linux-kernel - Re: [PATCH v2] x86: Avoid relocation information in final vmlinux

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Message-ID: <Y35CNdPVwq11NCYN@zn.tnic>
Date:   Wed, 23 Nov 2022 16:54:29 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Petr Pavlu <petr.pavlu@...e.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, nicolas@...sle.eu,
        masahiroy@...nel.org, kirill.shutemov@...ux.intel.com,
        tony.luck@...el.com, michael.roth@....com, nathan@...nel.org,
        ndesaulniers@...gle.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] x86: Avoid relocation information in final vmlinux

On Wed, Nov 23, 2022 at 04:43:20PM +0100, Petr Pavlu wrote:
> The only post-link analysis tool in this case should be arch/x86/tools/relocs.
> It produces a vmlinux.relocs file which is appended to vmlinux.bin. This is
> all internal to the Linux build. I'm not aware of any external tooling, such
> as kernel debuggers, that would require this relocation information in
> vmlinux.

It would be good to know why --emit-relocs was added in the first place
- that might give us a hint. Lemme talk to Micha.

> The size command used in your example includes only allocatable code, data and
> bss sections. It does not show size of any relocation sections.

This:

361M vmlinux.before
361M vmlinux.after

is simple ls output.

Maybe I need something else enabled in my .config which would show this
significant difference *and* *explain* it.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette