linux-kernel - Re: [PATCH] uselib: default depending if libc5 was used

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Message-ID: <20151127093309.GA9458@x>
Date:	Fri, 27 Nov 2015 01:33:09 -0800
From:	Josh Triplett <josh@...htriplett.org>
To:	Riku Voipio <riku.voipio@...aro.org>
Cc:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org
Subject: Re: [PATCH] uselib: default depending if libc5 was used

On Fri, Nov 27, 2015 at 11:11:26AM +0200, Riku Voipio wrote:
> uselib hasn't been used since libc5; glibc does not use it.
> Deprecate uselib a bit more, by making the default y only
> if libc5 was widely used on the plaform.
> 
> This makes arm64 kernel built with defconfig slighly smaller
> 
> bloat-o-meter:
> add/remove: 0/3 grow/shrink: 0/2 up/down: 0/-1390 (-1390)
> function                                     old     new   delta
> kernel_config_data                         18164   18162      -2
> uselib_flags                                  20       -     -20
> padzero                                      216     192     -24
> sys_uselib                                   380       -    -380
> load_elf_library                             964       -    -964
> 
> Signed-off-by: Riku Voipio <riku.voipio@...aro.org>
> Cc: Josh Triplett <josh@...htriplett.org>

Seems sensible.  Can you also make it only "default y" on 32-bit x86,
not 64-bit x86, since the latter never had libc5?

With that change:
Reviewed-by: Josh Triplett <josh@...htriplett.org>

>  init/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/init/Kconfig b/init/Kconfig
> index c24b6f7..bef326d 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -285,7 +285,7 @@ config FHANDLE
>  
>  config USELIB
>  	bool "uselib syscall"
> -	default y
> +	def_bool ALPHA || M68K || SPARC || X86
>  	help
>  	  This option enables the uselib syscall, a system call used in the
>  	  dynamic linker from libc5 and earlier.  glibc does not use this
> -- 
> 2.6.2
> 
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