NOLOAD directive for .uicr_bootloader_start_address and .uicr_mbr_params_page

[Anne van Rossum]

The uicr_bootloader_start_address and .uicr_mbr_params_page have no NOLOAD directive (in all bootloader examples). With objcopy this will generate large object files. Locations like 0x10001014 lead to file sizes of approx. 256 MB.

                                                                                                      
SECTIONS                                                                                                                
{                                                                                                                       
  . = ALIGN(4);                                                                                                         
  .uicr_bootloader_start_address :                                                                                      
  {                                                                                                                     
    PROVIDE(__start_uicr_bootloader_start_address = .);                                                                 
    KEEP(*(SORT(.uicr_bootloader_start_address*)))                                                                      
    PROVIDE(__stop_uicr_bootloader_start_address = .);                                                                  
  } > uicr_bootloader_start_address                                                                                     
  . = ALIGN(4);                                                                                                         
  .uicr_mbr_params_page :                                                                                               
  {                                                                                                                     
    PROVIDE(__start_uicr_mbr_params_page = .);                                                                          
    KEEP(*(SORT(.uicr_mbr_params_page*)))                                                                               
    PROVIDE(__stop_uicr_mbr_params_page = .);                                                                           
  } > uicr_mbr_params_page                                                                                              
  . = ALIGN(4);                                                                                                         
  .mbr_params_page(NOLOAD) :                                                                                            
  {                                                                                                                     
    PROVIDE(__start_mbr_params_page = .);                                                                               
    KEEP(*(SORT(.mbr_params_page*)))                                                                                    
    PROVIDE(__stop_mbr_params_page = .);                                                                                
  } > mbr_params_page                                                                                                   
  . = ALIGN(4);                                                                                                         
  .bootloader_settings_page(NOLOAD) :                                                                                   
  {                                                                                                                     
    PROVIDE(__start_bootloader_settings_page = .);                                                                      
    KEEP(*(SORT(.bootloader_settings_page*)))                                                                           
    PROVIDE(__stop_bootloader_settings_page = .);                                                                       
  } > bootloader_settings_page                                                                                          
}                        

[Vidar Berg]

UICR is mapped to a different address range (0x10001000) so you will get around 256MB of byte padding if you try to generate a .bin file (doesn't have address records unlike intel hex). The solution is to first remove the UICR section from the hex file, then convert it to *.bin.  nrfutil does this when you generate a DFU package. 

[Anne van Rossum]

Yes, but then you'll have to maintain a list of sections to exclude.

arm-none-eabi-objcopy -O binary --remove-section .uicr_bootloader_start_address --remove-section .uicr_mbr_params_page bootloader.elf bootloader.bin

And that might change over time over SDK upgrades.

What's the reason not to add NOLOAD?

[Vidar Berg]

You want these registers to be set the first time your program the device which will not happen if you use the NOLOAD directive. If you need to use the *.bin file format you will have to split the FW into two separate binaries, one for the UICR and one for the bootloader. Otherwise, you will get a lot of byte padding. 

Edit: You can use NOLOAD, but then you need to program the UICR registers manually. 

[Anne van Rossum]

Check, yeah, we did that anyway. I forgot. I guess we've to check for changes in sections with each upgrade then.

I'll look into using nrfjprog instead, that will offload this task to your maintainers. :-)

PS: Never mind, I thought nrfjprog perhaps would also take .elf files, but it does only take .hex files. So I'll still have to copy and remove sections.