On Sat, Jun 25, 2022 at 7:35 PM ebashinskii <ebashinskii@proton.me> wrote:
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*?
This should answer most of the questions you may have about the kernel boot process: https://0xax.gitbooks.io/linux-insides/content/Booting/ :-)
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