path: root/Documentation/kbuild
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2021-04-29Merge tag 'kconfig-v5.13' of ↵Linus Torvalds
git:// Pull Kconfig updates from Masahiro Yamada: - Change 'option defconfig' to the environment variable KCONFIG_DEFCONFIG_LIST - Refactor tinyconfig without using allnoconfig_y - Remove 'option allnoconfig_y' syntax - Change 'option modules' to 'modules' - Do not use /boot/config-* etc. as base config for cross-compilation - Fix a search bug in nconf - Various code cleanups * tag 'kconfig-v5.13' of git:// (34 commits) kconfig: refactor .gitignore kconfig: highlight xconfig 'comment' lines with '***' kconfig: highlight gconfig 'comment' lines with '***' kconfig: gconf: remove unused code kconfig: remove unused PACKAGE definition kconfig: nconf: stop endless search loops kconfig: split menu.c out of parser.y kconfig: nconf: refactor in print_in_middle() kconfig: nconf: remove meaningless wattrset() call from show_menu() kconfig: nconf: change set_config_filename() to void function kconfig: nconf: refactor attributes setup code kconfig: nconf: remove unneeded default for menu prompt kconfig: nconf: get rid of (void) casts from wattrset() calls kconfig: nconf: fix NORMAL attributes kconfig: mconf,nconf: remove unneeded '\0' termination after snprintf() kconfig: use /boot/config-* etc. as DEFCONFIG_LIST only for native build kconfig: change sym_change_count to a boolean flag kconfig: nconf: fix core dump when searching in empty menu kconfig: lxdialog: A spello fix and a punctuation added kconfig: Couple of typo fixes ...
2021-04-25docs: kbuild: Fix a typo in the file Kconfig.recursion-issue-02Bhaskar Chowdhury
s/sematics/semantics/ Signed-off-by: Bhaskar Chowdhury <> Acked-by: Randy Dunlap <> Signed-off-by: Masahiro Yamada <>
2021-04-14kconfig: change "modules" from sub-option to first-level attributeMasahiro Yamada
Now "modules" is the only member of the "option" property. Remove "option", and move "modules" to the top level property. Signed-off-by: Masahiro Yamada <>
2021-04-14kconfig: remove allnoconfig_y optionMasahiro Yamada
Now that the only user, CONFIG_EMBEDDED has stopped using this option, remove it entirely. Signed-off-by: Masahiro Yamada <>
2021-04-14kconfig: change defconfig_list option to environment variableMasahiro Yamada
"defconfig_list" is a weird option that defines a static symbol that declares the list of base config files in case the .config does not exist yet. This is quite different from other normal symbols; we just abused the "string" type and the "default" properties to list out the input files. They must be fixed values since these are searched for and loaded in the parse stage. It is an ugly hack, and should not exist in the first place. Providing this feature as an environment variable is a saner approach. Signed-off-by: Masahiro Yamada <>
2021-02-25Merge tag 'kbuild-v5.12' of ↵Linus Torvalds
git:// Pull Kbuild updates from Masahiro Yamada: - Fix false-positive build warnings for ARCH=ia64 builds - Optimize dictionary size for module compression with xz - Check the compiler and linker versions in Kconfig - Fix misuse of extra-y - Support DWARF v5 debug info - Clamp SUBLEVEL to 255 because stable releases 4.4.x and 4.9.x exceeded the limit - Add generic syscall{tbl,hdr}.sh for cleanups across arches - Minor cleanups of genksyms - Minor cleanups of Kconfig * tag 'kbuild-v5.12' of git:// (38 commits) initramfs: Remove redundant dependency of RD_ZSTD on BLK_DEV_INITRD kbuild: remove deprecated 'always' and 'hostprogs-y/m' kbuild: parse C= and M= before changing the working directory kbuild: reuse this-makefile to define abs_srctree kconfig: unify rule of config, menuconfig, nconfig, gconfig, xconfig kconfig: omit --oldaskconfig option for 'make config' kconfig: fix 'invalid option' for help option kconfig: remove dead code in conf_askvalue() kconfig: clean up nested if-conditionals in check_conf() kconfig: Remove duplicate call to sym_get_string_value() Makefile: Remove # characters from compiler string Makefile: reuse CC_VERSION_TEXT kbuild: check the minimum linker version in Kconfig kbuild: remove ld-version macro scripts: add generic scripts: add generic arch: syscalls: remove $(srctree)/ prefix from syscall tables arch: syscalls: add missing FORCE and fix 'targets' to make if_changed work gen_compile_commands: prune some directories kbuild: simplify access to the kernel's version ...
2021-02-22Merge tag 'scsi-misc' of git:// Torvalds
Pull SCSI updates from James Bottomley: "This series consists of the usual driver updates (ufs, ibmvfc, qla2xxx, hisi_sas, pm80xx) plus the removal of the gdth driver (which is bound to cause conflicts with a trivial change somewhere). The only big major rework of note is the one from Hannes trying to clean up our result handling code in the drivers to make it consistent" * tag 'scsi-misc' of git:// (194 commits) scsi: MAINTAINERS: Adjust to reflect gdth scsi driver removal scsi: ufs: Give clk scaling min gear a value scsi: lpfc: Fix 'physical' typos scsi: megaraid_mbox: Fix spelling of 'allocated' scsi: qla2xxx: Simplify the calculation of variables scsi: message: fusion: Fix 'physical' typos scsi: target: core: Change ASCQ for residual write scsi: target: core: Signal WRITE residuals scsi: target: core: Set residuals for 4Kn devices scsi: hisi_sas: Add trace FIFO debugfs support scsi: hisi_sas: Flush workqueue in hisi_sas_v3_remove() scsi: hisi_sas: Enable debugfs support by default scsi: hisi_sas: Don't check .nr_hw_queues in hisi_sas_task_prep() scsi: hisi_sas: Remove deferred probe check in hisi_sas_v2_probe() scsi: lpfc: Add auto select on IRQ_POLL scsi: ncr53c8xx: Fix typos scsi: lpfc: Fix ancient double free scsi: qla2xxx: Fix some memory corruption scsi: qla2xxx: Remove redundant NULL check scsi: megaraid: Fix ifnullfree.cocci warnings ...
2021-02-21Merge tag 'oprofile-removal-5.12' of ↵Linus Torvalds
git:// Pull oprofile and dcookies removal from Viresh Kumar: "Remove oprofile and dcookies support The 'oprofile' user-space tools don't use the kernel OPROFILE support any more, and haven't in a long time. User-space has been converted to the perf interfaces. The dcookies stuff is only used by the oprofile code. Now that oprofile's support is getting removed from the kernel, there is no need for dcookies as well. Remove kernel's old oprofile and dcookies support" * tag 'oprofile-removal-5.12' of git:// fs: Remove dcookies support drivers: Remove CONFIG_OPROFILE support arch: xtensa: Remove CONFIG_OPROFILE support arch: x86: Remove CONFIG_OPROFILE support arch: sparc: Remove CONFIG_OPROFILE support arch: sh: Remove CONFIG_OPROFILE support arch: s390: Remove CONFIG_OPROFILE support arch: powerpc: Remove oprofile arch: powerpc: Stop building and using oprofile arch: parisc: Remove CONFIG_OPROFILE support arch: mips: Remove CONFIG_OPROFILE support arch: microblaze: Remove CONFIG_OPROFILE support arch: ia64: Remove rest of perfmon support arch: ia64: Remove CONFIG_OPROFILE support arch: hexagon: Don't select HAVE_OPROFILE arch: arc: Remove CONFIG_OPROFILE support arch: arm: Remove CONFIG_OPROFILE support arch: alpha: Remove CONFIG_OPROFILE support
2021-02-16kbuild: doc: remove "Objects which export symbols" sectionMasahiro Yamada
EXPORT_SYMBOL is unrelated to makefiles. No need to mention it. Signed-off-by: Masahiro Yamada <>
2021-02-01kbuild: remove PYTHON variableMasahiro Yamada
Python retired in 2020, and some distributions do not provide the 'python' command any more. As in commit 51839e29cb59 ("scripts: switch explicitly to Python 3"), we need to use more specific 'python3' to invoke scripts even if they are written in a way compatible with both Python 2 and 3. This commit removes the variable 'PYTHON', and switches the existing users to 'PYTHON3'. BTW, PEP 394 ( is a helpful material. Signed-off-by: Masahiro Yamada <>
2021-01-30Documentation/llvm: Add a section about supported architecturesNathan Chancellor
The most common question around building the Linux kernel with clang is "does it work?" and the answer has always been "it depends on your architecture, configuration, and LLVM version" with no hard answers for users wanting to experiment. LLVM support has significantly improved over the past couple of years, resulting in more architectures and configurations supported, and continuous integration has made it easier to see what works and what does not. Add a section that goes over what architectures are supported in the current kernel version, how they should be built (with just clang or the LLVM utilities as well), and the level of support they receive. This will make it easier for people to try out building their kernel with LLVM and reporting issues that come about from it. Suggested-by: Miguel Ojeda <> Signed-off-by: Nathan Chancellor <> Reviewed-by: Nick Desaulniers <> Signed-off-by: Masahiro Yamada <>
2021-01-29arch: sparc: Remove CONFIG_OPROFILE supportViresh Kumar
The "oprofile" user-space tools don't use the kernel OPROFILE support any more, and haven't in a long time. User-space has been converted to the perf interfaces. Remove the old oprofile's architecture specific support. Suggested-by: Christoph Hellwig <> Suggested-by: Linus Torvalds <> Signed-off-by: Viresh Kumar <> Acked-by: Robert Richter <> Acked-by: William Cohen <> Acked-by: Al Viro <> Acked-by: Thomas Gleixner <>
2021-01-26doc: gcc-plugins: update gcc-plugins.rstMasahiro Yamada
This document was written a long time ago. Update it. [1] Drop the version information The range of the supported GCC versions are always changing. The current minimal GCC version is 4.9, and commit 1e860048c53e ("gcc-plugins: simplify GCC plugin-dev capability test") removed the old code accordingly. We do not need to mention specific version ranges like "all gcc versions from 4.5 to 6.0" since we forget to update the documentation when we raise the minimal compiler version. [2] Drop the C compiler statements Since commit 77342a02ff6e ("gcc-plugins: drop support for GCC <= 4.7") the GCC plugin infrastructure only supports g++. [3] Drop supported architectures As of v5.11-rc4, the infrastructure supports more architectures; arm, arm64, mips, powerpc, riscv, s390, um, and x86. (just grep "select HAVE_GCC_PLUGINS") Again, we miss to update this document when a new architecture is supported. Let's just say "only some architectures". [4] Update the apt-get example We are now discussing to bump the minimal version to GCC 5. The GCC 4.9 support will be removed sooner or later. Change the package example to gcc-10-plugin-dev while we are here. [5] Update the build target Since commit ce2fd53a10c7 ("kbuild: descend into scripts/gcc-plugins/ via scripts/Makefile"), "make gcc-plugins" is not supported. "make scripts" builds all the enabled plugins, including some other tools. [6] Update the steps for adding a new plugin At first, all CONFIG options for GCC plugins were located in arch/Kconfig. After commit 45332b1bdfdc ("gcc-plugins: split out Kconfig entries to scripts/gcc-plugins/Kconfig"), scripts/gcc-plugins/Kconfig became the central place to collect plugin CONFIG options. In my understanding, this requirement no longer exists because commit 9f671e58159a ("security: Create "kernel hardening" config area") moved some of plugin CONFIG options to another file. Find an appropriate place to add the new CONFIG. The sub-directory support was never used by anyone, and removed by commit c17d6179ad5a ("gcc-plugins: remove unused GCC_PLUGIN_SUBDIR"). Remove the useless $(src)/ prefix. Signed-off-by: Masahiro Yamada <>
2021-01-23Documentation/Kbuild: Remove references to gcc-plugin.shRobert Karszniewicz has been removed in commit 1e860048c53e ("gcc-plugins: simplify GCC plugin-dev capability test"). Signed-off-by: Robert Karszniewicz <> Reviewed-by: Kees Cook <> Signed-off-by: Masahiro Yamada <>
2021-01-22scsi: Drop gdth driverHannes Reinecke
The gdth driver refers to a SCSI parallel, PCI-only HBA RAID adapter which was manufactured by the now-defunct ICP Vortex company, later acquired by Adaptec and superseded by the aacraid series of controllers. The driver itself would require a major overhaul before any modifications can be attempted, but seeing that it's unlikely to have any users left it should rather be removed completely. Link: Cautiously-Acked-by: Christoph Hellwig <> Signed-off-by: Hannes Reinecke <> Signed-off-by: Martin K. Petersen <>
2021-01-11Documentation: kbuild: Fix section referenceViresh Kumar
Section 3.11 was incorrectly called 3.9, fix it. Signed-off-by: Viresh Kumar <> Signed-off-by: Masahiro Yamada <>
2020-12-22Merge tag 'kconfig-v5.11' of ↵Linus Torvalds
git:// Pull Kconfig updates from Masahiro Yamada: - Support only Qt5 for qconf - Validate signal/slot connection at compile time of qconf - Sanitize header includes * tag 'kconfig-v5.11' of git:// kconfig: doc: fix $(fileno) to $(filename) kconfig: fix return value of do_error_if() kconfig: clean up header inclusion kconfig: qconf: show Qt version in the About dialog kconfig: make lkc.h self-sufficient #include-wise kconfig: qconf: convert to Qt5 new signal/slot connection syntax kconfig: qconf: use a variable to pass packages to pkg-config kconfig: qconf: drop Qt4 support
2020-12-21kconfig: doc: fix $(fileno) to $(filename)Masahiro Yamada
This is a typo. Signed-off-by: Masahiro Yamada <>
2020-12-21Documentation/kbuild: Document platform dependency practisesGeert Uytterhoeven
Document best practises for using architecture and platform dependencies. Signed-off-by: Geert Uytterhoeven <> Signed-off-by: Masahiro Yamada <>
2020-12-21Documentation/kbuild: Document COMPILE_TEST dependenciesGeert Uytterhoeven
Document best practises for using COMPILE_TEST dependencies. Signed-off-by: Geert Uytterhoeven <> Acked-by: Arnd Bergmann <> Signed-off-by: Masahiro Yamada <>
2020-12-21kbuild: doc: document subdir-y syntaxMasahiro Yamada
There is no explanation about subdir-y. Let's document it. Signed-off-by: Masahiro Yamada <> Reviewed-by: Randy Dunlap <>
2020-12-21kbuild: doc: clarify the difference between extra-y and always-yMasahiro Yamada
The difference between extra-y and always-y is obscure. Basically, Kbuild builds targets listed in extra-y and always-y in visited Makefiles without relying on any dependency. The difference is that extra-y is used to list the targets needed for vmlinux whereas always-y is used to list the targets that must be always built irrespective of final targets. Kbuild skips extra-y when it is building only modules (i.e. 'make modules'). This is the long-standing behavior since extra-y was introduced in 2003, and it is explained in that commit log [1]. For clarification, this is the extra-y vs always-y table: extra-y always-y 'make' y y 'make vmlinux' y y 'make modules' n y Kbuild skips extra-y also when building external modules since obviously it never builds vmlinux. Unfortunately, extra-y is wrongly used in many places of upstream code, and even in external modules. Using extra-y in external module Makefiles is wrong. What you should use is probably always-y or 'targets'. The current documentation for extra-y is misleading. I rewrote it, and moved it to the section 3.7. always-y is not documented anywhere. I added. [1]: Signed-off-by: Masahiro Yamada <> Reviewed-by: Randy Dunlap <>
2020-12-21kbuild: doc: split if_changed explanation to a separate sectionMasahiro Yamada
The if_changed macro is currently explained in the section "Commands useful for building a boot image", but the use of if_changed is not limited to the boot image. It is often used together with custom rules. Let's split it as a separate section, and insert it after the "Custom Rules" section. I slightly reworded the explanation, re-numbered to fill the <deleted> section, and also fixed the broken indentation of the Note: part. Signed-off-by: Masahiro Yamada <>
2020-12-21kbuild: doc: merge 'Special Rules' and 'Custom kbuild commands' sectionsMasahiro Yamada
The two sections "3.10 Special Rules" and "7.8 Custom kbuild commands" are related because you must understand both of them when you write custom rules. Actually I do not understand the policy about what to go into "3 The kbuild files" and what into "7 Architecture Makefile". This commit reworks the custom rule explanation as follows: - Merged "7.8 Custom kbuild commands" into "3.10 Special Rules". - Reword "Special Rules" to "Custom Rules" for consistency. - Update the example for kecho because the blackfin Makefile does not exist any more. - Replace the example for cmd_<command> with a simpler one. Signed-off-by: Masahiro Yamada <>
2020-12-21kbuild: doc: fix 'List directories to visit when descending' sectionMasahiro Yamada
Fix stale information: - Fix the section number in the reference from 6.4 to 7.4. - Remove init-y and net-y. They were removed by commit 23febe375d94 ("kbuild: merge init-y into core-y") and commit 95fb6317b3ab ("kbuild: merge net-y and virt-y into drivers-y"), respectively. - Update the example because arch/sparc64/Makefile does not exit. Signed-off-by: Masahiro Yamada <>
2020-12-21kbuild: doc: replace arch/$(ARCH)/ with arch/$(SRCARCH)/Masahiro Yamada
Precisely speaking, the arch directory is specified by $(SRCARCH), not $(ARCH). In old days, $(ARCH) actually matched to the arch directory because 32-bit and 64-bit were supported as separate architectures. Most architectures (except arm/arm64) were unified like follows: arch/i386, arch/x86_64 -> arch/x86 arch/sh, arch/sh64 -> arch/sh arch/sparc, arch/sparc64 -> arch/sparc To not break the user interface, commit 6752ed90da03 ("Kbuild: allow arch/xxx to use a different source path") introduced SRCARCH to point to the arch directory, still allowing to pass in the former ARCH=i386 or ARCH=x86_64. Update the documents for preciseness, and add the explanation of SRCARCH. Signed-off-by: Masahiro Yamada <> Reviewed-by: Randy Dunlap <>
2020-12-21kbuild: doc: update the description about kbuild MakefilesMasahiro Yamada
This line was written in 2003. Now we have much more Makefiles. The number of Makefiles is not important. The point is we have a Makefile in (almost) every directory. Signed-off-by: Masahiro Yamada <>
2020-11-02kbuild: remove unused OBJSIZEVasily Gorbik
The "size" tool has been solely used by s390 to enforce .bss section usage restrictions in early startup code. Since commit 980d5f9ab36b ("s390/boot: enable .bss section for compressed kernel") and commit 2e83e0eb85ca ("s390: clean .bss before running uncompressed kernel") these restrictions have been lifted for the decompressor and uncompressed kernel and the size tool is now unused. Signed-off-by: Vasily Gorbik <> Reviewed-by: Nathan Chancellor <> Signed-off-by: Masahiro Yamada <>
2020-10-13kbuild: doc: describe proper script invocationLukas Bulwahn
During an investigation to fix up the execute bits of scripts in the kernel repository, Andrew Morton and Kees Cook pointed out that the execute bit should not matter, and that build scripts cannot rely on that. Kees could not point to any documentation, though. Masahiro Yamada explained the convention of setting execute bits to make it easier for manual script invocation. Provide some basic documentation how the build shall invoke scripts, such that the execute bits do not matter, and acknowledge that execute bits are useful nonetheless. This serves as reference for further clean-up patches in the future. Suggested-by: Andrew Morton <> Suggested-by: Kees Cook <> Signed-off-by: Lukas Bulwahn <> Signed-off-by: Andrew Morton <> Cc: Masahiro Yamada <> Cc: Michal Marek <> Cc: Jonathan Corbet <> Cc: Ujjwal Kumar <> Cc: Lukas Bulwahn <> Link: Link: Link: Link: Signed-off-by: Linus Torvalds <>
2020-10-12Merge tag 'docs-5.10' of git:// Torvalds
Pull documentation updates from Jonathan Corbet: "As hoped, things calmed down for docs this cycle; fewer changes and almost no conflicts at all. This includes: - A reworked and expanded user-mode Linux document - Some simplifications and improvements for submitting-patches.rst - An emergency fix for (some) problems with Sphinx 3.x - Some welcome automarkup improvements to automatically generate cross-references to struct definitions and other documents - The usual collection of translation updates, typo fixes, etc" * tag 'docs-5.10' of git:// (81 commits) gpiolib: Update indentation in driver.rst for code excerpts Documentation/admin-guide: tainted-kernels: Fix typo occured Documentation: better locations for sysfs-pci, sysfs-tagging docs: programming-languages: refresh blurb on clang support Documentation: kvm: fix a typo Documentation: Chinese translation of Documentation/arm64/amu.rst doc: zh_CN: index files in arm64 subdirectory mailmap: add entry for <> doc: seq_file: clarify role of *pos in ->next() docs: trace: ring-buffer-design.rst: use the new SPDX tag Documentation: kernel-parameters: clarify "module." parameters Fix references to nommu-mmap.rst docs: rewrite admin-guide/sysctl/abi.rst docs: fb: Remove vesafb scrollback boot option docs: fb: Remove sstfb scrollback boot option docs: fb: Remove matroxfb scrollback boot option docs: fb: Remove framebuffer scrollback boot option docs: replace the old User Mode Linux HowTo with a new one Documentation/admin-guide: blockdev/ramdisk: remove use of "rdev" Documentation/admin-guide: README & svga: remove use of "rdev" ...
2020-09-26Documentation/llvm: Fix clang target examplesFlorian Fainelli
clang --target=<triple> is how we can specify a particular toolchain triple to be use, fix the two occurences in the documentation. Fixes: fcf1b6a35c16 ("Documentation/llvm: add documentation on building w/ Clang/LLVM") Signed-off-by: Florian Fainelli <> Reviewed-by: Nick Desaulniers <> Reviewed-by: Nathan Chancellor <> Signed-off-by: Masahiro Yamada <>
2020-09-03kbuild: Documentation: clean up makefiles.rstRandy Dunlap
This is a general cleanup of kbuild/makefiles.rst: * Use "Chapter" for major heading references and use "section" for the next-level heading references, for consistency. * Section 3.8 was deleted long ago. * Drop the ending ':' in section names in the contents list. * Correct some section numbering references. * Correct verb agreement typo. * Fix run-on sentence punctuation. Signed-off-by: Randy Dunlap <> Signed-off-by: Masahiro Yamada <>
2020-08-31Documentation: add minimum clang/llvm versionNick Desaulniers
Based on a vote at the LLVM BoF at Plumbers 2020, we decided to start small, supporting just one formal upstream release of LLVM for now. We can probably widen the support window of supported versions over time. Also, note that LLVM's release process is different than GCC's. GCC tends to have 1 major release per year while releasing minor updates to the past 3 major versions. LLVM tends to support one major release and one minor release every six months. Signed-off-by: Nick Desaulniers <> Tested-by: Gustavo A. R. Silva <> Tested-by: Nathan Chancellor <> Reviewed-by: Kees Cook <> Reviewed-by: Nathan Chancellor <> Reviewed-by: Masahiro Yamada <> Acked-by: Will Deacon <> Link: Signed-off-by: Jonathan Corbet <>
2020-08-31Documentation/llvm: Improve formatting of commands, variables, and argumentsNathan Chancellor
While reviewing a separate patch, I noticed that the formatting of the commands, variables, and arguments was not in a monospaced font like the rest of the Kbuild documentation (see kbuild/kconfig.rst for an example). This is due to a lack of "::" before indented command blocks and single backticks instead of double backticks for inline formatting. Add those so that the document looks nicer in an HTML format, while not ruining the look in plain text. As a result of this, we can remove the escaped backslashes in the last code block and move them to single backslashes. Signed-off-by: Nathan Chancellor <> Reviewed-by: Nick Desaulniers <> Signed-off-by: Masahiro Yamada <>
2020-08-09Merge tag 'kbuild-v5.9' of ↵Linus Torvalds
git:// Pull Kbuild updates from Masahiro Yamada: - run the checker (e.g. sparse) after the compiler - remove unneeded cc-option tests for old compiler flags - fix tar-pkg to install dtbs - introduce ccflags-remove-y and asflags-remove-y syntax - allow to trace functions in sub-directories of lib/ - introduce hostprogs-always-y and userprogs-always-y syntax - various Makefile cleanups * tag 'kbuild-v5.9' of git:// kbuild: stop filtering out $(GCC_PLUGINS_CFLAGS) from cc-option base kbuild: include scripts/Makefile.* only when relevant CONFIG is enabled kbuild: introduce hostprogs-always-y and userprogs-always-y kbuild: sort hostprogs before passing it to ifneq kbuild: move host .so build rules to scripts/gcc-plugins/Makefile kbuild: Replace HTTP links with HTTPS ones kbuild: trace functions in subdirectories of lib/ kbuild: introduce ccflags-remove-y and asflags-remove-y kbuild: do not export LDFLAGS_vmlinux kbuild: always create directories of targets powerpc/boot: add DTB to 'targets' kbuild: buildtar: add dtbs support kbuild: remove cc-option test of -ffreestanding kbuild: remove cc-option test of -fno-stack-protector Revert "kbuild: Create directory for target DTB" kbuild: run the checker after the compiler
2020-08-10kbuild: introduce hostprogs-always-y and userprogs-always-yMasahiro Yamada
To build host programs, you need to add the program names to 'hostprogs' to use the necessary build rule, but it is not enough to build them because there is no dependency. There are two types of host programs: built as the prerequisite of another (e.g. gen_crc32table in lib/Makefile), or always built when Kbuild visits the Makefile (e.g. genksyms in scripts/genksyms/Makefile). The latter is typical in Makefiles under scripts/, which contains host programs globally used during the kernel build. To build them, you need to add them to both 'hostprogs' and 'always-y'. This commit adds hostprogs-always-y as a shorthand. The same applies to user programs. net/bpfilter/Makefile builds bpfilter_umh on demand, hence always-y is unneeded. In contrast, programs under samples/ are added to both 'userprogs' and 'always-y' so they are always built when Kbuild visits the Makefiles. userprogs-always-y works as a shorthand. Signed-off-by: Masahiro Yamada <> Acked-by: Miguel Ojeda <>
2020-08-10kbuild: Replace HTTP links with HTTPS onesAlexander A. Klimov
Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov <> Signed-off-by: Masahiro Yamada <>
2020-08-10kbuild: introduce ccflags-remove-y and asflags-remove-yMasahiro Yamada
CFLAGS_REMOVE_<file>.o filters out flags when compiling a particular object, but there is no convenient way to do that for every object in a directory. Add ccflags-remove-y and asflags-remove-y to make it easily. Use ccflags-remove-y to clean up some Makefiles. The add/remove order works as follows: [1] KBUILD_CFLAGS specifies compiler flags used globally [2] ccflags-y adds compiler flags for all objects in the current Makefile [3] ccflags-remove-y removes compiler flags for all objects in the current Makefile (New feature) [4] CFLAGS_<file> adds compiler flags per file. [5] CFLAGS_REMOVE_<file> removes compiler flags per file. Having [3] before [4] allows us to remove flags from most (but not all) objects in the current Makefile. For example, kernel/trace/Makefile removes $(CC_FLAGS_FTRACE) from all objects in the directory, then adds it back to trace_selftest_dynamic.o and CFLAGS_trace_kprobe_selftest.o The same applies to lib/livepatch/Makefile. Please note ccflags-remove-y has no effect to the sub-directories. In contrast, the previous notation got rid of compiler flags also from all the sub-directories. The following are not affected because they have no sub-directories: arch/arm/boot/compressed/ arch/powerpc/xmon/ arch/sh/ kernel/trace/ However, lib/ has several sub-directories. To keep the behavior, I added ccflags-remove-y to all Makefiles in subdirectories of lib/, except the following: lib/vdso/Makefile - Kbuild does not descend into this Makefile lib/raid/test/Makefile - This is not used for the kernel build I think commit 2464a609ded0 ("ftrace: do not trace library functions") excluded too much. In the next commit, I will remove ccflags-remove-y from the sub-directories of lib/. Suggested-by: Sami Tolvanen <> Signed-off-by: Masahiro Yamada <> Acked-by: Steven Rostedt (VMware) <> Acked-by: Michael Ellerman <> (powerpc) Acked-by: Brendan Higgins <> (KUnit) Tested-by: Anders Roxell <>
2020-08-04Merge tag 'docs-5.9' of git:// Torvalds
Pull documentation updates from Jonathan Corbet: "It's been a busy cycle for documentation - hopefully the busiest for a while to come. Changes include: - Some new Chinese translations - Progress on the battle against double words words and non-HTTPS URLs - Some block-mq documentation - More RST conversions from Mauro. At this point, that task is essentially complete, so we shouldn't see this kind of churn again for a while. Unless we decide to switch to asciidoc or something...:) - Lots of typo fixes, warning fixes, and more" * tag 'docs-5.9' of git:// (195 commits) scripts/kernel-doc: optionally treat warnings as errors docs: ia64: correct typo mailmap: add entry for <> doc/zh_CN: add cpu-load Chinese version Documentation/admin-guide: tainted-kernels: fix spelling mistake MAINTAINERS: adjust kprobes.rst entry to new location devices.txt: document rfkill allocation PCI: correct flag name docs: filesystems: vfs: correct flag name docs: filesystems: vfs: correct sync_mode flag names docs: path-lookup: markup fixes for emphasis docs: path-lookup: more markup fixes docs: path-lookup: fix HTML entity mojibake CREDITS: Replace HTTP links with HTTPS ones docs: process: Add an example for creating a fixes tag doc/zh_CN: add Chinese translation prefer section doc/zh_CN: add clearing-warn-once Chinese version doc/zh_CN: add admin-guide index doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label futex: MAINTAINERS: Re-add selftests directory ...
2020-07-13Documentation: kbuild/kconfig-language: eliminate duplicated wordRandy Dunlap
Drop the doubled word "the". Signed-off-by: Randy Dunlap <> Acked-by: Masahiro Yamada <> Cc: Jonathan Corbet <> Cc: Cc: Masahiro Yamada <> Cc: Michal Marek <> Cc: Link: Signed-off-by: Jonathan Corbet <>
2020-07-07kbuild: remove cc-option test of -fno-stack-protectorMasahiro Yamada
Some Makefiles already pass -fno-stack-protector unconditionally. For example, arch/arm64/kernel/vdso/Makefile, arch/x86/xen/Makefile. No problem report so far about hard-coding this option. So, we can assume all supported compilers know -fno-stack-protector. GCC 4.8 and Clang support this option ( Get rid of cc-option from -fno-stack-protector. Remove CONFIG_CC_HAS_STACKPROTECTOR_NONE, which is always 'y'. Note: arch/mips/vdso/Makefile adds -fno-stack-protector twice, first unconditionally, and second conditionally. I removed the second one. Signed-off-by: Masahiro Yamada <> Reviewed-by: Kees Cook <> Acked-by: Ard Biesheuvel <> Reviewed-by: Nick Desaulniers <>
2020-06-28docs: kbuild: fix ReST formattingDov Murik
Commit cd238effefa2 ("docs: kbuild: convert docs to ReST and rename to *.rst") missed a ReST header and a verbatim file content area. Signed-off-by: Dov Murik <> Signed-off-by: Masahiro Yamada <>
2020-06-28gcc-plugins: fix gcc-plugins directory path in documentationMasahiro Yamada
Fix typos "plgins" -> "plugins". Signed-off-by: Masahiro Yamada <> Acked-by: Kees Cook <>
2020-06-06kbuild: doc: rename LDFLAGS to KBUILD_LDFLAGSMasahiro Yamada
Commit d503ac531a52 ("kbuild: rename LDFLAGS to KBUILD_LDFLAGS") missed to update the documentation. Signed-off-by: Masahiro Yamada <>
2020-05-26kbuild: doc: remove documentation about copying Module.symvers aroundMasahiro Yamada
This is a left-over of commit 39808e451fdf ("kbuild: do not read $(KBUILD_EXTMOD)/Module.symvers"). Kbuild no longer supports this way. Signed-off-by: Masahiro Yamada <>
2020-05-17kbuild: doc: document the new syntax 'userprogs'Masahiro Yamada
Kbuild now supports the syntax 'userprogs' to compile userspace programs for the same architecture as the kernel. Insert the section '5 Userspace Program support' to explain it. I copy-pasted '4 Host Program support' and fixed it up. Signed-off-by: Masahiro Yamada <> Acked-by: Sam Ravnborg <>
2020-04-23Documentation: kbuild: fix the section title formatMasahiro Yamada
Make it consistent with the other sections. Signed-off-by: Masahiro Yamada <>
2020-04-09kbuild: support LLVM=1 to switch the default tools to Clang/LLVMMasahiro Yamada
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: 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 <> Reviewed-by: Nathan Chancellor <> Tested-by: Nathan Chancellor <> # build Tested-by: Nick Desaulniers <> Reviewed-by: Nick Desaulniers <>
2020-04-09kbuild: replace AS=clang with LLVM_IAS=1Masahiro Yamada
The 'AS' variable is unused for building the kernel. Only the remaining usage is to turn on the integrated assembler. A boolean flag is a better fit for this purpose. AS=clang was added for experts. So, I replaced it with LLVM_IAS=1, breaking the backward compatibility. Suggested-by: Nick Desaulniers <> Signed-off-by: Masahiro Yamada <> Reviewed-by: Nathan Chancellor <> Reviewed-by: Nick Desaulniers <>
2020-04-09Documentation/llvm: fix the name of llvm-sizeFangrui Song
The tool is called llvm-size, not llvm-objsize. Fixes: fcf1b6a35c16 ("Documentation/llvm: add documentation on building w/ Clang/LLVM") Signed-off-by: Fangrui Song <> Reviewed-by: Nick Desaulniers <> Reviewed-by: Nathan Chancellor <> Signed-off-by: Masahiro Yamada <>