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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 locking/atomics: Use sed(1) instead of non-standard head(1) option 2019-06-25 10:17:07 +02:00
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 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 166 2019-05-30 11:26:39 -07:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
adjust_autoksyms.sh kbuild: split adjust_autoksyms.sh in two parts 2020-03-03 20:49:21 +09:00
asn1_compiler.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
bin2c.c kbuild: move bin2c back to scripts/ from scripts/basic/ 2018-07-18 01:18:05 +09:00
bloat-o-meter bloat-o-meter: ignore __addressable_ symbols 2018-12-28 12:11:44 -08:00
bootgraph.pl treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 391 2019-06-05 17:37:11 +02:00
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 bpfilter: check compiler capability in Kconfig 2018-06-28 13:36:39 +09:00
check_extable.sh
check-sysctl-docs docs: add a script to check sysctl docs 2020-02-25 03:35:16 -07:00
checkincludes.pl
checkkconfigsymbols.py treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 166 2019-05-30 11:26:39 -07:00
checkpatch.pl checkpatch: avoid warning about uninitialized_var() 2020-04-07 10:43:44 -07:00
checkstack.pl scripts/checkstack.pl: Fix arm64 wrong or unknown architecture 2019-06-05 02:33:10 +09:00
checksyscalls.sh checksyscalls: fix up mq_timedreceive and stat exceptions 2019-02-19 21:27:53 +01:00
checkversion.pl
clang-version.sh kbuild: update comment block of scripts/clang-version.sh 2019-03-04 22:34:54 +09:00
cleanfile
cleanpatch
coccicheck coccicheck: return proper error code on fail 2018-08-14 08:58:56 +09:00
config
const_structs.checkpatch
decode_stacktrace.sh scripts/decode_stacktrace: Accept dash/underscore in modules 2019-07-12 11:05:41 -07:00
decodecode scripts/decodecode: set ARCH when running natively on arm/arm64 2018-12-28 12:11:44 -08:00
depmod.sh kbuild: modules_install: warn when missing System.map file 2018-09-09 09:14:07 +09:00
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_xc3028.pl treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 339 2019-06-05 17:37:07 +02:00
extract-cert.c
extract-ikconfig
extract-module-sig.pl
extract-sys-certs.pl
extract-vmlinux treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 378 2019-06-05 17:37:10 +02:00
faddr2line scripts/faddr2line: fix location of start_kernel in comment 2018-11-18 10:15:09 -08:00
file-size.sh kbuild: Use ls(1) instead of stat(1) to obtain file size 2018-03-26 02:01:24 +09:00
find-unused-docs.sh scripts/find-unused-docs: Fix massive false positives 2020-01-27 14:25:06 -07:00
gcc-goto.sh jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
gcc-ld
gcc-plugin.sh gcc-plugins: drop support for GCC <= 4.7 2020-04-09 00:13:45 +09:00
gcc-version.sh kbuild: clean up scripts/gcc-version.sh 2019-03-04 22:35:04 +09:00
gcc-x86_32-has-stack-protector.sh stack-protector: test compiler capability in Kconfig and drop AUTO mode 2018-06-08 18:56:00 +09:00
gcc-x86_64-has-stack-protector.sh stack-protector: Fix test with 32-bit userland and CONFIG_64BIT=y 2018-06-25 23:21:13 +09:00
gen_autoksyms.sh kbuild: generate autoksyms.h early 2020-03-03 20:49:21 +09:00
gen_compile_commands.py gen_compile_commands: lower the entry count threshold 2019-07-27 12:18:19 +09:00
gen_ksymdeps.sh kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS 2018-12-01 23:13:14 +09:00
get_abi.pl doc: ABI scripts: add a SPDX header file 2019-06-21 16:58:37 +02:00
get_dvb_firmware treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61 2019-05-24 17:36:45 +02:00
get_maintainer.pl scripts/get_maintainer.pl: deprioritize old Fixes: addresses 2020-02-21 11:22:15 -08:00
gfp-translate treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 166 2019-05-30 11:26:39 -07:00
headerdep.pl
headers_check.pl
headers_install.sh kbuild: re-implement detection of CONFIG options leaked to user-space 2019-08-21 21:05:21 +09:00
insert-sys-cert.c
jobserver-exec docs, parallelism: Rearrange how jobserver reservations are made 2019-11-22 10:35:18 -07:00
kallsyms.c scripts/kallsyms: fix wrong kallsyms_relative_base 2020-03-19 23:40:20 +09:00
Kbuild.include kbuild: remove *.tmp file when filechk fails 2020-01-16 00:26:22 +09:00
Kconfig.include gcc-plugins: drop support for GCC <= 4.7 2020-04-09 00:13:45 +09:00
kernel-doc scripts/kernel-doc: Add support for named variable macro arguments 2019-11-07 13:17:24 -07:00
ld-version.sh
leaking_addresses.pl treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 166 2019-05-30 11:26:39 -07:00
Lindent
link-vmlinux.sh bpf: Support llvm-objcopy for vmlinux BTF 2020-03-19 12:32:38 +01:00
Makefile kbuild: remove -I$(srctree)/tools/include from scripts/Makefile 2020-04-09 00:13:45 +09:00
Makefile.asm-generic kbuild: force all architectures except um to include mandatory-y 2019-03-17 12:56:32 +09:00
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 gcc-plugins: structleak: Generalize to all variable types 2019-03-04 09:29:41 -08:00
Makefile.headersinst kbuild: move headers_check rule to usr/include/Makefile 2019-11-15 00:23:10 +09:00
Makefile.host gcc-plugins: drop support for GCC <= 4.7 2020-04-09 00:13:45 +09:00
Makefile.kasan kasan/arm64: fix CONFIG_KASAN_SW_TAGS && KASAN_INLINE 2019-08-15 13:24:04 +01:00
Makefile.kcov treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile.lib kbuild: Always validate DT binding examples 2020-03-03 20:49:21 +09:00
Makefile.modfinal kbuild: move modkern_{c,a}flags to Makefile.lib from Makefile.build 2019-08-22 01:14:11 +09:00
Makefile.modinst kbuild: modinst: read modules.order instead of $(MODVERDIR)/*.mod 2019-07-17 22:39:27 +09:00
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 kbuild: modsign: read modules.order instead of $(MODVERDIR)/*.mod 2019-07-17 22:39:27 +09:00
Makefile.package kbuild: Add make dir-pkg build option 2019-11-11 20:10:01 +09:00
Makefile.ubsan ubsan: split "bounds" checker from other options 2020-04-07 10:43:44 -07:00
makelst
markup_oops.pl treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 373 2019-06-05 17:37:10 +02:00
mkcompile_h kbuild: mkcompile_h: Include $LD version in /proc/version 2020-04-09 00:13:45 +09:00
mkmakefile kbuild: get rid of $(realpath ...) from scripts/mkmakefile 2019-08-29 23:54:29 +09:00
mksysmap
mkuboot.sh
module-common.lds
modules-check.sh kbuild: get rid of kernel/ prefix from in-tree modules.{order,builtin} 2019-07-17 22:39:27 +09:00
namespace.pl namespace: fix namespace.pl script to support relative paths 2019-10-05 15:29:49 +09:00
nsdeps scripts/nsdeps: support nsdeps for external module builds 2019-11-11 20:10:01 +09:00
objdiff treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 199 2019-05-30 11:29:23 -07:00
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 ARM: 8950/1: ftrace/recordmcount: filter relocation types 2020-01-19 16:08:25 +00:00
recordmcount.h recordmcount: Fix nop_mcount() function 2019-10-12 20:49:33 -04:00
recordmcount.pl treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 166 2019-05-30 11:26:39 -07:00
setlocalversion scripts: setlocalversion: replace backquote to dollar parenthesis 2019-11-11 20:10:01 +09:00
show_delta treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 438 2019-06-05 17:37:17 +02:00
sign-file.c
sorttable.c scripts/sorttable: Implement build-time ORC unwind table sorting 2019-12-13 10:47:58 +01:00
sorttable.h scripts/sorttable: Implement build-time ORC unwind table sorting 2019-12-13 10:47:58 +01:00
spdxcheck-test.sh scripts: add spdxcheck.py self test 2018-12-28 12:11:44 -08:00
spdxcheck.py spdxcheck.py: fix directory structures 2019-06-01 15:51:31 -07:00
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 MAINTAINERS & files: Canonize the e-mails I use at files 2018-05-04 06:21:06 -04:00
stackdelta
stackusage
subarch.include selftests: add headers_install to lib.mk 2018-09-05 08:12:09 -06:00
tags.sh kbuild: add a flag to force absolute path for srctree 2019-07-11 00:05:09 +09:00
tools-support-relr.sh scripts/tools-support-relr.sh: un-quote variables 2019-11-13 10:52:05 +00:00
unifdef.c unifdef: use memcpy instead of strncpy 2018-11-30 14:45:01 -08:00
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