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Re: [PATCH] Introduce --enable-math-noprivate
On 08/06/2018 06:03, Szabolcs Nagy wrote:
> On 07/06/18 14:38, Florian Weimer wrote:
>> On 05/16/2018 06:54 AM, Florian Weimer wrote:
>>> On 05/11/2018 05:43 PM, Florian Weimer wrote:
>>>> Avoid errno@GLIBC_PRIVATE if enabled. Additional work is needed
>>>> to eliminate further GLIBC_PRIVATE symbol references.
>>>>
>>>> 2018-05-11 Florian Weimer<fweimer@redhat.com>
>>>>
>>>> Introduce --enable-math-noprivate.
>>>> Avoid errno@GLIBC_PRIVATE if enabled.
>>>> * config.h.in (CONFIG_MATH_NOPRIVATE): Define.
>>>> * config.make.in (config-math-noprivate): New variable.
>>>> * configure.ac: Recognize --enable-math-noprivate option.
>>>> * manual/install.texi (Configuring and compiling): Document
>>>> --enable-math-noprivate.
>>>> * configure: Regenerate.
>>>> * INSTALL: Likewise.
>>>> * include/errno.h: Do not redefine errno for libm, libmvec if
>>>> CONFIG_MATH_NOPRIVATE.
>>>
>>> Ping. These patches
>>>
>>> <https://sourceware.org/ml/libc-alpha/2018-05/msg00501.html>
>>> <https://sourceware.org/ml/libc-alpha/2018-05/msg00541.html>
>>>
>>> allow building libm.so.6 without GLIBC_PRIVATE references on aarch64, and on x86-64 if --disable-multi-arch is also specified (I have a patch to add multi-arch support for the latter, but I need to come up with something that reduces the maintenance burden).
>>
>> Ping?
>>
>> What's the general feeling regarding this feature?
>
> independently updatable libm can be useful
> (or something that works from an LD_LIBRARY_PATH)
> when users of a very-stable-distro want to use the
> latest libm (assuming libm improves over time) or
> somebody wants to provide a libm with different
> precision guarantees.
>
> but i can see that ifunc may be ugly to implement.
> (or soft float, or fenv or strtod using nan)
>
> if one updates libm.so will that also update math.h?
> or we just want a libm with backward compatible abi?
> either way i think it should be possible to do and
> since glibc is currently very hard to update on a
> system it can be useful.
I think it should be a transitional configuration option with a plan to make it
default and later remove it once we have all bits upstream (maybe next release).
Which kind of fixes do you see it still requires to make it a default option?