0x12009000 is just RAM, as it's writable.

I've extracted the boot.bin and found that function at 0x0418491C. But I'm not talking about boot.bin. I'm talking about the bootloader, which is not boot.bin. Bootloader is stored inside flash region number 5. Put rrgn,5,1:/5.bin into update.txt to dump it.
Those names boot.bin and fw_all.bin are quite bad, they don't reflect the real things.