<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/tools/perf/Makefile.config, branch v6.17</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>tools: Remove libcrypto dependency</title>
<updated>2025-06-26T17:51:41+00:00</updated>
<author>
<name>Yuzhuo Jing</name>
<email>yuzhuo@google.com</email>
</author>
<published>2025-06-25T20:23:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8e63fd1e00f59eab01ab43eb094abc380f8d0c28'/>
<id>8e63fd1e00f59eab01ab43eb094abc380f8d0c28</id>
<content type='text'>
Remove all occurrence of libcrypto in the build system.

Signed-off-by: Yuzhuo Jing &lt;yuzhuo@google.com&gt;
Signed-off-by: Eric Biggers &lt;ebiggers@kernel.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250625202311.23244-5-ebiggers@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Remove all occurrence of libcrypto in the build system.

Signed-off-by: Yuzhuo Jing &lt;yuzhuo@google.com&gt;
Signed-off-by: Eric Biggers &lt;ebiggers@kernel.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250625202311.23244-5-ebiggers@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf build: enable -fno-strict-aliasing</title>
<updated>2025-06-26T17:51:40+00:00</updated>
<author>
<name>Eric Biggers</name>
<email>ebiggers@kernel.org</email>
</author>
<published>2025-06-25T20:23:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=55a18d2f3ff79c9082225f44e0abbaea6286bf99'/>
<id>55a18d2f3ff79c9082225f44e0abbaea6286bf99</id>
<content type='text'>
perf pulls in code from kernel headers that assumes it is being built
with -fno-strict-aliasing, namely put_unaligned_*() from
&lt;linux/unaligned.h&gt; which write the data using packed structs that lack
the may_alias attribute.  Enable -fno-strict-aliasing to prevent
miscompilations in sha1.c which would otherwise occur due to this issue.

Signed-off-by: Eric Biggers &lt;ebiggers@kernel.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250625202311.23244-2-ebiggers@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
perf pulls in code from kernel headers that assumes it is being built
with -fno-strict-aliasing, namely put_unaligned_*() from
&lt;linux/unaligned.h&gt; which write the data using packed structs that lack
the may_alias attribute.  Enable -fno-strict-aliasing to prevent
miscompilations in sha1.c which would otherwise occur due to this issue.

Signed-off-by: Eric Biggers &lt;ebiggers@kernel.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250625202311.23244-2-ebiggers@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf build: The bfd features are opt-in, stop testing for them by default</title>
<updated>2025-06-24T17:27:50+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2025-06-20T21:24:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=970ae86307718c347aff8fe4bf6e780bcce26c58'/>
<id>970ae86307718c347aff8fe4bf6e780bcce26c58</id>
<content type='text'>
These are leftovers noticed while updating a build container.

We don't need those so that test-all.c can build and thus speed up the
feature detection.

Test for those features only if the user asks for BUILD_NONDISTRO=1 to
build with libbfd.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Reviewed-by: James Clark &lt;james.clark@linaro.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250620212435.93846-4-acme@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
These are leftovers noticed while updating a build container.

We don't need those so that test-all.c can build and thus speed up the
feature detection.

Test for those features only if the user asks for BUILD_NONDISTRO=1 to
build with libbfd.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Reviewed-by: James Clark &lt;james.clark@linaro.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250620212435.93846-4-acme@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf build: Add the libpfm devel fedora package name to the hint</title>
<updated>2025-06-24T17:27:50+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2025-06-20T21:24:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7c750d399b60e17f2a346690e0d34aae9c086eac'/>
<id>7c750d399b60e17f2a346690e0d34aae9c086eac</id>
<content type='text'>
Just to follow the pattern with other devel packages.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Reviewed-by: James Clark &lt;james.clark@linaro.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250620212435.93846-3-acme@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Just to follow the pattern with other devel packages.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Reviewed-by: James Clark &lt;james.clark@linaro.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250620212435.93846-3-acme@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf build: Suggest java-latest-openjdk-devel instead of old 1.8.0 one</title>
<updated>2025-06-24T17:27:49+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2025-06-20T21:24:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c335a4e927537996b425025586d5d8db2763124c'/>
<id>c335a4e927537996b425025586d5d8db2763124c</id>
<content type='text'>
Just tidying up the suggestion to pick the latest and not some specific
version.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Reviewed-by: James Clark &lt;james.clark@linaro.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250620212435.93846-2-acme@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Just tidying up the suggestion to pick the latest and not some specific
version.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Reviewed-by: James Clark &lt;james.clark@linaro.org&gt;
Reviewed-by: Ian Rogers &lt;irogers@google.com&gt;
Link: https://lore.kernel.org/r/20250620212435.93846-2-acme@kernel.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf build: detect support for libbpf's emit_strings option</title>
<updated>2025-06-20T21:48:14+00:00</updated>
<author>
<name>Blake Jones</name>
<email>blakejones@google.com</email>
</author>
<published>2025-06-12T19:49:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1d0654b7fdc5431b85035f6e76b4bc57679575d8'/>
<id>1d0654b7fdc5431b85035f6e76b4bc57679575d8</id>
<content type='text'>
This creates a config option that detects libbpf's ability to display
character arrays as strings, which was just added to the BPF tree
(https://git.kernel.org/bpf/bpf-next/c/87c9c79a02b4).

To test this change, I built perf (from later in this patch set) with:

 - static libbpf (default, using source from kernel tree)
 - dynamic libbpf (LIBBPF_DYNAMIC=1 LIBBPF_INCLUDE=/usr/local/include)

For both the static and dynamic versions, I used headers with and without
the ".emit_strings" option.

I verified that of the four resulting binaries, the two with
".emit_strings" would successfully record BPF_METADATA events, and the two
without wouldn't.  All four binaries would successfully display
BPF_METADATA events, because the relevant bit of libbpf code is only used
during "perf record".

Signed-off-by: Blake Jones &lt;blakejones@google.com&gt;
Link: https://lore.kernel.org/r/20250612194939.162730-2-blakejones@google.com
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This creates a config option that detects libbpf's ability to display
character arrays as strings, which was just added to the BPF tree
(https://git.kernel.org/bpf/bpf-next/c/87c9c79a02b4).

To test this change, I built perf (from later in this patch set) with:

 - static libbpf (default, using source from kernel tree)
 - dynamic libbpf (LIBBPF_DYNAMIC=1 LIBBPF_INCLUDE=/usr/local/include)

For both the static and dynamic versions, I used headers with and without
the ".emit_strings" option.

I verified that of the four resulting binaries, the two with
".emit_strings" would successfully record BPF_METADATA events, and the two
without wouldn't.  All four binaries would successfully display
BPF_METADATA events, because the relevant bit of libbpf code is only used
during "perf record".

Signed-off-by: Blake Jones &lt;blakejones@google.com&gt;
Link: https://lore.kernel.org/r/20250612194939.162730-2-blakejones@google.com
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge remote-tracking branch 'torvalds/master' into perf-tools-next</title>
<updated>2025-05-07T15:51:38+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2025-05-07T15:51:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8330d092f789ca7859042c80cbf3ea496bc53d99'/>
<id>8330d092f789ca7859042c80cbf3ea496bc53d99</id>
<content type='text'>
To pick up fixes from the latest perf-tools pull request from Namhyung
and get perf-tools-next in line with thinngs in other areas it uses,
like tools/lib/bpf, etc.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
To pick up fixes from the latest perf-tools pull request from Namhyung
and get perf-tools-next in line with thinngs in other areas it uses,
like tools/lib/bpf, etc.

Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf tools: Fix in-source libperf build</title>
<updated>2025-04-29T19:32:31+00:00</updated>
<author>
<name>James Clark</name>
<email>james.clark@linaro.org</email>
</author>
<published>2025-04-29T14:22:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8988c4b91945173a6b5505764915d470f0238fdc'/>
<id>8988c4b91945173a6b5505764915d470f0238fdc</id>
<content type='text'>
When libperf is built alone in-source, $(OUTPUT) isn't set. This causes
the generated uapi path to resolve to '/../arch' which results in a
permissions error:

  mkdir: cannot create directory '/../arch': Permission denied

Fix it by removing the preceding '/..' which means that it gets
generated either in the tools/lib/perf part of the tree or the OUTPUT
folder. Some other rules that rely on OUTPUT further refine this
conditionally depending on whether it's an in-source or out-of-source
build, but I don't think we need the extra complexity here. And this
rule is slightly different to others because the header is needed by
both libperf and Perf. This is further complicated by the fact that Perf
always passes O=... to libperf even for in source builds, meaning that
OUTPUT isn't set consistently between projects.

Because we're no longer going one level up to try to generate the file
in the tools/ folder, Perf's include rule needs to descend into libperf.
Also fix the clean rule while we're here.

Reported-by: Thorsten Leemhuis &lt;linux@leemhuis.info&gt;
Closes: https://lore.kernel.org/linux-perf-users/7703f88e-ccb7-4c98-9da4-8aad224e780f@leemhuis.info/
Fixes: bfb713ea53c7 ("perf tools: Fix arm64 build by generating unistd_64.h")
Signed-off-by: James Clark &lt;james.clark@linaro.org&gt;
Tested-by: Thorsten Leemhuis &lt;linux@leemhuis.info&gt;
Link: https://lore.kernel.org/r/20250429-james-perf-fix-libperf-in-source-build-v1-1-a1a827ac15e5@linaro.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When libperf is built alone in-source, $(OUTPUT) isn't set. This causes
the generated uapi path to resolve to '/../arch' which results in a
permissions error:

  mkdir: cannot create directory '/../arch': Permission denied

Fix it by removing the preceding '/..' which means that it gets
generated either in the tools/lib/perf part of the tree or the OUTPUT
folder. Some other rules that rely on OUTPUT further refine this
conditionally depending on whether it's an in-source or out-of-source
build, but I don't think we need the extra complexity here. And this
rule is slightly different to others because the header is needed by
both libperf and Perf. This is further complicated by the fact that Perf
always passes O=... to libperf even for in source builds, meaning that
OUTPUT isn't set consistently between projects.

Because we're no longer going one level up to try to generate the file
in the tools/ folder, Perf's include rule needs to descend into libperf.
Also fix the clean rule while we're here.

Reported-by: Thorsten Leemhuis &lt;linux@leemhuis.info&gt;
Closes: https://lore.kernel.org/linux-perf-users/7703f88e-ccb7-4c98-9da4-8aad224e780f@leemhuis.info/
Fixes: bfb713ea53c7 ("perf tools: Fix arm64 build by generating unistd_64.h")
Signed-off-by: James Clark &lt;james.clark@linaro.org&gt;
Tested-by: Thorsten Leemhuis &lt;linux@leemhuis.info&gt;
Link: https://lore.kernel.org/r/20250429-james-perf-fix-libperf-in-source-build-v1-1-a1a827ac15e5@linaro.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf tools: Fix arm64 build by generating unistd_64.h</title>
<updated>2025-04-23T15:57:12+00:00</updated>
<author>
<name>James Clark</name>
<email>james.clark@linaro.org</email>
</author>
<published>2025-04-17T13:55:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=bfb713ea53c746b07ae69fe97fa9b5388e4f34f9'/>
<id>bfb713ea53c746b07ae69fe97fa9b5388e4f34f9</id>
<content type='text'>
Since pulling in the kernel changes in commit 22f72088ffe6 ("tools
headers: Update the syscall table with the kernel sources"), arm64 is
no longer using a generic syscall header and generates one from the
syscall table. Therefore we must also generate the syscall header for
arm64 before building Perf.

Add it as a dependency to libperf which uses one syscall number. Perf
uses more, but as libperf is a dependency of Perf it will be generated
for both.

Future platforms that need this will have to add their own syscall-y
targets in libperf manually. Unfortunately the arch specific files that
do this (e.g. arch/arm64/include/asm/Kbuild) can't easily be imported
into the Perf build. But Perf only needs a subset of the generated files
anyway, so redefining them is probably the correct thing to do.

Fixes: 22f72088ffe6 ("tools headers: Update the syscall table with the kernel sources")
Signed-off-by: James Clark &lt;james.clark@linaro.org&gt;
Tested-by: Harshit Mogalapalli &lt;harshit.m.mogalapalli@oracle.com&gt;
Link: https://lore.kernel.org/r/20250417-james-perf-fix-gen-syscall-v1-1-1d268c923901@linaro.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Since pulling in the kernel changes in commit 22f72088ffe6 ("tools
headers: Update the syscall table with the kernel sources"), arm64 is
no longer using a generic syscall header and generates one from the
syscall table. Therefore we must also generate the syscall header for
arm64 before building Perf.

Add it as a dependency to libperf which uses one syscall number. Perf
uses more, but as libperf is a dependency of Perf it will be generated
for both.

Future platforms that need this will have to add their own syscall-y
targets in libperf manually. Unfortunately the arch specific files that
do this (e.g. arch/arm64/include/asm/Kbuild) can't easily be imported
into the Perf build. But Perf only needs a subset of the generated files
anyway, so redefining them is probably the correct thing to do.

Fixes: 22f72088ffe6 ("tools headers: Update the syscall table with the kernel sources")
Signed-off-by: James Clark &lt;james.clark@linaro.org&gt;
Tested-by: Harshit Mogalapalli &lt;harshit.m.mogalapalli@oracle.com&gt;
Link: https://lore.kernel.org/r/20250417-james-perf-fix-gen-syscall-v1-1-1d268c923901@linaro.org
Signed-off-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf build: Warn when libdebuginfod devel files are not available</title>
<updated>2025-04-10T13:45:02+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2025-04-08T14:37:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=4fce4b91fd1aabb326c46e237eb4b19ab72598f8'/>
<id>4fce4b91fd1aabb326c46e237eb4b19ab72598f8</id>
<content type='text'>
While working on 'perf version --build-options' I noticed that:

  $ perf version --build-options
  perf version 6.15.rc1.g312a07a00d31
                   aio: [ on  ]  # HAVE_AIO_SUPPORT
                   bpf: [ on  ]  # HAVE_LIBBPF_SUPPORT
         bpf_skeletons: [ on  ]  # HAVE_BPF_SKEL
            debuginfod: [ OFF ]  # HAVE_DEBUGINFOD_SUPPORT
  &lt;SNIP&gt;

And looking at tools/perf/Makefile.config I also noticed that it is not
opt-in, meaning we will attempt to build with it in all normal cases.

So add the usual warning at build time to let the user know that
something recommended is missing, now we see:

  Makefile.config:563: No elfutils/debuginfod.h found, no debuginfo server support, please install elfutils-debuginfod-client-devel or equivalent

And after following the recommendation:

  $ perf check feature debuginfod
            debuginfod: [ on  ]  # HAVE_DEBUGINFOD_SUPPORT
  $ ldd ~/bin/perf | grep debuginfo
	libdebuginfod.so.1 =&gt; /lib64/libdebuginfod.so.1 (0x00007fee5cf5f000)
  $

With this feature on several perf tools will fetch what is needed and
not require all the contents of the debuginfo packages, for instance:

  # rpm -qa | grep kernel-debuginfo
  # pahole --running_kernel_vmlinux
  pahole: couldn't find a vmlinux that matches the running kernel
  HINT: Maybe you're inside a container or missing a debuginfo package?
  #
  # perf trace -e open* perf probe --vars icmp_rcv
      0.000 ( 0.005 ms): perf/97391 openat(dfd: CWD, filename: "/etc/ld.so.cache", flags: RDONLY|CLOEXEC) = 3
      0.014 ( 0.004 ms): perf/97391 openat(dfd: CWD, filename: "/lib64/libm.so.6", flags: RDONLY|CLOEXEC) = 3
  &lt;SNIP&gt;
  32130.100 ( 0.008 ms): perf/97391 openat(dfd: CWD, filename: "/root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo") = 3
  &lt;SNIP&gt;
  Available variables at icmp_rcv
        @&lt;icmp_rcv+0&gt;
                struct sk_buff* skb
  &lt;SNIP&gt;
  #
  # pahole --running_kernel_vmlinux
  /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo
  # file /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo
  /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, BuildID[sha1]=aa3c82b4a13f9c0e0301bebb20fe958c4db6f362, with debug_info, not stripped
  # ls -la /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo
  -r--------. 1 root root 475401512 Mar 27 21:00 /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo
  #

Then, cached:

  # perf stat --null perf probe --vars icmp_rcv
  Available variables at icmp_rcv
        @&lt;icmp_rcv+0&gt;
                struct sk_buff* skb

   Performance counter stats for 'perf probe --vars icmp_rcv':

       0.671389041 seconds time elapsed

       0.519176000 seconds user
       0.150860000 seconds sys

Fixes: c7a14fdcb3fa7736 ("perf build-ids: Fall back to debuginfod query if debuginfo not found")
Tested-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Dmitriy Vyukov &lt;dvyukov@google.com&gt;
Cc: Howard Chu &lt;howardchu95@gmail.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Frank Ch. Eigler &lt;fche@redhat.com&gt;
Link: https://lore.kernel.org/r/Z_dkNDj9EPFwPqq1@gmail.com
[ Folded patch from Ingo to have the debian/ubuntu devel package added build warning message ]
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
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While working on 'perf version --build-options' I noticed that:

  $ perf version --build-options
  perf version 6.15.rc1.g312a07a00d31
                   aio: [ on  ]  # HAVE_AIO_SUPPORT
                   bpf: [ on  ]  # HAVE_LIBBPF_SUPPORT
         bpf_skeletons: [ on  ]  # HAVE_BPF_SKEL
            debuginfod: [ OFF ]  # HAVE_DEBUGINFOD_SUPPORT
  &lt;SNIP&gt;

And looking at tools/perf/Makefile.config I also noticed that it is not
opt-in, meaning we will attempt to build with it in all normal cases.

So add the usual warning at build time to let the user know that
something recommended is missing, now we see:

  Makefile.config:563: No elfutils/debuginfod.h found, no debuginfo server support, please install elfutils-debuginfod-client-devel or equivalent

And after following the recommendation:

  $ perf check feature debuginfod
            debuginfod: [ on  ]  # HAVE_DEBUGINFOD_SUPPORT
  $ ldd ~/bin/perf | grep debuginfo
	libdebuginfod.so.1 =&gt; /lib64/libdebuginfod.so.1 (0x00007fee5cf5f000)
  $

With this feature on several perf tools will fetch what is needed and
not require all the contents of the debuginfo packages, for instance:

  # rpm -qa | grep kernel-debuginfo
  # pahole --running_kernel_vmlinux
  pahole: couldn't find a vmlinux that matches the running kernel
  HINT: Maybe you're inside a container or missing a debuginfo package?
  #
  # perf trace -e open* perf probe --vars icmp_rcv
      0.000 ( 0.005 ms): perf/97391 openat(dfd: CWD, filename: "/etc/ld.so.cache", flags: RDONLY|CLOEXEC) = 3
      0.014 ( 0.004 ms): perf/97391 openat(dfd: CWD, filename: "/lib64/libm.so.6", flags: RDONLY|CLOEXEC) = 3
  &lt;SNIP&gt;
  32130.100 ( 0.008 ms): perf/97391 openat(dfd: CWD, filename: "/root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo") = 3
  &lt;SNIP&gt;
  Available variables at icmp_rcv
        @&lt;icmp_rcv+0&gt;
                struct sk_buff* skb
  &lt;SNIP&gt;
  #
  # pahole --running_kernel_vmlinux
  /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo
  # file /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo
  /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, BuildID[sha1]=aa3c82b4a13f9c0e0301bebb20fe958c4db6f362, with debug_info, not stripped
  # ls -la /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo
  -r--------. 1 root root 475401512 Mar 27 21:00 /root/.cache/debuginfod_client/aa3c82b4a13f9c0e0301bebb20fe958c4db6f362/debuginfo
  #

Then, cached:

  # perf stat --null perf probe --vars icmp_rcv
  Available variables at icmp_rcv
        @&lt;icmp_rcv+0&gt;
                struct sk_buff* skb

   Performance counter stats for 'perf probe --vars icmp_rcv':

       0.671389041 seconds time elapsed

       0.519176000 seconds user
       0.150860000 seconds sys

Fixes: c7a14fdcb3fa7736 ("perf build-ids: Fall back to debuginfod query if debuginfo not found")
Tested-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Dmitriy Vyukov &lt;dvyukov@google.com&gt;
Cc: Howard Chu &lt;howardchu95@gmail.com&gt;
Cc: Ian Rogers &lt;irogers@google.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Frank Ch. Eigler &lt;fche@redhat.com&gt;
Link: https://lore.kernel.org/r/Z_dkNDj9EPFwPqq1@gmail.com
[ Folded patch from Ingo to have the debian/ubuntu devel package added build warning message ]
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
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