linux/Documentation/admin-guide
Linus Torvalds 535a265d7f perf tools changes for v6.6:
perf tools maintainership:
 
 - Add git information for perf-tools and perf-tools-next trees/branches to the
   MAINTAINERS file. That is where development now takes place and myself and
   Namhyung Kim have write access, more people to come as we emulate other
   maintainer groups.
 
 perf record:
 
 - Record kernel data maps when 'perf record --data' is used, so that global variables can
   be resolved and used in tools that do data profiling.
 
 perf trace:
 
 - Remove the old, experimental support for BPF events in which a .c file was passed as
   an event: "perf trace -e hello.c" to then get compiled and loaded.
 
   The only known usage for that, that shipped with the kernel as an example for such events,
   augmented the raw_syscalls tracepoints and was converted to a libbpf skeleton, reusing all
   the user space components and the BPF code connected to the syscalls.
 
   In the end just the way to glue the BPF part and the user space type beautifiers changed,
   now being performed by libbpf skeletons.
 
   The next step is to use BTF to do pretty printing of all syscall types, as discussed with
   Alan Maguire and others.
 
   Now, on a perf built with BUILD_BPF_SKEL=1 we get most if not all path/filenames/strings,
   some of the networking data structures, perf_event_attr, etc, i.e. systemwide tracing of
   nanosleep calls and perf_event_open syscalls while 'perf stat' runs 'sleep' for 5 seconds:
 
   # perf trace -a -e *nanosleep,perf* perf stat -e cycles,instructions sleep 5
      0.000 (   9.034 ms): perf/327641 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0 (PERF_COUNT_HW_CPU_CYCLES), sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 327642 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 3
      9.039 (   0.006 ms): perf/327641 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0x1 (PERF_COUNT_HW_INSTRUCTIONS), sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 327642 (perf-exec), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 4
          ? (           ): gpm/991  ... [continued]: clock_nanosleep())               = 0
     10.133 (           ): sleep/327642 clock_nanosleep(rqtp: { .tv_sec: 5, .tv_nsec: 0 }, rmtp: 0x7ffd36f83ed0) ...
          ? (           ): pool-gsd-smart/3051  ... [continued]: clock_nanosleep())   = 0
     30.276 (           ): gpm/991 clock_nanosleep(rqtp: { .tv_sec: 2, .tv_nsec: 0 }, rmtp: 0x7ffcc6f73710) ...
    223.215 (1000.430 ms): pool-gsd-smart/3051 clock_nanosleep(rqtp: { .tv_sec: 1, .tv_nsec: 0 }, rmtp: 0x7f6e7fffec90) = 0
     30.276 (2000.394 ms): gpm/991  ... [continued]: clock_nanosleep())               = 0
   1230.814 (           ): pool-gsd-smart/3051 clock_nanosleep(rqtp: { .tv_sec: 1, .tv_nsec: 0 }, rmtp: 0x7f6e7fffec90) ...
   1230.814 (1000.404 ms): pool-gsd-smart/3051  ... [continued]: clock_nanosleep())   = 0
   2030.886 (           ): gpm/991 clock_nanosleep(rqtp: { .tv_sec: 2, .tv_nsec: 0 }, rmtp: 0x7ffcc6f73710) ...
   2237.709 (1000.153 ms): pool-gsd-smart/3051 clock_nanosleep(rqtp: { .tv_sec: 1, .tv_nsec: 0 }, rmtp: 0x7f6e7fffec90) = 0
          ? (           ): crond/1172  ... [continued]: clock_nanosleep())            = 0
   3242.699 (           ): pool-gsd-smart/3051 clock_nanosleep(rqtp: { .tv_sec: 1, .tv_nsec: 0 }, rmtp: 0x7f6e7fffec90) ...
   2030.886 (2000.385 ms): gpm/991  ... [continued]: clock_nanosleep())               = 0
   3728.078 (           ): crond/1172 clock_nanosleep(rqtp: { .tv_sec: 60, .tv_nsec: 0 }, rmtp: 0x7ffe0971dcf0) ...
   3242.699 (1000.158 ms): pool-gsd-smart/3051  ... [continued]: clock_nanosleep())   = 0
   4031.409 (           ): gpm/991 clock_nanosleep(rqtp: { .tv_sec: 2, .tv_nsec: 0 }, rmtp: 0x7ffcc6f73710) ...
     10.133 (5000.375 ms): sleep/327642  ... [continued]: clock_nanosleep())          = 0
 
  Performance counter stats for 'sleep 5':
 
          2,617,347      cycles
          1,855,997      instructions                     #    0.71  insn per cycle
 
        5.002282128 seconds time elapsed
 
        0.000855000 seconds user
        0.000852000 seconds sys
   #
 
 perf annotate:
 
 - Building with binutils' libopcode now is opt-in (BUILD_NONDISTRO=1) for
   licensing reasons, and we missed a build test on tools/perf/tests makefile.
 
   Since we now default to NDEBUG=1, we ended up segfaulting when building with
   BUILD_NONDISTRO=1 because a needed initialization routine was being "error
   checked" via an assert.
 
   Fix it by explicitly checking the result and aborting instead if it fails.
 
   We better back propagate the error, but at least 'perf annotate' on samples
   collected for a BPF program is back working when perf is built with
   BUILD_NONDISTRO=1.
 
 perf report/top:
 
 - Add back TUI hierarchy mode header, that is seen when using 'perf report/top --hierarchy'.
 
 - Fix the number of entries for 'e' key in the TUI that was preventing navigation of
   lines when expanding an entry.
 
 perf report/script:
 
 - Support cross platform register handling, allowing a perf.data file collected
   on one architecture to have registers sampled correctly displayed when
   analysis tools such as 'perf report' and 'perf script' are used on a different
   architecture.
 
 - Fix handling of event attributes in pipe mode, i.e. when one uses:
 
 	perf record -o - | perf report -i -
 
   When no perf.data files are used.
 
 - Handle files generated via pipe mode with a version of perf and then read
   also via pipe mode with a different version of perf, where the event attr
   record may have changed, use the record size field to properly support this
   version mismatch.
 
 perf probe:
 
 - Accessing global variables from uprobes isn't supported, make the error
   message state that instead of stating that some minimal kernel version is
   needed to have that feature. This seems just a tool limitation, the kernel
   probably has all that is needed.
 
 perf tests:
 
 - Fix a reference count related leak in the dlfilter v0 API where the result
   of a thread__find_symbol_fb() is not matched with an addr_location__exit()
   to drop the reference counts of the resolved components (machine, thread, map,
   symbol, etc). Add a dlfilter test to make sure that doesn't regresses.
 
 - Lots of fixes for the 'perf test' written in shell script related to problems
   found with the shellcheck utility.
 
 - Fixes for 'perf test' shell scripts testing features enabled when perf is
   built with BUILD_BPF_SKEL=1, such as 'perf stat' bpf counters.
 
 - Add perf record sample filtering test, things like the following example, that gets
   implemented as a BPF filter attached to the event:
 
    # perf record -e task-clock -c 10000 --filter 'ip < 0xffffffff00000000'
 
 - Improve the way the task_analyzer test checks if libtraceevent is linked,
   using 'perf version --build-options' instead of the more expensinve
   'perf record -e "sched:sched_switch"'.
 
 - Add support for riscv in the mmap-basic test. (This went as well via the RiscV tree, same contents).
 
 libperf:
 
 - Implement riscv mmap support (This went as well via the RiscV tree, same contents).
 
 perf script:
 
 - New tool that converts perf.data files to the firefox profiler format so that one can use
   the visualizer at https://profiler.firefox.com/. Done by Anup Sharma as part of this year's
   Google Summer of Code.
 
   One can generate the output and upload it to the web interface but Anup also automated
   everything:
 
      perf script gecko -F 99 -a sleep 60
 
 - Support syscall name parsing on arm64.
 
 - Print "cgroup" field on the same line as "comm".
 
 perf bench:
 
 - Add new 'uprobe' benchmark to measure the overhead of uprobes with/without
   BPF programs attached to it.
 
 - breakpoints are not available on power9, skip that test.
 
 perf stat:
 
 - Add #num_cpus_online literal to be used in 'perf stat' metrics, and add this extra
   'perf test' check that exemplifies its purpose:
 
 	TEST_ASSERT_VAL("#num_cpus_online",
                        expr__parse(&num_cpus_online, ctx, "#num_cpus_online") == 0);
 	TEST_ASSERT_VAL("#num_cpus", expr__parse(&num_cpus, ctx, "#num_cpus") == 0);
 	TEST_ASSERT_VAL("#num_cpus >= #num_cpus_online", num_cpus >= num_cpus_online);
 
 Miscellaneous:
 
 - Improve tool startup time by lazily reading PMU, JSON, sysfs data.
 
 - Improve error reporting in the parsing of events, passing YYLTYPE to error routines,
   so that the output can show were the parsing error was found.
 
 - Add 'perf test' entries to check the parsing of events improvements.
 
 - Fix various leak for things detected by -fsanitize=address, mostly things that would
   be freed at tool exit, including:
 
   - Free evsel->filter on the destructor.
 
   - Allow tools to register a thread->priv destructor and use it in 'perf trace'.
 
   - Free evsel->priv in 'perf trace'.
 
   - Free string returned by synthesize_perf_probe_point() when the caller fails
     to do all it needs.
 
 - Adjust various compiler options to not consider errors some warnings when
   building with broken headers found in things like python, flex, bison, as we
   otherwise build with -Werror. Some for gcc, some for clang, some for some
   specific version of those, some for some specific version of flex or bison, or
   some specific combination of these components, bah.
 
 - Allow customization of clang options for BPF target, this helps building on
   gentoo where there are other oddities where BPF targets gets passed some compiler
   options intended for the native build, so building with WERROR=0 helps while
   these oddities are fixed.
 
 - Dont pass ERR_PTR() values to perf_session__delete() in 'perf top' and 'perf lock',
   fixing some segfaults when handling some odd failures.
 
 - Add LTO build option.
 
 - Fix format of unordered lists in the perf docs (tools/perf/Documentation).
 
 - Overhaul the bison files, using constructs such as YYNOMEM.
 
 - Remove unused tokens from the bison .y files.
 
 - Add more comments to various structs.
 
 - A few LoongArch enablement patches.
 
 Vendor events (JSON):
 
 - Add JSON metrics for Yitian 710 DDR (aarch64). Things like:
 
 	EventName, BriefDescription
 	visible_window_limit_reached_rd, "At least one entry in read queue reaches the visible window limit.",
 	visible_window_limit_reached_wr, "At least one entry in write queue reaches the visible window limit.",
 	op_is_dqsosc_mpc	       , "A DQS Oscillator MPC command to DRAM.",
 	op_is_dqsosc_mrr	       , "A DQS Oscillator MRR command to DRAM.",
 	op_is_tcr_mrr		       , "A Temperature Compensated Refresh(TCR) MRR command to DRAM.",
 
 - Add AmpereOne metrics (aarch64).
 
 - Update N2 and V2 metrics (aarch64) and events using Arm telemetry repo.
 
 - Update scale units and descriptions of common topdown metrics on aarch64. Things like:
 
   - "MetricExpr": "stall_slot_frontend / (#slots * cpu_cycles)",
   - "BriefDescription": "Frontend bound L1 topdown metric",
   + "MetricExpr": "100 * (stall_slot_frontend / (#slots * cpu_cycles))",
   + "BriefDescription": "This metric is the percentage of total slots that were stalled due to resource constraints in the frontend of the processor.",
 
 - Update events for intel: meteorlake to 1.04, sapphirerapids to 1.15, Icelake+ metric constraints.
 
 - Update files for the power10 platform.
 
 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Merge tag 'perf-tools-for-v6.6-1-2023-09-05' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools

Pull perf tools updates from Arnaldo Carvalho de Melo:
 "perf tools maintainership:

   - Add git information for perf-tools and perf-tools-next trees and
     branches to the MAINTAINERS file. That is where development now
     takes place and myself and Namhyung Kim have write access, more
     people to come as we emulate other maintainer groups.

  perf record:

   - Record kernel data maps when 'perf record --data' is used, so that
     global variables can be resolved and used in tools that do data
     profiling.

  perf trace:

   - Remove the old, experimental support for BPF events in which a .c
     file was passed as an event: "perf trace -e hello.c" to then get
     compiled and loaded.

     The only known usage for that, that shipped with the kernel as an
     example for such events, augmented the raw_syscalls tracepoints and
     was converted to a libbpf skeleton, reusing all the user space
     components and the BPF code connected to the syscalls.

     In the end just the way to glue the BPF part and the user space
     type beautifiers changed, now being performed by libbpf skeletons.

     The next step is to use BTF to do pretty printing of all syscall
     types, as discussed with Alan Maguire and others.

     Now, on a perf built with BUILD_BPF_SKEL=1 we get most if not all
     path/filenames/strings, some of the networking data structures,
     perf_event_attr, etc, i.e. systemwide tracing of nanosleep calls
     and perf_event_open syscalls while 'perf stat' runs 'sleep' for 5
     seconds:

      # perf trace -a -e *nanosleep,perf* perf stat -e cycles,instructions sleep 5
         0.000 (   9.034 ms): perf/327641 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0 (PERF_COUNT_HW_CPU_CYCLES), sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 327642 (perf), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 3
         9.039 (   0.006 ms): perf/327641 perf_event_open(attr_uptr: { type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0x1 (PERF_COUNT_HW_INSTRUCTIONS), sample_type: IDENTIFIER, read_format: TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING, disabled: 1, inherit: 1, enable_on_exec: 1, exclude_guest: 1 }, pid: 327642 (perf-exec), cpu: -1, group_fd: -1, flags: FD_CLOEXEC) = 4
             ? (           ): gpm/991  ... [continued]: clock_nanosleep())               = 0
        10.133 (           ): sleep/327642 clock_nanosleep(rqtp: { .tv_sec: 5, .tv_nsec: 0 }, rmtp: 0x7ffd36f83ed0) ...
             ? (           ): pool-gsd-smart/3051  ... [continued]: clock_nanosleep())   = 0
        30.276 (           ): gpm/991 clock_nanosleep(rqtp: { .tv_sec: 2, .tv_nsec: 0 }, rmtp: 0x7ffcc6f73710) ...
       223.215 (1000.430 ms): pool-gsd-smart/3051 clock_nanosleep(rqtp: { .tv_sec: 1, .tv_nsec: 0 }, rmtp: 0x7f6e7fffec90) = 0
        30.276 (2000.394 ms): gpm/991  ... [continued]: clock_nanosleep())               = 0
      1230.814 (           ): pool-gsd-smart/3051 clock_nanosleep(rqtp: { .tv_sec: 1, .tv_nsec: 0 }, rmtp: 0x7f6e7fffec90) ...
      1230.814 (1000.404 ms): pool-gsd-smart/3051  ... [continued]: clock_nanosleep())   = 0
      2030.886 (           ): gpm/991 clock_nanosleep(rqtp: { .tv_sec: 2, .tv_nsec: 0 }, rmtp: 0x7ffcc6f73710) ...
      2237.709 (1000.153 ms): pool-gsd-smart/3051 clock_nanosleep(rqtp: { .tv_sec: 1, .tv_nsec: 0 }, rmtp: 0x7f6e7fffec90) = 0
             ? (           ): crond/1172  ... [continued]: clock_nanosleep())            = 0
      3242.699 (           ): pool-gsd-smart/3051 clock_nanosleep(rqtp: { .tv_sec: 1, .tv_nsec: 0 }, rmtp: 0x7f6e7fffec90) ...
      2030.886 (2000.385 ms): gpm/991  ... [continued]: clock_nanosleep())               = 0
      3728.078 (           ): crond/1172 clock_nanosleep(rqtp: { .tv_sec: 60, .tv_nsec: 0 }, rmtp: 0x7ffe0971dcf0) ...
      3242.699 (1000.158 ms): pool-gsd-smart/3051  ... [continued]: clock_nanosleep())   = 0
      4031.409 (           ): gpm/991 clock_nanosleep(rqtp: { .tv_sec: 2, .tv_nsec: 0 }, rmtp: 0x7ffcc6f73710) ...
        10.133 (5000.375 ms): sleep/327642  ... [continued]: clock_nanosleep())          = 0

      Performance counter stats for 'sleep 5':

             2,617,347      cycles
             1,855,997      instructions                     #    0.71  insn per cycle

           5.002282128 seconds time elapsed

           0.000855000 seconds user
           0.000852000 seconds sys

  perf annotate:

   - Building with binutils' libopcode now is opt-in (BUILD_NONDISTRO=1)
     for licensing reasons, and we missed a build test on
     tools/perf/tests makefile.

     Since we now default to NDEBUG=1, we ended up segfaulting when
     building with BUILD_NONDISTRO=1 because a needed initialization
     routine was being "error checked" via an assert.

     Fix it by explicitly checking the result and aborting instead if it
     fails.

     We better back propagate the error, but at least 'perf annotate' on
     samples collected for a BPF program is back working when perf is
     built with BUILD_NONDISTRO=1.

  perf report/top:

   - Add back TUI hierarchy mode header, that is seen when using 'perf
     report/top --hierarchy'.

   - Fix the number of entries for 'e' key in the TUI that was
     preventing navigation of lines when expanding an entry.

  perf report/script:

   - Support cross platform register handling, allowing a perf.data file
     collected on one architecture to have registers sampled correctly
     displayed when analysis tools such as 'perf report' and 'perf
     script' are used on a different architecture.

   - Fix handling of event attributes in pipe mode, i.e. when one uses:

  	perf record -o - | perf report -i -

     When no perf.data files are used.

   - Handle files generated via pipe mode with a version of perf and
     then read also via pipe mode with a different version of perf,
     where the event attr record may have changed, use the record size
     field to properly support this version mismatch.

  perf probe:

   - Accessing global variables from uprobes isn't supported, make the
     error message state that instead of stating that some minimal
     kernel version is needed to have that feature. This seems just a
     tool limitation, the kernel probably has all that is needed.

  perf tests:

   - Fix a reference count related leak in the dlfilter v0 API where the
     result of a thread__find_symbol_fb() is not matched with an
     addr_location__exit() to drop the reference counts of the resolved
     components (machine, thread, map, symbol, etc). Add a dlfilter test
     to make sure that doesn't regresses.

   - Lots of fixes for the 'perf test' written in shell script related
     to problems found with the shellcheck utility.

   - Fixes for 'perf test' shell scripts testing features enabled when
     perf is built with BUILD_BPF_SKEL=1, such as 'perf stat' bpf
     counters.

   - Add perf record sample filtering test, things like the following
     example, that gets implemented as a BPF filter attached to the
     event:

       # perf record -e task-clock -c 10000 --filter 'ip < 0xffffffff00000000'

   - Improve the way the task_analyzer test checks if libtraceevent is
     linked, using 'perf version --build-options' instead of the more
     expensinve 'perf record -e "sched:sched_switch"'.

   - Add support for riscv in the mmap-basic test. (This went as well
     via the RiscV tree, same contents).

  libperf:

   - Implement riscv mmap support (This went as well via the RiscV tree,
     same contents).

  perf script:

   - New tool that converts perf.data files to the firefox profiler
     format so that one can use the visualizer at
     https://profiler.firefox.com/. Done by Anup Sharma as part of this
     year's Google Summer of Code.

     One can generate the output and upload it to the web interface but
     Anup also automated everything:

       perf script gecko -F 99 -a sleep 60

   - Support syscall name parsing on arm64.

   - Print "cgroup" field on the same line as "comm".

  perf bench:

   - Add new 'uprobe' benchmark to measure the overhead of uprobes
     with/without BPF programs attached to it.

   - breakpoints are not available on power9, skip that test.

  perf stat:

   - Add #num_cpus_online literal to be used in 'perf stat' metrics, and
     add this extra 'perf test' check that exemplifies its purpose:

  	TEST_ASSERT_VAL("#num_cpus_online",
                         expr__parse(&num_cpus_online, ctx, "#num_cpus_online") == 0);
  	TEST_ASSERT_VAL("#num_cpus", expr__parse(&num_cpus, ctx, "#num_cpus") == 0);
  	TEST_ASSERT_VAL("#num_cpus >= #num_cpus_online", num_cpus >= num_cpus_online);

  Miscellaneous:

   - Improve tool startup time by lazily reading PMU, JSON, sysfs data.

   - Improve error reporting in the parsing of events, passing YYLTYPE
     to error routines, so that the output can show were the parsing
     error was found.

   - Add 'perf test' entries to check the parsing of events
     improvements.

   - Fix various leak for things detected by -fsanitize=address, mostly
     things that would be freed at tool exit, including:

       - Free evsel->filter on the destructor.

       - Allow tools to register a thread->priv destructor and use it in
         'perf trace'.

       - Free evsel->priv in 'perf trace'.

       - Free string returned by synthesize_perf_probe_point() when the
         caller fails to do all it needs.

   - Adjust various compiler options to not consider errors some
     warnings when building with broken headers found in things like
     python, flex, bison, as we otherwise build with -Werror. Some for
     gcc, some for clang, some for some specific version of those, some
     for some specific version of flex or bison, or some specific
     combination of these components, bah.

   - Allow customization of clang options for BPF target, this helps
     building on gentoo where there are other oddities where BPF targets
     gets passed some compiler options intended for the native build, so
     building with WERROR=0 helps while these oddities are fixed.

   - Dont pass ERR_PTR() values to perf_session__delete() in 'perf top'
     and 'perf lock', fixing some segfaults when handling some odd
     failures.

   - Add LTO build option.

   - Fix format of unordered lists in the perf docs
     (tools/perf/Documentation)

   - Overhaul the bison files, using constructs such as YYNOMEM.

   - Remove unused tokens from the bison .y files.

   - Add more comments to various structs.

   - A few LoongArch enablement patches.

  Vendor events (JSON):

   - Add JSON metrics for Yitian 710 DDR (aarch64). Things like:

  	EventName, BriefDescription
  	visible_window_limit_reached_rd, "At least one entry in read queue reaches the visible window limit.",
  	visible_window_limit_reached_wr, "At least one entry in write queue reaches the visible window limit.",
  	op_is_dqsosc_mpc	       , "A DQS Oscillator MPC command to DRAM.",
  	op_is_dqsosc_mrr	       , "A DQS Oscillator MRR command to DRAM.",
  	op_is_tcr_mrr		       , "A Temperature Compensated Refresh(TCR) MRR command to DRAM.",

   - Add AmpereOne metrics (aarch64).

   - Update N2 and V2 metrics (aarch64) and events using Arm telemetry
     repo.

   - Update scale units and descriptions of common topdown metrics on
     aarch64. Things like:
       - "MetricExpr": "stall_slot_frontend / (#slots * cpu_cycles)",
       - "BriefDescription": "Frontend bound L1 topdown metric",
       + "MetricExpr": "100 * (stall_slot_frontend / (#slots * cpu_cycles))",
       + "BriefDescription": "This metric is the percentage of total slots that were stalled due to resource constraints in the frontend of the processor.",

   - Update events for intel: meteorlake to 1.04, sapphirerapids to
     1.15, Icelake+ metric constraints.

   - Update files for the power10 platform"

* tag 'perf-tools-for-v6.6-1-2023-09-05' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools: (217 commits)
  perf parse-events: Fix driver config term
  perf parse-events: Fixes relating to no_value terms
  perf parse-events: Fix propagation of term's no_value when cloning
  perf parse-events: Name the two term enums
  perf list: Don't print Unit for "default_core"
  perf vendor events intel: Fix modifier in tma_info_system_mem_parallel_reads for skylake
  perf dlfilter: Avoid leak in v0 API test use of resolve_address()
  perf metric: Add #num_cpus_online literal
  perf pmu: Remove str from perf_pmu_alias
  perf parse-events: Make common term list to strbuf helper
  perf parse-events: Minor help message improvements
  perf pmu: Avoid uninitialized use of alias->str
  perf jevents: Use "default_core" for events with no Unit
  perf test stat_bpf_counters_cgrp: Enhance perf stat cgroup BPF counter test
  perf test shell stat_bpf_counters: Fix test on Intel
  perf test shell record_bpf_filter: Skip 6.2 kernel
  libperf: Get rid of attr.id field
  perf tools: Convert to perf_record_header_attr_id()
  libperf: Add perf_record_header_attr_id()
  perf tools: Handle old data in PERF_RECORD_ATTR
  ...
2023-09-09 20:06:17 -07:00
..
acpi Documentation: ACPI: fix typo in ssdt-overlays.rst 2023-07-04 08:30:49 -06:00
aoe
auxdisplay
blockdev docs nbd: userspace NBD now favors github over sourceforge 2023-04-27 19:15:11 -06:00
cgroup-v1 cgroup: Changes for v6.6 2023-09-01 15:58:21 -07:00
cifs cifs: correct references in Documentation to old fs/cifs path 2023-05-24 16:29:21 -05:00
device-mapper Documentation: dm-integrity: Document an example of how the tunables relate. 2023-06-22 18:39:51 -04:00
gpio gpiolib: remove legacy gpio_export() 2023-03-06 12:33:01 +02:00
hw-vuln x86/cpu: Rename srso_(.*)_alias to srso_alias_\1 2023-08-16 21:58:53 +02:00
kdump - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list") 2023-08-29 14:25:26 -07:00
laptops Documentation: admin-guide: correct spelling 2023-02-02 11:04:42 -07:00
LSM
media media: docs: qcom_camss: Update Code Aurora references 2023-07-19 12:57:48 +02:00
mm Documentation work keeps chugging along; stuff for 6.6 includes: 2023-08-30 20:05:42 -07:00
namespaces
nfs
perf perf docs: Update metric usage for Alibaba's T-Head PMU driver (arm64) 2023-07-28 19:01:17 -03:00
pm platform/x86/intel-uncore-freq: Support for cluster level controls 2023-05-09 11:54:42 +02:00
sysctl io_uring-6.6-2023-09-08 2023-09-08 21:32:28 -07:00
thermal It has been a moderately calm cycle for documentation; the significant 2023-02-22 12:00:20 -08:00
abi-obsolete.rst
abi-removed.rst
abi-stable.rst
abi-testing.rst
abi.rst
bcache.rst bcache: Remove dead references to cache_readaheads 2023-06-15 07:30:11 -06:00
binderfs.rst
binfmt-misc.rst
bootconfig.rst Allow forcing unconditional bootconfig processing 2023-02-22 08:27:48 +09:00
braille-console.rst
btmrvl.rst
bug-bisect.rst
bug-hunting.rst
cgroup-v2.rst Documentation: cgroup-v2.rst: Correct number of stats entries 2023-08-03 14:12:28 -10:00
clearing-warn-once.rst
cpu-load.rst
cputopology.rst
dell_rbu.rst
devices.rst docs: admin: devices: drop confusing outdated statement on Latex 2022-07-14 15:03:56 -06:00
devices.txt Documentation: devices.txt: Fix minors for ttyCPM* 2023-08-22 15:31:40 +02:00
dynamic-debug-howto.rst dyndbg: add source filename to prefix 2023-08-04 15:28:41 +02:00
edid.rst
efi-stub.rst docs: efi-stub: Fix paths for x86 / arm stubs 2022-07-28 09:41:56 -06:00
ext4.rst ext4: Remove the logic to trim inode PAs 2023-04-06 01:13:13 -04:00
features.rst
filesystem-monitoring.rst
highuid.rst
hw_random.rst docs: admin-guide: hw_random: Make document title more generic and concise 2022-11-09 14:02:40 -07:00
index.rst Commit volume in documentation is relatively low this time, but there is 2023-04-24 12:35:49 -07:00
init.rst
initrd.rst
iostats.rst
java.rst
jfs.rst
kernel-parameters.rst docs: kernel-parameters: Refer to the correct bitmap function 2023-08-18 11:03:52 -06:00
kernel-parameters.txt workqueue: Changes for v6.6 2023-09-01 16:06:32 -07:00
kernel-per-CPU-kthreads.rst docs: ftrace: always use canonical ftrace path 2023-01-31 14:02:30 -07:00
lcd-panel-cgram.rst
ldm.rst
lockup-watchdogs.rst
md.rst Documentation: admin-guide: correct spelling 2023-02-02 11:04:42 -07:00
module-signing.rst Documentation: Fix typos 2023-08-18 11:29:03 -06:00
mono.rst
numastat.rst
parport.rst
perf-security.rst
pnp.rst
pstore-blk.rst
quickly-build-trimmed-linux.rst docs: quickly-build-trimmed-linux: various small fixes and improvements 2023-05-16 12:50:05 -06:00
ramoops.rst
rapidio.rst
ras.rst docs: move x86 documentation into Documentation/arch/ 2023-03-30 12:58:51 -06:00
README.rst There's not a huge amount of activity in the docs tree this time around, 2022-10-03 10:23:32 -07:00
reporting-issues.rst Documentation/security-bugs: move from admin-guide/ to process/ 2023-03-12 15:56:43 +01:00
reporting-regressions.rst
rtc.rst
serial-console.rst Documentation: serial-console: Fix literal block marker 2023-08-28 12:42:03 -06:00
spkguide.txt Documentation: admin-guide: correct spelling 2023-02-02 11:04:42 -07:00
svga.rst
syscall-user-dispatch.rst ptrace: Provide set/get interface for syscall user dispatch 2023-04-16 14:23:07 +02:00
sysfs-rules.rst
sysrq.rst Documentation: admin-guide: correct spelling 2023-02-02 11:04:42 -07:00
tainted-kernels.rst x86/microcode: Document the whole late loading problem 2022-08-18 15:57:53 +02:00
thunderbolt.rst
ufs.rst
unicode.rst docs: admin: unicode: update information on state of lanana.org document 2023-03-14 12:27:39 -06:00
vga-softcursor.rst
video-output.rst
workload-tracing.rst docs: add workload-tracing document to admin-guide 2023-02-02 10:43:13 -07:00
xfs.rst Documentation: admin-guide: correct "it's" to possessive "its" 2023-07-14 13:17:55 -06:00

.. _readme:

Linux kernel release 6.x <http://kernel.org/>
=============================================

These are the release notes for Linux version 6.  Read them carefully,
as they tell you what this is all about, explain how to install the
kernel, and what to do if something goes wrong.

What is Linux?
--------------

  Linux is a clone of the operating system Unix, written from scratch by
  Linus Torvalds with assistance from a loosely-knit team of hackers across
  the Net. It aims towards POSIX and Single UNIX Specification compliance.

  It has all the features you would expect in a modern fully-fledged Unix,
  including true multitasking, virtual memory, shared libraries, demand
  loading, shared copy-on-write executables, proper memory management,
  and multistack networking including IPv4 and IPv6.

  It is distributed under the GNU General Public License v2 - see the
  accompanying COPYING file for more details.

On what hardware does it run?
-----------------------------

  Although originally developed first for 32-bit x86-based PCs (386 or higher),
  today Linux also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
  UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, Cell,
  IBM S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64 Xtensa, and
  ARC architectures.

  Linux is easily portable to most general-purpose 32- or 64-bit architectures
  as long as they have a paged memory management unit (PMMU) and a port of the
  GNU C compiler (gcc) (part of The GNU Compiler Collection, GCC). Linux has
  also been ported to a number of architectures without a PMMU, although
  functionality is then obviously somewhat limited.
  Linux has also been ported to itself. You can now run the kernel as a
  userspace application - this is called UserMode Linux (UML).

Documentation
-------------

 - There is a lot of documentation available both in electronic form on
   the Internet and in books, both Linux-specific and pertaining to
   general UNIX questions.  I'd recommend looking into the documentation
   subdirectories on any Linux FTP site for the LDP (Linux Documentation
   Project) books.  This README is not meant to be documentation on the
   system: there are much better sources available.

 - There are various README files in the Documentation/ subdirectory:
   these typically contain kernel-specific installation notes for some
   drivers for example. Please read the
   :ref:`Documentation/process/changes.rst <changes>` file, as it
   contains information about the problems, which may result by upgrading
   your kernel.

Installing the kernel source
----------------------------

 - If you install the full sources, put the kernel tarball in a
   directory where you have permissions (e.g. your home directory) and
   unpack it::

     xz -cd linux-6.x.tar.xz | tar xvf -

   Replace "X" with the version number of the latest kernel.

   Do NOT use the /usr/src/linux area! This area has a (usually
   incomplete) set of kernel headers that are used by the library header
   files.  They should match the library, and not get messed up by
   whatever the kernel-du-jour happens to be.

 - You can also upgrade between 6.x releases by patching.  Patches are
   distributed in the xz format.  To install by patching, get all the
   newer patch files, enter the top level directory of the kernel source
   (linux-6.x) and execute::

     xz -cd ../patch-6.x.xz | patch -p1

   Replace "x" for all versions bigger than the version "x" of your current
   source tree, **in_order**, and you should be ok.  You may want to remove
   the backup files (some-file-name~ or some-file-name.orig), and make sure
   that there are no failed patches (some-file-name# or some-file-name.rej).
   If there are, either you or I have made a mistake.

   Unlike patches for the 6.x kernels, patches for the 6.x.y kernels
   (also known as the -stable kernels) are not incremental but instead apply
   directly to the base 6.x kernel.  For example, if your base kernel is 6.0
   and you want to apply the 6.0.3 patch, you must not first apply the 6.0.1
   and 6.0.2 patches. Similarly, if you are running kernel version 6.0.2 and
   want to jump to 6.0.3, you must first reverse the 6.0.2 patch (that is,
   patch -R) **before** applying the 6.0.3 patch. You can read more on this in
   :ref:`Documentation/process/applying-patches.rst <applying_patches>`.

   Alternatively, the script patch-kernel can be used to automate this
   process.  It determines the current kernel version and applies any
   patches found::

     linux/scripts/patch-kernel linux

   The first argument in the command above is the location of the
   kernel source.  Patches are applied from the current directory, but
   an alternative directory can be specified as the second argument.

 - Make sure you have no stale .o files and dependencies lying around::

     cd linux
     make mrproper

   You should now have the sources correctly installed.

Software requirements
---------------------

   Compiling and running the 6.x kernels requires up-to-date
   versions of various software packages.  Consult
   :ref:`Documentation/process/changes.rst <changes>` for the minimum version numbers
   required and how to get updates for these packages.  Beware that using
   excessively old versions of these packages can cause indirect
   errors that are very difficult to track down, so don't assume that
   you can just update packages when obvious problems arise during
   build or operation.

Build directory for the kernel
------------------------------

   When compiling the kernel, all output files will per default be
   stored together with the kernel source code.
   Using the option ``make O=output/dir`` allows you to specify an alternate
   place for the output files (including .config).
   Example::

     kernel source code: /usr/src/linux-6.x
     build directory:    /home/name/build/kernel

   To configure and build the kernel, use::

     cd /usr/src/linux-6.x
     make O=/home/name/build/kernel menuconfig
     make O=/home/name/build/kernel
     sudo make O=/home/name/build/kernel modules_install install

   Please note: If the ``O=output/dir`` option is used, then it must be
   used for all invocations of make.

Configuring the kernel
----------------------

   Do not skip this step even if you are only upgrading one minor
   version.  New configuration options are added in each release, and
   odd problems will turn up if the configuration files are not set up
   as expected.  If you want to carry your existing configuration to a
   new version with minimal work, use ``make oldconfig``, which will
   only ask you for the answers to new questions.

 - Alternative configuration commands are::

     "make config"      Plain text interface.

     "make menuconfig"  Text based color menus, radiolists & dialogs.

     "make nconfig"     Enhanced text based color menus.

     "make xconfig"     Qt based configuration tool.

     "make gconfig"     GTK+ based configuration tool.

     "make oldconfig"   Default all questions based on the contents of
                        your existing ./.config file and asking about
                        new config symbols.

     "make olddefconfig"
                        Like above, but sets new symbols to their default
                        values without prompting.

     "make defconfig"   Create a ./.config file by using the default
                        symbol values from either arch/$ARCH/defconfig
                        or arch/$ARCH/configs/${PLATFORM}_defconfig,
                        depending on the architecture.

     "make ${PLATFORM}_defconfig"
                        Create a ./.config file by using the default
                        symbol values from
                        arch/$ARCH/configs/${PLATFORM}_defconfig.
                        Use "make help" to get a list of all available
                        platforms of your architecture.

     "make allyesconfig"
                        Create a ./.config file by setting symbol
                        values to 'y' as much as possible.

     "make allmodconfig"
                        Create a ./.config file by setting symbol
                        values to 'm' as much as possible.

     "make allnoconfig" Create a ./.config file by setting symbol
                        values to 'n' as much as possible.

     "make randconfig"  Create a ./.config file by setting symbol
                        values to random values.

     "make localmodconfig" Create a config based on current config and
                           loaded modules (lsmod). Disables any module
                           option that is not needed for the loaded modules.

                           To create a localmodconfig for another machine,
                           store the lsmod of that machine into a file
                           and pass it in as a LSMOD parameter.

                           Also, you can preserve modules in certain folders
                           or kconfig files by specifying their paths in
                           parameter LMC_KEEP.

                   target$ lsmod > /tmp/mylsmod
                   target$ scp /tmp/mylsmod host:/tmp

                   host$ make LSMOD=/tmp/mylsmod \
                           LMC_KEEP="drivers/usb:drivers/gpu:fs" \
                           localmodconfig

                           The above also works when cross compiling.

     "make localyesconfig" Similar to localmodconfig, except it will convert
                           all module options to built in (=y) options. You can
                           also preserve modules by LMC_KEEP.

     "make kvm_guest.config"   Enable additional options for kvm guest kernel
                               support.

     "make xen.config"   Enable additional options for xen dom0 guest kernel
                         support.

     "make tinyconfig"  Configure the tiniest possible kernel.

   You can find more information on using the Linux kernel config tools
   in Documentation/kbuild/kconfig.rst.

 - NOTES on ``make config``:

    - Having unnecessary drivers will make the kernel bigger, and can
      under some circumstances lead to problems: probing for a
      nonexistent controller card may confuse your other controllers.

    - A kernel with math-emulation compiled in will still use the
      coprocessor if one is present: the math emulation will just
      never get used in that case.  The kernel will be slightly larger,
      but will work on different machines regardless of whether they
      have a math coprocessor or not.

    - The "kernel hacking" configuration details usually result in a
      bigger or slower kernel (or both), and can even make the kernel
      less stable by configuring some routines to actively try to
      break bad code to find kernel problems (kmalloc()).  Thus you
      should probably answer 'n' to the questions for "development",
      "experimental", or "debugging" features.

Compiling the kernel
--------------------

 - Make sure you have at least gcc 5.1 available.
   For more information, refer to :ref:`Documentation/process/changes.rst <changes>`.

 - Do a ``make`` to create a compressed kernel image. It is also
   possible to do ``make install`` if you have lilo installed to suit the
   kernel makefiles, but you may want to check your particular lilo setup first.

   To do the actual install, you have to be root, but none of the normal
   build should require that. Don't take the name of root in vain.

 - If you configured any of the parts of the kernel as ``modules``, you
   will also have to do ``make modules_install``.

 - Verbose kernel compile/build output:

   Normally, the kernel build system runs in a fairly quiet mode (but not
   totally silent).  However, sometimes you or other kernel developers need
   to see compile, link, or other commands exactly as they are executed.
   For this, use "verbose" build mode.  This is done by passing
   ``V=1`` to the ``make`` command, e.g.::

     make V=1 all

   To have the build system also tell the reason for the rebuild of each
   target, use ``V=2``.  The default is ``V=0``.

 - Keep a backup kernel handy in case something goes wrong.  This is
   especially true for the development releases, since each new release
   contains new code which has not been debugged.  Make sure you keep a
   backup of the modules corresponding to that kernel, as well.  If you
   are installing a new kernel with the same version number as your
   working kernel, make a backup of your modules directory before you
   do a ``make modules_install``.

   Alternatively, before compiling, use the kernel config option
   "LOCALVERSION" to append a unique suffix to the regular kernel version.
   LOCALVERSION can be set in the "General Setup" menu.

 - In order to boot your new kernel, you'll need to copy the kernel
   image (e.g. .../linux/arch/x86/boot/bzImage after compilation)
   to the place where your regular bootable kernel is found.

 - Booting a kernel directly from a floppy without the assistance of a
   bootloader such as LILO, is no longer supported.

   If you boot Linux from the hard drive, chances are you use LILO, which
   uses the kernel image as specified in the file /etc/lilo.conf.  The
   kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
   /boot/bzImage.  To use the new kernel, save a copy of the old image
   and copy the new image over the old one.  Then, you MUST RERUN LILO
   to update the loading map! If you don't, you won't be able to boot
   the new kernel image.

   Reinstalling LILO is usually a matter of running /sbin/lilo.
   You may wish to edit /etc/lilo.conf to specify an entry for your
   old kernel image (say, /vmlinux.old) in case the new one does not
   work.  See the LILO docs for more information.

   After reinstalling LILO, you should be all set.  Shutdown the system,
   reboot, and enjoy!

   If you ever need to change the default root device, video mode,
   etc. in the kernel image, use your bootloader's boot options
   where appropriate.  No need to recompile the kernel to change
   these parameters.

 - Reboot with the new kernel and enjoy.

If something goes wrong
-----------------------

If you have problems that seem to be due to kernel bugs, please follow the
instructions at 'Documentation/admin-guide/reporting-issues.rst'.

Hints on understanding kernel bug reports are in
'Documentation/admin-guide/bug-hunting.rst'. More on debugging the kernel
with gdb is in 'Documentation/dev-tools/gdb-kernel-debugging.rst' and
'Documentation/dev-tools/kgdb.rst'.