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189a977e4d
The BPF filter needs libbpf/BPF-skeleton support and root privilege.
Add error messages to help users understand the problem easily.
When it's not build with BPF support (make BUILD_BPF_SKEL=0).
$ sudo perf record -e cycles --filter "pid != 0" true
Error: BPF filter is requested but perf is not built with BPF.
Please make sure to build with libbpf and BPF skeleton.
Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]
--filter <filter>
event filter
When it supports BPF but runs without root or CAP_BPF. Note that it
also checks pinned BPF filters.
$ perf record -e cycles --filter "pid != 0" -o /dev/null true
Error: BPF filter only works for users with the CAP_BPF capability!
Please run 'perf record --setup-filter pin' as root first.
Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]
--filter <filter>
event filter
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250604174835.1852481-1-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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.