ab0809af0b
Improve the error message returned on failed perf_event_open() on AMD systems when using IBS (Instruction-Based Sampling). Output of executing 'perf record -e ibs_op// true' as a non root user BEFORE this patch (perf will add the 'u' modifier at the end to exclude kernel/hypervisor sampling): The sys_perf_event_open() syscall returned with 22 (Invalid argument)for event (ibs_op//u). /bin/dmesg | grep -i perf may provide additional information. Output after: AMD IBS can't exclude kernel events. Try running at a higher privilege level. Output of executing 'sudo perf record -e ibs_op// true' BEFORE this patch: Error: The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (ibs_op//). /bin/dmesg | grep -i perf may provide additional information. Output after: Error: Invalid event (ibs_op//) in per-thread mode, enable system wide with '-a'. Folowing the suggestion: $ sudo perf record -a -e ibs_op// true [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.664 MB perf.data (194 samples) ] $ Signed-off-by: Kim Phillips <kim.phillips@amd.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: João Martins <joao.m.martins@oracle.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Michael Petlan <mpetlan@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rafael@kernel.org> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Cc: Robert Richter <robert.richter@amd.com> Cc: Sandipan Das <sandipan.das@amd.com> Cc: Song Liu <songliubraving@fb.com> Cc: Stephane Eranian <eranian@google.com> Link: http://lore.kernel.org/lkml/20220322221517.2510440-12-eranian@google.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 Restructured Text 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.