linux-kernel - Re: [PATCH] [RFT] m68k: enable HAVE_LD_DEAD_CODE_DATA

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Message-ID: <f648b6fa-61c7-7d60-ba21-c1c759faf929@physik.fu-berlin.de>
Date:   Thu, 25 Feb 2021 12:28:16 +0100
From:   John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
To:     Arnd Bergmann <arnd@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Arnd Bergmann <arnd@...db.de>, Kees Cook <keescook@...omium.org>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [RFT] m68k: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION

Hi Arnd!

On 2/25/21 12:14 PM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> While experimenting with CONFIG_TRIM_UNUSED_KSYMS across architectures,
> I noticed that this unsurprisingly works best when combined with the
> --gc-sections linker flag, which is not currently allowed on m68k.
> 
> Enabling it with this patch shows significant improvements
> for kernel size, looking at m68k defconfig with gcc-10, I get
> 
> 4005135 1374302 167108 5546545 54a231 vmlinux-normal
> 3916254 1378078 167108 5461440 5355c0 vmlinux+trim
> 4012933 1362514 164280 5539727 54878f vmlinux+gcsection
> 3797884 1334194 164640 5296718 50d24e vmlinux+gcsection+trim
> 
> There are probably bugs somewhere, but if someone is able to test this
> patch and fix any issues that come up, would be a useful improvement
> for memory-limited machines.

Thanks, that sounds like a very helpful improvement. I'll test the patch next
week when I'm on vacation and report back if it works - unless someone beats
me to it ;-).

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@...ian.org
`. `'   Freie Universitaet Berlin - glaubitz@...sik.fu-berlin.de
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