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From:   Florian Weimer <fweimer@redhat.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Dave Martin <Dave.Martin@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Yu-cheng Yu <yu-cheng.yu@intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-mm@kvack.org, linux-arch@vger.kernel.org,
        linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
        Andy Lutomirski <luto@amacapital.net>,
        Balbir Singh <bsingharora@gmail.com>,
        Borislav Petkov <bp@alien8.de>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Eugene Syromiatnikov <esyr@redhat.com>,
        "H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        Randy Dunlap <rdunlap@infradead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>
Subject: Re: [PATCH v7 22/27] binfmt_elf: Extract .note.gnu.property from an ELF file
References: <20190606200646.3951-23-yu-cheng.yu@intel.com>
        <20190607180115.GJ28398@e103592.cambridge.arm.com>
        <94b9c55b3b874825fda485af40ab2a6bc3dad171.camel@intel.com>
        <87lfy9cq04.fsf@oldenburg2.str.redhat.com>
        <20190611114109.GN28398@e103592.cambridge.arm.com>
        <031bc55d8dcdcf4f031e6ff27c33fd52c61d33a5.camel@intel.com>
        <20190612093238.GQ28398@e103592.cambridge.arm.com>
        <87imt4jwpt.fsf@oldenburg2.str.redhat.com>
        <alpine.DEB.2.21.1906171418220.1854@nanos.tec.linutronix.de>
        <20190618091248.GB2790@e103592.cambridge.arm.com>
        <20190618124122.GH3419@hirez.programming.kicks-ass.net>
Date:   Tue, 18 Jun 2019 14:47:00 +0200
In-Reply-To: <20190618124122.GH3419@hirez.programming.kicks-ass.net> (Peter
        Zijlstra's message of "Tue, 18 Jun 2019 14:41:22 +0200")
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* Peter Zijlstra:

> I'm not sure I read Thomas' comment like that. In my reading keeping the
> PT_NOTE fallback is exactly one of those 'fly workarounds'. By not
> supporting PT_NOTE only the 'fine' people already shit^Hpping this out
> of tree are affected, and we don't have to care about them at all.

Just to be clear here: There was an ABI document that required PT_NOTE
parsing.  The Linux kernel does *not* define the x86-64 ABI, it only
implements it.  The authoritative source should be the ABI document.

In this particularly case, so far anyone implementing this ABI extension
tried to provide value by changing it, sometimes successfully.  Which
makes me wonder why we even bother to mainatain ABI documentation.  The
kernel is just very late to the party.

Thanks,
Florian