SDK 8.0.0 DFU bootloader code size too large, gcc

[Eliot Stock]

I've taken the example project at nRF51_SDK_8.0.0_5fc2c3a/examples/dfu/bootloader and attempted to build it using gcc. I'm going for a single bank update over BLE. The SDK docs here...

developer.nordicsemi.com/.../a00088.html

...claim the bootloader can be built in under 16kB but mine is coming in at over 64kB, so clearly I'm doing something quite wrong.

gcc_nrf51_bootloader_xxac.ld(/attachment/1833090283e7aacc3d6f36a5c294ab07)

bootloader_s110.Map

I've attached my linker script and my *.Map file for the bootloader. There's plenty of discussion here about getting this working but I can't find another thread with a working linker script and makefile for SDK 8.0.0 and gcc.

[Mike F]

I'm trying to do the same thing. I don't have everything working yet, but ran into this issue. I suspect that if you optimize for size -Os rather than speed -O3, you will be able to load it at 0x3c000.

[Vidar Berg]

Hi, from your map file it seems like your bootloader is actually 32K . I am not sure if GCC is able to compile it to 16K, but you can try to optimize for size as Mike suggested.

Here are some files that I have modified to use the bootloader with GCC and SDK 8.0.0. The linker file here allocates 21K in flash for the bootloader allowing -O3 optimization. Remember to change dfu_types.h-->BOOTLOADER_REGION_START according to the linker settings.

• makefile
• bootloader_util_gcc_mod .c
• dfu_ble_svc_gcc.c
• gcc_nrf51_bootloader_xxac.ld

Note that the modifications are not necessary correct, and may have unexpected side effects due to little testing. Also, did not add the bond sharing feature mentioned here.

EDIT 13.4.2015 Added missing linker file.

[Mike F]

GCC can do it, here's an example. The bootloader_util_gcc.c file in the SDK is fairly close. This works with both single and dual bank updates. It would be nice if a GCC version, like this, was included in future versions of the SDK.

First, if you set m_uicr_bootloader_start_address as a volatile, BOOTLOADER_REGION_START will be written to flash when you program the hex file. If not, it will be optimized out so you'll have to program BOOTLOADER_REGION_START into the UICR later.

Next, you have to pass the argument start_addr to the assembly template so you get the expected application reset vector. If you don't do this the DFU will upload successfully but the application will not start. The code above address this start_addr issue.

I left out isr_abort because it isn't working for whatever reason. I only get to the bootloader after a restart so I don't need this code or this code (or the bond sharing feature) but it does makes sense to get a gcc version of this working.

bltest.tgz

bootloader_s110v8_xxaa.map

[Eliot Stock]

Thank you very much indeed! This builds on my machine and weighs in at about 18KB. I'm now playing spot the difference with my own Makefile and sources and these ones to see how mine is getting so big. I haven't run it as a bootloader yet.

[Mike F]

I wonder why it is so much larger when you compile it. I just added my map file so you can compare.

$ grep '__Vectors\|__exidx_end' bootloader_s110v8_xxaa.map 
            0x000000000003c000                __Vectors
            0x000000000003f3d8                __exidx_end = .