Interrupt in Bootloader not working

[bvrm]

I'm using interrupt_handler.c for a bootloader without a softdevice from this source. Interrupt handling in the main app seems to work fine. But interrupts in the bootloader leading to a reset.

For example my uart interrupt.

1. on an uart interrupt section bootloop is called
2. jumps to uart0
3. jumps to execute
4. execute jumps to 0x0000 0000

Why?

[uart.c]
void UART0_IRQHandler_Bootloader(void)
{
    // some code
}


[interrupt_handler.c]
bootload 
        CMP R0, #0x24;
        BEQ swi0
        CMP R0, #0x21;
        BEQ rtc1
        CMP R0, #0x16;
        BEQ gpiote
        CMP R0, #0x12;
        BEQ uart0
        //RETURN code needed
uart0
        EXTERN  UART0_IRQHandler_Bootloader[WEAK]     
        LDR    R0,=UART0_IRQHandler_Bootloader
        B execute ;            
execute            
        BX     R0  ;

I did some investigations: R0 is loaded with 0x0000 0000 is above example. When removing [WEAK] everything works as expected. Leaving [WEAK] linker (Keil 5.14) is removing UART0_IRQHandler_Bootloader section.

Removing Unused input sections from the image.

    Removing main.o(.rev16_text), (4 bytes).
    Removing main.o(.revsh_text), (4 bytes).
    Removing main.o(i.init), (60 bytes).
    Removing uartreader.o(.rev16_text), (4 bytes).
    Removing uartreader.o(.revsh_text), (4 bytes).
    Removing uartreader.o(i.UART0_IRQHandler_Bootloader), (140 bytes).
    Removing uartreader.o(.bss), (50 bytes).
    Removing arm_startup_nrf51.o(HEAP), (1024 bytes).
    Removing system_nrf51.o(.rev16_text), (4 bytes).
    Removing system_nrf51.o(.revsh_text), (4 bytes).
    Removing system_nrf51.o(i.SystemCoreClockUpdate), (16 bytes).

11 unused section(s) (total 1314 bytes) removed from the image.

[Hung Bui]

@bvrm : I assume you have some code inside UART0_IRQHandler_Bootloader(). It's pretty strange that something being removed.

Could you attach your project so I can try to compile it here ? Do you have the same issue with my example ?

The reason we added WEAK is that we want to made the compiler work even if in the bootloader we don't implement the interrupt handler. But it's not the case here, so I think it should be safe to remove WEAK.