linux.git/Documentation/kbuild, branch v5.11

kbuild: remove PYTHON variable

2021-02-01T01:37:19+00:00

Python retired in 2020, and some distributions do not provide the
'python' command any more.

As in commit 51839e29cb59 ("scripts: switch explicitly to Python 3"),
we need to use more specific 'python3' to invoke scripts even if they
are written in a way compatible with both Python 2 and 3.

This commit removes the variable 'PYTHON', and switches the existing
users to 'PYTHON3'.

BTW, PEP 394 (https://www.python.org/dev/peps/pep-0394/) is a helpful
material.

Signed-off-by: Masahiro Yamada

Documentation/llvm: Add a section about supported architectures

2021-01-29T21:06:35+00:00

The most common question around building the Linux kernel with clang is
"does it work?" and the answer has always been "it depends on your
architecture, configuration, and LLVM version" with no hard answers for
users wanting to experiment. LLVM support has significantly improved
over the past couple of years, resulting in more architectures and
configurations supported, and continuous integration has made it easier
to see what works and what does not.

Add a section that goes over what architectures are supported in the
current kernel version, how they should be built (with just clang or the
LLVM utilities as well), and the level of support they receive. This
will make it easier for people to try out building their kernel with
LLVM and reporting issues that come about from it.

Suggested-by: Miguel Ojeda 
Signed-off-by: Nathan Chancellor 
Reviewed-by: Nick Desaulniers 
Signed-off-by: Masahiro Yamada

doc: gcc-plugins: update gcc-plugins.rst

2021-01-25T21:23:20+00:00

This document was written a long time ago. Update it.

[1] Drop the version information

The range of the supported GCC versions are always changing. The
current minimal GCC version is 4.9, and commit 1e860048c53e
("gcc-plugins: simplify GCC plugin-dev capability test") removed the
old code accordingly.

We do not need to mention specific version ranges like "all gcc versions
from 4.5 to 6.0" since we forget to update the documentation when we
raise the minimal compiler version.

[2] Drop the C compiler statements

Since commit 77342a02ff6e ("gcc-plugins: drop support for GCC <= 4.7")
the GCC plugin infrastructure only supports g++.

[3] Drop supported architectures

As of v5.11-rc4, the infrastructure supports more architectures;
arm, arm64, mips, powerpc, riscv, s390, um, and x86. (just grep
"select HAVE_GCC_PLUGINS") Again, we miss to update this document when a
new architecture is supported. Let's just say "only some architectures".

[4] Update the apt-get example

We are now discussing to bump the minimal version to GCC 5. The GCC 4.9
support will be removed sooner or later. Change the package example to
gcc-10-plugin-dev while we are here.

[5] Update the build target

Since commit ce2fd53a10c7 ("kbuild: descend into scripts/gcc-plugins/
via scripts/Makefile"), "make gcc-plugins" is not supported.
"make scripts" builds all the enabled plugins, including some other
tools.

[6] Update the steps for adding a new plugin

At first, all CONFIG options for GCC plugins were located in arch/Kconfig.
After commit 45332b1bdfdc ("gcc-plugins: split out Kconfig entries to
scripts/gcc-plugins/Kconfig"), scripts/gcc-plugins/Kconfig became the
central place to collect plugin CONFIG options. In my understanding,
this requirement no longer exists because commit 9f671e58159a ("security:
Create "kernel hardening" config area") moved some of plugin CONFIG
options to another file. Find an appropriate place to add the new CONFIG.

The sub-directory support was never used by anyone, and removed by
commit c17d6179ad5a ("gcc-plugins: remove unused GCC_PLUGIN_SUBDIR").

Remove the useless $(src)/ prefix.

Signed-off-by: Masahiro Yamada

Documentation/Kbuild: Remove references to gcc-plugin.sh

2021-01-23T09:30:26+00:00

gcc-plugin.sh has been removed in commit
1e860048c53e ("gcc-plugins: simplify GCC plugin-dev capability test").

Signed-off-by: Robert Karszniewicz 
Reviewed-by: Kees Cook 
Signed-off-by: Masahiro Yamada

Documentation: kbuild: Fix section reference

2021-01-10T20:14:38+00:00

Section 3.11 was incorrectly called 3.9, fix it.

Signed-off-by: Viresh Kumar 
Signed-off-by: Masahiro Yamada

Merge tag 'kconfig-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2020-12-22T22:04:25+00:00

Pull Kconfig updates from Masahiro Yamada:

 - Support only Qt5 for qconf

 - Validate signal/slot connection at compile time of qconf

 - Sanitize header includes

* tag 'kconfig-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kconfig: doc: fix $(fileno) to $(filename)
  kconfig: fix return value of do_error_if()
  kconfig: clean up header inclusion
  kconfig: qconf: show Qt version in the About dialog
  kconfig: make lkc.h self-sufficient #include-wise
  kconfig: qconf: convert to Qt5 new signal/slot connection syntax
  kconfig: qconf: use a variable to pass packages to pkg-config
  kconfig: qconf: drop Qt4 support

kconfig: doc: fix $(fileno) to $(filename)

2020-12-21T07:01:44+00:00

This is a typo.

Signed-off-by: Masahiro Yamada

Documentation/kbuild: Document platform dependency practises

2020-12-21T04:57:08+00:00

Document best practises for using architecture and platform dependencies.

Signed-off-by: Geert Uytterhoeven 
Signed-off-by: Masahiro Yamada

Documentation/kbuild: Document COMPILE_TEST dependencies

2020-12-21T04:57:08+00:00

Document best practises for using COMPILE_TEST dependencies.

Signed-off-by: Geert Uytterhoeven 
Acked-by: Arnd Bergmann 
Signed-off-by: Masahiro Yamada

kbuild: doc: document subdir-y syntax

2020-12-21T04:57:07+00:00

There is no explanation about subdir-y.

Let's document it.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Randy Dunlap