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

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Message-ID: <Y3+Ql1ETyO9FP2xU@zn.tnic>
Date:   Thu, 24 Nov 2022 16:41:11 +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 Thu, Nov 24, 2022 at 02:33:28PM +0100, Petr Pavlu wrote:
> If the before case is with RANDOMIZE_BASE=n and the after case is with
> RANDOMIZE_BASE=y then it makes sense the resulting sizes are similar. With
> RANDOMIZE_BASE=n, vmlinux is linked without --emit-relocs and so there will be
> no relocation sections at all. With RANDOMIZE_BASE=y and my patch, the
> sections get created but are stripped eventually. The increased size in the
> second case is likely due to the logic to support the relocation process.

This is in both cases with your patch, once with RANDOMIZE_BASE=y and
once with RANDOMIZE_BASE=n.

IOW, your patch actually makes my vmlinux bigger by 51K.

IOW, I cannot reproduce your

| Configuration      | With relocs | Stripped relocs |
| x86_64_defconfig   |       70 MB |           43 MB |

claim, but not with a defconfig but with my specially tailored config.

I guess the next thing I'll try is without your patch.

-- 
Regards/Gruss,
    Boris.

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