linux-brain/tools
Masahiro Yamada 62353048e2 kbuild: support LLVM=1 to switch the default tools to Clang/LLVM
commit a0d1c951ef08ed24f35129267e3595d86f57f5d3 upstream.

As Documentation/kbuild/llvm.rst implies, building the kernel with a
full set of LLVM tools gets very verbose and unwieldy.

Provide a single switch LLVM=1 to use Clang and LLVM tools instead
of GCC and Binutils. You can pass it from the command line or as an
environment variable.

Please note LLVM=1 does not turn on the integrated assembler. You need
to pass LLVM_IAS=1 to use it. When the upstream kernel is ready for the
integrated assembler, I think we can make it default.

We discussed what we need, and we agreed to go with a simple boolean
flag that switches both target and host tools:

  https://lkml.org/lkml/2020/3/28/494
  https://lkml.org/lkml/2020/4/3/43

Some items discussed, but not adopted:

- LLVM_DIR

  When multiple versions of LLVM are installed, I just thought supporting
  LLVM_DIR=/path/to/my/llvm/bin/ might be useful.

  CC      = $(LLVM_DIR)clang
  LD      = $(LLVM_DIR)ld.lld
    ...

  However, we can handle this by modifying PATH. So, we decided to not do
  this.

- LLVM_SUFFIX

  Some distributions (e.g. Debian) package specific versions of LLVM with
  naming conventions that use the version as a suffix.

  CC      = clang$(LLVM_SUFFIX)
  LD      = ld.lld(LLVM_SUFFIX)
    ...

  will allow a user to pass LLVM_SUFFIX=-11 to use clang-11 etc.,
  but the suffixed versions in /usr/bin/ are symlinks to binaries in
  /usr/lib/llvm-#/bin/, so this can also be handled by PATH.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com> # build
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-26 10:40:47 +02:00
..
accounting tools/accounting/getdelays.c: fix netlink attribute length 2020-04-13 10:48:08 +02:00
arch x86/syscalls: Revert "x86/syscalls: Make __X32_SYSCALL_BIT be unsigned long" 2020-06-03 08:21:29 +02:00
bpf tools, bpftool: Fix wrong return value in do_dump() 2020-08-19 08:16:19 +02:00
build tools build feature: Quote CC and CXX for their arguments 2020-08-21 13:05:38 +02:00
cgroup iocost_monitor: drop string wrap around numbers when outputting json 2020-06-22 09:31:01 +02:00
debugging
firewire treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
firmware Driver Core and debugfs changes for 5.3-rc1 2019-07-12 12:24:03 -07:00
gpio tools: gpio: Fix out-of-tree build regression 2020-04-17 10:50:17 +02:00
hv - First round of vmbus hibernation support from Dexuan Cui. 2019-09-24 12:36:31 -07:00
iio tools: iio: add .gitignore 2019-08-18 20:45:57 +01:00
include tools lib: Fix builds when glibc contains strlcpy() 2020-02-05 21:22:40 +00:00
io_uring tools/io_uring: sync with liburing 2019-05-23 10:25:26 -06:00
kvm/kvm_stat tools/kvm_stat: Fix kvm_exit filter name 2020-02-11 04:35:36 -08:00
laptop treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 505 2019-06-19 17:11:22 +02:00
leds leds: core: Add support for composing LED class device names 2019-07-25 20:07:52 +02:00
lib tools lib traceevent: Fix memory leak in process_dynamic_array_len 2020-08-11 15:33:38 +02:00
memory-model tools/memory-model: Fix data race detection for unordered store and load 2019-12-31 16:43:40 +01:00
nfsd
objtool kbuild: support LLVM=1 to switch the default tools to Clang/LLVM 2020-08-26 10:40:47 +02:00
pci tools: PCI: Fix fd leakage 2020-01-17 19:48:54 +01:00
pcmcia treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 247 2019-06-19 17:09:08 +02:00
perf perf bench mem: Always memset source before memcpy 2020-08-21 13:05:38 +02:00
power tools/power turbostat: Fix 32-bit capabilities warning 2020-04-08 09:08:39 +02:00
scripts tools: Let O= makes handle a relative path with -C option 2020-04-01 11:02:00 +02:00
spi treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 178 2019-05-30 11:29:19 -07:00
testing selftests/powerpc: ptrace-pkey: Don't update expected UAMOR value 2020-08-21 13:05:33 +02:00
thermal/tmon treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 89 2019-05-24 17:37:52 +02:00
time treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
usb usbip: Fix unsafe unaligned pointer usage 2020-02-24 08:36:44 +01:00
virtio tools/virtio: xen stub 2019-10-13 09:38:27 -04:00
vm tools/vm: fix cross-compile build 2020-04-29 16:33:15 +02:00
wmi treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Makefile tools: Keep list of tools in alphabetical order 2019-08-14 10:59:59 -03:00