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Roberto Sassu 629b98e2b1 tools, build: Retry detection of bfd-related features
While separate features have been defined to determine which linking flags
are required to use libbfd depending on the distribution (libbfd,
libbfd-liberty and libbfd-liberty-z), the same has not been done for other
features requiring linking to libbfd.

For example, disassembler-four-args requires linking to libbfd too, but it
should use the right linking flags. If not all the required ones are
specified, e.g. -liberty, detection will always fail even if the feature is
available.

Instead of creating new features, similarly to libbfd, simply retry
detection with the different set of flags until detection succeeds (or
fails, if the libraries are missing). In this way, feature detection is
transparent for the users of this building mechanism (e.g. perf), and those
users don't have for example to set an appropriate value for the
FEATURE_CHECK_LDFLAGS-disassembler-four-args variable.

The number of retries and features for which the retry mechanism is
implemented is low enough to make the increase in the complexity of
Makefile negligible.

Tested with perf and bpftool on Ubuntu 20.04.4 LTS, Fedora 36 and openSUSE
Tumbleweed.

Committer notes:

Do the retry for disassembler-init-styled as well.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20220719170555.2576993-1-roberto.sassu@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-08-10 10:44:01 -03:00
arch TTY / Serial driver changes for 6.0-rc1 2022-08-08 11:31:40 -07:00
block block: convert to advancing variants of iov_iter_get_pages{,_alloc}() 2022-08-08 22:37:22 -04:00
certs certs: make system keyring depend on x509 parser 2022-07-24 12:53:55 -07:00
crypto iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
Documentation remoteproc updates for v5.20 2022-08-08 15:16:29 -07:00
drivers iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
fs 12 server fixes, including for oopses, memory leaks and adding a channel lock 2022-08-08 20:15:13 -07:00
include iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
init Modules updates for 6.0 2022-08-08 14:12:19 -07:00
io_uring iov_iter work, part 1 - isolated cleanups and optimizations. 2022-08-03 13:50:22 -07:00
ipc Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
kernel remoteproc updates for v5.20 2022-08-08 15:16:29 -07:00
lib iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
net iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
samples Tracing updates for 5.20 / 6.0 2022-08-05 09:41:12 -07:00
scripts Modules updates for 6.0 2022-08-08 14:12:19 -07:00
security linux-kselftest-kunit-5.20-rc1 2022-08-02 19:34:45 -07:00
sound sound updates for 6.0-rc1 2022-08-06 10:19:51 -07:00
tools tools, build: Retry detection of bfd-related features 2022-08-10 10:44:01 -03:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt Merge remote-tracking branch 'kvm/next' into kvm-next-5.20 2022-08-01 03:21:00 -04:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS 12 server fixes, including for oopses, memory leaks and adding a channel lock 2022-08-08 20:15:13 -07:00
Makefile linux-kselftest-next-5.20-rc1 2022-08-02 19:44:56 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.