From: Karim Yaghmour <karim.yaghmour@opersys.com>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
ast@kernel.org, atishp04@gmail.com, dancol@google.com,
Dan Williams <dan.j.williams@intel.com>,
gregkh@linuxfoundation.org, Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
kernel-team@android.com, linux-doc@vger.kernel.org,
linux-kselftest@vger.kernel.org,
Manoj Rao <linux@manojrajarao.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
paulmck@linux.vnet.ibm.com,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
rdunlap@infradead.org, rostedt@goodmis.org,
Shuah Khan <shuah@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
yhs@fb.com
Subject: Re: [PATCH v2 1/2] Provide in-kernel headers for making it easy to extend the kernel
Date: Wed, 13 Feb 2019 17:50:10 -0500 [thread overview]
Message-ID: <c035159d-3a56-61d8-bad6-79401b25a227@opersys.com> (raw)
In-Reply-To: <20190211143600.15021-1-joel@joelfernandes.org>
On 2/11/19 9:35 AM, Joel Fernandes (Google) wrote:
> Introduce in-kernel headers and other artifacts which are made available
> as an archive through proc (/proc/kheaders.txz file). This archive makes
> it possible to build kernel modules, run eBPF programs, and other
> tracing programs that need to extend the kernel for tracing purposes
> without any dependency on the file system having headers and build
> artifacts.
>
> On Android and embedded systems, it is common to switch kernels but not
> have kernel headers available on the file system. Raw kernel headers
> also cannot be copied into the filesystem like they can be on other
> distros, due to licensing and other issues. There's no linux-headers
> package on Android. Further once a different kernel is booted, any
> headers stored on the file system will no longer be useful. By storing
> the headers as a compressed archive within the kernel, we can avoid these
> issues that have been a hindrance for a long time.
>
> The feature is also buildable as a module just in case the user desires
> it not being part of the kernel image. This makes it possible to load
> and unload the headers on demand. A tracing program, or a kernel module
> builder can load the module, do its operations, and then unload the
> module to save kernel memory. The total memory needed is 3.8MB.
>
> The code to read the headers is based on /proc/config.gz code and uses
> the same technique to embed the headers.
>
> To build a module, the below steps have been tested on an x86 machine:
> modprobe kheaders
> rm -rf $HOME/headers
> mkdir -p $HOME/headers
> tar -xvf /proc/kheaders.txz -C $HOME/headers >/dev/null
> cd my-kernel-module
> make -C $HOME/headers M=$(pwd) modules
> rmmod kheaders
>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Karim Yaghmour <karim.yaghmour@opersys.com>
> ---
>
> Changes since v1:
> - removed IKH_EXTRA variable, not needed (Masahiro Yamada)
> - small fix ups to selftest
> - added target to main Makefile etc
> - added MODULE_LICENSE to test module
> - made selftest more quiet
>
> Changes since RFC:
> Both changes bring size down to 3.8MB:
> - use xz for compression
> - strip comments except SPDX lines
> - Call out the module name in Kconfig
> - Also added selftests in second patch to ensure headers are always
> working.
>
> Documentation/dontdiff | 1 +
> init/Kconfig | 11 ++++++
> kernel/.gitignore | 2 ++
> kernel/Makefile | 27 ++++++++++++++
> kernel/kheaders.c | 74 +++++++++++++++++++++++++++++++++++++++
> scripts/gen_ikh_data.sh | 19 ++++++++++
> scripts/strip-comments.pl | 8 +++++
> 7 files changed, 142 insertions(+)
> create mode 100644 kernel/kheaders.c
> create mode 100755 scripts/gen_ikh_data.sh
> create mode 100755 scripts/strip-comments.pl
[snip]
--
Karim Yaghmour
CEO - Opersys inc. / www.opersys.com
http://twitter.com/karimyaghmour
next prev parent reply other threads:[~2019-02-13 22:50 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-11 14:35 [PATCH v2 1/2] Provide in-kernel headers for making it easy to extend the kernel Joel Fernandes (Google)
2019-02-11 14:36 ` [PATCH v2 2/2] Add selftests for module build using in-kernel headers Joel Fernandes (Google)
2019-02-13 22:50 ` Karim Yaghmour [this message]
2019-02-15 3:19 ` [PATCH v2 1/2] Provide in-kernel headers for making it easy to extend the kernel Alexei Starovoitov
2019-02-15 3:47 ` Joel Fernandes
2019-02-16 19:10 ` Manoj
2019-02-19 4:14 ` Masahiro Yamada
2019-02-19 4:28 ` Alexei Starovoitov
2019-02-19 4:34 ` Joel Fernandes
2019-02-19 4:42 ` Masahiro Yamada
2019-02-19 5:12 ` Joel Fernandes
2019-02-19 15:16 ` Joel Fernandes
2019-02-21 14:34 ` Masahiro Yamada
2019-02-21 15:29 ` Joel Fernandes
2019-03-25 13:49 ` Joel Fernandes
2019-03-27 17:31 ` Joel Fernandes
2019-04-03 7:48 ` Masahiro Yamada
2019-04-03 17:20 ` Joel Fernandes
2019-04-03 17:46 ` Daniel Colascione
2019-04-03 17:56 ` Joel Fernandes
2019-04-04 3:54 ` Masahiro Yamada
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