64 Commits
Author SHA1 Message Date
Thomas WeißschuhandNicolas Schier dcc99abebf kbuild: uapi: also test UAPI headers against C++ compilers
C++ language requirements differ from those of C.

Also test the headers against C++ compilers to make sure no errors
creep in accidentally.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260316-kbuild-uapi-c-v2-5-35d6d0ed863f@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-25 13:24:42 +01:00
Thomas WeißschuhandNicolas Schier b4ec38cb73 kbuild: uapi: handle UML in architecture-specific exclusion lists
When building User Mode Linux SRCARCH is set to 'um', while the actual
underlying architecture is provided in HEADER_ARCH.

Allow the exclusion lists to work on UML by comparing against
HEADER_ARCH when that is available.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260316-kbuild-uapi-c-v2-3-35d6d0ed863f@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-25 13:24:41 +01:00
Thomas WeißschuhandNicolas Schier cf82241309 kbuild: uapi: move all include path flags together
The argument to add the root of the UAPI header tree to the include path
is separated from the other arguments concerning the include path.

Move all include path arguments together for more consistency and
balanced line lengths.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260316-kbuild-uapi-c-v2-2-35d6d0ed863f@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-25 13:24:40 +01:00
Thomas WeißschuhandNicolas Schier 55d68ec5b9 kbuild: uapi: move some compiler arguments out of the command definition
Simplify the definition of cmd_hdrtest by moving some of it to a new
variable. This will both enable the upcoming reuse of those flags
and also the extension of cmd_hdrtest.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260316-kbuild-uapi-c-v2-1-35d6d0ed863f@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-25 13:24:40 +01:00
Thomas WeißschuhandNicolas Schier 510c7a5736 kbuild: uapi: simplify libc dependency logic
The only left user of the condition inverts it.

Invert the condition completely and simplify its user.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260227-kbuild-uapi-libc-v1-8-c17de0d19776@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-12 12:48:08 +01:00
Thomas WeißschuhandNicolas Schier 579f103fb9 kbuild: uapi: use custom stub headers instead of libc ones
Now that custom stub headers are provided for all libc headers used from
the UAPI headers, the dependency on the toolchain libc can be dropped.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260227-kbuild-uapi-libc-v1-7-c17de0d19776@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-12 12:48:08 +01:00
Thomas WeißschuhandNicolas Schier 0ef1b7a66b kbuild: uapi: only use dummy-include for headers which use libc
The headers which do not rely on libc are using built using -nostdinc.
For them the dummy headers are pointless.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260227-kbuild-uapi-libc-v1-5-c17de0d19776@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-12 12:48:08 +01:00
Thomas WeißschuhandNicolas Schier 60a16beedf kbuild: uapi: completely exclude linux/bpf_perf_event.h on nios2
This header is actually not buildable on nios. As nobody built nios2
with CONFIG_CC_CAN_LINK=y so far, this produced no errors.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260227-kbuild-uapi-libc-v1-4-c17de0d19776@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-12 12:48:07 +01:00
Thomas WeißschuhandNicolas Schier 45bd8643c1 kbuild: uapi: deduplicate linux/bpf_perf_event.h exclusions
This header is excluded for multiple architectures.
Use a single exclusion for all of them.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260227-kbuild-uapi-libc-v1-3-c17de0d19776@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-12 12:48:07 +01:00
Thomas WeißschuhandNicolas Schier a8c9d3cc23 kbuild: uapi: test linux/bpf_perf_event.h on powerpc
This header works now, so test it.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260227-kbuild-uapi-libc-v1-2-c17de0d19776@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2026-03-12 12:48:07 +01:00
Thomas WeißschuhandNathan Chancellor 2a0a30805a kbuild: uapi: drop dependency on CC_CAN_LINK
The header tests try to compile each header. Some UAPI headers depend on
libc headers so they need a full userspace toolchain to build. This
dependency is expressed in kconfig as a dependency on CC_CAN_LINK.
Many kernel builds do not satisfy CC_CAN_LINK as they only use a
minimal kernel (cross-) compiler. In those configurations the UAPI
headers are not tested at all.

However most UAPI headers do not even depend on any libc headers,
and such dependencies are undesired in any case. Also the static
analysis performed by headers_check.pl does not need CC_CAN_LINK.

Drop the hard dependency on CC_CAN_LINK and instead skip the affected
compilation step for exactly those headers which require libc.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://patch.msgid.link/20251223-uapi-nostdinc-v1-5-d91545d794f7@linutronix.de
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2026-01-16 15:02:11 -07:00
Thomas WeißschuhandNathan Chancellor 4ac85d9bc7 kbuild: uapi: split out command conditions into variables
The condition logic will become a bit more complicated.

Split them out into dedicated variables so they stay readable.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://patch.msgid.link/20251223-uapi-nostdinc-v1-4-d91545d794f7@linutronix.de
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2026-01-06 15:07:32 -07:00
Thomas WeißschuhandNathan Chancellor e2772ba5f4 kbuild: uapi: don't compile test bpf_perf_event.h on xtensa
The xtensa UAPI headers do not provide 'struct pt_regs',
triggering an error:

usr/include/linux/bpf_perf_event.h:14:28: error: field 'regs' has incomplete type

Disable the header tests for this file on xtensa.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://patch.msgid.link/20251223-uapi-nostdinc-v1-3-d91545d794f7@linutronix.de
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2026-01-06 15:07:32 -07:00
Thomas WeißschuhandNathan Chancellor 6059b880a9 kbuild: uapi: validate that headers do not use libc
The UAPI headers should be self-contained. That means they should not
use other headers from libc. Currently this is not enforced and various
dependencies have crept in.

Add a check to make sure no new ones are added.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://patch.msgid.link/20251223-uapi-nostdinc-v1-1-d91545d794f7@linutronix.de
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2026-01-06 15:07:32 -07:00
Thomas WeißschuhandNicolas Schier c4cb34aee1 kbuild: uapi: reuse KBUILD_USERCFLAGS
The toplevel Makefile already provides the compiler flags necessary to
build userspace applications for the target.

Make use of them instead of duplicating the logic.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20251014-kbuild-uapi-usercflags-v1-1-c162f9059c47@linutronix.de
Signed-off-by: Nicolas Schier <nsc@kernel.org>
2025-11-08 12:17:59 +01:00
Thomas WeißschuhandNathan Chancellor 3788d69db1 kbuild: uapi: fail header test on compiler warnings
Compiler warnings also indicate issues with the headers.

Make sure they don't go unnoticed.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://lore.kernel.org/r/20250813-kbuild-hdrtest-fixes-v2-2-8a7921ca3a03@linutronix.de
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2025-08-13 14:00:34 -07:00
Thomas WeißschuhandNathan Chancellor d4b7080be2 kbuild: uapi: rerun header tests when headers_check.pl changes
If the checks change they need to be rerun.

Add a Makefile dependency so this happens.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://lore.kernel.org/r/20250813-kbuild-hdrtest-fixes-v2-1-8a7921ca3a03@linutronix.de
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2025-08-13 14:00:33 -07:00
Randy DunlapandMasahiro Yamada 56045757ac usr/include: openrisc: don't HDRTEST bpf_perf_event.h
Since openrisc does not support PERF_EVENTS, omit the HDRTEST of
bpf_perf_event.h for arch/openrisc/.

Fixes a build error:
usr/include/linux/bpf_perf_event.h:14:28: error: field 'regs' has incomplete type

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Stafford Horne <shorne@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2025-05-12 15:03:17 +09:00
Arnd BergmannandMasahiro Yamada 02e9a22cee kbuild: hdrcheck: fix cross build with clang
The headercheck tries to call clang with a mix of compiler arguments
that don't include the target architecture. When building e.g. x86
headers on arm64, this produces a warning like

   clang: warning: unknown platform, assuming -mfloat-abi=soft

Add in the KBUILD_CPPFLAGS, which contain the target, in order to make it
build properly.

See also 1b71c2fb04 ("kbuild: userprogs: fix bitsize and target
detection on clang").

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Fixes: feb843a469 ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2025-03-05 04:06:45 +09:00
Geert UytterhoevenandMasahiro Yamada d67393f4d2 kbuild: Drop support for include/asm-<arch> in headers_check.pl
"include/asm-<arch>" was replaced by "arch/<arch>/include/asm" a long
time ago.  All assembler header files are now included using
"#include <asm/*>", so there is no longer a need to rewrite paths.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-12-21 11:43:17 +09:00
Masahiro Yamada b1992c3772 kbuild: use $(src) instead of $(srctree)/$(src) for source directory
Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:

    src := $(obj)

When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.

This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.

To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.

Going forward, the variables used in Makefiles will have the following
meanings:

  $(obj)     - directory in the object tree
  $(src)     - directory in the source tree  (changed by this commit)
  $(objtree) - the top of the kernel object tree
  $(srctree) - the top of the kernel source tree

Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
2024-05-10 04:34:52 +09:00
Ard Biesheuvel cf8e865810 arch: Remove Itanium (IA-64) architecture
The Itanium architecture is obsolete, and an informal survey [0] reveals
that any residual use of Itanium hardware in production is mostly HP-UX
or OpenVMS based. The use of Linux on Itanium appears to be limited to
enthusiasts that occasionally boot a fresh Linux kernel to see whether
things are still working as intended, and perhaps to churn out some
distro packages that are rarely used in practice.

None of the original companies behind Itanium still produce or support
any hardware or software for the architecture, and it is listed as
'Orphaned' in the MAINTAINERS file, as apparently, none of the engineers
that contributed on behalf of those companies (nor anyone else, for that
matter) have been willing to support or maintain the architecture
upstream or even be responsible for applying the odd fix. The Intel
firmware team removed all IA-64 support from the Tianocore/EDK2
reference implementation of EFI in 2018. (Itanium is the original
architecture for which EFI was developed, and the way Linux supports it
deviates significantly from other architectures.) Some distros, such as
Debian and Gentoo, still maintain [unofficial] ia64 ports, but many have
dropped support years ago.

While the argument is being made [1] that there is a 'for the common
good' angle to being able to build and run existing projects such as the
Grid Community Toolkit [2] on Itanium for interoperability testing, the
fact remains that none of those projects are known to be deployed on
Linux/ia64, and very few people actually have access to such a system in
the first place. Even if there were ways imaginable in which Linux/ia64
could be put to good use today, what matters is whether anyone is
actually doing that, and this does not appear to be the case.

There are no emulators widely available, and so boot testing Itanium is
generally infeasible for ordinary contributors. GCC still supports IA-64
but its compile farm [3] no longer has any IA-64 machines. GLIBC would
like to get rid of IA-64 [4] too because it would permit some overdue
code cleanups. In summary, the benefits to the ecosystem of having IA-64
be part of it are mostly theoretical, whereas the maintenance overhead
of keeping it supported is real.

So let's rip off the band aid, and remove the IA-64 arch code entirely.
This follows the timeline proposed by the Debian/ia64 maintainer [5],
which removes support in a controlled manner, leaving IA-64 in a known
good state in the most recent LTS release. Other projects will follow
once the kernel support is removed.

[0] https://lore.kernel.org/all/CAMj1kXFCMh_578jniKpUtx_j8ByHnt=s7S+yQ+vGbKt9ud7+kQ@mail.gmail.com/
[1] https://lore.kernel.org/all/0075883c-7c51-00f5-2c2d-5119c1820410@web.de/
[2] https://gridcf.org/gct-docs/latest/index.html
[3] https://cfarm.tetaneutral.net/machines/list/
[4] https://lore.kernel.org/all/87bkiilpc4.fsf@mid.deneb.enyo.de/
[5] https://lore.kernel.org/all/ff58a3e76e5102c94bb5946d99187b358def688a.camel@physik.fu-berlin.de/

Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-09-11 08:13:17 +00:00
Linus Torvalds df202b452f Merge tag 'kbuild-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:

 - Add HOSTPKG_CONFIG env variable to allow users to override pkg-config

 - Support W=e as a shorthand for KCFLAGS=-Werror

 - Fix CONFIG_IKHEADERS build to support toybox cpio

 - Add scripts/dummy-tools/pahole to ease distro packagers' life

 - Suppress false-positive warnings from checksyscalls.sh for W=2 build

 - Factor out the common code of arch/*/boot/install.sh into
   scripts/install.sh

 - Support 'kernel-install' tool in scripts/prune-kernel

 - Refactor module-versioning to link the symbol versions at the final
   link of vmlinux and modules

 - Remove CONFIG_MODULE_REL_CRCS because module-versioning now works in
   an arch-agnostic way

 - Refactor modpost, Makefiles

* tag 'kbuild-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (56 commits)
  genksyms: adjust the output format to modpost
  kbuild: stop merging *.symversions
  kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS
  modpost: extract symbol versions from *.cmd files
  modpost: add sym_find_with_module() helper
  modpost: change the license of EXPORT_SYMBOL to bool type
  modpost: remove left-over cross_compile declaration
  kbuild: record symbol versions in *.cmd files
  kbuild: generate a list of objects in vmlinux
  modpost: move *.mod.c generation to write_mod_c_files()
  modpost: merge add_{intree_flag,retpoline,staging_flag} to add_header
  scripts/prune-kernel: Use kernel-install if available
  kbuild: factor out the common installation code into scripts/install.sh
  modpost: split new_symbol() to symbol allocation and hash table addition
  modpost: make sym_add_exported() always allocate a new symbol
  modpost: make multiple export error
  modpost: dump Module.symvers in the same order of modules.order
  modpost: traverse the namespace_list in order
  modpost: use doubly linked list for dump_lists
  modpost: traverse unresolved symbols in order
  ...
2022-05-26 12:09:50 -07:00
Masahiro YamadaandArnd Bergmann 31a088b664 sparc: add asm/stat.h to UAPI compile-test coverage
asm/stat.h is currently excluded from the UAPI compile-test for
ARCH=sparc because of the errors like follows:

  In file included from <command-line>:
  ./usr/include/asm/stat.h:11:2: error: unknown type name 'ino_t'
     11 |  ino_t   st_ino;
        |  ^~~~~
    HDRTEST usr/include/asm/param.h
  ./usr/include/asm/stat.h:12:2: error: unknown type name 'mode_t'
     12 |  mode_t  st_mode;
        |  ^~~~~~
  ./usr/include/asm/stat.h:14:2: error: unknown type name 'uid_t'
     14 |  uid_t   st_uid;
        |  ^~~~~
  ./usr/include/asm/stat.h:15:2: error: unknown type name 'gid_t'
     15 |  gid_t   st_gid;
        |  ^~~~~

The errors can be fixed by prefixing the types with __kernel_.

Then, remove the no-header-test entry from user/include/Makefile.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2022-05-13 10:56:10 +02:00
Masahiro YamadaandArnd Bergmann c01013a2f8 powerpc: add asm/stat.h to UAPI compile-test coverage
asm/stat.h is currently excluded from the UAPI compile-test for
ARCH=powerpc because of the errors like follows:

    HDRTEST usr/include/asm/stat.h
  In file included from <command-line>:32:
  ./usr/include/asm/stat.h:32:2: error: unknown type name 'ino_t'
     32 |  ino_t  st_ino;
        |  ^~~~~
  ./usr/include/asm/stat.h:35:2: error: unknown type name 'mode_t'
     35 |  mode_t  st_mode;
        |  ^~~~~~
  ./usr/include/asm/stat.h:40:2: error: unknown type name 'uid_t'
     40 |  uid_t  st_uid;
        |  ^~~~~
  ./usr/include/asm/stat.h:41:2: error: unknown type name 'gid_t'
     41 |  gid_t  st_gid;
        |  ^~~~~

The errors can be fixed by prefixing the types with __kernel_.

Then, remove the no-header-test entry from user/include/Makefile.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2022-05-13 10:56:10 +02:00