From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Karim Yaghmour <karim.yaghmour@opersys.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
Joel Fernandes <joel@joelfernandes.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alexei Starovoitov <ast@kernel.org>,
atish patra <atishp04@gmail.com>,
Daniel Colascione <dancol@google.com>,
Dan Williams <dan.j.williams@intel.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Guenter Roeck <groeck@chromium.org>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Android Kernel Team <kernel-team@android.com>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
linux-trace-devel@vger.kernel.org,
Manoj Rao <linux@manojrajarao.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Qais Yousef <qais.yousef@arm.com>,
Randy Dunlap <rdunlap@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Shuah Khan <shuah@kernel.org>, Yonghong Song <yhs@fb.com>
Subject: Re: [PATCH v4 1/2] Provide in-kernel headers for making it easy to extend the kernel
Date: Mon, 11 Mar 2019 09:03:04 +0100 [thread overview]
Message-ID: <CAMuHMdVw=b_oS70F1LhXV0b9fn_p6OuCo2RDUQC=49PdJVW7xA@mail.gmail.com> (raw)
In-Reply-To: <3e84e1ef-e266-e983-5874-6c26ac7f38b8@opersys.com>
Hi Karim,
On Sat, Mar 9, 2019 at 10:44 PM Karim Yaghmour
<karim.yaghmour@opersys.com> wrote:
> On 3/9/19 2:26 PM, Geert Uytterhoeven wrote:
> > So how does this work, with kernel images and kernel modules supplied
> > by separate parties, not "bound" by the same kernel headers/API, as they
> > can be replaced separately?
>
> The thing with Android is that there isn't a "one size fits all". Google
> provides guidance, policies and at least one example implementation
> through the Pixel lines.
>
> Each vendor however is allowed a great degree of latitude with regards
> to what they decide to do. Personally, if I was advising a team working
> on an Android device where Joel's patch was available as part of their
> kernel I would just recommend that they build it in -- i.e. not as a
> module. Hence, there would be no module chasing game.
OK, that makes sense, if kernel and modules are separate.
So kernel size increase due to including the headers does matter.
> With regards to Google's guidelines for manufacturers, though, Google
> states that CONFIG_MODVERSIONS needs to be enabled, see here:
> https://source.android.com/devices/architecture/kernel/modular-kernels
> FWIW, that doesn't mean that modules are actually used. Devices don't
> necessarily have to be using modules.
Personally, I had mixed experiences with CONFIG_MODVERSIONS.
But that was a looong time ago, before Android.
Things may have improved.
> > Isn't the need for kernel headers for user-space tools something different,
> > as this is limited to the uapi versions, which are less (almost not) subject
> > to change, compared to the kernel headers needed for compiling kernel
> > modules?
>
> Sorry, I should've been clearer. I'm including eBPF/BCC into the
> "user-space tools" here. That was in fact my prime motivation in
> encouraging Joel at the last LPC to look at this. I've been integrating
> the teaching of eBPF into my AOSP debugging and performance analysis
> class (see CC courseware here:
> http://www.opersys.com/training/android-debug-and-performance), and it
> was pretty messy trying to show people how to benefit from such tools
> under Android. Joel's present set of patches would obviate this problem.
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?
Thanks!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2019-03-11 8:03 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-01 16:08 [PATCH v4 1/2] Provide in-kernel headers for making it easy to extend the kernel Joel Fernandes (Google)
2019-03-01 16:08 ` [PATCH v4 2/2] Add selftests for module build using in-kernel headers Joel Fernandes (Google)
2019-03-02 21:59 ` [PATCH v4 1/2] Provide in-kernel headers for making it easy to extend the kernel kbuild test robot
2019-03-03 16:11 ` Joel Fernandes
2019-03-06 12:26 ` Masahiro Yamada
2019-03-06 17:49 ` Joel Fernandes
2019-03-07 4:59 ` Masahiro Yamada
2019-03-07 14:54 ` Joel Fernandes
2019-03-07 23:23 ` Justin Capella
2019-03-06 18:16 ` Joel Fernandes
2019-03-07 4:54 ` Masahiro Yamada
2019-03-03 2:04 ` kbuild test robot
2019-03-04 14:00 ` Qais Yousef
2019-03-05 16:27 ` Joel Fernandes
2019-03-04 22:48 ` Dietmar Eggemann
2019-03-05 16:25 ` Joel Fernandes
2019-03-07 8:58 ` Geert Uytterhoeven
2019-03-07 15:03 ` Joel Fernandes
2019-03-07 15:23 ` Greg KH
2019-03-07 16:54 ` Joel Fernandes
[not found] ` <20190318185742.109dee5c@alans-desktop>
2019-03-18 21:11 ` Karim Yaghmour
2019-03-08 8:53 ` Geert Uytterhoeven
2019-03-08 13:42 ` Joel Fernandes
2019-03-08 13:57 ` Enrico Weigelt, metux IT consult
2019-03-08 14:04 ` Greg KH
2019-03-08 14:02 ` Greg KH
2019-03-08 17:58 ` Joel Fernandes
2019-03-08 17:59 ` Geert Uytterhoeven
2019-03-09 7:16 ` Greg KH
2019-03-09 11:40 ` Geert Uytterhoeven
2019-03-09 12:11 ` Greg KH
2019-03-09 16:51 ` Karim Yaghmour
2019-03-09 19:26 ` Geert Uytterhoeven
2019-03-09 21:44 ` Karim Yaghmour
2019-03-11 8:03 ` Geert Uytterhoeven [this message]
2019-03-12 15:15 ` Karim Yaghmour
2019-03-11 23:36 ` Steven Rostedt
2019-03-11 23:58 ` Daniel Colascione
2019-03-12 0:39 ` Joel Fernandes
2019-03-12 1:28 ` Steven Rostedt
2019-03-12 1:38 ` Joel Fernandes
2019-03-13 1:18 ` Masami Hiramatsu
2019-03-14 12:27 ` Joel Fernandes
2019-03-15 13:14 ` Masami Hiramatsu
2019-03-12 1:45 ` Alexei Starovoitov
2019-03-12 15:26 ` Steven Rostedt
2019-03-12 1:22 ` Steven Rostedt
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