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  1. 29 4月, 2019 4 次提交
    • J
      init/config: Do not select BUILD_BIN2C for IKCONFIG · bc0c6045
      由 Joel Fernandes (Google) 提交于 
      Since commit 13610aa9 ("kernel/configs: use .incbin directive to
embed config_data.gz"), IKCONFIG no longer uses BUILD_BIN2C so prevent
it from being selected in Kconfig.
Reviewed-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NJoel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      bc0c6045
    • J
      Provide in-kernel headers to make extending kernel easier · 43d8ce9d
      由 Joel Fernandes (Google) 提交于 
      Introduce in-kernel headers which are made available as an archive
through proc (/proc/kheaders.tar.xz file). This archive makes it
possible to run eBPF and other tracing programs that need to extend the
kernel for tracing purposes without any dependency on the file system
having headers.

A github PR is sent for the corresponding BCC patch at:
https://github.com/iovisor/bcc/pull/2312

On Android and embedded systems, it is common to switch kernels but not
have kernel headers available on the file system. Further once a
different kernel is booted, any headers stored on the file system will
no longer be useful. This is an issue even well known to distros.
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 best way to use this feature is by building it in. Several users
have a need for this, when they switch debug kernels, they do not want to
update the filesystem or worry about it where to store the headers on
it. However, the feature is also buildable as a module in case the user
desires it not being part of the kernel image. This makes it possible to
load and unload the headers from memory on demand. A tracing program can
load the module, do its operations, and then unload the module to save
kernel memory. The total memory needed is 3.3MB.

By having the archive available at a fixed location independent of
filesystem dependencies and conventions, all debugging tools can
directly refer to the fixed location for the archive, without concerning
with where the headers on a typical filesystem which significantly
simplifies tooling that needs kernel headers.

The code to read the headers is based on /proc/config.gz code and uses
the same technique to embed the headers.

Other approaches were discussed such as having an in-memory mountable
filesystem, but that has drawbacks such as requiring an in-kernel xz
decompressor which we don't have today, and requiring usage of 42 MB of
kernel memory to host the decompressed headers at anytime. Also this
approach is simpler than such approaches.
Reviewed-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NJoel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      43d8ce9d
    • T
      kobject: Improve doc clarity kobject_init_and_add() · 1fd7c3b4
      由 Tobin C. Harding 提交于 
      Function kobject_init_and_add() is currently misused in a number of
places in the kernel.  On error return kobject_put() must be called but
is at times not.

Make the function documentation more explicit about calling
kobject_put() in the error path.
Signed-off-by: NTobin C. Harding <tobin@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      1fd7c3b4
    • T
      kobject: Improve docs for kobject_add/del · 92067f84
      由 Tobin C. Harding 提交于 
      There is currently some confusion on how to wind back
kobject_init_and_add() during the error paths in code that uses this
function.

Add documentation to kobject_add() and kobject_del() to help clarify the
usage.
Signed-off-by: NTobin C. Harding <tobin@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      92067f84
  3. 26 4月, 2019 19 次提交
  5. 25 4月, 2019 1 次提交
  7. 05 4月, 2019 14 次提交
  9. 01 4月, 2019 2 次提交