<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/tools/build, branch v5.4.301</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>tools build: Align warning options with perf</title>
<updated>2025-10-29T12:59:51+00:00</updated>
<author>
<name>Leo Yan</name>
<email>leo.yan@arm.com</email>
</author>
<published>2025-10-06T16:21:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=aeb1fe8a52b00c53efa60cbe6681005b9bb13e4e'/>
<id>aeb1fe8a52b00c53efa60cbe6681005b9bb13e4e</id>
<content type='text'>
[ Upstream commit 53d067feb8c4f16d1f24ce3f4df4450bb18c555f ]

The feature test programs are built without enabling '-Wall -Werror'
options. As a result, a feature may appear to be available, but later
building in perf can fail with stricter checks.

Make the feature test program use the same warning options as perf.

Fixes: 1925459b4d92 ("tools build: Fix feature Makefile issues with 'O='")
Signed-off-by: Leo Yan &lt;leo.yan@arm.com&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20251006-perf_build_android_ndk-v3-1-4305590795b2@arm.com
Cc: Palmer Dabbelt &lt;palmer@dabbelt.com&gt;
Cc: Albert Ou &lt;aou@eecs.berkeley.edu&gt;
Cc: Alexandre Ghiti &lt;alex@ghiti.fr&gt;
Cc: Nick Desaulniers &lt;nick.desaulniers+lkml@gmail.com&gt;
Cc: Justin Stitt &lt;justinstitt@google.com&gt;
Cc: Bill Wendling &lt;morbo@google.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@kernel.org&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: James Clark &lt;james.clark@linaro.org&gt;
Cc: linux-riscv@lists.infradead.org
Cc: llvm@lists.linux.dev
Cc: Paul Walmsley &lt;paul.walmsley@sifive.com&gt;
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 53d067feb8c4f16d1f24ce3f4df4450bb18c555f ]

The feature test programs are built without enabling '-Wall -Werror'
options. As a result, a feature may appear to be available, but later
building in perf can fail with stricter checks.

Make the feature test program use the same warning options as perf.

Fixes: 1925459b4d92 ("tools build: Fix feature Makefile issues with 'O='")
Signed-off-by: Leo Yan &lt;leo.yan@arm.com&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20251006-perf_build_android_ndk-v3-1-4305590795b2@arm.com
Cc: Palmer Dabbelt &lt;palmer@dabbelt.com&gt;
Cc: Albert Ou &lt;aou@eecs.berkeley.edu&gt;
Cc: Alexandre Ghiti &lt;alex@ghiti.fr&gt;
Cc: Nick Desaulniers &lt;nick.desaulniers+lkml@gmail.com&gt;
Cc: Justin Stitt &lt;justinstitt@google.com&gt;
Cc: Bill Wendling &lt;morbo@google.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@kernel.org&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: James Clark &lt;james.clark@linaro.org&gt;
Cc: linux-riscv@lists.infradead.org
Cc: llvm@lists.linux.dev
Cc: Paul Walmsley &lt;paul.walmsley@sifive.com&gt;
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tools/build: Don't pass test log files to linker</title>
<updated>2025-06-04T12:32:30+00:00</updated>
<author>
<name>Ian Rogers</name>
<email>irogers@google.com</email>
</author>
<published>2025-03-11T21:36:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=cf7c3d7e8796dce2e518ad529161c2dfb7c90352'/>
<id>cf7c3d7e8796dce2e518ad529161c2dfb7c90352</id>
<content type='text'>
[ Upstream commit 935e7cb5bb80106ff4f2fe39640f430134ef8cd8 ]

Separate test log files from object files. Depend on test log output
but don't pass to the linker.

Reviewed-by: James Clark &lt;james.clark@linaro.org&gt;
Signed-off-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250311213628.569562-2-irogers@google.com
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 935e7cb5bb80106ff4f2fe39640f430134ef8cd8 ]

Separate test log files from object files. Depend on test log output
but don't pass to the linker.

Reviewed-by: James Clark &lt;james.clark@linaro.org&gt;
Signed-off-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250311213628.569562-2-irogers@google.com
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tools features: Add feature test to check if libbfd has buildid support</title>
<updated>2023-09-23T09:00:05+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2020-09-03T16:44:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a12e9ba7f3460c52e11b7b644086f1559c485689'/>
<id>a12e9ba7f3460c52e11b7b644086f1559c485689</id>
<content type='text'>
[ Upstream commit e71e19a9ea70952a53d58a99971820ce6c1794a8 ]

Which is needed by the PE executable support, for instance.

Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jacek Caban &lt;jacek@codeweavers.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Remi Bernon &lt;rbernon@codeweavers.com&gt;
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Stable-dep-of: 7822a8913f4c ("perf build: Update build rule for generated files")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit e71e19a9ea70952a53d58a99971820ce6c1794a8 ]

Which is needed by the PE executable support, for instance.

Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jacek Caban &lt;jacek@codeweavers.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Remi Bernon &lt;rbernon@codeweavers.com&gt;
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Stable-dep-of: 7822a8913f4c ("perf build: Update build rule for generated files")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tools build: Switch to new openssl API for test-libcrypto</title>
<updated>2022-08-25T09:18:25+00:00</updated>
<author>
<name>Roberto Sassu</name>
<email>roberto.sassu@huawei.com</email>
</author>
<published>2022-07-19T17:05:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=215cbd3c0d40a45d1bd19f94bd8641363aba8212'/>
<id>215cbd3c0d40a45d1bd19f94bd8641363aba8212</id>
<content type='text'>
commit 5b245985a6de5ac18b5088c37068816d413fb8ed upstream.

Switch to new EVP API for detecting libcrypto, as Fedora 36 returns an
error when it encounters the deprecated function MD5_Init() and the others.

The error would be interpreted as missing libcrypto, while in reality it is
not.

Fixes: 6e8ccb4f624a73c5 ("tools/bpf: properly account for libbfd variations")
Signed-off-by: Roberto Sassu &lt;roberto.sassu@huawei.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Cc: bpf@vger.kernel.org
Cc: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: John Fastabend &lt;john.fastabend@gmail.com&gt;
Cc: KP Singh &lt;kpsingh@kernel.org&gt;
Cc: llvm@lists.linux.dev
Cc: Martin KaFai Lau &lt;martin.lau@linux.dev&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Cc: Nick Terrell &lt;terrelln@fb.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Quentin Monnet &lt;quentin@isovalent.com&gt;
Cc: Song Liu &lt;song@kernel.org&gt;
Cc: Stanislav Fomichev &lt;sdf@google.com&gt;
Link: https://lore.kernel.org/r/20220719170555.2576993-4-roberto.sassu@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 5b245985a6de5ac18b5088c37068816d413fb8ed upstream.

Switch to new EVP API for detecting libcrypto, as Fedora 36 returns an
error when it encounters the deprecated function MD5_Init() and the others.

The error would be interpreted as missing libcrypto, while in reality it is
not.

Fixes: 6e8ccb4f624a73c5 ("tools/bpf: properly account for libbfd variations")
Signed-off-by: Roberto Sassu &lt;roberto.sassu@huawei.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Cc: bpf@vger.kernel.org
Cc: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: John Fastabend &lt;john.fastabend@gmail.com&gt;
Cc: KP Singh &lt;kpsingh@kernel.org&gt;
Cc: llvm@lists.linux.dev
Cc: Martin KaFai Lau &lt;martin.lau@linux.dev&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Cc: Nick Terrell &lt;terrelln@fb.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Quentin Monnet &lt;quentin@isovalent.com&gt;
Cc: Song Liu &lt;song@kernel.org&gt;
Cc: Stanislav Fomichev &lt;sdf@google.com&gt;
Link: https://lore.kernel.org/r/20220719170555.2576993-4-roberto.sassu@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tools build: Use $(shell ) instead of `` to get embedded libperl's ccopts</title>
<updated>2022-04-15T12:18:40+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2022-04-04T20:28:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9e6980c68cbf194e690aa3dae8029bde8507db9e'/>
<id>9e6980c68cbf194e690aa3dae8029bde8507db9e</id>
<content type='text'>
commit 541f695cbcb6932c22638b06e0cbe1d56177e2e9 upstream.

Just like its done for ldopts and for both in tools/perf/Makefile.config.

Using `` to initialize PERL_EMBED_CCOPTS somehow precludes using:

  $(filter-out SOMETHING_TO_FILTER,$(PERL_EMBED_CCOPTS))

And we need to do it to allow for building with versions of clang where
some gcc options selected by distros are not available.

Tested-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt; # Debian/Selfmade LLVM-14 (x86-64)
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Fangrui Song &lt;maskray@google.com&gt;
Cc: Florian Fainelli &lt;f.fainelli@gmail.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: John Keeping &lt;john@metanate.com&gt;
Cc: Leo Yan &lt;leo.yan@linaro.org&gt;
Cc: Michael Petlan &lt;mpetlan@redhat.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Link: http://lore.kernel.org/lkml/YktYX2OnLtyobRYD@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 541f695cbcb6932c22638b06e0cbe1d56177e2e9 upstream.

Just like its done for ldopts and for both in tools/perf/Makefile.config.

Using `` to initialize PERL_EMBED_CCOPTS somehow precludes using:

  $(filter-out SOMETHING_TO_FILTER,$(PERL_EMBED_CCOPTS))

And we need to do it to allow for building with versions of clang where
some gcc options selected by distros are not available.

Tested-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt; # Debian/Selfmade LLVM-14 (x86-64)
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Fangrui Song &lt;maskray@google.com&gt;
Cc: Florian Fainelli &lt;f.fainelli@gmail.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: John Keeping &lt;john@metanate.com&gt;
Cc: Leo Yan &lt;leo.yan@linaro.org&gt;
Cc: Michael Petlan &lt;mpetlan@redhat.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Link: http://lore.kernel.org/lkml/YktYX2OnLtyobRYD@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tools build: Filter out options and warnings not supported by clang</title>
<updated>2022-04-15T12:18:40+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2022-04-05T13:33:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f0752ee5efdcd0890da73635c2c0bdb0d9161746'/>
<id>f0752ee5efdcd0890da73635c2c0bdb0d9161746</id>
<content type='text'>
commit 41caff459a5b956b3e23ba9ca759dd0629ad3dda upstream.

These make the feature check fail when using clang, so remove them just
like is done in tools/perf/Makefile.config to build perf itself.

Adding -Wno-compound-token-split-by-macro to tools/perf/Makefile.config
when building with clang is also necessary to avoid these warnings
turned into errors (-Werror):

    CC      /tmp/build/perf/util/scripting-engines/trace-event-perl.o
  In file included from util/scripting-engines/trace-event-perl.c:35:
  In file included from /usr/lib64/perl5/CORE/perl.h:4085:
  In file included from /usr/lib64/perl5/CORE/hv.h:659:
  In file included from /usr/lib64/perl5/CORE/hv_func.h:34:
  In file included from /usr/lib64/perl5/CORE/sbox32_hash.h:4:
  /usr/lib64/perl5/CORE/zaphod32_hash.h:150:5: error: '(' and '{' tokens introducing statement expression appear in different macro expansion contexts [-Werror,-Wcompound-token-split-by-macro]
      ZAPHOD32_SCRAMBLE32(state[0],0x9fade23b);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /usr/lib64/perl5/CORE/zaphod32_hash.h:80:38: note: expanded from macro 'ZAPHOD32_SCRAMBLE32'
  #define ZAPHOD32_SCRAMBLE32(v,prime) STMT_START {  \
                                       ^~~~~~~~~~
  /usr/lib64/perl5/CORE/perl.h:737:29: note: expanded from macro 'STMT_START'
  #   define STMT_START   (void)( /* gcc supports "({ STATEMENTS; })" */
                                ^
  /usr/lib64/perl5/CORE/zaphod32_hash.h:150:5: note: '{' token is here
      ZAPHOD32_SCRAMBLE32(state[0],0x9fade23b);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /usr/lib64/perl5/CORE/zaphod32_hash.h:80:49: note: expanded from macro 'ZAPHOD32_SCRAMBLE32'
  #define ZAPHOD32_SCRAMBLE32(v,prime) STMT_START {  \
                                                  ^
  /usr/lib64/perl5/CORE/zaphod32_hash.h:150:5: error: '}' and ')' tokens terminating statement expression appear in different macro expansion contexts [-Werror,-Wcompound-token-split-by-macro]
      ZAPHOD32_SCRAMBLE32(state[0],0x9fade23b);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /usr/lib64/perl5/CORE/zaphod32_hash.h:87:41: note: expanded from macro 'ZAPHOD32_SCRAMBLE32'
      v ^= (v&gt;&gt;23);                       \
                                          ^
  /usr/lib64/perl5/CORE/zaphod32_hash.h:150:5: note: ')' token is here
      ZAPHOD32_SCRAMBLE32(state[0],0x9fade23b);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /usr/lib64/perl5/CORE/zaphod32_hash.h:88:3: note: expanded from macro 'ZAPHOD32_SCRAMBLE32'
  } STMT_END
    ^~~~~~~~
  /usr/lib64/perl5/CORE/perl.h:738:21: note: expanded from macro 'STMT_END'
  #   define STMT_END     )
                          ^

Please refer to the discussion on the Link: tag below, where Nathan
clarifies the situation:

&lt;quote&gt;
acme&gt; And then get to the problems at the end of this message, which seem
acme&gt; similar to the problem described here:
acme&gt;
acme&gt; From  Nathan Chancellor &lt;&gt;
acme&gt; Subject	[PATCH] mwifiex: Remove unnecessary braces from HostCmd_SET_SEQ_NO_BSS_INFO
acme&gt;
acme&gt; https://lkml.org/lkml/2020/9/1/135
acme&gt;
acme&gt; So perhaps in this case its better to disable that
acme&gt; -Werror,-Wcompound-token-split-by-macro when building with clang?

Yes, I think that is probably the best solution. As far as I can tell,
at least in this file and context, the warning appears harmless, as the
"create a GNU C statement expression from two different macros" is very
much intentional, based on the presence of PERL_USE_GCC_BRACE_GROUPS.
The warning is fixed in upstream Perl by just avoiding creating GNU C
statement expressions using STMT_START and STMT_END:

  https://github.com/Perl/perl5/issues/18780
  https://github.com/Perl/perl5/pull/18984

If I am reading the source code correctly, an alternative to disabling
the warning would be specifying -DPERL_GCC_BRACE_GROUPS_FORBIDDEN but it
seems like that might end up impacting more than just this site,
according to the issue discussion above.
&lt;/quote&gt;

Based-on-a-patch-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt;
Tested-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt; # Debian/Selfmade LLVM-14 (x86-64)
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Fangrui Song &lt;maskray@google.com&gt;
Cc: Florian Fainelli &lt;f.fainelli@gmail.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: John Keeping &lt;john@metanate.com&gt;
Cc: Leo Yan &lt;leo.yan@linaro.org&gt;
Cc: Michael Petlan &lt;mpetlan@redhat.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Link: http://lore.kernel.org/lkml/YkxWcYzph5pC1EK8@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 41caff459a5b956b3e23ba9ca759dd0629ad3dda upstream.

These make the feature check fail when using clang, so remove them just
like is done in tools/perf/Makefile.config to build perf itself.

Adding -Wno-compound-token-split-by-macro to tools/perf/Makefile.config
when building with clang is also necessary to avoid these warnings
turned into errors (-Werror):

    CC      /tmp/build/perf/util/scripting-engines/trace-event-perl.o
  In file included from util/scripting-engines/trace-event-perl.c:35:
  In file included from /usr/lib64/perl5/CORE/perl.h:4085:
  In file included from /usr/lib64/perl5/CORE/hv.h:659:
  In file included from /usr/lib64/perl5/CORE/hv_func.h:34:
  In file included from /usr/lib64/perl5/CORE/sbox32_hash.h:4:
  /usr/lib64/perl5/CORE/zaphod32_hash.h:150:5: error: '(' and '{' tokens introducing statement expression appear in different macro expansion contexts [-Werror,-Wcompound-token-split-by-macro]
      ZAPHOD32_SCRAMBLE32(state[0],0x9fade23b);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /usr/lib64/perl5/CORE/zaphod32_hash.h:80:38: note: expanded from macro 'ZAPHOD32_SCRAMBLE32'
  #define ZAPHOD32_SCRAMBLE32(v,prime) STMT_START {  \
                                       ^~~~~~~~~~
  /usr/lib64/perl5/CORE/perl.h:737:29: note: expanded from macro 'STMT_START'
  #   define STMT_START   (void)( /* gcc supports "({ STATEMENTS; })" */
                                ^
  /usr/lib64/perl5/CORE/zaphod32_hash.h:150:5: note: '{' token is here
      ZAPHOD32_SCRAMBLE32(state[0],0x9fade23b);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /usr/lib64/perl5/CORE/zaphod32_hash.h:80:49: note: expanded from macro 'ZAPHOD32_SCRAMBLE32'
  #define ZAPHOD32_SCRAMBLE32(v,prime) STMT_START {  \
                                                  ^
  /usr/lib64/perl5/CORE/zaphod32_hash.h:150:5: error: '}' and ')' tokens terminating statement expression appear in different macro expansion contexts [-Werror,-Wcompound-token-split-by-macro]
      ZAPHOD32_SCRAMBLE32(state[0],0x9fade23b);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /usr/lib64/perl5/CORE/zaphod32_hash.h:87:41: note: expanded from macro 'ZAPHOD32_SCRAMBLE32'
      v ^= (v&gt;&gt;23);                       \
                                          ^
  /usr/lib64/perl5/CORE/zaphod32_hash.h:150:5: note: ')' token is here
      ZAPHOD32_SCRAMBLE32(state[0],0x9fade23b);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /usr/lib64/perl5/CORE/zaphod32_hash.h:88:3: note: expanded from macro 'ZAPHOD32_SCRAMBLE32'
  } STMT_END
    ^~~~~~~~
  /usr/lib64/perl5/CORE/perl.h:738:21: note: expanded from macro 'STMT_END'
  #   define STMT_END     )
                          ^

Please refer to the discussion on the Link: tag below, where Nathan
clarifies the situation:

&lt;quote&gt;
acme&gt; And then get to the problems at the end of this message, which seem
acme&gt; similar to the problem described here:
acme&gt;
acme&gt; From  Nathan Chancellor &lt;&gt;
acme&gt; Subject	[PATCH] mwifiex: Remove unnecessary braces from HostCmd_SET_SEQ_NO_BSS_INFO
acme&gt;
acme&gt; https://lkml.org/lkml/2020/9/1/135
acme&gt;
acme&gt; So perhaps in this case its better to disable that
acme&gt; -Werror,-Wcompound-token-split-by-macro when building with clang?

Yes, I think that is probably the best solution. As far as I can tell,
at least in this file and context, the warning appears harmless, as the
"create a GNU C statement expression from two different macros" is very
much intentional, based on the presence of PERL_USE_GCC_BRACE_GROUPS.
The warning is fixed in upstream Perl by just avoiding creating GNU C
statement expressions using STMT_START and STMT_END:

  https://github.com/Perl/perl5/issues/18780
  https://github.com/Perl/perl5/pull/18984

If I am reading the source code correctly, an alternative to disabling
the warning would be specifying -DPERL_GCC_BRACE_GROUPS_FORBIDDEN but it
seems like that might end up impacting more than just this site,
according to the issue discussion above.
&lt;/quote&gt;

Based-on-a-patch-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt;
Tested-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt; # Debian/Selfmade LLVM-14 (x86-64)
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Fangrui Song &lt;maskray@google.com&gt;
Cc: Florian Fainelli &lt;f.fainelli@gmail.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: John Keeping &lt;john@metanate.com&gt;
Cc: Leo Yan &lt;leo.yan@linaro.org&gt;
Cc: Michael Petlan &lt;mpetlan@redhat.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Link: http://lore.kernel.org/lkml/YkxWcYzph5pC1EK8@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tools build: Remove needless libpython-version feature check that breaks test-all fast path</title>
<updated>2021-12-14T13:49:03+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2021-11-30T13:12:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e9ca63a07dd35d56cf0df57228c54970fb5e0c89'/>
<id>e9ca63a07dd35d56cf0df57228c54970fb5e0c89</id>
<content type='text'>
commit 3d1d57debee2d342a47615707588b96658fabb85 upstream.

Since 66dfdff03d196e51 ("perf tools: Add Python 3 support") we don't use
the tools/build/feature/test-libpython-version.c version in any Makefile
feature check:

  $ find tools/ -type f | xargs grep feature-libpython-version
  $

The only place where this was used was removed in 66dfdff03d196e51:

  -        ifneq ($(feature-libpython-version), 1)
  -          $(warning Python 3 is not yet supported; please set)
  -          $(warning PYTHON and/or PYTHON_CONFIG appropriately.)
  -          $(warning If you also have Python 2 installed, then)
  -          $(warning try something like:)
  -          $(warning $(and ,))
  -          $(warning $(and ,)  make PYTHON=python2)
  -          $(warning $(and ,))
  -          $(warning Otherwise, disable Python support entirely:)
  -          $(warning $(and ,))
  -          $(warning $(and ,)  make NO_LIBPYTHON=1)
  -          $(warning $(and ,))
  -          $(error   $(and ,))
  -        else
  -          LDFLAGS += $(PYTHON_EMBED_LDFLAGS)
  -          EXTLIBS += $(PYTHON_EMBED_LIBADD)
  -          LANG_BINDINGS += $(obj-perf)python/perf.so
  -          $(call detected,CONFIG_LIBPYTHON)
  -        endif

And nowadays we either build with PYTHON=python3 or just install the
python3 devel packages and perf will build against it.

But the leftover feature-libpython-version check made the fast path
feature detection to break in all cases except when python2 devel files
were installed:

  $ rpm -qa | grep python.*devel
  python3-devel-3.9.7-1.fc34.x86_64
  $ rm -rf /tmp/build/perf ; mkdir -p /tmp/build/perf ;
  $ make -C tools/perf O=/tmp/build/perf install-bin
  make: Entering directory '/var/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j32' parallel build
    HOSTCC  /tmp/build/perf/fixdep.o
  &lt;SNIP&gt;
  $ cat /tmp/build/perf/feature/test-all.make.output
  In file included from test-all.c:18:
  test-libpython-version.c:5:10: error: #error
      5 |         #error
        |          ^~~~~
  $ ldd ~/bin/perf | grep python
	libpython3.9.so.1.0 =&gt; /lib64/libpython3.9.so.1.0 (0x00007fda6dbcf000)
  $

As python3 is the norm these days, fix this by just removing the unused
feature-libpython-version feature check, making the test-all fast path
to work with the common case.

With this:

  $ rm -rf /tmp/build/perf ; mkdir -p /tmp/build/perf ;
  $ make -C tools/perf O=/tmp/build/perf install-bin |&amp; head
  make: Entering directory '/var/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j32' parallel build
    HOSTCC  /tmp/build/perf/fixdep.o
    HOSTLD  /tmp/build/perf/fixdep-in.o
    LINK    /tmp/build/perf/fixdep

  Auto-detecting system features:
  ...                         dwarf: [ on  ]
  ...            dwarf_getlocations: [ on  ]
  ...                         glibc: [ on  ]
  $ ldd ~/bin/perf | grep python
	libpython3.9.so.1.0 =&gt; /lib64/libpython3.9.so.1.0 (0x00007f58800b0000)
  $ cat /tmp/build/perf/feature/test-all.make.output
  $

Reviewed-by: James Clark &lt;james.clark@arm.com&gt;
Fixes: 66dfdff03d196e51 ("perf tools: Add Python 3 support")
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jaroslav Škarvada &lt;jskarvad@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Link: https://lore.kernel.org/lkml/YaYmeeC6CS2b8OSz@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 3d1d57debee2d342a47615707588b96658fabb85 upstream.

Since 66dfdff03d196e51 ("perf tools: Add Python 3 support") we don't use
the tools/build/feature/test-libpython-version.c version in any Makefile
feature check:

  $ find tools/ -type f | xargs grep feature-libpython-version
  $

The only place where this was used was removed in 66dfdff03d196e51:

  -        ifneq ($(feature-libpython-version), 1)
  -          $(warning Python 3 is not yet supported; please set)
  -          $(warning PYTHON and/or PYTHON_CONFIG appropriately.)
  -          $(warning If you also have Python 2 installed, then)
  -          $(warning try something like:)
  -          $(warning $(and ,))
  -          $(warning $(and ,)  make PYTHON=python2)
  -          $(warning $(and ,))
  -          $(warning Otherwise, disable Python support entirely:)
  -          $(warning $(and ,))
  -          $(warning $(and ,)  make NO_LIBPYTHON=1)
  -          $(warning $(and ,))
  -          $(error   $(and ,))
  -        else
  -          LDFLAGS += $(PYTHON_EMBED_LDFLAGS)
  -          EXTLIBS += $(PYTHON_EMBED_LIBADD)
  -          LANG_BINDINGS += $(obj-perf)python/perf.so
  -          $(call detected,CONFIG_LIBPYTHON)
  -        endif

And nowadays we either build with PYTHON=python3 or just install the
python3 devel packages and perf will build against it.

But the leftover feature-libpython-version check made the fast path
feature detection to break in all cases except when python2 devel files
were installed:

  $ rpm -qa | grep python.*devel
  python3-devel-3.9.7-1.fc34.x86_64
  $ rm -rf /tmp/build/perf ; mkdir -p /tmp/build/perf ;
  $ make -C tools/perf O=/tmp/build/perf install-bin
  make: Entering directory '/var/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j32' parallel build
    HOSTCC  /tmp/build/perf/fixdep.o
  &lt;SNIP&gt;
  $ cat /tmp/build/perf/feature/test-all.make.output
  In file included from test-all.c:18:
  test-libpython-version.c:5:10: error: #error
      5 |         #error
        |          ^~~~~
  $ ldd ~/bin/perf | grep python
	libpython3.9.so.1.0 =&gt; /lib64/libpython3.9.so.1.0 (0x00007fda6dbcf000)
  $

As python3 is the norm these days, fix this by just removing the unused
feature-libpython-version feature check, making the test-all fast path
to work with the common case.

With this:

  $ rm -rf /tmp/build/perf ; mkdir -p /tmp/build/perf ;
  $ make -C tools/perf O=/tmp/build/perf install-bin |&amp; head
  make: Entering directory '/var/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j32' parallel build
    HOSTCC  /tmp/build/perf/fixdep.o
    HOSTLD  /tmp/build/perf/fixdep-in.o
    LINK    /tmp/build/perf/fixdep

  Auto-detecting system features:
  ...                         dwarf: [ on  ]
  ...            dwarf_getlocations: [ on  ]
  ...                         glibc: [ on  ]
  $ ldd ~/bin/perf | grep python
	libpython3.9.so.1.0 =&gt; /lib64/libpython3.9.so.1.0 (0x00007f58800b0000)
  $ cat /tmp/build/perf/feature/test-all.make.output
  $

Reviewed-by: James Clark &lt;james.clark@arm.com&gt;
Fixes: 66dfdff03d196e51 ("perf tools: Add Python 3 support")
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jaroslav Škarvada &lt;jskarvad@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Link: https://lore.kernel.org/lkml/YaYmeeC6CS2b8OSz@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tools: Factor HOSTCC, HOSTLD, HOSTAR definitions</title>
<updated>2021-01-30T12:54:10+00:00</updated>
<author>
<name>Jean-Philippe Brucker</name>
<email>jean-philippe@linaro.org</email>
</author>
<published>2020-11-10T16:43:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=43546b74ce6cae3d0c2fa772970f2f3eeb2a0d6e'/>
<id>43546b74ce6cae3d0c2fa772970f2f3eeb2a0d6e</id>
<content type='text'>
commit c8a950d0d3b926a02c7b2e713850d38217cec3d1 upstream.

Several Makefiles in tools/ need to define the host toolchain variables.
Move their definition to tools/scripts/Makefile.include

Signed-off-by: Jean-Philippe Brucker &lt;jean-philippe@linaro.org&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Acked-by: Jiri Olsa &lt;jolsa@redhat.com&gt;
Acked-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Link: https://lore.kernel.org/bpf/20201110164310.2600671-2-jean-philippe@linaro.org
Cc: Alistair Delva &lt;adelva@google.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit c8a950d0d3b926a02c7b2e713850d38217cec3d1 upstream.

Several Makefiles in tools/ need to define the host toolchain variables.
Move their definition to tools/scripts/Makefile.include

Signed-off-by: Jean-Philippe Brucker &lt;jean-philippe@linaro.org&gt;
Signed-off-by: Andrii Nakryiko &lt;andrii@kernel.org&gt;
Acked-by: Jiri Olsa &lt;jolsa@redhat.com&gt;
Acked-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Link: https://lore.kernel.org/bpf/20201110164310.2600671-2-jean-philippe@linaro.org
Cc: Alistair Delva &lt;adelva@google.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>tools build feature: Quote CC and CXX for their arguments</title>
<updated>2020-08-21T11:05:38+00:00</updated>
<author>
<name>Daniel Díaz</name>
<email>daniel.diaz@linaro.org</email>
</author>
<published>2020-08-12T22:15:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=5c90739d36ce621d6589af50b4398ceedcf4f1c7'/>
<id>5c90739d36ce621d6589af50b4398ceedcf4f1c7</id>
<content type='text'>
[ Upstream commit fa5c893181ed2ca2f96552f50073786d2cfce6c0 ]

When using a cross-compilation environment, such as OpenEmbedded,
the CC an CXX variables are set to something more than just a
command: there are arguments (such as --sysroot) that need to be
passed on to the compiler so that the right set of headers and
libraries are used.

For the particular case that our systems detected, CC is set to
the following:

  export CC="aarch64-linaro-linux-gcc  --sysroot=/oe/build/tmp/work/machine/perf/1.0-r9/recipe-sysroot"

Without quotes, detection is as follows:

  Auto-detecting system features:
  ...                         dwarf: [ OFF ]
  ...            dwarf_getlocations: [ OFF ]
  ...                         glibc: [ OFF ]
  ...                          gtk2: [ OFF ]
  ...                        libbfd: [ OFF ]
  ...                        libcap: [ OFF ]
  ...                        libelf: [ OFF ]
  ...                       libnuma: [ OFF ]
  ...        numa_num_possible_cpus: [ OFF ]
  ...                       libperl: [ OFF ]
  ...                     libpython: [ OFF ]
  ...                     libcrypto: [ OFF ]
  ...                     libunwind: [ OFF ]
  ...            libdw-dwarf-unwind: [ OFF ]
  ...                          zlib: [ OFF ]
  ...                          lzma: [ OFF ]
  ...                     get_cpuid: [ OFF ]
  ...                           bpf: [ OFF ]
  ...                        libaio: [ OFF ]
  ...                       libzstd: [ OFF ]
  ...        disassembler-four-args: [ OFF ]

  Makefile.config:414: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.
  Makefile.perf:230: recipe for target 'sub-make' failed
  make[1]: *** [sub-make] Error 2
  Makefile:69: recipe for target 'all' failed
  make: *** [all] Error 2

With CC and CXX quoted, some of those features are now detected.

Fixes: e3232c2f39ac ("tools build feature: Use CC and CXX from parent")
Signed-off-by: Daniel Díaz &lt;daniel.diaz@linaro.org&gt;
Reviewed-by: Thomas Hebb &lt;tommyhebb@gmail.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andriin@fb.com&gt;
Cc: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: John Fastabend &lt;john.fastabend@gmail.com&gt;
Cc: KP Singh &lt;kpsingh@chromium.org&gt;
Cc: Martin KaFai Lau &lt;kafai@fb.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Song Liu &lt;songliubraving@fb.com&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Yonghong Song &lt;yhs@fb.com&gt;
Link: http://lore.kernel.org/lkml/20200812221518.2869003-1-daniel.diaz@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit fa5c893181ed2ca2f96552f50073786d2cfce6c0 ]

When using a cross-compilation environment, such as OpenEmbedded,
the CC an CXX variables are set to something more than just a
command: there are arguments (such as --sysroot) that need to be
passed on to the compiler so that the right set of headers and
libraries are used.

For the particular case that our systems detected, CC is set to
the following:

  export CC="aarch64-linaro-linux-gcc  --sysroot=/oe/build/tmp/work/machine/perf/1.0-r9/recipe-sysroot"

Without quotes, detection is as follows:

  Auto-detecting system features:
  ...                         dwarf: [ OFF ]
  ...            dwarf_getlocations: [ OFF ]
  ...                         glibc: [ OFF ]
  ...                          gtk2: [ OFF ]
  ...                        libbfd: [ OFF ]
  ...                        libcap: [ OFF ]
  ...                        libelf: [ OFF ]
  ...                       libnuma: [ OFF ]
  ...        numa_num_possible_cpus: [ OFF ]
  ...                       libperl: [ OFF ]
  ...                     libpython: [ OFF ]
  ...                     libcrypto: [ OFF ]
  ...                     libunwind: [ OFF ]
  ...            libdw-dwarf-unwind: [ OFF ]
  ...                          zlib: [ OFF ]
  ...                          lzma: [ OFF ]
  ...                     get_cpuid: [ OFF ]
  ...                           bpf: [ OFF ]
  ...                        libaio: [ OFF ]
  ...                       libzstd: [ OFF ]
  ...        disassembler-four-args: [ OFF ]

  Makefile.config:414: *** No gnu/libc-version.h found, please install glibc-dev[el].  Stop.
  Makefile.perf:230: recipe for target 'sub-make' failed
  make[1]: *** [sub-make] Error 2
  Makefile:69: recipe for target 'all' failed
  make: *** [all] Error 2

With CC and CXX quoted, some of those features are now detected.

Fixes: e3232c2f39ac ("tools build feature: Use CC and CXX from parent")
Signed-off-by: Daniel Díaz &lt;daniel.diaz@linaro.org&gt;
Reviewed-by: Thomas Hebb &lt;tommyhebb@gmail.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Andrii Nakryiko &lt;andriin@fb.com&gt;
Cc: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: John Fastabend &lt;john.fastabend@gmail.com&gt;
Cc: KP Singh &lt;kpsingh@chromium.org&gt;
Cc: Martin KaFai Lau &lt;kafai@fb.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Song Liu &lt;songliubraving@fb.com&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Yonghong Song &lt;yhs@fb.com&gt;
Link: http://lore.kernel.org/lkml/20200812221518.2869003-1-daniel.diaz@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>tools build feature: Use CC and CXX from parent</title>
<updated>2020-08-21T11:05:34+00:00</updated>
<author>
<name>Thomas Hebb</name>
<email>tommyhebb@gmail.com</email>
</author>
<published>2020-07-27T04:08:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=4f69483568d6732fa61164b2dba3158726ee5cd9'/>
<id>4f69483568d6732fa61164b2dba3158726ee5cd9</id>
<content type='text'>
[ Upstream commit e3232c2f39acafd5a29128425bc30b9884642cfa ]

commit c8c188679ccf ("tools build: Use the same CC for feature detection
and actual build") changed these assignments from unconditional (:=) to
conditional (?=) so that they wouldn't clobber values from the
environment. However, conditional assignment does not work properly for
variables that Make implicitly sets, among which are CC and CXX. To
quote tools/scripts/Makefile.include, which handles this properly:

  # Makefiles suck: This macro sets a default value of $(2) for the
  # variable named by $(1), unless the variable has been set by
  # environment or command line. This is necessary for CC and AR
  # because make sets default values, so the simpler ?= approach
  # won't work as expected.

In other words, the conditional assignments will not run even if the
variables are not overridden in the environment; Make will set CC to
"cc" and CXX to "g++" when it starts[1], meaning the variables are not
empty by the time the conditional assignments are evaluated. This breaks
cross-compilation when CROSS_COMPILE is set but CC isn't, since "cc"
gets used for feature detection instead of the cross compiler (and
likewise for CXX).

To fix the issue, just pass down the values of CC and CXX computed by
the parent Makefile, which gets included by the Makefile that actually
builds whatever we're detecting features for and so is guaranteed to
have good values. This is a better solution anyway, since it means we
aren't trying to replicate the logic of the parent build system and so
don't risk it getting out of sync.

Leave PKG_CONFIG alone, since 1) there's no common logic to compute it
in Makefile.include, and 2) it's not an implicit variable, so
conditional assignment works properly.

[1] https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html

Fixes: c8c188679ccf ("tools build: Use the same CC for feature detection and actual build")
Signed-off-by: Thomas Hebb &lt;tommyhebb@gmail.com&gt;
Acked-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: David Carrillo-Cisneros &lt;davidcc@google.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Igor Lubashev &lt;ilubashe@akamai.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Quentin Monnet &lt;quentin@isovalent.com&gt;
Cc: Song Liu &lt;songliubraving@fb.com&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: thomas hebb &lt;tommyhebb@gmail.com&gt;
Link: http://lore.kernel.org/lkml/0a6e69d1736b0fa231a648f50b0cce5d8a6734ef.1595822871.git.tommyhebb@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
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<pre>
[ Upstream commit e3232c2f39acafd5a29128425bc30b9884642cfa ]

commit c8c188679ccf ("tools build: Use the same CC for feature detection
and actual build") changed these assignments from unconditional (:=) to
conditional (?=) so that they wouldn't clobber values from the
environment. However, conditional assignment does not work properly for
variables that Make implicitly sets, among which are CC and CXX. To
quote tools/scripts/Makefile.include, which handles this properly:

  # Makefiles suck: This macro sets a default value of $(2) for the
  # variable named by $(1), unless the variable has been set by
  # environment or command line. This is necessary for CC and AR
  # because make sets default values, so the simpler ?= approach
  # won't work as expected.

In other words, the conditional assignments will not run even if the
variables are not overridden in the environment; Make will set CC to
"cc" and CXX to "g++" when it starts[1], meaning the variables are not
empty by the time the conditional assignments are evaluated. This breaks
cross-compilation when CROSS_COMPILE is set but CC isn't, since "cc"
gets used for feature detection instead of the cross compiler (and
likewise for CXX).

To fix the issue, just pass down the values of CC and CXX computed by
the parent Makefile, which gets included by the Makefile that actually
builds whatever we're detecting features for and so is guaranteed to
have good values. This is a better solution anyway, since it means we
aren't trying to replicate the logic of the parent build system and so
don't risk it getting out of sync.

Leave PKG_CONFIG alone, since 1) there's no common logic to compute it
in Makefile.include, and 2) it's not an implicit variable, so
conditional assignment works properly.

[1] https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html

Fixes: c8c188679ccf ("tools build: Use the same CC for feature detection and actual build")
Signed-off-by: Thomas Hebb &lt;tommyhebb@gmail.com&gt;
Acked-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: David Carrillo-Cisneros &lt;davidcc@google.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Igor Lubashev &lt;ilubashe@akamai.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Quentin Monnet &lt;quentin@isovalent.com&gt;
Cc: Song Liu &lt;songliubraving@fb.com&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: thomas hebb &lt;tommyhebb@gmail.com&gt;
Link: http://lore.kernel.org/lkml/0a6e69d1736b0fa231a648f50b0cce5d8a6734ef.1595822871.git.tommyhebb@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
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