linux-toradex.git/arch/x86/Makefile, branch master Linux kernel for Apalis and Colibri modules Merge tag 'kbuild-7.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux 2026-10-21T20:45:44+00:00 Linus Torvalds torvalds@linux-foundation.org 2026-10-21T20:45:44+00:00 bb29b957eaaa15be33243550d9ee576c2d601669 Pull Kbuild / Kconfig updates from Nathan Chancellor: "Kbuild: - Suppress compiler flags in debug info for external module builds - Use '-fmacro-prefix-map' in more places in the build - Merge initial set of changes from Lorenzo's speed up series, along with some fixes found through testing: - Avoid allocating .modinfo in vmlinux - Speed up kallsyms by indexing symbols by token and outputting binary data to disk directly then including in assembly via .incbin - Don't sort $(NM) output when unnecessary - Only emit relocations on the final vmlinx link - Reimplement mksysmap in C - Move many cc-option and ld-option calls into the Kconfig stage to cache their results - Use pigz for gzip compression when available - Move gen_init_cpio and gen_initramfs.sh from usr/ to scripts/ - Add a TOML configuration to scripts/container and update documentation accordingly - Add a generic, opt-in mechanism for checking that headers can compile standalone - Update machine function splitting argument for LLVM 24 rename in AutoFDO build - Miscellaneous minor clean ups, fixes, and hardening, mostly found/fixed via LLMs Kconfig: - Turn recursive ranges into an error - Fix savedefconfig for defaults that were adjusted for being out of range and revert a previously applied workaround - Improvements and hardening around integer and hexadecimal values - Emit a warning when selecting or implying a choice symbol, which has no effect - Emit a warning when KCONFIG_PROBABILITY is malformed - Introduce def_string / def_int / def_hex to mirror the existing def_bool / def_tristate to succinctly set a value and type at the same time. - Add cc-option-str and ld-option-str macros to act like Kbuild's cc-option and ld-option, returning the string when the option is supported, allowing many checks to be moved into Kconfig - Minor usability improvements to Kconfig tests" * tag 'kbuild-7.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (59 commits) kbuild: AutoFDO: Update split machine function argument for upstream rename kbuild: Mark the initcall ordering recipe as recursive kbuild: Mark the gzip recipes as recursive localmodconfig: Explicitly report boolean configs during integrity check scripts/make_fit: Ignore schema checks when decomposing DTBs clang-tools: Import os for broken pipe handling kconfig: use the value argument in sym_get_near_range_bound() kconfig: fix infinite loop in conf_choice() when no choice value is visible kconfig: cleanup stale comment about 'keys' array kconfig: Improve ergonomics around disabling warnings with cc-option scripts/Kconfig.toolchain: Drop compiler symbols from dependencies checkkconfigsymbols.py: Parse Git status output line by line gen_init_cpio: stop parsing on lines with a missing argument list .gitignore: drop Module.markers .gitignore: ignore pacman package signatures kbuild: add header check facility as a manually run static analyzer Documentation: dev-tools: refer to user ID rather than id Documentation: dev-tools: update container.rst with config file scripts: add TOML config to container tool kconfig: tests: {old,save}defconfig: Forward dynamic keyword arguments ... 
Pull Kbuild / Kconfig updates from Nathan Chancellor:
 "Kbuild:

   - Suppress compiler flags in debug info for external module builds

   - Use '-fmacro-prefix-map' in more places in the build

   - Merge initial set of changes from Lorenzo's speed up series, along
     with some fixes found through testing:

     - Avoid allocating .modinfo in vmlinux

     - Speed up kallsyms by indexing symbols by token and outputting
       binary data to disk directly then including in assembly via
       .incbin

     - Don't sort $(NM) output when unnecessary

     - Only emit relocations on the final vmlinx link

     - Reimplement mksysmap in C

     - Move many cc-option and ld-option calls into the Kconfig stage to
       cache their results

     - Use pigz for gzip compression when available

   - Move gen_init_cpio and gen_initramfs.sh from usr/ to scripts/

   - Add a TOML configuration to scripts/container and update
     documentation accordingly

   - Add a generic, opt-in mechanism for checking that headers can
     compile standalone

   - Update machine function splitting argument for LLVM 24 rename in
     AutoFDO build

   - Miscellaneous minor clean ups, fixes, and hardening, mostly
     found/fixed via LLMs

  Kconfig:

   - Turn recursive ranges into an error

   - Fix savedefconfig for defaults that were adjusted for being out of
     range and revert a previously applied workaround

   - Improvements and hardening around integer and hexadecimal values

   - Emit a warning when selecting or implying a choice symbol, which
     has no effect

   - Emit a warning when KCONFIG_PROBABILITY is malformed

   - Introduce def_string / def_int / def_hex to mirror the existing
     def_bool / def_tristate to succinctly set a value and type at the
     same time.

   - Add cc-option-str and ld-option-str macros to act like Kbuild's
     cc-option and ld-option, returning the string when the option is
     supported, allowing many checks to be moved into Kconfig

   - Minor usability improvements to Kconfig tests"

* tag 'kbuild-7.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (59 commits)
  kbuild: AutoFDO: Update split machine function argument for upstream rename
  kbuild: Mark the initcall ordering recipe as recursive
  kbuild: Mark the gzip recipes as recursive
  localmodconfig: Explicitly report boolean configs during integrity check
  scripts/make_fit: Ignore schema checks when decomposing DTBs
  clang-tools: Import os for broken pipe handling
  kconfig: use the value argument in sym_get_near_range_bound()
  kconfig: fix infinite loop in conf_choice() when no choice value is visible
  kconfig: cleanup stale comment about 'keys' array
  kconfig: Improve ergonomics around disabling warnings with cc-option
  scripts/Kconfig.toolchain: Drop compiler symbols from dependencies
  checkkconfigsymbols.py: Parse Git status output line by line
  gen_init_cpio: stop parsing on lines with a missing argument list
  .gitignore: drop Module.markers
  .gitignore: ignore pacman package signatures
  kbuild: add header check facility as a manually run static analyzer
  Documentation: dev-tools: refer to user ID rather than id
  Documentation: dev-tools: update container.rst with config file
  scripts: add TOML config to container tool
  kconfig: tests: {old,save}defconfig: Forward dynamic keyword arguments
  ...
kbuild: avoid re-running compiler and linker probes 2026-09-25T23:16:36+00:00 Lorenzo Stoakes (ARM) ljs@kernel.org 2026-09-23T17:18:01+00:00 454e00cf8ee5aff555ad5865b8c3dbf3731afcc9 Each kernel make invocation begins with ~30 compiler and linker runs each of which performs duplicate probe for a number of compiler and linker options. This is useless work - the compiler and its version is known, so use these to determine which options are available, once. Using the newly introduced cc-option-str, track the result of each probe in CC_OPT_*, LD_OPT_* variables and have Makefile's simply append the symbol. Some care has to be taken around negative options, i.e. -Wno-xxx, as gcc accepts an unknown -Wno- without complaint and only complains later, so instead probe the positive form for these cases. Use CC_HAS_* For those probes that gate a Makefile conditional rather than a simple option, as per the established pattern for this. This change avoids a subtle issue with ppc32 (big endian) - clang doesn't accept -fno-stack-clash-protection on this sub-target, so keep this option in the Makefile. With gcc and clang, defconfig and allmodconfig, the recorded command lines are unchanged, a build with nothing to do rebuilds nothing and W=1 continues to function correctly. Doing this improves all builds, but has a particularly positive impact on no-op builds (builds where nothing has changed). Whole build, 128-thread Threadripper 9980X, best of N runs: before after delta ------------------------------- x86 defconfig, no-op make, gcc 0.78s 0.60s -0.18s (-23%) x86 defconfig, no-op make, clang 0.94s 0.66s -0.28s (-30%) x86 defconfig, touch mm/vma.c, gcc 8.6s 8.5s -0.16s (-2%) x86 defconfig, touch mm/vma.c, clang 8.0s 7.7s -0.24s (-3%) x86 defconfig, clean, clang 29.8s 29.4s -0.37s (-1%) x86 allmodconfig, no-op make, gcc 12.9s 12.7s -0.23s (-2%) x86 allmodconfig, no-op make, clang 14.2s 13.9s -0.29s (-2%) x86 allmodconfig, touch mm/vma.c, clang 32.2s 31.9s -0.30s (-1%) Assisted-by: LLM Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org> Link: https://patch.msgid.link/20260923-build-speedup-v4-12-73128809a4a4@kernel.org Signed-off-by: Nathan Chancellor <nathan@kernel.org> 
Each kernel make invocation begins with ~30 compiler and linker runs each
of which performs duplicate probe for a number of compiler and linker
options.

This is useless work - the compiler and its version is known, so use these
to determine which options are available, once.

Using the newly introduced cc-option-str, track the result of each probe in
CC_OPT_*, LD_OPT_* variables and have Makefile's simply append the symbol.

Some care has to be taken around negative options, i.e. -Wno-xxx, as gcc
accepts an unknown -Wno- without complaint and only complains later, so
instead probe the positive form for these cases.

Use CC_HAS_* For those probes that gate a Makefile conditional rather than
a simple option, as per the established pattern for this.

This change avoids a subtle issue with ppc32 (big endian) - clang doesn't
accept -fno-stack-clash-protection on this sub-target, so keep this option
in the Makefile.

With gcc and clang, defconfig and allmodconfig, the recorded command
lines are unchanged, a build with nothing to do rebuilds nothing and W=1
continues to function correctly.

Doing this improves all builds, but has a particularly positive impact on
no-op builds (builds where nothing has changed).

Whole build, 128-thread Threadripper 9980X, best of N runs:

                                         before   after     delta
                                         -------------------------------
  x86 defconfig, no-op make, gcc           0.78s    0.60s    -0.18s (-23%)
  x86 defconfig, no-op make, clang         0.94s    0.66s    -0.28s (-30%)
  x86 defconfig, touch mm/vma.c, gcc        8.6s     8.5s    -0.16s (-2%)
  x86 defconfig, touch mm/vma.c, clang      8.0s     7.7s    -0.24s (-3%)
  x86 defconfig, clean, clang              29.8s    29.4s    -0.37s (-1%)
  x86 allmodconfig, no-op make, gcc        12.9s    12.7s    -0.23s (-2%)
  x86 allmodconfig, no-op make, clang      14.2s    13.9s    -0.29s (-2%)
  x86 allmodconfig, touch mm/vma.c, clang  32.2s    31.9s    -0.30s (-1%)

Assisted-by: LLM
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Link: https://patch.msgid.link/20260923-build-speedup-v4-12-73128809a4a4@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
x86/build/64: Prevent native builds from generating EGPR use 2026-09-19T04:43:38+00:00 Chang S. Bae chang.seok.bae@intel.com 2026-09-16T23:00:03+00:00 63edf5a009ae366369a1b484cd9ae4ee7c51946c Omar reports that CONFIG_X86_NATIVE_CPU=y allows builds to opportunistically emit instructions using %r16-%r31 (EGPRs) when the build host supports APX since the commit: ea1dcca1de12 ("x86/kbuild/64: Add the CONFIG_X86_NATIVE_CPU option to locally optimize the kernel with '-march=native'") But the kernel is not yet prepared to use new registers internally. For example, there is no context-switch support for general in-kernel use. Explicitly disable EGPR use when building with -march=native. For C, since GCC 14 and Clang 18, both compilers support suppressing EGPR use with -mno-apx-features=egpr, whose availability can be detected via cc-option. For Rust, pass features=-apxf through the generated JSON to avoid unstable-feature warnings, see https://github.com/rust-lang/rust/issues/139284 Note Rust only accepts the option to disable APX instructions entirely or not. Support for this gating also depends on the Rust/LLVM combination. Rust 1.88 introduced the `apxf` feature option, but versions prior to 1.93 may emit an `apxf` attribute to the backend that only LLVM 23 or later can interpret. Restrict native Rust builds accordingly. Fixes: ea1dcca1de12 ("x86/kbuild/64: Add the CONFIG_X86_NATIVE_CPU option to locally optimize the kernel with '-march=native'") Reported-by: Omar Avelar <omar.avelar@intel.com> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Acked-by: Miguel Ojeda <ojeda@kernel.org> Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260916230003.1144622-1-chang.seok.bae@intel.com 
Omar reports that CONFIG_X86_NATIVE_CPU=y allows builds to opportunistically
emit instructions using %r16-%r31 (EGPRs) when the build host supports APX
since the commit:

  ea1dcca1de12 ("x86/kbuild/64: Add the CONFIG_X86_NATIVE_CPU option to locally optimize the kernel with '-march=native'")

But the kernel is not yet prepared to use new registers internally. For
example, there is no context-switch support for general in-kernel use.

Explicitly disable EGPR use when building with -march=native.

For C, since GCC 14 and Clang 18, both compilers support suppressing EGPR
use with -mno-apx-features=egpr, whose availability can be detected via
cc-option.

For Rust, pass features=-apxf through the generated JSON to avoid
unstable-feature warnings, see

  https://github.com/rust-lang/rust/issues/139284

Note Rust only accepts the option to disable APX instructions entirely or not.

Support for this gating also depends on the Rust/LLVM combination. Rust
1.88 introduced the `apxf` feature option, but versions prior to 1.93 may
emit an `apxf` attribute to the backend that only LLVM 23 or later can
interpret. Restrict native Rust builds accordingly.

Fixes: ea1dcca1de12 ("x86/kbuild/64: Add the CONFIG_X86_NATIVE_CPU option to locally optimize the kernel with '-march=native'")
Reported-by: Omar Avelar <omar.avelar@intel.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260916230003.1144622-1-chang.seok.bae@intel.com
Merge tag 'x86-cpu-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip 2026-06-15T09:55:17+00:00 Linus Torvalds torvalds@linux-foundation.org 2026-06-15T09:55:17+00:00 ff5ccdb8d5bd242f1064c6f7996603e47e28d095 Pull x86 cpuid updates from Ingo Molnar: - CPUID API updates (Ahmed S. Darwish): - Introduce a centralized CPUID parser - Introduce a centralized CPUID data model - Introduce <asm/cpuid/leaf_types.h> - Rename cpuid_leaf()/cpuid_subleaf() APIs - treewide: Explicitly include the x86 CPUID headers - Update to x86-cpuid-db v3.1 (Maciej Wieczor-Retman) - Continued removal of pre-i586 support and related simplifications (Ingo Molnar) - Add Intel CPU model number for rugged Panther Lake (Tony Luck) - Misc fixes, updates and cleanups by Arnd Bergmann, Chao Gao, Lukas Bulwahn, Sohil Mehta, Maciej Wieczor-Retman. * tag 'x86-cpu-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: (25 commits) x86/cpu: Make CONFIG_X86_CX8 unconditional x86/cpu: Remove unused !CONFIG_X86_TSC code x86/cpuid: Update bitfields to x86-cpuid-db v3.1 tools/x86/kcpuid: Update bitfields to x86-cpuid-db v3.1 x86/cpu: Make CONFIG_X86_TSC unconditional MAINTAINERS: Drop obsolete FPU EMULATOR section x86/cpu: Fix a F00F bug warning and clean up surrounding code x86/cpu: Add Intel CPU model number for rugged Panther Lake x86/cpuid: Introduce a centralized CPUID parser x86/cpu: Introduce a centralized CPUID data model x86/cpuid: Introduce <asm/cpuid/leaf_types.h> x86/cpuid: Rename cpuid_leaf()/cpuid_subleaf() APIs x86/cpu: Do not include the CPUID API header in asm/processor.h Documentation: core-api/cpu_hotplug: Remove stale cpu0_hotplug docs x86/cpu, cpufreq: Remove AMD ELAN support x86/fpu: Remove the math-emu/ FPU emulation library x86/fpu: Remove the 'no387' boot option x86/fpu: Remove MATH_EMULATION and related glue code treewide: Explicitly include the x86 CPUID headers x86/cpu: Remove the CONFIG_X86_INVD_BUG quirk ... 
Pull x86 cpuid updates from Ingo Molnar:

 - CPUID API updates (Ahmed S. Darwish):
    - Introduce a centralized CPUID parser
    - Introduce a centralized CPUID data model
    - Introduce <asm/cpuid/leaf_types.h>
    - Rename cpuid_leaf()/cpuid_subleaf() APIs
    - treewide: Explicitly include the x86 CPUID headers

 - Update to x86-cpuid-db v3.1 (Maciej Wieczor-Retman)

 - Continued removal of pre-i586 support and related simplifications
   (Ingo Molnar)

 - Add Intel CPU model number for rugged Panther Lake (Tony Luck)

 - Misc fixes, updates and cleanups by Arnd Bergmann, Chao Gao, Lukas
   Bulwahn, Sohil Mehta, Maciej Wieczor-Retman.

* tag 'x86-cpu-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: (25 commits)
  x86/cpu: Make CONFIG_X86_CX8 unconditional
  x86/cpu: Remove unused !CONFIG_X86_TSC code
  x86/cpuid: Update bitfields to x86-cpuid-db v3.1
  tools/x86/kcpuid: Update bitfields to x86-cpuid-db v3.1
  x86/cpu: Make CONFIG_X86_TSC unconditional
  MAINTAINERS: Drop obsolete FPU EMULATOR section
  x86/cpu: Fix a F00F bug warning and clean up surrounding code
  x86/cpu: Add Intel CPU model number for rugged Panther Lake
  x86/cpuid: Introduce a centralized CPUID parser
  x86/cpu: Introduce a centralized CPUID data model
  x86/cpuid: Introduce <asm/cpuid/leaf_types.h>
  x86/cpuid: Rename cpuid_leaf()/cpuid_subleaf() APIs
  x86/cpu: Do not include the CPUID API header in asm/processor.h
  Documentation: core-api/cpu_hotplug: Remove stale cpu0_hotplug docs
  x86/cpu, cpufreq: Remove AMD ELAN support
  x86/fpu: Remove the math-emu/ FPU emulation library
  x86/fpu: Remove the 'no387' boot option
  x86/fpu: Remove MATH_EMULATION and related glue code
  treewide: Explicitly include the x86 CPUID headers
  x86/cpu: Remove the CONFIG_X86_INVD_BUG quirk
  ...
Merge tag 'kbuild-7.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux 2026-06-14T23:31:15+00:00 Linus Torvalds torvalds@linux-foundation.org 2026-06-14T23:31:15+00:00 73f399414a84d715bb1794182aaea852b11d0962 Pull Kbuild / Kconfig updates from Nathan Chancellor: "Kbuild: - Remove broken module linking exclusion for BTF - Add documentation around how offset header files work - Include unstripped vDSO libraries in pacman packages - Bump minimum version of LLVM for building the kernel to 17.0.1 and clean up unnecessary workarounds - Use a context manager in run-clang-tools - Add dist macro value if present to release tag for RPM packages - Detect and report truncated buf_printf() output in modpost - Add __llvm_covfun and __llvm_covmap to section whitelist in modpost - Support Clang's distributed ThinLTO mode - Remove architecture specific configurations for AutoFDO and Propeller to ease individual architecture maintenance Kconfig: - Add kconfig-sym-check target to look for dangling Kconfig symbol references and invalid tristate literal values - Harden against potential NULL pointer dereference - Fix typo in Kconfig test comment" * tag 'kbuild-7.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (31 commits) kconfig: tests: fix typo in comment kconfig: Remove the architecture specific config for Propeller kconfig: Remove the architecture specific config for AutoFDO modpost: Add __llvm_covfun and __llvm_covmap to section_white_list kconfig: add kconfig-sym-check static checker kbuild: Remove unnecessary 'T' modifier in cmd_ar_builtin_fixup kbuild: distributed build support for Clang ThinLTO kbuild: move vmlinux.a build rule to scripts/Makefile.vmlinux_a scripts: modpost: detect and report truncated buf_printf() output kbuild: rpm-pkg: append %{?dist} macro to Release tag run-clang-tools: run multiprocessing.Pool as context manager compiler-clang.h: Drop explicit version number from "all" diagnostic macro compiler-clang.h: Remove __cleanup -Wunused-variable workaround kbuild: Remove check for broken scoping with clang < 17 in CC_HAS_ASM_GOTO_OUTPUT x86/entry/vdso32: Remove conditional omission of '.cfi_offset eflags' x86/module: Revert "Deal with GOT based stack cookie load on Clang < 17" x86/build: Drop unnecessary '-ffreestanding' addition to KBUILD_CFLAGS scripts/Makefile.warn: Drop -Wformat handling for clang < 16 riscv: Drop tautological condition from TOOLCHAIN_NEEDS_OLD_ISA_SPEC riscv: Remove tautological condition from selection of ARCH_SUPPORTS_CFI ... 
Pull Kbuild / Kconfig updates from Nathan Chancellor:
 "Kbuild:

   - Remove broken module linking exclusion for BTF

   - Add documentation around how offset header files work

   - Include unstripped vDSO libraries in pacman packages

   - Bump minimum version of LLVM for building the kernel to 17.0.1 and
     clean up unnecessary workarounds

   - Use a context manager in run-clang-tools

   - Add dist macro value if present to release tag for RPM packages

   - Detect and report truncated buf_printf() output in modpost

   - Add __llvm_covfun and __llvm_covmap to section whitelist in modpost

   - Support Clang's distributed ThinLTO mode

   - Remove architecture specific configurations for AutoFDO and
     Propeller to ease individual architecture maintenance

  Kconfig:

   - Add kconfig-sym-check target to look for dangling Kconfig symbol
     references and invalid tristate literal values

   - Harden against potential NULL pointer dereference

   - Fix typo in Kconfig test comment"

* tag 'kbuild-7.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (31 commits)
  kconfig: tests: fix typo in comment
  kconfig: Remove the architecture specific config for Propeller
  kconfig: Remove the architecture specific config for AutoFDO
  modpost: Add __llvm_covfun and __llvm_covmap to section_white_list
  kconfig: add kconfig-sym-check static checker
  kbuild: Remove unnecessary 'T' modifier in cmd_ar_builtin_fixup
  kbuild: distributed build support for Clang ThinLTO
  kbuild: move vmlinux.a build rule to scripts/Makefile.vmlinux_a
  scripts: modpost: detect and report truncated buf_printf() output
  kbuild: rpm-pkg: append %{?dist} macro to Release tag
  run-clang-tools: run multiprocessing.Pool as context manager
  compiler-clang.h: Drop explicit version number from "all" diagnostic macro
  compiler-clang.h: Remove __cleanup -Wunused-variable workaround
  kbuild: Remove check for broken scoping with clang < 17 in CC_HAS_ASM_GOTO_OUTPUT
  x86/entry/vdso32: Remove conditional omission of '.cfi_offset eflags'
  x86/module: Revert "Deal with GOT based stack cookie load on Clang < 17"
  x86/build: Drop unnecessary '-ffreestanding' addition to KBUILD_CFLAGS
  scripts/Makefile.warn: Drop -Wformat handling for clang < 16
  riscv: Drop tautological condition from TOOLCHAIN_NEEDS_OLD_ISA_SPEC
  riscv: Remove tautological condition from selection of ARCH_SUPPORTS_CFI
  ...
x86/build: Drop unnecessary '-ffreestanding' addition to KBUILD_CFLAGS 2026-05-27T22:20:05+00:00 Nathan Chancellor nathan@kernel.org 2026-05-17T23:05:14+00:00 7b3281fcb43c5fce8d4d2b0996d3ac719cb5068b Now that the minimum supported version of LLVM for building the kernel has been raised to 17.0.1, the addition of '-ffreestanding' to KBUILD_CFLAGS for 32-bit x86 is unnecessary, as the linked LLVM bug is resolved in all supported LLVM versions. 16cb16e0d285 ("x86/build: Remove -ffreestanding on i386 with GCC") intended to make the addition of '-ffreestanding' clang only but due to a bug in the adjusted check from d70da12453ac ("hardening: Enable i386 FORTIFY_SOURCE on Clang 16+") it has been applied for all versions of GCC and clang < 16.0.0. There are no known problems with removing this for GCC but if one surfaces, it can be restored under a CONFIG_CC_IS_GCC block. Link: https://patch.msgid.link/20260517-bump-minimum-supported-llvm-version-to-17-v2-11-b3b8cda46bdd@kernel.org Signed-off-by: Nathan Chancellor <nathan@kernel.org> 
Now that the minimum supported version of LLVM for building the kernel
has been raised to 17.0.1, the addition of '-ffreestanding' to
KBUILD_CFLAGS for 32-bit x86 is unnecessary, as the linked LLVM bug is
resolved in all supported LLVM versions.

  16cb16e0d285 ("x86/build: Remove -ffreestanding on i386 with GCC")

intended to make the addition of '-ffreestanding' clang only but due to
a bug in the adjusted check from

  d70da12453ac ("hardening: Enable i386 FORTIFY_SOURCE on Clang 16+")

it has been applied for all versions of GCC and clang < 16.0.0. There
are no known problems with removing this for GCC but if one surfaces, it
can be restored under a CONFIG_CC_IS_GCC block.

Link: https://patch.msgid.link/20260517-bump-minimum-supported-llvm-version-to-17-v2-11-b3b8cda46bdd@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
rust: kasan/kbuild: fix rustc-option when cross-compiling 2026-05-26T07:44:54+00:00 Alice Ryhl aliceryhl@google.com 2026-05-07T11:14:42+00:00 4a44b17406cb5a93f90af3df9392b3a45eb336fb The Makefile version of rustc-option currently checks whether the option exists for the host target instead of the target actually being compiled for. It was done this way in commit 46e24a545cdb ("rust: kasan/kbuild: fix missing flags on first build") to avoid a circular dependency on target.json. However, because of this, rustc-option currently does not function when cross-compiling from x86_64 to aarch64 if CONFIG_SHADOW_CALL_STACK is enabled. This is because KBUILD_RUSTFLAGS contains -Zfixed-x18 under this configuration. Since that flag does not exist on the host target, rustc-option runs into a compilation failure every time, leading to all flags being rejected as unsupported. To fix this, update rustc-option to pass a --target parameter so that the host target is not used. For targets using target.json, use a built-in target that is as close as possible to the target created with target.json to avoid the circular dependency on target.json. One scenario where this causes a boot failure: * Cross-compiled from x86_64 to aarch64. * With CONFIG_SHADOW_CALL_STACK=y * With CONFIG_KASAN_SW_TAGS=y * With CONFIG_KASAN_INLINE=n Then the resulting kernel image will fail to boot when it first calls into Rust code with a crash along the lines of "Unable to handle kernel paging request at virtual address 0ffffffc08541796". This is because the call threshold is not specified, so rustc will inline kasan operations, but the kasan shadow offset is not specified, which leads to the inlined kasan instructions being incorrect. Note that the -Zsanitizer=kernel-hwaddress parameter itself does not lead to a rustc-option failure despite being aarch64-specific because RUSTFLAGS_KASAN has not yet been added to KBUILD_RUSTFLAGS when rustc-option is evaluated by the kasan Makefile. Cc: stable@vger.kernel.org Fixes: 46e24a545cdb ("rust: kasan/kbuild: fix missing flags on first build") Signed-off-by: Alice Ryhl <aliceryhl@google.com> Link: https://patch.msgid.link/20260507-rustc-option-cross-v2-1-2f650a49c2b5@google.com [ Edited slightly: - Reset variable to avoid using the environment. - Use a simply expanded variable flavor for simplicity. - Export variable so that behavior in sub-`make`s is consistent. This matches other variables. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org> 
The Makefile version of rustc-option currently checks whether the option
exists for the host target instead of the target actually being compiled
for. It was done this way in commit 46e24a545cdb ("rust: kasan/kbuild:
fix missing flags on first build") to avoid a circular dependency on
target.json. However, because of this, rustc-option currently does not
function when cross-compiling from x86_64 to aarch64 if
CONFIG_SHADOW_CALL_STACK is enabled. This is because KBUILD_RUSTFLAGS
contains -Zfixed-x18 under this configuration. Since that flag does not
exist on the host target, rustc-option runs into a compilation failure
every time, leading to all flags being rejected as unsupported.

To fix this, update rustc-option to pass a --target parameter so that
the host target is not used. For targets using target.json, use a
built-in target that is as close as possible to the target created with
target.json to avoid the circular dependency on target.json.

One scenario where this causes a boot failure:
* Cross-compiled from x86_64 to aarch64.
* With CONFIG_SHADOW_CALL_STACK=y
* With CONFIG_KASAN_SW_TAGS=y
* With CONFIG_KASAN_INLINE=n
Then the resulting kernel image will fail to boot when it first calls
into Rust code with a crash along the lines of "Unable to handle kernel
paging request at virtual address 0ffffffc08541796". This is because the
call threshold is not specified, so rustc will inline kasan operations,
but the kasan shadow offset is not specified, which leads to the inlined
kasan instructions being incorrect.

Note that the -Zsanitizer=kernel-hwaddress parameter itself does not
lead to a rustc-option failure despite being aarch64-specific because
RUSTFLAGS_KASAN has not yet been added to KBUILD_RUSTFLAGS when
rustc-option is evaluated by the kasan Makefile.

Cc: stable@vger.kernel.org
Fixes: 46e24a545cdb ("rust: kasan/kbuild: fix missing flags on first build")
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260507-rustc-option-cross-v2-1-2f650a49c2b5@google.com
[ Edited slightly:
    - Reset variable to avoid using the environment.
    - Use a simply expanded variable flavor for simplicity.
    - Export variable so that behavior in sub-`make`s is consistent.

  This matches other variables. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
x86/fpu: Remove MATH_EMULATION and related glue code 2026-05-08T05:33:03+00:00 Ingo Molnar mingo@kernel.org 2025-05-15T08:28:27+00:00 ab05214025ee2af262591cd48df17883648bdb1a Now that support for 486 CPUs is gone upstream, remove the x86 mathemu code integration. Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20250425084216.3913608-9-mingo@kernel.org 
Now that support for 486 CPUs is gone upstream, remove
the x86 mathemu code integration.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250425084216.3913608-9-mingo@kernel.org
kbuild: Consolidate C dialect options 2026-03-12T11:52:37+00:00 Nathan Chancellor nathan@kernel.org 2026-02-23T19:10:28+00:00 ec4c28276c140a9338700041112f64f8d7ccc3e9 Introduce CC_FLAGS_DIALECT to make it easier to update the various places in the tree that rely on the GNU C standard and Microsoft extensions flags atomically. All remaining uses of '-std=gnu11' and '-fms-extensions' are in the tools directory (which has its own build system) and other standalone Makefiles. This will allow the kernel to use a narrower option to enable the Microsoft anonymous tagged structure extension in a simpler manner. Place the CC_FLAGS_DIALECT block after the configuration include (so that a future change can move the selection of the flag to Kconfig) but before the arch/$(SRCARCH)/Makefile include (so that CC_FLAGS_DIALECT is available for use in those Makefiles). Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nicolas Schier <nsc@kernel.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Helge Deller <deller@gmx.de> # parisc Link: https://patch.msgid.link/20260223-fms-anonymous-structs-v1-1-8ee406d3c36c@kernel.org Signed-off-by: Nicolas Schier <nsc@kernel.org> 
Introduce CC_FLAGS_DIALECT to make it easier to update the various
places in the tree that rely on the GNU C standard and Microsoft
extensions flags atomically. All remaining uses of '-std=gnu11' and
'-fms-extensions' are in the tools directory (which has its own build
system) and other standalone Makefiles. This will allow the kernel to
use a narrower option to enable the Microsoft anonymous tagged structure
extension in a simpler manner. Place the CC_FLAGS_DIALECT block after
the configuration include (so that a future change can move the
selection of the flag to Kconfig) but before the
arch/$(SRCARCH)/Makefile include (so that CC_FLAGS_DIALECT is available
for use in those Makefiles).

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Helge Deller <deller@gmx.de>  # parisc
Link: https://patch.msgid.link/20260223-fms-anonymous-structs-v1-1-8ee406d3c36c@kernel.org
Signed-off-by: Nicolas Schier <nsc@kernel.org>
x86/entry/vdso: Update the object paths for "make vdso_install" 2026-01-16T20:58:45+00:00 H. Peter Anvin hpa@zytor.com 2026-01-16T20:40:54+00:00 b3683f3ba079940f91f4a26004250559f170eda9 The location of the vdso binary files in the object tree has changed; update "make vdso_install" to match. Closes: https://lore.kernel.org/16ea64d1-2a9b-46f9-9fcc-42958f599eb6@leemhuis.info Fixes: 693c819fedcd ("x86/entry/vdso: Refactor the vdso build") Reported-by: Thorsten Leemhuis <linux@leemhuis.info> Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://patch.msgid.link/20260116204057.386268-2-hpa@zytor.com 
The location of the vdso binary files in the object tree has changed;
update "make vdso_install" to match.

Closes: https://lore.kernel.org/16ea64d1-2a9b-46f9-9fcc-42958f599eb6@leemhuis.info
Fixes: 693c819fedcd ("x86/entry/vdso: Refactor the vdso build")
Reported-by: Thorsten Leemhuis <linux@leemhuis.info>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://patch.msgid.link/20260116204057.386268-2-hpa@zytor.com