Changes in Makefile.compiler

1c4494c1 - rust: kbuild: use `pound` to support GNU Make < 4.3

Mon, 14 Apr 2025 17:12:41 +0000

rust: kbuild: use `pound` to support GNU Make < 4.3GNU Make 4.3 changed the behavior of `#` inside commands in commitc6966b323811 ("[SV 20513] Un-escaped # are not comments in functioninvocations"): * WARNING: Backward-incompatibility! Number signs (#) appearing inside a macro reference or function invocation no longer introduce comments and should not be escaped with backslashes: thus a call such as: foo := $(shell echo '#') is legal. Previously the number sign needed to be escaped, for example: foo := $(shell echo '\#') Now this latter will resolve to "\#". If you want to write makefiles portable to both versions, assign the number sign to a variable: H := \# foo := $(shell echo '$H') This was claimed to be fixed in 3.81, but wasn't, for some reason. To detect this change search for 'nocomment' in the .FEATURES variable.Unlike other commits in the kernel about this issue, such as commit633174a7046e ("lib/raid6/test/Makefile: Use $(pound) instead of \#for Make 4.3"), that fixed the issue for newer GNU Makes, in our caseit was the opposite, i.e. we need to fix it for the older ones: someonebuilding with e.g. 4.2.1 gets the following error: scripts/Makefile.compiler:81: *** unterminated call to function 'call': missing ')'. Stop.Thus use the existing variable to fix it.Reported-by: moyi geek <1441339168@qq.com>Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/291565/topic/x/near/512001985Cc: stable@vger.kernel.orgFixes: e72a076c620f ("kbuild: fix issues with rustc-option")Reviewed-by: Nicolas Schier Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250414171241.2126137-1-ojeda@kernel.orgSigned-off-by: Miguel Ojeda List of files: /linux-6.15/scripts/Makefile.compiler

46e24a54 - rust: kasan/kbuild: fix missing flags on first build

Tue, 08 Apr 2025 22:03:11 +0000

rust: kasan/kbuild: fix missing flags on first buildIf KASAN is enabled, and one runs in a clean repository e.g.: make LLVM=1 prepare make LLVM=1 prepareThen the Rust code gets rebuilt, which should not happen.The reason is some of the LLVM KASAN `rustc` flags are added in thesecond run: -Cllvm-args=-asan-instrumentation-with-call-threshold=10000 -Cllvm-args=-asan-stack=0 -Cllvm-args=-asan-globals=1 -Cllvm-args=-asan-kernel-mem-intrinsic-prefix=1Further runs do not rebuild Rust because the flags do not change anymore.Rebuilding like that in the second run is bad, even if this just happenswith KASAN enabled, but missing flags in the first one is even worse.The root issue is that we pass, for some architectures and for the moment,a generated `target.json` file. That file is not ready by the time `rustc`gets called for the flag test, and thus the flag test fails just becausethe file is not available, e.g.: $ ... --target=./scripts/target.json ... -Cllvm-args=... error: target file "./scripts/target.json" does not existThere are a few approaches we could take here to solve this. For instance,we could ensure that every time that the config is rebuilt, we regeneratethe file and recompute the flags. Or we could use the LLVM version tocheck for these flags, instead of testing the flag (which may have otheradvantages, such as allowing us to detect renames on the LLVM side).However, it may be easier than that: `rustc` is aware of the `-Cllvm-args`regardless of the `--target` (e.g. I checked that the list printedis the same, plus that I can check for these flags even if I passa completely unrelated target), and thus we can just eliminate thedependency completely.Thus filter out the target.This does mean that `rustc-option` cannot be used to test a flag thatrequires the right target, but we don't have other users yet, it is aminimal change and we want to get rid of custom targets in the future.We could only filter in the case `target.json` is used, to make it workin more cases, but then it would be harder to notice that it may notwork in a couple architectures.Cc: Matthew Maurer Cc: Sami Tolvanen Cc: stable@vger.kernel.orgFixes: e3117404b411 ("kbuild: rust: Enable KASAN support")Tested-by: Alice Ryhl Link: https://lore.kernel.org/r/20250408220311.1033475-1-ojeda@kernel.orgSigned-off-by: Miguel Ojeda List of files: /linux-6.15/scripts/Makefile.compiler

ac954145 - kbuild: rust: add rustc-min-version support function

Mon, 10 Feb 2025 16:42:45 +0000

kbuild: rust: add rustc-min-version support functionIntroduce `rustc-min-version` support function that mimics`{gcc,clang}-min-version` ones, following commit 88b61e3bff93("Makefile.compiler: replace cc-ifversion with compiler-specific macros").In addition, use it in the first use case we have in the kernel (whichwas done independently to minimize the changes needed for the fix).Signed-off-by: Miguel Ojeda Reviewed-by: Fiona Behrens Reviewed-by: Nicolas Schier Signed-off-by: Masahiro Yamada List of files: /linux-6.15/scripts/Makefile.compiler

13b25489 - kbuild: change working directory to external module directory with M=

Sun, 10 Nov 2024 01:34:33 +0000

kbuild: change working directory to external module directory with M=Currently, Kbuild always operates in the output directory of the kernel,even when building external modules. This increases the risk of externalmodule Makefiles attempting to write to the kernel directory.This commit switches the working directory to the external moduledirectory, allowing the removal of the $(KBUILD_EXTMOD)/ prefix fromsome build artifacts.The command for building external modules maintains backwardcompatibility, but Makefiles that rely on working in the kerneldirectory may break. In such cases, $(objtree) and $(srctree) shouldbe used to refer to the output and source directories of the kernel.The appearance of the build log will change as follows:[Before] $ make -C /path/to/my/linux M=/path/to/my/externel/module make: Entering directory '/path/to/my/linux' CC [M] /path/to/my/externel/module/helloworld.o MODPOST /path/to/my/externel/module/Module.symvers CC [M] /path/to/my/externel/module/helloworld.mod.o CC [M] /path/to/my/externel/module/.module-common.o LD [M] /path/to/my/externel/module/helloworld.ko make: Leaving directory '/path/to/my/linux'[After] $ make -C /path/to/my/linux M=/path/to/my/externel/module make: Entering directory '/path/to/my/linux' make[1]: Entering directory '/path/to/my/externel/module' CC [M] helloworld.o MODPOST Module.symvers CC [M] helloworld.mod.o CC [M] .module-common.o LD [M] helloworld.ko make[1]: Leaving directory '/path/to/my/externel/module' make: Leaving directory '/path/to/my/linux'Printing "Entering directory" twice is cumbersome. This will beaddressed later.Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier List of files: /linux-6.15/scripts/Makefile.compiler

e72a076c - kbuild: fix issues with rustc-option

Wed, 09 Oct 2024 11:41:59 +0000

kbuild: fix issues with rustc-optionFix a few different compiler errors that cause rustc-option to givewrong results.If KBUILD_RUSTFLAGS or the flags being tested contain any -Z flags, thenthe error below is generated. The RUSTC_BOOTSTRAP environment variableis added to fix this error. error: the option `Z` is only accepted on the nightly compiler help: consider switching to a nightly toolchain: `rustup default nightly` note: selecting a toolchain with `+toolchain` arguments require a rustup proxy; see note: for more information about Rust's stability policy, see error: 1 nightly option were parsedNote that RUSTC_BOOTSTRAP is also defined in the top-level Makefile,but Make-exported variables are unfortunately *not* inherited. That said,this is changing as of commit 98da874c4303 ("[SV 10593] Export variablesto $(shell ...) commands"), which is part of Make 4.4.The probe may also fail with the error message below. To fix it,the /dev/null argument is replaced with a file containing the crateattribute #![no_core]. The #![no_core] attribute ensures that rustc doesnot look for the standard library. It's not possible to instead supplya standard library (i.e. `core`) to rustc, as we need `rustc-option`before the Rust standard library is compiled. error[E0463]: can't find crate for `std` | = note: the `aarch64-unknown-none` target may not be installed = help: consider downloading the target with `rustup target add aarch64-unknown-none` = help: consider building the standard library from source with `cargo build -Zbuild-std`The -o and --out-dir parameters are altered to fix this warning: warning: ignoring --out-dir flag due to -o flagThe --sysroot flag is provided as we would otherwise require it to bepresent in KBUILD_RUSTFLAGS. The --emit=obj flag is used to write theresulting object file to /dev/null instead of writing it to a filein $(TMPOUT).I verified that the Kconfig version of rustc-option doesn't have thesame issues.Fixes: c42297438aee ("kbuild: rust: Define probing macros for rustc")Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Signed-off-by: Alice Ryhl Acked-by: Masahiro Yamada Link: https://lore.kernel.org/r/20241009-rustc-option-bootstrap-v3-1-5fa0d520efba@google.com[ Reworded as discussed in the list. - Miguel ]Signed-off-by: Miguel Ojeda List of files: /linux-6.15/scripts/Makefile.compiler

b55da847 - kbuild: refactor cc-option-yn, cc-disable-warning, rust-option-yn macros

Wed, 09 Oct 2024 10:27:37 +0000

kbuild: refactor cc-option-yn, cc-disable-warning, rust-option-yn macroscc-option-yn and cc-disable-warning duplicate the compile command seena few lines above. These can be defined based on cc-option.I also refactored rustc-option-yn in the same way, although there arecurrently no users of it.Signed-off-by: Masahiro Yamada Reviewed-by: Alice Ryhl Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/20241009102821.2675718-1-masahiroy@kernel.orgSigned-off-by: Miguel Ojeda List of files: /linux-6.15/scripts/Makefile.compiler

c4229743 - kbuild: rust: Define probing macros for rustc

Tue, 20 Aug 2024 19:48:56 +0000

kbuild: rust: Define probing macros for rustcCreates flag probe macro variants for `rustc`. These are helpfulbecause:1. The kernel now supports a minimum `rustc` version rather than a single version.2. `rustc` links against a range of LLVM revisions, occasionally even ones without an official release number. Since the availability of some Rust flags depends on which LLVM it has been linked against, probing is necessary.Signed-off-by: Matthew Maurer Link: https://github.com/Rust-for-Linux/linux/pull/1087Link: https://lore.kernel.org/r/20240820194910.187826-2-mmaurer@google.comSigned-off-by: Miguel Ojeda List of files: /linux-6.15/scripts/Makefile.compiler

0ee695a4 - kbuild: Add -Wa,--fatal-warnings to as-instr invocation

Thu, 25 Jan 2024 17:32:11 +0000

kbuild: Add -Wa,--fatal-warnings to as-instr invocationCertain assembler instruction tests may only induce warnings from theassembler on an unsupported instruction or option, which causes as-instrto succeed when it was expected to fail. Some tests workaround thislimitation by additionally testing that invalid input fails as expected.However, this is fragile if the assembler is changed to accept theinvalid input, as it will cause the instruction/option to be unavailablelike it was unsupported even when it is.Use '-Wa,--fatal-warnings' in the as-instr macro to turn these warningsinto hard errors, which avoids this fragility and makes tests morerobust and well formed.Cc: stable@vger.kernel.orgSuggested-by: Eric Biggers Signed-off-by: Nathan Chancellor Tested-by: Eric Biggers Tested-by: Andy Chiu Reviewed-by: Andy Chiu Tested-by: Conor Dooley Reviewed-by: Conor Dooley Acked-by: Masahiro Yamada Link: https://lore.kernel.org/r/20240125-fix-riscv-option-arch-llvm-18-v1-1-390ac9cc3cd0@kernel.orgSigned-off-by: Palmer Dabbelt List of files: /linux-6.15/scripts/Makefile.compiler

54a11654 - powerpc: remove checks for binutils older than 2.25

Thu, 19 Jan 2023 08:22:50 +0000

powerpc: remove checks for binutils older than 2.25Commit e4412739472b ("Documentation: raise minimum supported version ofbinutils to 2.25") allows us to remove the checks for old binutils.There is no more user for ld-ifversion. Remove it as well.Signed-off-by: Masahiro Yamada Reviewed-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://msgid.link/20230119082250.151485-1-masahiroy@kernel.org List of files: /linux-6.15/scripts/Makefile.compiler

43fc0a99 - kbuild: Add KBUILD_CPPFLAGS to as-option invocation

Tue, 06 Jun 2023 22:40:35 +0000

kbuild: Add KBUILD_CPPFLAGS to as-option invocationAfter commit feb843a469fb ("kbuild: add $(CLANG_FLAGS) toKBUILD_CPPFLAGS"), there is an error while building certain PowerPCassembly files with clang: arch/powerpc/lib/copypage_power7.S: Assembler messages: arch/powerpc/lib/copypage_power7.S:34: Error: junk at end of line: `0b01000' arch/powerpc/lib/copypage_power7.S:35: Error: junk at end of line: `0b01010' arch/powerpc/lib/copypage_power7.S:37: Error: junk at end of line: `0b01000' arch/powerpc/lib/copypage_power7.S:38: Error: junk at end of line: `0b01010' arch/powerpc/lib/copypage_power7.S:40: Error: junk at end of line: `0b01010' clang: error: assembler command failed with exit code 1 (use -v to see invocation)as-option only uses KBUILD_AFLAGS, so after removing CLANG_FLAGS fromKBUILD_AFLAGS, there is no more '--target=' or '--prefix=' flags. As aresult of those missing flags, the host targetwill be tested during as-option calls and likely fail, meaning necessaryflags may not get added when building assembly files, resulting inerrors like seen above.Add KBUILD_CPPFLAGS to as-option invocations to clear up the errors.This should have been done in commit d5c8d6e0fa61 ("kbuild: Updateassembler calls to use proper flags and language target"), whichswitched from using the assembler target to the assembler-with-cpptarget, so flags that affect preprocessing are passed along in allrelevant tests. as-option now mirrors cc-option.Fixes: feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS")Reported-by: Linux Kernel Functional Testing Closes: https://lore.kernel.org/CA+G9fYs=koW9WardsTtora+nMgLR3raHz-LSLr58tgX4T5Mxag@mail.gmail.com/Signed-off-by: Nathan Chancellor Tested-by: Naresh Kamboju Signed-off-by: Masahiro Yamada List of files: /linux-6.15/scripts/Makefile.compiler

cff6e7f5 - kbuild: Add CLANG_FLAGS to as-instr

Thu, 01 Jun 2023 19:50:39 +0000

kbuild: Add CLANG_FLAGS to as-instrA future change will move CLANG_FLAGS from KBUILD_{A,C}FLAGS toKBUILD_CPPFLAGS so that '--target' is available while preprocessing.When that occurs, the following errors appear multiple times whenbuilding ARCH=powerpc powernv_defconfig: ld.lld: error: vmlinux.a(arch/powerpc/kernel/head_64.o):(.text+0x12d4): relocation R_PPC64_ADDR16_HI out of range: -4611686018409717520 is not in [-2147483648, 2147483647]; references '__start___soft_mask_table' ld.lld: error: vmlinux.a(arch/powerpc/kernel/head_64.o):(.text+0x12e8): relocation R_PPC64_ADDR16_HI out of range: -4611686018409717392 is not in [-2147483648, 2147483647]; references '__stop___soft_mask_table'Diffing the .o.cmd files reveals that -DHAVE_AS_ATHIGH=1 is not presentanymore, because as-instr only uses KBUILD_AFLAGS, which will no longercontain '--target'.Mirror Kconfig's as-instr and add CLANG_FLAGS explicitly to theinvocation to ensure the target information is always present.Signed-off-by: Nathan Chancellor Signed-off-by: Masahiro Yamada List of files: /linux-6.15/scripts/Makefile.compiler

d5c8d6e0 - kbuild: Update assembler calls to use proper flags and language target

Thu, 12 Jan 2023 03:05:01 +0000

kbuild: Update assembler calls to use proper flags and language targetas-instr uses KBUILD_AFLAGS, but as-option uses KBUILD_CFLAGS. This cancause as-option to fail unexpectedly when CONFIG_WERROR is set, becauseclang will emit -Werror,-Wunused-command-line-argument for various -mand -f flags in KBUILD_CFLAGS for assembler sources.Callers of as-option and as-instr should be adding flags toKBUILD_AFLAGS / aflags-y, not KBUILD_CFLAGS / cflags-y. UseKBUILD_AFLAGS in all macros to clear up the initial problem.Unfortunately, -Wunused-command-line-argument can still be triggeredwith clang by the presence of warning flags or macro definitions because'-x assembler' is used, instead of '-x assembler-with-cpp', which willconsume these flags. Switch to '-x assembler-with-cpp' in places where'-x assembler' is used, as the compiler is always used as the driver forout of line assembler sources in the kernel.Finally, add -Werror to these macros so that they behave consistentlywhether or not CONFIG_WERROR is set.[nathan: Reworded and expanded on problems in commit message Use '-x assembler-with-cpp' in a couple more places]Link: https://github.com/ClangBuiltLinux/linux/issues/1699Suggested-by: Masahiro Yamada Signed-off-by: Nick Desaulniers Signed-off-by: Nathan Chancellor Tested-by: Linux Kernel Functional Testing Tested-by: Anders Roxell Signed-off-by: Masahiro Yamada List of files: /linux-6.15/scripts/Makefile.compiler

fccb3d3e - kbuild: add test-{ge,gt,le,lt} macros

Sun, 11 Dec 2022 02:46:47 +0000

kbuild: add test-{ge,gt,le,lt} macrosGNU Make 4.4 introduced $(intcmp ...), which is useful to compare twointegers without forking a new process.Add test-{ge,gt,le,lt} macros, which work more efficiently with GNUMake >= 4.4. For older Make versions, they fall back to the 'test'shell command.The first two parameters to $(intcmp ...) must not be empty. To avoidthe syntax error, I appended '0' to them. Fortunately, '00' is treatedas '0'. This is needed because CONFIG options may expand to an emptystring when the kernel configuration is not included.Signed-off-by: Masahiro Yamada Acked-by: Palmer Dabbelt # RISC-VReviewed-by: Nathan Chancellor Reviewed-by: Nicolas Schier List of files: /linux-6.15/scripts/Makefile.compiler

88b61e3b - Makefile.compiler: replace cc-ifversion with compiler-specific macros

Mon, 19 Sep 2022 17:08:28 +0000

Makefile.compiler: replace cc-ifversion with compiler-specific macroscc-ifversion is GCC specific. Replace it with compiler specificvariants. Update the users of cc-ifversion to use these new macros.Link: https://github.com/ClangBuiltLinux/linux/issues/350Link: https://lore.kernel.org/llvm/CAGG=3QWSAUakO42kubrCap8fp-gm1ERJJAYXTnP1iHk_wrH=BQ@mail.gmail.com/Suggested-by: Bill Wendling Reviewed-by: Nathan Chancellor Signed-off-by: Nick Desaulniers Signed-off-by: Masahiro Yamada List of files: /linux-6.15/scripts/Makefile.compiler

dd298656 - kbuild: set EXIT trap before creating temporary directory

Thu, 28 Jul 2022 03:14:33 +0000

kbuild: set EXIT trap before creating temporary directorySwap the order of 'mkdir' and 'trap' just in case the subshell isinterrupted between 'mkdir' and 'trap' although the effect might besubtle.This does not intend to make the cleanup perfect. There are more casesthat miss to remove the tmp directory, for example: - When interrupted, dash does not invoke the EXIT trap (bash does) - 'rm' command might be interrupted before removing the directoryI am not addressing all the cases since the tmp directory is harmlessafter all.Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers List of files: /linux-6.15/scripts/Makefile.compiler

e3456056 - kbuild: remove TMPO from try-run

Thu, 15 Apr 2021 07:26:59 +0000

kbuild: remove TMPO from try-runTMPO is only used by arch/x86/Makefile.Change arch/x86/Makefile to use $$TMPO.o and remove TMPO fromscripts/Makefile.compiler.Signed-off-by: Masahiro Yamada List of files: /linux-6.15/scripts/Makefile.compiler

57fd251c - kbuild: split cc-option and friends to scripts/Makefile.compiler

Sun, 28 Feb 2021 06:10:27 +0000

kbuild: split cc-option and friends to scripts/Makefile.compilerscripts/Kbuild.include is included everywhere, but macros such ascc-option are needed by build targets only.For example, when 'make clean' traverses the tree, it does not needto evaluate $(call cc-option,).Split cc-option, ld-option, etc. to scripts/Makefile.compiler, whichis only included from the top Makefile and scripts/Makefile.build.Signed-off-by: Masahiro Yamada List of files: /linux-6.15/scripts/Makefile.compiler