diff options
Diffstat (limited to 'Documentation/kbuild')
| -rw-r--r-- | Documentation/kbuild/gcc-plugins.rst | 47 | ||||
| -rw-r--r-- | Documentation/kbuild/llvm.rst | 44 | ||||
| -rw-r--r-- | Documentation/kbuild/makefiles.rst | 3 |
3 files changed, 66 insertions, 28 deletions
diff --git a/Documentation/kbuild/gcc-plugins.rst b/Documentation/kbuild/gcc-plugins.rst index 4b1c10f88e30..3349966f213d 100644 --- a/Documentation/kbuild/gcc-plugins.rst +++ b/Documentation/kbuild/gcc-plugins.rst @@ -11,16 +11,13 @@ compiler [1]_. They are useful for runtime instrumentation and static analysis. We can analyse, change and add further code during compilation via callbacks [2]_, GIMPLE [3]_, IPA [4]_ and RTL passes [5]_. -The GCC plugin infrastructure of the kernel supports all gcc versions from -4.5 to 6.0, building out-of-tree modules, cross-compilation and building in a -separate directory. -Plugin source files have to be compilable by both a C and a C++ compiler as well -because gcc versions 4.5 and 4.6 are compiled by a C compiler, -gcc-4.7 can be compiled by a C or a C++ compiler, -and versions 4.8+ can only be compiled by a C++ compiler. +The GCC plugin infrastructure of the kernel supports building out-of-tree +modules, cross-compilation and building in a separate directory. +Plugin source files have to be compilable by a C++ compiler. -Currently the GCC plugin infrastructure supports only the x86, arm, arm64 and -powerpc architectures. +Currently the GCC plugin infrastructure supports only some architectures. +Grep "select HAVE_GCC_PLUGINS" to find out which architectures support +GCC plugins. This infrastructure was ported from grsecurity [6]_ and PaX [7]_. @@ -47,20 +44,13 @@ Files This is a compatibility header for GCC plugins. It should be always included instead of individual gcc headers. -**$(src)/scripts/gcc-plugin.sh** - - This script checks the availability of the included headers in - gcc-common.h and chooses the proper host compiler to build the plugins - (gcc-4.7 can be built by either gcc or g++). - **$(src)/scripts/gcc-plugins/gcc-generate-gimple-pass.h, $(src)/scripts/gcc-plugins/gcc-generate-ipa-pass.h, $(src)/scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h, $(src)/scripts/gcc-plugins/gcc-generate-rtl-pass.h** These headers automatically generate the registration structures for - GIMPLE, SIMPLE_IPA, IPA and RTL passes. They support all gcc versions - from 4.5 to 6.0. + GIMPLE, SIMPLE_IPA, IPA and RTL passes. They should be preferred to creating the structures by hand. @@ -68,21 +58,25 @@ Usage ===== You must install the gcc plugin headers for your gcc version, -e.g., on Ubuntu for gcc-4.9:: +e.g., on Ubuntu for gcc-10:: - apt-get install gcc-4.9-plugin-dev + apt-get install gcc-10-plugin-dev Or on Fedora:: dnf install gcc-plugin-devel -Enable a GCC plugin based feature in the kernel config:: +Enable the GCC plugin infrastructure and some plugin(s) you want to use +in the kernel config:: - CONFIG_GCC_PLUGIN_CYC_COMPLEXITY = y + CONFIG_GCC_PLUGINS=y + CONFIG_GCC_PLUGIN_CYC_COMPLEXITY=y + CONFIG_GCC_PLUGIN_LATENT_ENTROPY=y + ... -To compile only the plugin(s):: +To compile the minimum tool set including the plugin(s):: - make gcc-plugins + make scripts or just run the kernel make and compile the whole kernel with the cyclomatic complexity GCC plugin. @@ -91,7 +85,8 @@ the cyclomatic complexity GCC plugin. 4. How to add a new GCC plugin ============================== -The GCC plugins are in $(src)/scripts/gcc-plugins/. You can use a file or a directory -here. It must be added to $(src)/scripts/gcc-plugins/Makefile, -$(src)/scripts/Makefile.gcc-plugins and $(src)/arch/Kconfig. +The GCC plugins are in scripts/gcc-plugins/. You need to put plugin source files +right under scripts/gcc-plugins/. Creating subdirectories is not supported. +It must be added to scripts/gcc-plugins/Makefile, scripts/Makefile.gcc-plugins +and a relevant Kconfig file. See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin. diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst index 21c847890d03..b18401d2ba82 100644 --- a/Documentation/kbuild/llvm.rst +++ b/Documentation/kbuild/llvm.rst @@ -63,6 +63,50 @@ They can be enabled individually. The full list of the parameters: :: Currently, the integrated assembler is disabled by default. You can pass ``LLVM_IAS=1`` to enable it. +Supported Architectures +----------------------- + +LLVM does not target all of the architectures that Linux supports and +just because a target is supported in LLVM does not mean that the kernel +will build or work without any issues. Below is a general summary of +architectures that currently work with ``CC=clang`` or ``LLVM=1``. Level +of support corresponds to "S" values in the MAINTAINERS files. If an +architecture is not present, it either means that LLVM does not target +it or there are known issues. Using the latest stable version of LLVM or +even the development tree will generally yield the best results. +An architecture's ``defconfig`` is generally expected to work well, +certain configurations may have problems that have not been uncovered +yet. Bug reports are always welcome at the issue tracker below! + +.. list-table:: + :widths: 10 10 10 + :header-rows: 1 + + * - Architecture + - Level of support + - ``make`` command + * - arm + - Supported + - ``LLVM=1`` + * - arm64 + - Supported + - ``LLVM=1`` + * - mips + - Maintained + - ``CC=clang`` + * - powerpc + - Maintained + - ``CC=clang`` + * - riscv + - Maintained + - ``CC=clang`` + * - s390 + - Maintained + - ``CC=clang`` + * - x86 + - Supported + - ``LLVM=1`` + Getting Help ------------ diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 9f6a11881951..910c6303c7ea 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -755,7 +755,7 @@ more details, with real examples. bits on the scripts nonetheless. Kbuild provides variables $(CONFIG_SHELL), $(AWK), $(PERL), - $(PYTHON) and $(PYTHON3) to refer to interpreters for the respective + and $(PYTHON3) to refer to interpreters for the respective scripts. Example:: @@ -1317,7 +1317,6 @@ When kbuild executes, the following steps are followed (roughly): libs-y += arch/sparc/lib/ drivers-$(CONFIG_PM) += arch/sparc/power/ - drivers-$(CONFIG_OPROFILE) += arch/sparc/oprofile/ 7.5 Architecture-specific boot images ------------------------------------- |