Merge tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
"Build system:
- add CONFIG_UNUSED_KSYMS_WHITELIST, which will be useful to define a
fixed set of export symbols for Generic Kernel Image (GKI)
- allow to run 'make dt_binding_check' without .config
- use full schema for checking DT examples in *.yaml files
- make modpost fail for missing MODULE_IMPORT_NS(), which makes more
sense because we know the produced modules are never loadable
- Remove unused 'AS' variable
Kconfig:
- sanitize DEFCONFIG_LIST, and remove ARCH_DEFCONFIG from Kconfig
files
- relax the 'imply' behavior so that symbols implied by 'y' can
become 'm'
- make 'imply' obey 'depends on' in order to make 'imply' really weak
Misc:
- add documentation on building the kernel with Clang/LLVM
- revive __HAVE_ARCH_STRLEN for 32bit sparc to use optimized strlen()
- fix warning from deb-pkg builds when CONFIG_DEBUG_INFO=n
- various script and Makefile cleanups"
* tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
Makefile: Update kselftest help information
kbuild: deb-pkg: fix warning when CONFIG_DEBUG_INFO is unset
kbuild: add outputmakefile to no-dot-config-targets
kbuild: remove AS variable
net: wan: wanxl: refactor the firmware rebuild rule
net: wan: wanxl: use $(M68KCC) instead of $(M68KAS) for rebuilding firmware
net: wan: wanxl: use allow to pass CROSS_COMPILE_M68k for rebuilding firmware
kbuild: add comment about grouped target
kbuild: add -Wall to KBUILD_HOSTCXXFLAGS
kconfig: remove unused variable in qconf.cc
sparc: revive __HAVE_ARCH_STRLEN for 32bit sparc
kbuild: refactor Makefile.dtbinst more
kbuild: compute the dtbs_install destination more simply
Makefile: disallow data races on gcc-10 as well
kconfig: make 'imply' obey the direct dependency
kconfig: allow symbols implied by y to become m
net: drop_monitor: use IS_REACHABLE() to guard net_dm_hw_report()
modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n
modpost: rework and consolidate logging interface
kbuild: allow to run dt_binding_check without kernel configuration
...
This commit is contained in:
Linus Torvalds
@@ -2,7 +2,8 @@
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# Makefile for Sphinx documentation
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#
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subdir-y := devicetree/bindings/
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# for cleaning
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subdir- := devicetree/bindings
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# Check for broken documentation file references
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ifeq ($(CONFIG_WARN_MISSING_DOCUMENTS),y)
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@@ -1,2 +1,2 @@
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*.example.dts
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processed-schema.yaml
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processed-schema*.yaml
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@@ -2,7 +2,6 @@
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DT_DOC_CHECKER ?= dt-doc-validate
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DT_EXTRACT_EX ?= dt-extract-example
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DT_MK_SCHEMA ?= dt-mk-schema
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DT_MK_SCHEMA_FLAGS := $(if $(DT_SCHEMA_FILES), -u)
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quiet_cmd_chk_binding = CHKDT $(patsubst $(srctree)/%,%,$<)
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cmd_chk_binding = $(DT_DOC_CHECKER) -u $(srctree)/$(src) $< ; \
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@@ -11,26 +10,35 @@ quiet_cmd_chk_binding = CHKDT $(patsubst $(srctree)/%,%,$<)
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$(obj)/%.example.dts: $(src)/%.yaml FORCE
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$(call if_changed,chk_binding)
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DT_TMP_SCHEMA := processed-schema.yaml
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# Use full schemas when checking %.example.dts
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DT_TMP_SCHEMA := $(obj)/processed-schema-examples.yaml
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quiet_cmd_mk_schema = SCHEMA $@
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cmd_mk_schema = $(DT_MK_SCHEMA) $(DT_MK_SCHEMA_FLAGS) -o $@ $(real-prereqs)
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DT_DOCS = $(shell \
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DT_DOCS = $(addprefix $(src)/, \
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$(shell \
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cd $(srctree)/$(src) && \
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find * \( -name '*.yaml' ! \
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-name $(DT_TMP_SCHEMA) ! \
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-name 'processed-schema*' ! \
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-name '*.example.dt.yaml' \) \
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)
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))
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DT_SCHEMA_FILES ?= $(addprefix $(src)/,$(DT_DOCS))
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DT_SCHEMA_FILES ?= $(DT_DOCS)
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ifeq ($(CHECK_DTBS),)
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extra-y += $(patsubst $(src)/%.yaml,%.example.dts, $(DT_SCHEMA_FILES))
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extra-y += $(patsubst $(src)/%.yaml,%.example.dt.yaml, $(DT_SCHEMA_FILES))
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endif
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extra-$(CHECK_DT_BINDING) += $(patsubst $(src)/%.yaml,%.example.dts, $(DT_SCHEMA_FILES))
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extra-$(CHECK_DT_BINDING) += $(patsubst $(src)/%.yaml,%.example.dt.yaml, $(DT_SCHEMA_FILES))
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extra-$(CHECK_DT_BINDING) += processed-schema-examples.yaml
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$(obj)/$(DT_TMP_SCHEMA): $(DT_SCHEMA_FILES) FORCE
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override DTC_FLAGS := \
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-Wno-avoid_unnecessary_addr_size \
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-Wno-graph_child_address
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$(obj)/processed-schema-examples.yaml: $(DT_DOCS) FORCE
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$(call if_changed,mk_schema)
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extra-y += $(DT_TMP_SCHEMA)
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$(obj)/processed-schema.yaml: DT_MK_SCHEMA_FLAGS := -u
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$(obj)/processed-schema.yaml: $(DT_SCHEMA_FILES) FORCE
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$(call if_changed,mk_schema)
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extra-y += processed-schema.yaml
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@@ -147,6 +147,10 @@ Note that ``dtbs_check`` will skip any binding schema files with errors. It is
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necessary to use ``dt_binding_check`` to get all the validation errors in the
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binding schema files.
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It is possible to run both in a single command::
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make dt_binding_check dtbs_check
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It is also possible to run checks with a single schema file by setting the
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``DT_SCHEMA_FILES`` variable to a specific schema file.
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@@ -20,6 +20,7 @@ Kernel Build System
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issues
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reproducible-builds
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gcc-plugins
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llvm
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.. only:: subproject and html
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@@ -159,11 +159,11 @@ applicable everywhere (see syntax).
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Given the following example::
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config FOO
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tristate
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tristate "foo"
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imply BAZ
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config BAZ
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tristate
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tristate "baz"
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depends on BAR
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The following values are possible:
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@@ -173,7 +173,10 @@ applicable everywhere (see syntax).
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=== === ============= ==============
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n y n N/m/y
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m y m M/y/n
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y y y Y/n
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y y y Y/m/n
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n m n N/m
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m m m M/n
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y m n M/n
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y n * N
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=== === ============= ==============
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@@ -181,6 +184,24 @@ applicable everywhere (see syntax).
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ability to hook into a secondary subsystem while allowing the user to
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configure that subsystem out without also having to unset these drivers.
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Note: If the combination of FOO=y and BAR=m causes a link error,
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you can guard the function call with IS_REACHABLE()::
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foo_init()
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{
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if (IS_REACHABLE(CONFIG_BAZ))
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baz_register(&foo);
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...
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}
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Note: If the feature provided by BAZ is highly desirable for FOO,
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FOO should imply not only BAZ, but also its dependency BAR::
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config FOO
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tristate "foo"
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imply BAR
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imply BAZ
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- limiting menu display: "visible if" <expr>
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This attribute is only applicable to menu blocks, if the condition is
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@@ -0,0 +1,80 @@
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==============================
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Building Linux with Clang/LLVM
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==============================
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This document covers how to build the Linux kernel with Clang and LLVM
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utilities.
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About
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-----
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The Linux kernel has always traditionally been compiled with GNU toolchains
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such as GCC and binutils. Ongoing work has allowed for `Clang
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<https://clang.llvm.org/>`_ and `LLVM <https://llvm.org/>`_ utilities to be
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used as viable substitutes. Distributions such as `Android
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<https://www.android.com/>`_, `ChromeOS
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<https://www.chromium.org/chromium-os>`_, and `OpenMandriva
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<https://www.openmandriva.org/>`_ use Clang built kernels. `LLVM is a
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collection of toolchain components implemented in terms of C++ objects
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<https://www.aosabook.org/en/llvm.html>`_. Clang is a front-end to LLVM that
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supports C and the GNU C extensions required by the kernel, and is pronounced
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"klang," not "see-lang."
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Clang
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-----
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The compiler used can be swapped out via `CC=` command line argument to `make`.
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`CC=` should be set when selecting a config and during a build.
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make CC=clang defconfig
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make CC=clang
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Cross Compiling
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---------------
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A single Clang compiler binary will typically contain all supported backends,
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which can help simplify cross compiling.
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ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make CC=clang
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`CROSS_COMPILE` is not used to prefix the Clang compiler binary, instead
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`CROSS_COMPILE` is used to set a command line flag: `--target <triple>`. For
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example:
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clang --target aarch64-linux-gnu foo.c
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LLVM Utilities
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--------------
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LLVM has substitutes for GNU binutils utilities. These can be invoked as
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additional parameters to `make`.
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make CC=clang AS=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \\
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OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump OBJSIZE=llvm-objsize \\
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READELF=llvm-readelf HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar \\
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HOSTLD=ld.lld
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Getting Help
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------------
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- `Website <https://clangbuiltlinux.github.io/>`_
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- `Mailing List <https://groups.google.com/forum/#!forum/clang-built-linux>`_: <clang-built-linux@googlegroups.com>
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- `Issue Tracker <https://github.com/ClangBuiltLinux/linux/issues>`_
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- IRC: #clangbuiltlinux on chat.freenode.net
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- `Telegram <https://t.me/ClangBuiltLinux>`_: @ClangBuiltLinux
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- `Wiki <https://github.com/ClangBuiltLinux/linux/wiki>`_
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- `Beginner Bugs <https://github.com/ClangBuiltLinux/linux/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22>`_
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Getting LLVM
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-------------
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- http://releases.llvm.org/download.html
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- https://github.com/llvm/llvm-project
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- https://llvm.org/docs/GettingStarted.html
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- https://llvm.org/docs/CMake.html
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- https://apt.llvm.org/
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- https://www.archlinux.org/packages/extra/x86_64/llvm/
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- https://github.com/ClangBuiltLinux/tc-build
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- https://github.com/ClangBuiltLinux/linux/wiki/Building-Clang-from-source
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- https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/
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Reference in New Issue
Block a user