Problem with Jumping from Bootloader to Apploader with cortex_m::asm::bootload

Hi everyone,

I’m working on an embedded Rust project using Embassy, cortex-m, and a STM32L471RG. I’ve set up a bootloader and an apploader, but I’m running into a strange issue when trying to jump from the bootloader to the apploader.

Here’s the function I’m using to perform the jump:

fn jump_to_apploader() -> ! {
unsafe {
let start = &__apploader_origin as *const u32 as u32;
info!("booting to apploader at 0x{:X}", start);
let p = cortex_m::Peripherals::steal();
p.SCB.vtor.write(start);
cortex_m::asm::bootload(start as *const u32)
}
}

When I call this, the code completely stops running — it doesn’t execute the apploader, and I don’t even hit my panic handler. It’s just stuck.

Here is my panic handler for reference:

#[cfg(target_os = "none")]
#[panic_handler]
fn panic(info: &core::panic::PanicInfo) -> ! {
use defmt::error;
error!("{}: {}", info, defmt::Display2Format(&info.message()));
cortex_m::peripheral::SCB::sys_reset();
}

So far:

The jump address (__apploader_origin) is set correctly in the linker script.

The log message shows the expected address before jumping.

After cortex_m::asm::bootload, the MCU seems to hang completely — no reset, no panic, no debug logs.

Has anyone faced a similar issue before?
Could this be related to stack pointer initialization, interrupts still enabled, or something about how bootload expects the vector table?
Any hints or debugging approaches would be greatly appreciated!

Start with the jump_to_apploader function and the linker script definition of __apploader_origin, then inspect cortex_m::asm::bootload's expected vector-table and stack-pointer layout. Use the reported address and a debugger to determine whether control reaches a valid apploader entry point; done means identifying the handoff failure and documenting a reproducible fix.