CPU: Intel x86 KabyLake. I'm using 5.17 Kernel built from upstream and GRUB 2.04 When debugging the kernel initialization process I found out that there is a function void main(void) in the source file arch/x86/boot/main.c (source link: https://elixir.bootlin.com/linux/v5.17/source/arch/x86/boot/main.c#L134) which seems to be the entry point which the boot loader is supposed to jump into. But objdump-ing the Kernel image shows that there is no such symbol as main. GDB attached to QEMU does not know about this symbol either. The earliest stage of Kernel Initialization I could manage to catch with GDB is x86_64_start_kernel (source link: https://elixir.bootlin.com/linux/v5.17/source/arch/x86/kernel/head64.c#L467) The question is what function GRUB actually jump into passing control to the Kernel code and what is the purpose of arch/x86/boot/main.c::main?