linux-kernel - Re: [musl] Re: [PATCH resent] uapi libc compat: allow non-glibc to opt out of uapi definitions

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Message-ID: <ada50de2-fe13-a087-af60-c975bf234a4d@redhat.com>
Date:   Wed, 8 Mar 2017 12:29:53 -0500
From:   Carlos O'Donell <carlos@...hat.com>
To:     Rich Felker <dalias@...ifal.cx>
Cc:     linux-kernel@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>, linux-api@...r.kernel.org,
        musl@...ts.openwall.com
Subject: Re: [musl] Re: [PATCH resent] uapi libc compat: allow non-glibc to
 opt out of uapi definitions

On 03/08/2017 11:25 AM, Rich Felker wrote:
> On Wed, Mar 08, 2017 at 10:53:00AM -0500, Carlos O'Donell wrote:
>> On 11/11/2016 07:08 AM, Felix Janda wrote:
>>> Currently, libc-compat.h detects inclusion of specific glibc headers,
>>> and defines corresponding _UAPI_DEF_* macros, which in turn are used in
>>> uapi headers to prevent definition of conflicting structures/constants.
>>> There is no such detection for other c libraries, for them the
>>> _UAPI_DEF_* macros are always defined as 1, and so none of the possibly
>>> conflicting definitions are suppressed.
>>>
>>> This patch enables non-glibc c libraries to request the suppression of
>>> any specific interface by defining the corresponding _UAPI_DEF_* macro
>>> as 0.
>>>
>>> This patch together with the recent musl libc commit
>>>
>>> http://git.musl-libc.org/cgit/musl/commit/?id=04983f2272382af92eb8f8838964ff944fbb8258
>>
>> Would it be possible to amend the musl patch to define the macros to 1.
> 
> I don't follow. They're defined to 0 explicitly to tell the kernel
> headers not to define their own versions of these structs, etc. since
> they would clash. Defining to 1 would have the opposite meaning.

My apologies, I must have misread the original musl patch.

Defining them to a known value is exactly what I was looking for.

The other outstanding questions remain.

-- 
Cheers,
Carlos.