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[166.171.249.100]) by smtp.googlemail.com with ESMTPSA id a24sm12226917pfo.160.2019.03.12.08.15.22 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Mar 2019 08:15:27 -0700 (PDT) Subject: Re: [PATCH v4 1/2] Provide in-kernel headers for making it easy to extend the kernel To: Geert Uytterhoeven Cc: Greg KH , Joel Fernandes , LKML , Andrew Morton , Alexei Starovoitov , atish patra , Daniel Colascione , Dan Williams , Dietmar Eggemann , Guenter Roeck , Jonathan Corbet , Kees Cook , Android Kernel Team , "open list:DOCUMENTATION" , "open list:KERNEL SELFTEST FRAMEWORK" , linux-trace-devel@vger.kernel.org, Manoj Rao , Masahiro Yamada , Masami Hiramatsu , Qais Yousef , Randy Dunlap , Steven Rostedt , Shuah Khan , Yonghong Song References: <20190301160856.129678-1-joel@joelfernandes.org> <20190307150343.GB258852@google.com> <20190308140251.GC25768@kroah.com> <20190309071648.GE3882@kroah.com> <20190309121141.GA30173@kroah.com> <3e84e1ef-e266-e983-5874-6c26ac7f38b8@opersys.com> From: Karim Yaghmour Message-ID: Date: Tue, 12 Mar 2019 08:15:18 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-trace-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Hi Geert, On 3/11/19 4:03 AM, Geert Uytterhoeven wrote: [ snip ] > OK. > > Now about the actual solution: what is your opinion on embedding e.g. > a squashfs image in the kernel instead, which would be a more generic > solution, not adding more ABI to /proc? I'm not familiar enough with the intricacies of squashfs to have an educated opinion, but I hear that it's got its quirks (need for user-space tools, etc.) and possibly security issues. Also, I wonder whether it's a generalized solution that still kicks the ABI can down the road -- ultimately the kernel would still have a path/format/foo for making kheaders available in that squashfs image and that convention would become ABI. The only "benefit" being that said ABI wouldn't appear under /proc, and, tbh, I'm not sure that that's actually a benefit or is even idiomatic since kconfig.gz is already under /proc. To an extent, the precedent set by kconfig favors kheaders to also be available in the same location using a similar mechanism ... i.e. bonus points for consistency. But that's my hand-wavy gut-reaction response to your question. I'm sure others on this thread have far more informed opinions about the specifics than I could have. My priority was to clarify the basis for the need being addressed. Cheers, -- Karim Yaghmour CEO - Opersys inc. / www.opersys.com http://twitter.com/karimyaghmour