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Ilya Leoshkevich authored
When directories are used as prerequisites in Makefiles, they can cause
a lot of unnecessary rebuilds, because a directory is considered changed
whenever a file in this directory is added, removed or modified.

If the only thing a target is interested in is the existence of the
directory it depends on, which is the case for selftests/bpf, this
directory should be specified as an order-only prerequisite: it would
still be created in case it does not exist, but it would not trigger a
rebuild of a target in case it's considered changed.

Signed-off-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
e46fc22e
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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.