Re: [PATCH v2] uselib: default depending if libc5 was used

[Geert Uytterhoeven]

Hi Andrew,

On Tue, Dec 1, 2015 at 1:31 AM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Fri, 27 Nov 2015 12:07:10 -0800 Josh Triplett <josh@xxxxxxxxxxxxxxxx> wrote:
>> On Fri, Nov 27, 2015 at 01:14:20PM +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
>>
>> One question below.
>>
>> > v2: Disable on X86_64 if no 32bit support
>> >  init/Kconfig | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/init/Kconfig b/init/Kconfig
>> > index c24b6f7..a4bc657 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_32 || (X86_64 && IA32_EMULATION)
>>
>> IA32_EMULATION depends on X86_64, so doesn't that reduce to:
>>       def_bool ALPHA || M68K || SPARC || X86_32 || IA32_EMULATION
>
> It's a bit old fashioned to add an expression like this at the
> definition site anyway.  The cool new thing is to do
>
>         def_bool ARCH_WANT_USELIB
>
> then go off and define ARCH_WANT_USELIB in the appropriate places in
> the per-arch Kconfig files.

That's useful for new to-be-implemented features, but this dependency list is
(hopefully) cast in stone. No new architecture should need this.
So I see no reason to clutter up more Kconfig files.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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