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Masahiro Yamada 02a6e4be2f kbuild: prevent exported headers from including <stdlib.h>, <stdbool.h>
Some UAPI headers included <stdlib.h>, like this:

  #ifndef __KERNEL__
  #include <stdlib.h>
  #endif

As it turned out, they just included it for no good reason.

After some fixes, now I can compile-test UAPI headers
(CONFIG_UAPI_HEADER_TEST=y) without including <stdlib.h> from the
system header search paths.

To avoid somebody getting it back again, this commit adds the dummy
header, usr/dummy-include/stdlib.h

I added $(srctree)/usr/dummy-include to the header search paths.
Because it is searched before the system directories, if someone
tries to include <stdlib.h>, they will see the error message.

While I am here, I also replaced $(objtree)/usr/include with $(obj),
but it has no functional change.

If we can make kernel headers self-contained (that is, none of exported
kernel headers includes system headers), we will be able to add the
-nostdinc flag, but that is much far from where we stand now.

As a realistic solution, we can ban header inclusion individually by
putting a dummy header into usr/dummy-include/.

Currently, no header include <stdbool.h>. I put it as well before somebody
attempts to use it.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-13 10:56:10 +02:00
Documentation Updates to Tracing: 2022-04-03 12:26:01 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch A set of x86 fixes and updates: 2022-04-03 12:15:47 -07:00
block for-5.18/block-2022-04-01 2022-04-01 16:20:00 -07:00
certs Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
drivers A single revert to fix a boot regression seen when clk_put() started 2022-04-03 12:21:14 -07:00
fs Updates to Tracing: 2022-04-03 12:26:01 -07:00
include agpgart.h: do not include <stdlib.h> from exported header 2022-05-13 10:56:10 +02:00
init Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel Updates to Tracing: 2022-04-03 12:26:01 -07:00
lib for-5.18/block-2022-04-01 2022-04-01 16:20:00 -07:00
mm Filesystem/VFS changes for 5.18, part two 2022-04-01 13:50:50 -07:00
net Networking fixes for 5.18-rc1 and rethook patches. 2022-03-31 11:23:31 -07:00
samples dma-mapping updates for Linux 5.18 2022-03-29 08:50:14 -07:00
scripts modpost: restore the warning message for missing symbol versions 2022-04-03 03:11:51 +09:00
security hardening updates for v5.18-rc1-fix1 2022-03-31 11:43:01 -07:00
sound sound fixes for 5.18-rc1 2022-04-01 10:32:46 -07:00
tools A set of x86 fixes and updates: 2022-04-03 12:15:47 -07:00
usr kbuild: prevent exported headers from including <stdlib.h>, <stdbool.h> 2022-05-13 10:56:10 +02:00
virt KVM: Remove dirty handling from gfn_to_pfn_cache completely 2022-04-02 05:34:41 -04:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Kirill's email 2022-04-01 11:46:09 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS chrome platform changes for 5.18 2022-04-02 10:44:18 -07:00
Makefile Linux 5.18-rc1 2022-04-03 14:08:21 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.