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References: <20220330201755.29319-1-mathieu.desnoyers@efficios.com> <20220330162152.17b1b660@gandalf.local.home>
In-Reply-To: <20220330162152.17b1b660@gandalf.local.home>
From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Thu, 31 Mar 2022 16:29:30 +0900
Message-ID: <CAK7LNATm5FjZsXL6aKUMhXwQAqTuO9+LmAk3LGjpAib7NZBDmg@mail.gmail.com>
Subject: Re: [PATCH] tracing: do not export user_events uapi
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Beau Belgrave <beaub@linux.microsoft.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        linux-trace-devel <linux-trace-devel@vger.kernel.org>,
        bpf <bpf@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
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On Thu, Mar 31, 2022 at 5:21 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
>
> Adding the build maintainers.
>
> -- Steve
>
> On Wed, 30 Mar 2022 16:17:55 -0400
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
>
> > In addition to mark the USER_EVENTS feature BROKEN until all interested
> > parties figure out the user-space API, do not install the uapi header.
> >
> > This prevents situations where a non-final uapi header would end up
> > being installed into a distribution image and used to build user-space
> > programs that would then run against newer kernels that will implement
> > user events with a different ABI.
> >
> > Link: https://lore.kernel.org/all/20220330155835.5e1f6669@gandalf.local.home
> >
> > Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> > ---
> >  include/uapi/Kbuild | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/include/uapi/Kbuild b/include/uapi/Kbuild
> > index 61ee6e59c930..425ea8769ddc 100644
> > --- a/include/uapi/Kbuild
> > +++ b/include/uapi/Kbuild
> > @@ -12,3 +12,6 @@ ifeq ($(wildcard $(objtree)/arch/$(SRCARCH)/include/generated/uapi/asm/kvm_para.
> >  no-export-headers += linux/kvm_para.h
> >  endif
> >  endif
> > +
> > +# API is not finalized
> > +no-export-headers += linux/user_events.h
>


Well, the intended usage of no-export-headers is to
cater to the UAPI supported by only some architectures.
We have kvm(_para).h here because not all architectures
support kvm.

If you do not want to export the UAPI,
you should not put it in include/uapi/.

After the API is finalized, you can move it to
include/uapi.


-- 
Best Regards
Masahiro Yamada