WSL2-Linux-Kernel/scripts
Masahiro Yamada 76426e2388 kbuild: add dummy toolchains to enable all cc-option etc. in Kconfig
Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG
options your compiler does not support. This works well if you configure
and build the kernel on the same host machine.

It is inconvenient if you prepare the .config that is carried to a
different build environment (typically this happens when you package
the kernel for distros) because using a different compiler potentially
produces different CONFIG options than the real build environment.
So, you probably want to make as many options visible as possible.
In other words, you need to create a super-set of CONFIG options that
cover any build environment. If some of the CONFIG options turned out
to be unsupported on the build machine, they are automatically disabled
by the nature of Kconfig.

However, it is not feasible to get a full-featured compiler for every
arch.

This issue was discussed here:

  https://lkml.org/lkml/2019/12/9/620

Other than distros, savedefconfig is also a problem. Some arch sub-systems
periodically resync defconfig files. If you use a less-capable compiler
for savedefconfig, options that do not meet 'depends on $(cc-option,...)'
will be forcibly disabled. So, 'make defconfig && make savedefconfig'
may silently change the behavior.

This commit adds a set of dummy toolchains that pretend to support any
feature.

Most of compiler features are tested by cc-option, which simply checks
the exit code of $(CC). The dummy tools are shell scripts that always
exit with 0. So, $(cc-option, ...) is evaluated as 'y'.

There are more complicated checks such as:

  scripts/gcc-x86_{32,64}-has-stack-protector.sh
  scripts/gcc-plugin.sh
  scripts/tools-support-relr.sh

scripts/dummy-tools/gcc passes all checks.

From the top directory of the source tree, you can do:

   $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Tested-by: Jeremy Cline <jcline@redhat.com>
2020-04-09 00:13:45 +09:00
..
atomic
basic SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
coccinelle mm: remove __krealloc 2020-02-04 03:05:24 +00:00
dtc SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
dummy-tools kbuild: add dummy toolchains to enable all cc-option etc. in Kconfig 2020-04-09 00:13:45 +09:00
gcc-plugins gcc-plugins: drop support for GCC <= 4.7 2020-04-09 00:13:45 +09:00
gdb .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
genksyms .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
kconfig kconfig: qconf: Fix a few alignment issues 2020-04-09 00:13:45 +09:00
ksymoops
mod Char/Misc driver patches for 5.7-rc1 2020-04-03 13:22:40 -07:00
package kbuild: deb-pkg: fix warning when CONFIG_DEBUG_INFO is unset 2020-03-30 09:23:00 +09:00
selinux SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
tracing
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
Kbuild.include
Kconfig.include gcc-plugins: drop support for GCC <= 4.7 2020-04-09 00:13:45 +09:00
Lindent
Makefile kbuild: remove -I$(srctree)/tools/include from scripts/Makefile 2020-04-09 00:13:45 +09:00
Makefile.asm-generic
Makefile.build kbuild: link lib-y objects to vmlinux forcibly when CONFIG_MODULES=y 2020-04-09 00:13:45 +09:00
Makefile.clean gcc-plugins: drop support for GCC <= 4.7 2020-04-09 00:13:45 +09:00
Makefile.dtbinst kbuild: refactor Makefile.dtbinst more 2020-03-25 10:19:43 +09:00
Makefile.extrawarn kbuild: Enable -Wtautological-compare 2020-04-09 00:13:45 +09:00
Makefile.gcc-plugins
Makefile.headersinst
Makefile.host gcc-plugins: drop support for GCC <= 4.7 2020-04-09 00:13:45 +09:00
Makefile.kasan
Makefile.kcov
Makefile.lib kbuild: Always validate DT binding examples 2020-03-03 20:49:21 +09:00
Makefile.modfinal
Makefile.modinst
Makefile.modpost modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n 2020-03-13 10:04:36 +09:00
Makefile.modsign
Makefile.package
Makefile.ubsan ubsan: split "bounds" checker from other options 2020-04-07 10:43:44 -07:00
adjust_autoksyms.sh kbuild: split adjust_autoksyms.sh in two parts 2020-03-03 20:49:21 +09:00
asn1_compiler.c
bin2c.c
bloat-o-meter
bootgraph.pl
bpf_helpers_doc.py bpf_helpers_doc.py: Fix warning when compiling bpftool 2020-03-13 20:53:40 +01:00
cc-can-link.sh
check-sysctl-docs docs: add a script to check sysctl docs 2020-02-25 03:35:16 -07:00
check_extable.sh
checkincludes.pl
checkkconfigsymbols.py
checkpatch.pl checkpatch: avoid warning about uninitialized_var() 2020-04-07 10:43:44 -07:00
checkstack.pl
checksyscalls.sh
checkversion.pl
clang-version.sh
cleanfile
cleanpatch
coccicheck
config
const_structs.checkpatch
decode_stacktrace.sh
decodecode
depmod.sh
diffconfig
documentation-file-ref-check SCSI misc on 20200402 2020-04-02 17:03:53 -07:00
export_report.pl modpost: move the namespace field in Module.symvers last 2020-03-17 08:59:03 +09:00
extract-cert.c
extract-ikconfig
extract-module-sig.pl
extract-sys-certs.pl
extract-vmlinux
extract_xc3028.pl
faddr2line
file-size.sh
find-unused-docs.sh
gcc-goto.sh
gcc-ld
gcc-plugin.sh gcc-plugins: drop support for GCC <= 4.7 2020-04-09 00:13:45 +09:00
gcc-version.sh
gcc-x86_32-has-stack-protector.sh
gcc-x86_64-has-stack-protector.sh
gen_autoksyms.sh kbuild: generate autoksyms.h early 2020-03-03 20:49:21 +09:00
gen_compile_commands.py
gen_ksymdeps.sh
get_abi.pl
get_dvb_firmware
get_maintainer.pl scripts/get_maintainer.pl: deprioritize old Fixes: addresses 2020-02-21 11:22:15 -08:00
gfp-translate
headerdep.pl
headers_check.pl
headers_install.sh
insert-sys-cert.c
jobserver-exec
kallsyms.c scripts/kallsyms: fix wrong kallsyms_relative_base 2020-03-19 23:40:20 +09:00
kernel-doc
ld-version.sh
leaking_addresses.pl
link-vmlinux.sh bpf: Support llvm-objcopy for vmlinux BTF 2020-03-19 12:32:38 +01:00
makelst
markup_oops.pl
mkcompile_h kbuild: mkcompile_h: Include $LD version in /proc/version 2020-04-09 00:13:45 +09:00
mkmakefile
mksysmap
mkuboot.sh
module-common.lds
modules-check.sh
namespace.pl
nsdeps
objdiff
parse-maintainers.pl parse-maintainers: Do not sort section content by default 2020-03-26 15:08:27 -07:00
patch-kernel
profile2linkerlist.pl
prune-kernel
recordmcount.c
recordmcount.h
recordmcount.pl
setlocalversion
show_delta
sign-file.c
sorttable.c
sorttable.h
spdxcheck-test.sh
spdxcheck.py
spelling.txt scripts/spelling.txt: add more spellings to spelling.txt 2020-04-02 09:35:25 -07:00
sphinx-pre-install scripts/sphinx-pre-install: add '-p python3' to virtualenv 2020-03-02 13:08:11 -07:00
split-man.pl
stackdelta
stackusage
subarch.include
tags.sh
tools-support-relr.sh
unifdef.c
ver_linux ver_linux: Query ld cache for versions of libc/libcpp run-time 2020-02-10 13:35:15 -08:00
xen-hypercalls.sh
xz_wrap.sh