>(AFAIK). The code directly defines ENV_IS_EMBEDDED to force that 
>>functionality even though it is copied to ram for execution (and thereby 
>>    
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>This has nothing to do with execution.
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>>        My question is: What is your opinion of this approach? It seems 
>>    
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>You misunderstand the function.
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>Best regards,
>
>Wolfgang Denk
>
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