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

Grant Edwards grante@visi.com
Tue Nov 7 15:39:00 GMT 2006


>> 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.

-- 
Grant Edwards                   grante             Yow!  I selected E5... but
                                  at               I didn't hear "Sam the Sham
                               visi.com            and the Pharoahs"!

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