[ECOS] Re: Limit region of flash used by RedBoot for FIS?

[Gary Thomas]

Grant Edwards wrote:
>>> In fact a quick examination of fis_init() suggests it does
>>> erase after the end of the cfg/fis blocks.
>> Sure looks like it always erases all the way to the end in
>> the following snippet from fis_init()
>>
>> 482             // Lastly, anything at the end, if there is any
>> 483             if ( erase_start < (((CYG_ADDRESS)flash_end)+1) ) {
>> 484                 erase_size = ((CYG_ADDRESS)flash_end - erase_start) + 1;
>> 485                 if ((stat = flash_erase((void *)erase_start, erase_size,
>> 486                                         (void **)&err_addr)) != 0) {
>> 487                     diag_printf("   initialization failed at %p: %s\n",
>> 488                                 err_addr, flash_errmsg(stat));
>> 489                 }
> 
> I need to look more closely at it, but I _think_ that simply
> deleting the above code will prevent fis_init() from erasing
> the area above the direcotry block, but that still won't
> prevent other code such as fis_free() from using blocks above
> the directory block, will it?
> 
> AFAICT, all of the fis code uses flash_end as the end of usable
> flash.  Setting CYGNUM_REDBOOT_FIS_DIRECTORY_BLOCK has no
> effect on flash_end -- all it does is determine the location of
> the directory block.
> 
> IMO, there needs to be a CYGNUM_REDBOOT_FLASH_RESERVED_TOP
> value that is subtracted from flash_end they way
> CYGNUM_REDBOOT_FLASH_RESERVED_BASE is added to flash_start.
> 

As I said, that's how it was expected to work.  I don't think
we've ever needed to have a reserved area at the end as you do,
so it may not work in practice.

Patches more than welcome, as always :-)

-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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