How to do IRQ forwarding from bootloader?

Question

Hello, 
 I've had to redesign my bootloader and I am now stuck with a problem that I can not solve. I need to know the correct workflow for switching from bootloader to application and I was unable to figure it out. 
 
 I am writing the UICR_BOOTADDR register with the address of my bootloader 
 I have two projects, one for my bootloader and one for my application at fitting addresses 
 My bootloader does not need the softdevice 
 
 When the bootaddress is set, all interrupts will be forwarded by the MBR to my bootloader. Before I start my application, I am doing the following: 
 interrupts_disable();

sd_mbr_command_t com;
com.command = SD_MBR_COMMAND_VECTOR_TABLE_BASE_SET;
com.params.base_set.address = SD_SIZE_GET(MBR_SIZE);
err = sd_mbr_command(&com);

bootloader_util_app_start(CODE_REGION_1_START); //copied this function from the SDK code.
 
 My app starts, but I have so far been unable to enable the softdevice or use sd_softdevice_vector_table_base_set. If I do not flash the bootloader and just the application, everything works as expected. It must have something to do with the interrupt table, but I am a bit lost there. 
 What is the correct order in which I call these functions? Also, GCC will not compile the bootloader_util_app_start function depending on the settings of the optimizer,...? 
 What does the SD_MBR_COMMAND_VECTOR_TABLE_BASE_SET do? I get the feeling that it changes something persistently that is then remembered after a reboot....

Vidar Berg · Accepted Answer

Since the application relies on the softdevice being present you can try to use the code below: 
 void bootloader_app_start(uint32_t app_addr)
{
 // If the applications CRC has been checked and passed, the magic number will be written and we
// can start the application safely.
sd_mbr_command_t com = {SD_MBR_COMMAND_INIT_SD, };

uint32_t err_code = sd_mbr_command(&com);
APP_ERROR_CHECK(err_code);

interrupts_disable();

// Set base address for the applications vector table
err_code = sd_softdevice_vector_table_base_set(app_addr);
APP_ERROR_CHECK(err_code);

// Branch to the reset handler for the application
bootloader_util_app_start(app_addr);

}
 
 If you compile without optimization you need to add '-fomit-frame-pointer' to the compiler flags for it to compile correctly. 
 SD_MBR_COMMAND_VECTOR_TABLE_BASE_SET does set the address persistently within the MBR, but you don't want this in this case as the bootloader should always start first