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James Clark 79373082fa perf python: Autodetect python3 binary
Some distros don't come with python2 and only have python3 available.
This causes the "'import perf' in python" self test to fail.

This change adds python3 to the list of possible python versions
that are autodetected but maintains the priorities for
'python2' and 'python' detection. Python3 has the lowest priority.

Committer notes:

On a fedora system without python2 packages the 'perf test python'
continues to work:

  # python2
  bash: python2: command not found...
  Similar command is: 'python'
  # rpm -qa | grep python2
  #

That "Similar command" gives the clue:

  # rpm -qf /usr/bin/python
  python-unversioned-command-3.8.5-5.fc32.noarch
  # rpm -ql python-unversioned-command
  /usr/bin/python
  /usr/share/man/man1/python.1.gz
  #

With it in place the 'python' binary is found and perf builds the python
binding using python3:

  # perf test -v python
  19: 'import perf' in python                                         :
  --- start ---
  test child forked, pid 379988
  python usage test: "echo "import sys ; sys.path.append('/tmp/build/perf/python'); import perf" | '/usr/bin/python' "
  test child finished with 0
  ---- end ----
  'import perf' in python: Ok
  #

Looking at that path:

  # ls -la /tmp/build/perf/python
  total 1864
  drwxrwxr-x.  2 acme acme      60 Oct 13 16:20 .
  drwxrwxr-x. 18 acme acme    4420 Oct 13 16:28 ..
  -rwxrwxr-x.  1 acme acme 1907216 Oct 13 16:28 perf.cpython-38-x86_64-linux-gnu.so
  #

And:

  # ldd ~/bin/perf | grep python
  	libpython3.8.so.1.0 => /lib64/libpython3.8.so.1.0 (0x00007f5471187000)
  #

As soon as we remove it:

  # rpm -e python-unversioned-command-3.8.5-5.fc32.noarch
  # hash -r
  # python
  bash: python: command not found...
  Install package 'python-unversioned-command' to provide command 'python'? [N/y] n
  #

And rebuilding perf now doesn't find python in the system:

  make: Entering directory '/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j24' parallel build
  <SNIP>
  Makefile.config:786: No python interpreter was found: disables Python support - please install python-devel/python-dev
  <SNIP>

After this patch:

  $ rpm -qi python-unversioned-command
  package python-unversioned-command is not installed
  $
  $ python
  bash: python: command not found...
  Install package 'python-unversioned-command' to provide command 'python'? [N/y] ^C
  $
  $ m
  make: Entering directory '/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j24' parallel build
  <SNIP>
    CC       /tmp/build/perf/tests/attr.o
    CC       /tmp/build/perf/tests/python-use.o
    DESCEND  plugins
    GEN      /tmp/build/perf/python/perf.so
    INSTALL  trace_plugins
    LD       /tmp/build/perf/tests/perf-in.o
    LD       /tmp/build/perf/perf-in.o
    LINK     /tmp/build/perf/perf
  <SNIP>
  make: Leaving directory '/home/acme/git/perf/tools/perf'
  19: 'import perf' in python                                         : Ok
  $ ldd ~/bin/perf | grep python
  	libpython3.8.so.1.0 => /lib64/libpython3.8.so.1.0 (0x00007f2c8c708000)
  $ ls -la /tmp/build/perf/python
  total 1864
  drwxrwxr-x.  2 acme acme      60 Oct 13 16:20 .
  drwxrwxr-x. 18 acme acme    4420 Oct 13 16:31 ..
  -rwxrwxr-x.  1 acme acme 1907216 Oct 13 16:31 perf.cpython-38-x86_64-linux-gnu.so
  $

Signed-off-by: James Clark <james.clark@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LPU-Reference: 20201005080645.6588-1-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-10-13 16:25:57 -03:00
Documentation Kbuild fixes for v5.9 (4th) 2020-09-27 12:18:57 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch Two fixes for the x86 interrupt code: 2020-09-27 12:15:21 -07:00
block SCSI fixes on 20200926 2020-09-26 11:18:37 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-08-30 15:53:44 -07:00
drivers A set of clocksource/clockevents updates: 2020-09-27 12:11:35 -07:00
fs NFS client bugfixes for Linux 5.9 2020-09-28 11:05:56 -07:00
include NFS client bugfixes for Linux 5.9 2020-09-28 11:05:56 -07:00
init bootconfig: init: make xbc_namebuf static 2020-09-18 22:17:05 -04:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel mm/fork: Pass new vma pointer into copy_page_range() 2020-09-27 11:21:35 -07:00
lib lib/memregion.c: include memregion.h 2020-09-26 10:33:57 -07:00
mm mm: do not rely on mm == current->mm in __get_user_pages_locked 2020-09-28 09:21:50 -07:00
net Fixes: 2020-09-25 10:46:11 -07:00
samples treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
scripts scripts/kallsyms: skip ppc compiler stub *.long_branch.* / *.plt_branch.* 2020-09-25 00:41:54 +09:00
security device_cgroup RCU warning fix from Amol Grover <frextrite@gmail.com> 2020-09-15 16:26:57 -07:00
sound sound fixes for 5.9-rc7 2020-09-24 09:00:05 -07:00
tools perf python: Autodetect python3 binary 2020-10-13 16:25:57 -03:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: fix memory leak in kvm_io_bus_unregister_dev() 2020-09-11 13:15:11 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2020-09-01 12:53:42 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 .gitignore: Add ZSTD-compressed files 2020-07-31 11:50:49 +02:00
.mailmap mailmap: add older email addresses for Kees Cook 2020-09-19 13:13:38 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: Replace HTTP links with HTTPS ones 2020-07-23 14:53:58 -06:00
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 media fixes for v5.9-rc7 2020-09-24 09:05:04 -07:00
Makefile Linux 5.9-rc7 2020-09-27 14:38:10 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

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.