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Groups > linux.kernel > #1278662 > unrolled thread

[PATCH] uselib: default depending if libc5 was used

Started byRiku Voipio <riku.voipio@linaro.org>
First post2015-11-27 10:20 +0100
Last post2015-11-27 21:10 +0100
Articles 4 — 2 participants

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  [PATCH] uselib: default depending if libc5 was used Riku Voipio <riku.voipio@linaro.org> - 2015-11-27 10:20 +0100
    Re: [PATCH] uselib: default depending if libc5 was used Josh Triplett <josh@joshtriplett.org> - 2015-11-27 10:40 +0100
      Re: [PATCH] uselib: default depending if libc5 was used Riku Voipio <riku.voipio@linaro.org> - 2015-11-27 11:50 +0100
        Re: [PATCH] uselib: default depending if libc5 was used Josh Triplett <josh@joshtriplett.org> - 2015-11-27 21:10 +0100

#1278662 — [PATCH] uselib: default depending if libc5 was used

FromRiku Voipio <riku.voipio@linaro.org>
Date2015-11-27 10:20 +0100
Subject[PATCH] uselib: default depending if libc5 was used
Message-ID<qznma-UI-7@gated-at.bofh.it>
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@linaro.org>
Cc: Josh Triplett <josh@joshtriplett.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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#1278672

FromJosh Triplett <josh@joshtriplett.org>
Date2015-11-27 10:40 +0100
Message-ID<qznFw-11n-13@gated-at.bofh.it>
In reply to#1278662
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@linaro.org>
> Cc: Josh Triplett <josh@joshtriplett.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@joshtriplett.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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#1278713

FromRiku Voipio <riku.voipio@linaro.org>
Date2015-11-27 11:50 +0100
Message-ID<qzoLg-1HO-15@gated-at.bofh.it>
In reply to#1278672
On 27 November 2015 at 11:33, Josh Triplett <josh@joshtriplett.org> wrote:
> 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@linaro.org>
>> Cc: Josh Triplett <josh@joshtriplett.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?

but running 32bit libc5 apps is possible with X86_64 kernel, so the
check would become:

|| X86_32 || (X86_64 && IA32_EMULATION)

> With that change:
> Reviewed-by: Josh Triplett <josh@joshtriplett.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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#1278943

FromJosh Triplett <josh@joshtriplett.org>
Date2015-11-27 21:10 +0100
Message-ID<qzxvc-7sb-5@gated-at.bofh.it>
In reply to#1278713
On Fri, Nov 27, 2015 at 12:48:29PM +0200, Riku Voipio wrote:
> On 27 November 2015 at 11:33, Josh Triplett <josh@joshtriplett.org> wrote:
> > 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@linaro.org>
> >> Cc: Josh Triplett <josh@joshtriplett.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?
> 
> but running 32bit libc5 apps is possible with X86_64 kernel, so the
> check would become:
> 
> || X86_32 || (X86_64 && IA32_EMULATION)

Fair point.  Seems unlikely that anyone would do so, but certainly possible.

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