Re: [PATCH 1/2] x86/boot: move early_serial_base to .data section

From: Ingo Molnar
Date: Tue May 07 2019 - 04:29:03 EST

* Pingfan Liu <kernelfans@xxxxxxxxx> wrote:

> arch/x86/boot/compressed/head_64.S clears BSS after relocated. If early
> serial is set up before clearing BSS, the early_serial_base will be reset
> to 0.
> Initializing early_serial_base as -1 to push it to .data section.

I'm wondering whether it's wise to clear the BSS after relocation to
begin with. It already gets cleared once, and an implicit zeroing of all
fields on kernel relocation sounds dubious to me.

Is there a strong reason for that? I.e. is there some uninitialized or
otherwise important-to-clear data there?