In the environment of ubuntu 20.04 (the version of kernel headers is 5.4), there is an error in building perf: CC trace/beauty/fs_at_flags.o trace/beauty/fs_at_flags.c: In function ‘faccessat2__scnprintf_flags’: trace/beauty/fs_at_flags.c:35:14: error: ‘AT_EACCESS’ undeclared (first use in this function); did you mean ‘DN_ACCESS’? 35 | if (flags & AT_EACCESS) { | ^~~~~~~~~~ | DN_ACCESS trace/beauty/fs_at_flags.c:35:14: note: each undeclared identifier is reported only once for each function it appears in commit 8a1ad4413519b10f ("tools headers: Remove now unused copies of uapi/{fcntl,openat2}.h and asm/fcntl.h") removes fcntl.h from tools headers directory, and fs_at_flags.c uses the 'AT_EACCESS' macro. This macro was introduced in the kernel version v5.8. For system with a kernel version older than this version, it will cause compilation to fail. Fixes: 8a1ad4413519b10f ("tools headers: Remove now unused copies of uapi/{fcntl,openat2}.h and asm/fcntl.h") Signed-off-by: Yang Jihong <yangjihong@bytedance.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Clark <james.clark@arm.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20240403122558.1438841-1-yangjihong@bytedance.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the reStructuredText markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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