Pull Kbuild fixes from Nicolas Schier:
- builddeb - avoid recompiles for non-cross-compiles
Avoid triggering complete rebuilds for non-cross-compile Debian
package builds by only triggering the rebuild of host tools for
actual cross-compile builds
- Never respect CONFIG_WERROR / W=e to fixdep
Avoid spurious rebuilds of fixdep w/ and w/o -Werror during a single
kbuild invocation by never respecting CONFIG_WERROR for fixdep
* tag 'kbuild-fixes-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
kbuild: Never respect CONFIG_WERROR / W=e to fixdep
kbuild: builddeb - avoid recompiles for non-cross-compiles
The fixdep hostprog may be built multiple times during a single build.
Once during the configuration phase and later during the regular phase.
As only the regular build phase respects CONFIG_WERROR / W=e, the
compiler flags might change between the phases, leading to rebuilds.
Example, the rebuilds will happen twice on each invocation of the build:
$ make allyesconfig prepare
make[1]: Entering directory '/tmp/deleteme'
HOSTCC scripts/basic/fixdep
#
# No change to .config
#
HOSTCC scripts/basic/fixdep
DESCEND objtool
INSTALL libsubcmd_headers
make[1]: Leaving directory '/tmp/deleteme'
Fix the compilation flags used for scripts/basic/ before
scripts/Makefile.warn is evaluated to stop CONFIG_WERROR / W=e
influencing the fixdep build to avoid the spurious rebuilds.
Fixes: 7ded7d37e5 ("scripts/Makefile.extrawarn: Respect CONFIG_WERROR / W=e for hostprogs")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260422-kbuild-scripts-basic-werror-v1-1-8c6912ff22e0@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
Pull Kbuild/Kconfig updates from Nicolas Schier:
"Kbuild:
- reject unexpected values for LLVM=
- uapi: remove usage of toolchain headers
- switch from '-fms-extensions' to '-fms-anonymous-structs' when
available (currently: clang >= 23.0.0)
- reduce the number of compiler-generated suffixes for clang thin-lto
build
- reduce output spam ("GEN Makefile") when building out of tree
- improve portability for testing headers
- also test UAPI headers against C++ compilers
- drop build ID architecture allow-list in vdso_install
- only run checksyscalls when necessary
- update the debug information notes in reproducible-builds.rst
- expand inlining hints with -fdiagnostics-show-inlining-chain
Kconfig:
- forbid multiple entries with the same symbol in a choice
- error out on duplicated kconfig inclusion"
* tag 'kbuild-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (35 commits)
kbuild: expand inlining hints with -fdiagnostics-show-inlining-chain
kconfig: forbid multiple entries with the same symbol in a choice
Documentation: kbuild: Update the debug information notes in reproducible-builds.rst
checksyscalls: move instance functionality into generic code
checksyscalls: only run when necessary
checksyscalls: fail on all intermediate errors
checksyscalls: move path to reference table to a variable
kbuild: vdso_install: drop build ID architecture allow-list
kbuild: vdso_install: gracefully handle images without build ID
kbuild: vdso_install: hide readelf warnings
kbuild: vdso_install: split out the readelf invocation
kbuild: uapi: also test UAPI headers against C++ compilers
kbuild: uapi: provide a C++ compatible dummy definition of NULL
kbuild: uapi: handle UML in architecture-specific exclusion lists
kbuild: uapi: move all include path flags together
kbuild: uapi: move some compiler arguments out of the command definition
check-uapi: use dummy libc includes
check-uapi: honor ${CROSS_COMPILE} setting
check-uapi: link into shared objects
kbuild: reduce output spam when building out of tree
...
Pull Rust updates from Miguel Ojeda:
"Toolchain and infrastructure:
- Bump the minimum Rust version to 1.85.0 (and 'bindgen' to 0.71.1).
As proposed in LPC 2025 and the Maintainers Summit [1], we are
going to follow Debian Stable's Rust versions as our minimum
versions.
Debian Trixie was released on 2025-08-09 with a Rust 1.85.0 and
'bindgen' 0.71.1 toolchain, which is a fair amount of time for e.g.
kernel developers to upgrade.
Other major distributions support a Rust version that is high
enough as well, including:
+ Arch Linux.
+ Fedora Linux.
+ Gentoo Linux.
+ Nix.
+ openSUSE Slowroll and openSUSE Tumbleweed.
+ Ubuntu 25.10 and 26.04 LTS. In addition, 24.04 LTS using
their versioned packages.
The merged patch series comes with the associated cleanups and
simplifications treewide that can be performed thanks to both
bumps, as well as documentation updates.
In addition, start using 'bindgen''s '--with-attribute-custom-enum'
feature to set the 'cfi_encoding' attribute for the 'lru_status'
enum used in Binder.
Link: https://lwn.net/Articles/1050174/ [1]
- Add experimental Kconfig option ('CONFIG_RUST_INLINE_HELPERS') that
inlines C helpers into Rust.
Essentially, it performs a step similar to LTO, but just for the
helpers, i.e. very local and fast.
It relies on 'llvm-link' and its '--internalize' flag, and requires
a compatible LLVM between Clang and 'rustc' (i.e. same major
version, 'CONFIG_RUSTC_CLANG_LLVM_COMPATIBLE'). It is only enabled
for two architectures for now.
The result is a measurable speedup in different workloads that
different users have tested. For instance, for the null block
driver, it amounts to a 2%.
- Support global per-version flags.
While we already have per-version flags in many places, we didn't
have a place to set global ones that depend on the compiler
version, i.e. in 'rust_common_flags', which sometimes is needed to
e.g. tweak the lints set per version.
Use that to allow the 'clippy::precedence' lint for Rust < 1.86.0,
since it had a change in behavior.
- Support overriding the crate name and apply it to Rust Binder,
which wanted the module to be called 'rust_binder'.
- Add the remaining '__rust_helper' annotations (started in the
previous cycle).
'kernel' crate:
- Introduce the 'const_assert!' macro: a more powerful version of
'static_assert!' that can refer to generics inside functions or
implementation bodies, e.g.:
fn f<const N: usize>() {
const_assert!(N > 1);
}
fn g<T>() {
const_assert!(size_of::<T>() > 0, "T cannot be ZST");
}
In addition, reorganize our set of build-time assertion macros
('{build,const,static_assert}!') to live in the 'build_assert'
module.
Finally, improve the docs as well to clarify how these are
different from one another and how to pick the right one to use,
and their equivalence (if any) to the existing C ones for extra
clarity.
- 'sizes' module: add 'SizeConstants' trait.
This gives us typed 'SZ_*' constants (avoiding casts) for use in
device address spaces where the address width depends on the
hardware (e.g. 32-bit MMIO windows, 64-bit GPU framebuffers, etc.),
e.g.:
let gpu_heap = 14 * u64::SZ_1M;
let mmio_window = u32::SZ_16M;
- 'clk' module: implement 'Send' and 'Sync' for 'Clk' and thus
simplify the users in Tyr and PWM.
- 'ptr' module: add 'const_align_up'.
- 'str' module: improve the documentation of the 'c_str!' macro to
explain that one should only use it for non-literal cases (for the
other case we instead use C string literals, e.g. 'c"abc"').
- Disallow the use of 'CStr::{as_ptr,from_ptr}' and clean one such
use in the 'task' module.
- 'sync' module: finish the move of 'ARef' and 'AlwaysRefCounted'
outside of the 'types' module, i.e. update the last remaining
instances and finally remove the re-exports.
- 'error' module: clarify that 'from_err_ptr' can return 'Ok(NULL)',
including runtime-tested examples.
The intention is to hopefully prevent UB that assumes the result of
the function is not 'NULL' if successful. This originated from a
case of UB I noticed in 'regulator' that created a 'NonNull' on it.
Timekeeping:
- Expand the example section in the 'HrTimer' documentation.
- Mark the 'ClockSource' trait as unsafe to ensure valid values for
'ktime_get()'.
- Add 'Delta::from_nanos()'.
'pin-init' crate:
- Replace the 'Zeroable' impls for 'Option<NonZero*>' with impls of
'ZeroableOption' for 'NonZero*'.
- Improve feature gate handling for unstable features.
- Declutter the documentation of implementations of 'Zeroable' for
tuples.
- Replace uses of 'addr_of[_mut]!' with '&raw [mut]'.
rust-analyzer:
- Add type annotations to 'generate_rust_analyzer.py'.
- Add support for scripts written in Rust ('generate_rust_target.rs',
'rustdoc_test_builder.rs', 'rustdoc_test_gen.rs').
- Refactor 'generate_rust_analyzer.py' to explicitly identify host
and target crates, improve readability, and reduce duplication.
And some other fixes, cleanups and improvements"
* tag 'rust-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (79 commits)
rust: sizes: add SizeConstants trait for device address space constants
rust: kernel: update `file_with_nul` comment
rust: kbuild: allow `clippy::precedence` for Rust < 1.86.0
rust: kbuild: support global per-version flags
rust: declare cfi_encoding for lru_status
docs: rust: general-information: use real example
docs: rust: general-information: simplify Kconfig example
docs: rust: quick-start: remove GDB/Binutils mention
docs: rust: quick-start: remove Nix "unstable channel" note
docs: rust: quick-start: remove Gentoo "testing" note
docs: rust: quick-start: add Ubuntu 26.04 LTS and remove subsection title
docs: rust: quick-start: update minimum Ubuntu version
docs: rust: quick-start: update Ubuntu versioned packages
docs: rust: quick-start: openSUSE provides `rust-src` package nowadays
rust: kbuild: remove "dummy parameter" workaround for `bindgen` < 0.71.1
rust: kbuild: update `bindgen --rust-target` version and replace comment
rust: rust_is_available: remove warning for `bindgen` < 0.69.5 && libclang >= 19.1
rust: rust_is_available: remove warning for `bindgen` 0.66.[01]
rust: bump `bindgen` minimum supported version to 0.71.1 (Debian Trixie)
rust: block: update `const_refs_to_static` MSRV TODO comment
...
Pull timekeeping updates from Andreas Hindborg:
- Expand the example section in the 'HrTimer' documentation.
- Mark the 'ClockSource' trait as unsafe to ensure valid values for
'ktime_get()'.
- Add 'Delta::from_nanos()'.
This is a back merge since the pull request has a newer base -- we will
avoid that in the future.
And, given it is a back merge, it happens to resolve the "subtle" conflict
around '--remap-path-{prefix,scope}' that I discussed in linux-next [1],
plus a few other common conflicts. The result matches what we did for
next-20260407.
The actual diffstat (i.e. using a temporary merge of upstream first) is:
rust/kernel/time.rs | 32 ++++-
rust/kernel/time/hrtimer.rs | 336 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 362 insertions(+), 6 deletions(-)
Link: https://lore.kernel.org/linux-next/CANiq72kdxB=W3_CV1U44oOK3SssztPo2wLDZt6LP94TEO+Kj4g@mail.gmail.com/ [1]
* tag 'rust-timekeeping-for-v7.1' of https://github.com/Rust-for-Linux/linux:
hrtimer: add usage examples to documentation
rust: time: make ClockSource unsafe trait
rust/time: Add Delta::from_nanos()
The Clippy `precedence` lint was extended in Rust 1.85.0 to include
bitmasking and shift operations [1]. However, because it generated
many hits, in Rust 1.86.0 it was split into a new `precedence_bits`
lint which is not enabled by default [2].
In other words, only Rust 1.85 has a different behavior. For instance,
it reports:
warning: operator precedence can trip the unwary
--> drivers/gpu/nova-core/fb/hal/ga100.rs:16:5
|
16 | / u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::read(bar).adr_39_08()) << FLUSH_SYSMEM_ADDR_SHIFT
17 | | | u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI::read(bar).adr_63_40())
18 | | << FLUSH_SYSMEM_ADDR_SHIFT_HI
| |_________________________________________^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#precedence
= note: `-W clippy::precedence` implied by `-W clippy::all`
= help: to override `-W clippy::all` add `#[allow(clippy::precedence)]`
help: consider parenthesizing your expression
|
16 ~ (u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::read(bar).adr_39_08()) << FLUSH_SYSMEM_ADDR_SHIFT) | (u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI::read(bar).adr_63_40())
17 + << FLUSH_SYSMEM_ADDR_SHIFT_HI)
|
While so far we try our best to keep all versions Clippy-clean, the
minimum (which is now Rust 1.85.0 after the bump) and the latest stable
are the most important ones; and this may be considered a "false positive"
with respect to the behavior in other versions.
Thus allow this lint for this version using the per-version flags
mechanism introduced in the previous commit.
Link: https://github.com/rust-lang/rust-clippy/issues/14097 [1]
Link: https://github.com/rust-lang/rust-clippy/pull/14115 [2]
Link: https://lore.kernel.org/rust-for-linux/DFVDKMMA7KPC.2DN0951H3H55Y@kernel.org/
Reviewed-by: Tamir Duberstein <tamird@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260405235309.418950-34-ojeda@kernel.org
[ Added paragraph from commit message to comment. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
`clippy::incompatible_msrv` is not buying us much, and we discussed
allowing it several times in the past.
For instance, there was recently another patch sent to `allow` it where
needed [1]. While that particular case would not be needed after the
minimum version bump to 1.85.0, it is simpler to just allow it to prevent
future instances.
[ In addition, the lint fired without taking into account the features
that have been enabled in a crate [2]. While this was improved in Rust
1.90.0 [3], it would still fire in a case like this patch. ]
Thus do so, and remove the last instance of locally allowing it we have
in the tree (except the one in the vendored `proc_macro2` crate).
Note that we still keep the `msrv` config option in `clippy.toml` since
that affects other lints as well.
Link: https://lore.kernel.org/rust-for-linux/20260404212831.78971-4-jhubbard@nvidia.com/ [1]
Link: https://github.com/rust-lang/rust-clippy/issues/14425 [2]
Link: https://github.com/rust-lang/rust-clippy/pull/14433 [3]
Link: https://patch.msgid.link/20260405235309.418950-8-ojeda@kernel.org
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Tamir Duberstein <tamird@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Clippy in Rust 1.88.0 (only) reports [1]:
warning: variables can be used directly in the `format!` string
--> rust/macros/module.rs:112:23
|
112 | let content = format!("{param}:{content}", param = param, content = content);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
= note: `-W clippy::uninlined-format-args` implied by `-W clippy::all`
= help: to override `-W clippy::all` add `#[allow(clippy::uninlined_format_args)]`
help: change this to
|
112 - let content = format!("{param}:{content}", param = param, content = content);
112 + let content = format!("{param}:{content}");
warning: variables can be used directly in the `format!` string
--> rust/macros/module.rs:198:14
|
198 | t => panic!("Unsupported parameter type {}", t),
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
= note: `-W clippy::uninlined-format-args` implied by `-W clippy::all`
= help: to override `-W clippy::all` add `#[allow(clippy::uninlined_format_args)]`
help: change this to
|
198 - t => panic!("Unsupported parameter type {}", t),
198 + t => panic!("Unsupported parameter type {t}"),
|
The reason it only triggers in that version is that the lint was moved
from `pedantic` to `style` in Rust 1.88.0 and then back to `pedantic`
in Rust 1.89.0 [2][3].
In the first case, the suggestion is fair and a pure simplification, thus
we will clean it up separately.
To keep the behavior the same across all versions, and since the lint
does not work for all macros (e.g. custom ones like `pr_info!`), disable
it globally.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://lore.kernel.org/rust-for-linux/CANiq72=drAtf3y_DZ-2o4jb6Az9J3Yj4QYwWnbRui4sm4AJD3Q@mail.gmail.com/ [1]
Link: https://github.com/rust-lang/rust-clippy/pull/15287 [2]
Link: https://github.com/rust-lang/rust-clippy/issues/15151 [3]
Link: https://patch.msgid.link/20260331205849.498295-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
A new experimental Kconfig option, `RUST_INLINE_HELPERS` is added to
allow C helpers (which were created to allow Rust to call into
inline/macro C functions without having to re-implement the logic in
Rust) to be inlined into Rust crates without performing global LTO.
If the option is enabled, the following is performed:
* For helpers, instead of compiling them to an object file to be linked
into vmlinux, they're compiled to LLVM IR bitcode. Two versions are
generated: one for built-in code (`helpers.bc`) and one for modules
(`helpers_module.bc`, with -DMODULE defined). This ensures that C
macros/inlines that behave differently for modules (e.g. static calls)
function correctly when inlined.
* When a Rust crate or object is compiled, instead of generating an
object file, LLVM bitcode is generated.
* llvm-link is invoked with --internalize to combine the helper bitcode
with the crate bitcode. This step is similar to LTO, but this is much
faster since it only needs to inline the helpers.
* clang is invoked to turn the combined bitcode into a final object file.
* Since clang may produce LLVM bitcode when LTO is enabled, and objtool
requires ELF input, $(cmd_ld_single) is invoked to ensure the object
is converted to ELF before objtool runs.
The --internalize flag tells llvm-link to treat all symbols in
helpers.bc using `internal` linkage [1]. This matches the behavior of
`clang` on `static inline` functions, and avoids exporting the symbol
from the object file.
To ensure that RUST_INLINE_HELPERS is not incompatible with BTF, we pass
the -g0 flag when building helpers. See commit 5daa0c35a1 ("rust:
Disallow BTF generation with Rust + LTO") for details.
We have an intended triple mismatch of `aarch64-unknown-none` vs
`aarch64-unknown-linux-gnu`, so we pass --suppress-warnings to llvm-link
to suppress it.
I considered adding some sort of check that KBUILD_MODNAME is not
present in helpers_module.bc, but this is actually not so easy to carry
out because .bc files store strings in a weird binary format, so you
cannot just grep it for a string to check whether it ended up using
KBUILD_MODNAME anywhere.
[ Andreas writes:
For the rnull driver, enabling helper inlining with this patch
gives an average speedup of 2% over the set of 120 workloads that
we publish on [2].
Link: https://rust-for-linux.com/null-block-driver [2]
This series also uncovered a pre-existing UB instance thanks to an
`objtool` warning which I noticed while testing the series (details
in the mailing list).
- Miguel ]
Link: https://github.com/llvm/llvm-project/pull/170397 [1]
Co-developed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Co-developed-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://patch.msgid.link/20260203-inline-helpers-v2-3-beb8547a03c9@google.com
[ Some changes, apart from the rebase:
- Added "(EXPERIMENTAL)" to Kconfig as the commit mentions.
- Added `depends on ARM64 || X86_64` and `!UML` for now, since this is
experimental, other architectures may require other changes (e.g.
the issues I mentioned in the mailing list for ARM and UML) and they
are not really tested so far. So let arch maintainers pick this up
if they think it is worth it.
- Gated the `cmd_ld_single` step also into the new mode, which also
means that any possible future `objcopy` step is done after the
translation, as expected.
- Added `.gitignore` for `.bc` with exception for existing script.
- Added `part-of-*` for helpers bitcode files as discussed, and
dropped `$(if $(filter %_module.bc,$@),-DMODULE)` since `-DMODULE`
is already there (would be duplicated otherwise).
- Moved `LLVM_LINK` to keep binutils list alphabetized.
- Fixed typo in title.
- Dropped second `cmd_ld_single` commit message paragraph.
- Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Pull Kbuild fixes from Nathan Chancellor:
"This mostly addresses some issues with the awk conversion in
scripts/kconfig/merge_config.sh.
- Fix typo to ensure .builtin-dtbs.S is properly cleaned
- Fix '==' bashism in scripts/kconfig/merge_config.sh
- Fix awk error in scripts/kconfig/merge_config.sh when base
configuration is empty
- Fix inconsistent indentation in scripts/kconfig/merge_config.sh"
* tag 'kbuild-fixes-7.0-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
scripts: kconfig: merge_config.sh: fix indentation
scripts: kconfig: merge_config.sh: pass output file as awk variable
scripts: kconfig: merge_config.sh: fix unexpected operator warning
kbuild: Delete .builtin-dtbs.S when running make clean
The current clang thin-lto build often produces lots of symbols with
suffix. The following is a partial list of such function call symbols:
...
ethnl_module_fw_flash_ntf.llvm.7631589765585346066
__nf_conntrack_alloc.llvm.6438426151906658917
tcp_can_early_drop.llvm.11937612064648250727
tcp_print_conntrack.llvm.11937612064648250727
...
In my particular build with current bpf-next, the number of '*.llvm.<hash>'
function calls is 1212. As the side effect of cross-file inlining,
some static variables may be promoted with '*.llvm.<hash>' as well.
In my same setup, the number of variables with such suffixes is 9.
Such symbols make kernel live patching difficult since
- a minor code change will change the hash and then the '*.llvm.<hash>'
symbol becomes another one with a different hash. Sometimes, maybe
the suffix is gone.
- a previous source-level symbol may become a one with suffix after live
patching code.
In [1], Song Liu suggested to reduce the number of '*.llvm.<hash>' functions
to make live patch easier. In respond of this, I implemented this
in llvm ([2]). The same thin-lto build with [2] only has two symbols with
suffix:
m_stop.llvm.14460341347352036579
m_next.llvm.14460341347352036579
This should make live patch much easier.
To support suffix symbol reduction, two lld flags are necessary to enable
this feature in kernel:
- Flag '--lto-whole-program-visibility' is needed as it ensures that all
non-assembly files are available in the same thin-lto lld, which is true
for kernel.
- Flag '-mllvm -always-rename-promoted-locals=false' is needed to enable
suffix reduction. Currently in llvm [1], only process mode is supported.
There is another distributed mode (across different processes or even
different machines) which is not supported yet ([2]). The kernel uses
process mode so it should work.
The assembly files may have some global functions/data which may potentially
conflict with thin-lto global symbols after the above two flags. But such assembly
global symbols are limited and tend to be uniquely named for its context.
Hence the conflict with globals in non-assembly codes is rare. If indeed the
conflict happens, we can rename either of them to avoid conflicts.
Nathan Chancellor suggested the following under thin-lto:
KBUILD_LDFLAGS += $(call ld-option,--lto-whole-program-visibility -mllvm -always-rename-promoted-locals=false)
The '-mllvm -always-rename-promoted-locals=false' flag is only available for llvm23.
So for llvm22 or earlier, the above KBUILD_LDFLAGS will ignore those two flags.
For llvm23 and later, two flags will be added to KBUILD_LDFLAGS.
[1] https://lpc.events/event/19/contributions/2212
[2] https://github.com/llvm/llvm-project/pull/178587
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org> # build
Link: https://patch.msgid.link/20260307050250.3767489-1-yonghong.song@linux.dev
Signed-off-by: Nicolas Schier <nsc@kernel.org>
Pull Rust fixes from Miguel Ojeda:
"Toolchain and infrastructure:
- Remap paths to avoid absolute ones starting with the upcoming Rust
1.95.0 release. This improves build reproducibility, avoids leaking
the exact path and avoids having the same path appear in two forms
The approach here avoids remapping debug information as well, in
order to avoid breaking tools that used the paths to access source
files, which was the previous attempt that needed to be reverted
- Allow 'unused_features' lint for the upcoming Rust 1.96.0 release.
While well-intentioned, we do not benefit much from the new lint
- Emit dependency information into '$(depfile)' directly to avoid a
temporary '.d' file (it was an old approach)
'kernel' crate:
- 'str' module: fix warning under '!CONFIG_BLOCK' by making
'NullTerminatedFormatter' public
- 'cpufreq' module: suppress false positive Clippy warning
'pin-init' crate:
- Remove '#[disable_initialized_field_access]' attribute which was
unsound. This means removing the support for structs with unaligned
fields (through the 'repr(packed)' attribute), for now
And document the load-bearing fact of field accessors (i.e. that
they are required for soundness)
- Replace shadowed return token by 'unsafe'-to-create token in order
to remain sound in the face of the likely upcoming Type Alias Impl
Trait (TAIT) and the next trait solver in upstream Rust"
* tag 'rust-fixes-7.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
rust: kbuild: allow `unused_features`
rust: cpufreq: suppress clippy::double_parens in Policy doctest
rust: pin-init: replace shadowed return token by `unsafe`-to-create token
rust: pin-init: internal: init: document load-bearing fact of field accessors
rust: pin-init: internal: init: remove `#[disable_initialized_field_access]`
rust: build: remap path to avoid absolute path
rust: kbuild: emit dep-info into $(depfile) directly
rust: str: make NullTerminatedFormatter public
Starting with the upcoming Rust 1.96.0 (to be released 2026-05-28),
`rustc` introduces the new lint `unused_features` [1], which warns [2]:
warning: feature `used_with_arg` is declared but not used
--> <crate attribute>:1:93
|
1 | #![feature(asm_const,asm_goto,arbitrary_self_types,lint_reasons,offset_of_nested,raw_ref_op,used_with_arg)]
| ^^^^^^^^^^^^^
|
= note: `#[warn(unused_features)]` (part of `#[warn(unused)]`) on by default
The original goal of using `-Zcrate-attr` automatically was that there
is a consistent set of features enabled and managed globally for all
Rust kernel code (modulo exceptions like the `rust/` crated).
While we could require crates to enable features manually (even if we
still keep the `-Zallow-features=` list, i.e. removing the `-Zcrate-attr`
list), it is not really worth making all developers worry about it just
for a new lint.
The features are expected to eventually become stable anyway (most already
did), and thus having to remove features in every file that may use them
is not worth it either.
Thus just allow the new lint globally.
The lint actually existed for a long time, which is why `rustc` does
not complain about an unknown lint in the stable versions we support,
but it was "disabled" years ago [3], and now it was made to work again.
For extra context, the new implementation of the lint has already been
improved to avoid linting about features that became stable thanks to
Benno's report and the ensuing discussion [4] [5], but while that helps,
it is still the case that we may have features enabled that are not used
for one reason or another in a particular crate.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://github.com/rust-lang/rust/pull/152164 [1]
Link: https://github.com/Rust-for-Linux/pin-init/pull/114 [2]
Link: https://github.com/rust-lang/rust/issues/44232 [3]
Link: https://github.com/rust-lang/rust/issues/153523 [4]
Link: https://github.com/rust-lang/rust/pull/153610 [5]
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260312111014.74198-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@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>
Linus Torvalds
Thomas Weißschuh
Miguel Ojeda
Justin Stitt
Gary Guo
Thomas Weißschuh
Yonghong Song
Nathan Chancellor