€•¤      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ%/translations/zh_CN/trace/user_events”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ%/translations/zh_TW/trace/user_events”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ%/translations/it_IT/trace/user_events”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ%/translations/ja_JP/trace/user_events”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ%/translations/ko_KR/trace/user_events”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒPortuguese (Brazilian)”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ%/translations/pt_BR/trace/user_events”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh–sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ%/translations/sp_SP/trace/user_events”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒ%user_events: User-based Event Tracing”h]”hŒ%user_events: User-based Event Tracing”…””}”(hh¼h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhh·h²hh³Œ?/var/lib/git/docbuild/linux/Documentation/trace/user_events.rst”h´KubhŒ
field_list”“”)”}”(hhh]”hŒfield”“”)”}”(hhh]”(hŒ
field_name”“”)”}”(hŒAuthor”h]”hŒAuthor”…””}”(hh×h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÕhhÒh³hÊh´K ubhŒ
field_body”“”)”}”(hŒBeau Belgrave
”h]”hŒ	paragraph”“”)”}”(hŒBeau Belgrave”h]”hŒBeau Belgrave”…””}”(hhíh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Khhçubah}”(h]”h ]”h"]”h$]”h&]”uh1håhhÒubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÐh³hÊh´KhhÍh²hubah}”(h]”h ]”h"]”h$]”h&]”uh1hËhh·h²hh³hÊh´Kubh¶)”}”(hhh]”(h»)”}”(hŒOverview”h]”hŒOverview”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj  h²hh³hÊh´Kubhì)”}”(hŒÑUser based trace events allow user processes to create events and trace data
that can be viewed via existing tools, such as ftrace and perf.
To enable this feature, build your kernel with CONFIG_USER_EVENTS=y.”h]”hŒÑUser based trace events allow user processes to create events and trace data
that can be viewed via existing tools, such as ftrace and perf.
To enable this feature, build your kernel with CONFIG_USER_EVENTS=y.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K	hj  h²hubhì)”}”(hŒ¤Programs can view status of the events via
/sys/kernel/tracing/user_events_status and can both register and write
data out via /sys/kernel/tracing/user_events_data.”h]”hŒ¤Programs can view status of the events via
/sys/kernel/tracing/user_events_status and can both register and write
data out via /sys/kernel/tracing/user_events_data.”…””}”(hj,  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Khj  h²hubhì)”}”(hX*  Programs can also use /sys/kernel/tracing/dynamic_events to register and
delete user based events via the u: prefix. The format of the command to
dynamic_events is the same as the ioctl with the u: prefix applied. This
requires CAP_PERFMON due to the event persisting, otherwise -EPERM is returned.”h]”hX*  Programs can also use /sys/kernel/tracing/dynamic_events to register and
delete user based events via the u: prefix. The format of the command to
dynamic_events is the same as the ioctl with the u: prefix applied. This
requires CAP_PERFMON due to the event persisting, otherwise -EPERM is returned.”…””}”(hj:  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Khj  h²hubhì)”}”(hX¯  Typically programs will register a set of events that they wish to expose to
tools that can read trace_events (such as ftrace and perf). The registration
process tells the kernel which address and bit to reflect if any tool has
enabled the event and data should be written. The registration will give back
a write index which describes the data when a write() or writev() is called
on the /sys/kernel/tracing/user_events_data file.”h]”hX¯  Typically programs will register a set of events that they wish to expose to
tools that can read trace_events (such as ftrace and perf). The registration
process tells the kernel which address and bit to reflect if any tool has
enabled the event and data should be written. The registration will give back
a write index which describes the data when a write() or writev() is called
on the /sys/kernel/tracing/user_events_data file.”…””}”(hjH  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Khj  h²hubhì)”}”(hŒ~The structures referenced in this document are contained within the
/include/uapi/linux/user_events.h file in the source tree.”h]”hŒ~The structures referenced in this document are contained within the
/include/uapi/linux/user_events.h file in the source tree.”…””}”(hjV  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Khj  h²hubhì)”}”(hŒ‹**NOTE:** *Both user_events_status and user_events_data are under the tracefs
filesystem and may be mounted at different paths than above.*”h]”(hŒstrong”“”)”}”(hŒ	**NOTE:**”h]”hŒNOTE:”…””}”(hjj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jh  hjd  ubhŒ ”…””}”(hjd  h²hh³Nh´NubhŒemphasis”“”)”}”(hŒ*Both user_events_status and user_events_data are under the tracefs
filesystem and may be mounted at different paths than above.*”h]”hŒBoth user_events_status and user_events_data are under the tracefs
filesystem and may be mounted at different paths than above.”…””}”(hj~  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j|  hjd  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K hj  h²hubeh}”(h]”Œoverview”ah ]”h"]”Œoverview”ah$]”h&]”uh1hµhh·h²hh³hÊh´Kubh¶)”}”(hhh]”(h»)”}”(hŒRegistering”h]”hŒRegistering”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjš  h²hh³hÊh´K$ubhì)”}”(hŒ‘Registering within a user process is done via ioctl() out to the
/sys/kernel/tracing/user_events_data file. The command to issue is
DIAG_IOCSREG.”h]”hŒ‘Registering within a user process is done via ioctl() out to the
/sys/kernel/tracing/user_events_data file. The command to issue is
DIAG_IOCSREG.”…””}”(hj«  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K%hjš  h²hubhì)”}”(hŒ<This command takes a packed struct user_reg as an argument::”h]”hŒ;This command takes a packed struct user_reg as an argument:”…””}”(hj¹  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K)hjš  h²hubhŒliteral_block”“”)”}”(hXY  struct user_reg {
      /* Input: Size of the user_reg structure being used */
      __u32 size;

      /* Input: Bit in enable address to use */
      __u8 enable_bit;

      /* Input: Enable size in bytes at address */
      __u8 enable_size;

      /* Input: Flags to use, if any */
      __u16 flags;

      /* Input: Address to update when enabled */
      __u64 enable_addr;

      /* Input: Pointer to string with event name, description and flags */
      __u64 name_args;

      /* Output: Index of the event to use when writing data */
      __u32 write_index;
} __attribute__((__packed__));”h]”hXY  struct user_reg {
      /* Input: Size of the user_reg structure being used */
      __u32 size;

      /* Input: Bit in enable address to use */
      __u8 enable_bit;

      /* Input: Enable size in bytes at address */
      __u8 enable_size;

      /* Input: Flags to use, if any */
      __u16 flags;

      /* Input: Address to update when enabled */
      __u64 enable_addr;

      /* Input: Pointer to string with event name, description and flags */
      __u64 name_args;

      /* Output: Index of the event to use when writing data */
      __u32 write_index;
} __attribute__((__packed__));”…””}”hjÉ  sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1jÇ  h³hÊh´K+hjš  h²hubhì)”}”(hŒJThe struct user_reg requires all the above inputs to be set appropriately.”h]”hŒJThe struct user_reg requires all the above inputs to be set appropriately.”…””}”(hjÙ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KBhjš  h²hubhŒbullet_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒ3size: This must be set to sizeof(struct user_reg).
”h]”hì)”}”(hŒ2size: This must be set to sizeof(struct user_reg).”h]”hŒ2size: This must be set to sizeof(struct user_reg).”…””}”(hjò  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KDhjî  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjé  h²hh³hÊh´Nubjí  )”}”(hŒYenable_bit: The bit to reflect the event status at the address specified by
enable_addr.
”h]”hì)”}”(hŒXenable_bit: The bit to reflect the event status at the address specified by
enable_addr.”h]”hŒXenable_bit: The bit to reflect the event status at the address specified by
enable_addr.”…””}”(hj
  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KFhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjé  h²hh³hÊh´Nubjí  )”}”(hŒÍenable_size: The size of the value specified by enable_addr.
This must be 4 (32-bit) or 8 (64-bit). 64-bit values are only allowed to be
used on 64-bit kernels, however, 32-bit can be used on all kernels.
”h]”hì)”}”(hŒÌenable_size: The size of the value specified by enable_addr.
This must be 4 (32-bit) or 8 (64-bit). 64-bit values are only allowed to be
used on 64-bit kernels, however, 32-bit can be used on all kernels.”h]”hŒÌenable_size: The size of the value specified by enable_addr.
This must be 4 (32-bit) or 8 (64-bit). 64-bit values are only allowed to be
used on 64-bit kernels, however, 32-bit can be used on all kernels.”…””}”(hj"  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KIhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjé  h²hh³hÊh´Nubjí  )”}”(hŒÇflags: The flags to use, if any.
Callers should first attempt to use flags and retry without flags to ensure
support for lower versions of the kernel. If a flag is not supported -EINVAL
is returned.
”h]”hì)”}”(hŒÆflags: The flags to use, if any.
Callers should first attempt to use flags and retry without flags to ensure
support for lower versions of the kernel. If a flag is not supported -EINVAL
is returned.”h]”hŒÆflags: The flags to use, if any.
Callers should first attempt to use flags and retry without flags to ensure
support for lower versions of the kernel. If a flag is not supported -EINVAL
is returned.”…””}”(hj:  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KMhj6  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjé  h²hh³hÊh´Nubjí  )”}”(hŒ“enable_addr: The address of the value to use to reflect event status. This
must be naturally aligned and write accessible within the user program.
”h]”hì)”}”(hŒ’enable_addr: The address of the value to use to reflect event status. This
must be naturally aligned and write accessible within the user program.”h]”hŒ’enable_addr: The address of the value to use to reflect event status. This
must be naturally aligned and write accessible within the user program.”…””}”(hjR  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KRhjN  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjé  h²hh³hÊh´Nubjí  )”}”(hŒYname_args: The name and arguments to describe the event, see command format
for details.
”h]”hì)”}”(hŒXname_args: The name and arguments to describe the event, see command format
for details.”h]”hŒXname_args: The name and arguments to describe the event, see command format
for details.”…””}”(hjj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KUhjf  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjé  h²hh³hÊh´Nubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ+”uh1jç  h³hÊh´KDhjš  h²hubhì)”}”(hŒ,The following flags are currently supported.”h]”hŒ,The following flags are currently supported.”…””}”(hj†  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KXhjš  h²hubjè  )”}”(hhh]”(jí  )”}”(hŒìUSER_EVENT_REG_PERSIST: The event will not delete upon the last reference
closing. Callers may use this if an event should exist even after the
process closes or unregisters the event. Requires CAP_PERFMON otherwise
-EPERM is returned.
”h]”hì)”}”(hŒëUSER_EVENT_REG_PERSIST: The event will not delete upon the last reference
closing. Callers may use this if an event should exist even after the
process closes or unregisters the event. Requires CAP_PERFMON otherwise
-EPERM is returned.”h]”hŒëUSER_EVENT_REG_PERSIST: The event will not delete upon the last reference
closing. Callers may use this if an event should exist even after the
process closes or unregisters the event. Requires CAP_PERFMON otherwise
-EPERM is returned.”…””}”(hj›  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KZhj—  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hj”  h²hh³hÊh´Nubjí  )”}”(hXê  USER_EVENT_REG_MULTI_FORMAT: The event can contain multiple formats. This
allows programs to prevent themselves from being blocked when their event
format changes and they wish to use the same name. When this flag is used the
tracepoint name will be in the new format of "name.unique_id" vs the older
format of "name". A tracepoint will be created for each unique pair of name
and format. This means if several processes use the same name and format,
they will use the same tracepoint. If yet another process uses the same name,
but a different format than the other processes, it will use a different
tracepoint with a new unique id. Recording programs need to scan tracefs for
the various different formats of the event name they are interested in
recording. The system name of the tracepoint will also use "user_events_multi"
instead of "user_events". This prevents single-format event names conflicting
with any multi-format event names within tracefs. The unique_id is output as
a hex string. Recording programs should ensure the tracepoint name starts with
the event name they registered and has a suffix that starts with . and only
has hex characters. For example to find all versions of the event "test" you
can use the regex "^test\.[0-9a-fA-F]+$".
”h]”hì)”}”(hXé  USER_EVENT_REG_MULTI_FORMAT: The event can contain multiple formats. This
allows programs to prevent themselves from being blocked when their event
format changes and they wish to use the same name. When this flag is used the
tracepoint name will be in the new format of "name.unique_id" vs the older
format of "name". A tracepoint will be created for each unique pair of name
and format. This means if several processes use the same name and format,
they will use the same tracepoint. If yet another process uses the same name,
but a different format than the other processes, it will use a different
tracepoint with a new unique id. Recording programs need to scan tracefs for
the various different formats of the event name they are interested in
recording. The system name of the tracepoint will also use "user_events_multi"
instead of "user_events". This prevents single-format event names conflicting
with any multi-format event names within tracefs. The unique_id is output as
a hex string. Recording programs should ensure the tracepoint name starts with
the event name they registered and has a suffix that starts with . and only
has hex characters. For example to find all versions of the event "test" you
can use the regex "^test\.[0-9a-fA-F]+$".”h]”hX  USER_EVENT_REG_MULTI_FORMAT: The event can contain multiple formats. This
allows programs to prevent themselves from being blocked when their event
format changes and they wish to use the same name. When this flag is used the
tracepoint name will be in the new format of â€œname.unique_idâ€ vs the older
format of â€œnameâ€. A tracepoint will be created for each unique pair of name
and format. This means if several processes use the same name and format,
they will use the same tracepoint. If yet another process uses the same name,
but a different format than the other processes, it will use a different
tracepoint with a new unique id. Recording programs need to scan tracefs for
the various different formats of the event name they are interested in
recording. The system name of the tracepoint will also use â€œuser_events_multiâ€
instead of â€œuser_eventsâ€. This prevents single-format event names conflicting
with any multi-format event names within tracefs. The unique_id is output as
a hex string. Recording programs should ensure the tracepoint name starts with
the event name they registered and has a suffix that starts with . and only
has hex characters. For example to find all versions of the event â€œtestâ€ you
can use the regex â€œ^test .[0-9a-fA-F]+$â€.”…””}”(hj³  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K_hj¯  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hj”  h²hh³hÊh´Nubeh}”(h]”h ]”h"]”h$]”h&]”j„  j…  uh1jç  h³hÊh´KZhjš  h²hubhì)”}”(hŒ2Upon successful registration the following is set.”h]”hŒ2Upon successful registration the following is set.”…””}”(hjÍ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Kqhjš  h²hubjè  )”}”(hhh]”jí  )”}”(hŒçwrite_index: The index to use for this file descriptor that represents this
event when writing out data. The index is unique to this instance of the file
descriptor that was used for the registration. See writing data for details.
”h]”hì)”}”(hŒæwrite_index: The index to use for this file descriptor that represents this
event when writing out data. The index is unique to this instance of the file
descriptor that was used for the registration. See writing data for details.”h]”hŒæwrite_index: The index to use for this file descriptor that represents this
event when writing out data. The index is unique to this instance of the file
descriptor that was used for the registration. See writing data for details.”…””}”(hjâ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KshjÞ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjÛ  h²hh³hÊh´Nubah}”(h]”h ]”h"]”h$]”h&]”j„  j…  uh1jç  h³hÊh´Kshjš  h²hubhì)”}”(hX  User based events show up under tracefs like any other event under the
subsystem named "user_events". This means tools that wish to attach to the
events need to use /sys/kernel/tracing/events/user_events/[name]/enable
or perf record -e user_events:[name] when attaching/recording.”h]”hX  User based events show up under tracefs like any other event under the
subsystem named â€œuser_eventsâ€. This means tools that wish to attach to the
events need to use /sys/kernel/tracing/events/user_events/[name]/enable
or perf record -e user_events:[name] when attaching/recording.”…””}”(hjü  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Kwhjš  h²hubhì)”}”(hX¦  **NOTE:** The event subsystem name by default is "user_events". Callers should
not assume it will always be "user_events". Operators reserve the right in the
future to change the subsystem name per-process to accommodate event isolation.
In addition if the USER_EVENT_REG_MULTI_FORMAT flag is used the tracepoint name
will have a unique id appended to it and the system name will be
"user_events_multi" as described above.”h]”(ji  )”}”(hŒ	**NOTE:**”h]”hŒNOTE:”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jh  hj
  ubhX©   The event subsystem name by default is â€œuser_eventsâ€. Callers should
not assume it will always be â€œuser_eventsâ€. Operators reserve the right in the
future to change the subsystem name per-process to accommodate event isolation.
In addition if the USER_EVENT_REG_MULTI_FORMAT flag is used the tracepoint name
will have a unique id appended to it and the system name will be
â€œuser_events_multiâ€ as described above.”…””}”(hj
  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K|hjš  h²hubh¶)”}”(hhh]”(h»)”}”(hŒCommand Format”h]”hŒCommand Format”…””}”(hj)  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj&  h²hh³hÊh´K„ubhì)”}”(hŒ)The command string format is as follows::”h]”hŒ(The command string format is as follows:”…””}”(hj7  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K…hj&  h²hubjÈ  )”}”(hŒ,name[:FLAG1[,FLAG2...]] [Field1[;Field2...]]”h]”hŒ,name[:FLAG1[,FLAG2...]] [Field1[;Field2...]]”…””}”hjE  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´K‡hj&  h²hubeh}”(h]”Œcommand-format”ah ]”h"]”Œcommand format”ah$]”h&]”uh1hµhjš  h²hh³hÊh´K„ubh¶)”}”(hhh]”(h»)”}”(hŒSupported Flags”h]”hŒSupported Flags”…””}”(hj^  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj[  h²hh³hÊh´KŠubhì)”}”(hŒNone yet”h]”hŒNone yet”…””}”(hjl  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K‹hj[  h²hubeh}”(h]”Œsupported-flags”ah ]”h"]”Œsupported flags”ah$]”h&]”uh1hµhjš  h²hh³hÊh´KŠubh¶)”}”(hhh]”(h»)”}”(hŒField Format”h]”hŒField Format”…””}”(hj…  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj‚  h²hh³hÊh´KŽubjÈ  )”}”(hŒtype name [size]”h]”hŒtype name [size]”…””}”hj“  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´K‘hj‚  h²hubhì)”}”(hŒBasic types are supported (__data_loc, u32, u64, int, char, char[20], etc).
User programs are encouraged to use clearly sized types like u32.”h]”hŒBasic types are supported (__data_loc, u32, u64, int, char, char[20], etc).
User programs are encouraged to use clearly sized types like u32.”…””}”(hj¡  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K“hj‚  h²hubhì)”}”(hŒN**NOTE:** *Long is not supported since size can vary between user and kernel.*”h]”(ji  )”}”(hŒ	**NOTE:**”h]”hŒNOTE:”…””}”(hj³  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jh  hj¯  ubhŒ ”…””}”(hj¯  h²hh³Nh´Nubj}  )”}”(hŒD*Long is not supported since size can vary between user and kernel.*”h]”hŒBLong is not supported since size can vary between user and kernel.”…””}”(hjÅ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j|  hj¯  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K–hj‚  h²hubhì)”}”(hŒ‘The size is only valid for types that start with a struct prefix.
This allows user programs to describe custom structs out to tools, if required.”h]”hŒ‘The size is only valid for types that start with a struct prefix.
This allows user programs to describe custom structs out to tools, if required.”…””}”(hjÙ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K˜hj‚  h²hubhì)”}”(hŒ1For example, a struct in C that looks like this::”h]”hŒ0For example, a struct in C that looks like this:”…””}”(hjç  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K›hj‚  h²hubjÈ  )”}”(hŒ#struct mytype {
  char data[20];
};”h]”hŒ#struct mytype {
  char data[20];
};”…””}”hjõ  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´Khj‚  h²hubhì)”}”(hŒ-Would be represented by the following field::”h]”hŒ,Would be represented by the following field:”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K¡hj‚  h²hubjÈ  )”}”(hŒstruct mytype myname 20”h]”hŒstruct mytype myname 20”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´K£hj‚  h²hubeh}”(h]”Œfield-format”ah ]”h"]”Œfield format”ah$]”h&]”uh1hµhjš  h²hh³hÊh´KŽubeh}”(h]”Œregistering”ah ]”h"]”Œregistering”ah$]”h&]”uh1hµhh·h²hh³hÊh´K$ubh¶)”}”(hhh]”(h»)”}”(hŒDeleting”h]”hŒDeleting”…””}”(hj2  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj/  h²hh³hÊh´K¦ubhì)”}”(hŒœDeleting an event from within a user process is done via ioctl() out to the
/sys/kernel/tracing/user_events_data file. The command to issue is
DIAG_IOCSDEL.”h]”hŒœDeleting an event from within a user process is done via ioctl() out to the
/sys/kernel/tracing/user_events_data file. The command to issue is
DIAG_IOCSDEL.”…””}”(hj@  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K§hj/  h²hubhì)”}”(hX)  This command only requires a single string specifying the event to delete by
its name. Delete will only succeed if there are no references left to the
event (in both user and kernel space). User programs should use a separate file
to request deletes than the one used for registration due to this.”h]”hX)  This command only requires a single string specifying the event to delete by
its name. Delete will only succeed if there are no references left to the
event (in both user and kernel space). User programs should use a separate file
to request deletes than the one used for registration due to this.”…””}”(hjN  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K«hj/  h²hubhì)”}”(hXŠ  **NOTE:** By default events will auto-delete when there are no references left
to the event. If programs do not want auto-delete, they must use the
USER_EVENT_REG_PERSIST flag when registering the event. Once that flag is used
the event exists until DIAG_IOCSDEL is invoked. Both register and delete of an
event that persists requires CAP_PERFMON, otherwise -EPERM is returned. When
there are multiple formats of the same event name, all events with the same
name will be attempted to be deleted. If only a specific version is wanted to
be deleted then the /sys/kernel/tracing/dynamic_events file should be used for
that specific format of the event.”h]”(ji  )”}”(hŒ	**NOTE:**”h]”hŒNOTE:”…””}”(hj`  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jh  hj\  ubhX   By default events will auto-delete when there are no references left
to the event. If programs do not want auto-delete, they must use the
USER_EVENT_REG_PERSIST flag when registering the event. Once that flag is used
the event exists until DIAG_IOCSDEL is invoked. Both register and delete of an
event that persists requires CAP_PERFMON, otherwise -EPERM is returned. When
there are multiple formats of the same event name, all events with the same
name will be attempted to be deleted. If only a specific version is wanted to
be deleted then the /sys/kernel/tracing/dynamic_events file should be used for
that specific format of the event.”…””}”(hj\  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K°hj/  h²hubeh}”(h]”Œdeleting”ah ]”h"]”Œdeleting”ah$]”h&]”uh1hµhh·h²hh³hÊh´K¦ubh¶)”}”(hhh]”(h»)”}”(hŒUnregistering”h]”hŒUnregistering”…””}”(hjƒ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj€  h²hh³hÊh´K»ubhì)”}”(hX„  If after registering an event it is no longer wanted to be updated then it can
be disabled via ioctl() out to the /sys/kernel/tracing/user_events_data file.
The command to issue is DIAG_IOCSUNREG. This is different than deleting, where
deleting actually removes the event from the system. Unregistering simply tells
the kernel your process is no longer interested in updates to the event.”h]”hX„  If after registering an event it is no longer wanted to be updated then it can
be disabled via ioctl() out to the /sys/kernel/tracing/user_events_data file.
The command to issue is DIAG_IOCSUNREG. This is different than deleting, where
deleting actually removes the event from the system. Unregistering simply tells
the kernel your process is no longer interested in updates to the event.”…””}”(hj‘  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K¼hj€  h²hubhì)”}”(hŒ>This command takes a packed struct user_unreg as an argument::”h]”hŒ=This command takes a packed struct user_unreg as an argument:”…””}”(hjŸ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KÂhj€  h²hubjÈ  )”}”(hXƒ  struct user_unreg {
      /* Input: Size of the user_unreg structure being used */
      __u32 size;

      /* Input: Bit to unregister */
      __u8 disable_bit;

      /* Input: Reserved, set to 0 */
      __u8 __reserved;

      /* Input: Reserved, set to 0 */
      __u16 __reserved2;

      /* Input: Address to unregister */
      __u64 disable_addr;
} __attribute__((__packed__));”h]”hXƒ  struct user_unreg {
      /* Input: Size of the user_unreg structure being used */
      __u32 size;

      /* Input: Bit to unregister */
      __u8 disable_bit;

      /* Input: Reserved, set to 0 */
      __u8 __reserved;

      /* Input: Reserved, set to 0 */
      __u16 __reserved2;

      /* Input: Address to unregister */
      __u64 disable_addr;
} __attribute__((__packed__));”…””}”hj­  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´KÄhj€  h²hubhì)”}”(hŒLThe struct user_unreg requires all the above inputs to be set appropriately.”h]”hŒLThe struct user_unreg requires all the above inputs to be set appropriately.”…””}”(hj»  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KÕhj€  h²hubjè  )”}”(hhh]”(jí  )”}”(hŒ5size: This must be set to sizeof(struct user_unreg).
”h]”hì)”}”(hŒ4size: This must be set to sizeof(struct user_unreg).”h]”hŒ4size: This must be set to sizeof(struct user_unreg).”…””}”(hjÐ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´K×hjÌ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjÉ  h²hh³hÊh´Nubjí  )”}”(hŒndisable_bit: This must be set to the bit to disable (same bit that was
previously registered via enable_bit).
”h]”hì)”}”(hŒmdisable_bit: This must be set to the bit to disable (same bit that was
previously registered via enable_bit).”h]”hŒmdisable_bit: This must be set to the bit to disable (same bit that was
previously registered via enable_bit).”…””}”(hjè  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KÙhjä  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjÉ  h²hh³hÊh´Nubjí  )”}”(hŒxdisable_addr: This must be set to the address to disable (same address that was
previously registered via enable_addr).
”h]”hì)”}”(hŒwdisable_addr: This must be set to the address to disable (same address that was
previously registered via enable_addr).”h]”hŒwdisable_addr: This must be set to the address to disable (same address that was
previously registered via enable_addr).”…””}”(hj   h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´KÜhjü  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jì  hjÉ  h²hh³hÊh´Nubeh}”(h]”h ]”h"]”h$]”h&]”j„  j…  uh1jç  h³hÊh´K×hj€  h²hubhì)”}”(hŒ»**NOTE:** Events are automatically unregistered when execve() is invoked. During
fork() the registered events will be retained and must be unregistered manually
in each process if wanted.”h]”(ji  )”}”(hŒ	**NOTE:**”h]”hŒNOTE:”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jh  hj  ubhŒ² Events are automatically unregistered when execve() is invoked. During
fork() the registered events will be retained and must be unregistered manually
in each process if wanted.”…””}”(hj  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Kßhj€  h²hubeh}”(h]”Œunregistering”ah ]”h"]”Œunregistering”ah$]”h&]”uh1hµhh·h²hh³hÊh´K»ubh¶)”}”(hhh]”(h»)”}”(hŒStatus”h]”hŒStatus”…””}”(hjA  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj>  h²hh³hÊh´Käubhì)”}”(hŒÞWhen tools attach/record user based events the status of the event is updated
in realtime. This allows user programs to only incur the cost of the write() or
writev() calls when something is actively attached to the event.”h]”hŒÞWhen tools attach/record user based events the status of the event is updated
in realtime. This allows user programs to only incur the cost of the write() or
writev() calls when something is actively attached to the event.”…””}”(hjO  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Kåhj>  h²hubhì)”}”(hŒÆThe kernel will update the specified bit that was registered for the event as
tools attach/detach from the event. User programs simply check if the bit is set
to see if something is attached or not.”h]”hŒÆThe kernel will update the specified bit that was registered for the event as
tools attach/detach from the event. User programs simply check if the bit is set
to see if something is attached or not.”…””}”(hj]  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Kéhj>  h²hubhì)”}”(hŒžAdministrators can easily check the status of all registered events by reading
the user_events_status file directly via a terminal. The output is as follows::”h]”hŒAdministrators can easily check the status of all registered events by reading
the user_events_status file directly via a terminal. The output is as follows:”…””}”(hjk  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Kíhj>  h²hubjÈ  )”}”(hŒ:Name [# Comments]
...

Active: ActiveCount
Busy: BusyCount”h]”hŒ:Name [# Comments]
...

Active: ActiveCount
Busy: BusyCount”…””}”hjy  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´Kðhj>  h²hubhì)”}”(hŒMFor example, on a system that has a single event the output looks like this::”h]”hŒLFor example, on a system that has a single event the output looks like this:”…””}”(hj‡  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Köhj>  h²hubjÈ  )”}”(hŒtest

Active: 1
Busy: 0”h]”hŒtest

Active: 1
Busy: 0”…””}”hj•  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´Køhj>  h²hubhì)”}”(hŒNIf a user enables the user event via ftrace, the output would change to this::”h]”hŒMIf a user enables the user event via ftrace, the output would change to this:”…””}”(hj£  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´Kýhj>  h²hubjÈ  )”}”(hŒ(test # Used by ftrace

Active: 1
Busy: 1”h]”hŒ(test # Used by ftrace

Active: 1
Busy: 1”…””}”hj±  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´Kÿhj>  h²hubeh}”(h]”Œstatus”ah ]”h"]”Œstatus”ah$]”h&]”uh1hµhh·h²hh³hÊh´Käubh¶)”}”(hhh]”(h»)”}”(hŒWriting Data”h]”hŒWriting Data”…””}”(hjÊ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjÇ  h²hh³hÊh´Mubhì)”}”(hŒéAfter registering an event the same fd that was used to register can be used
to write an entry for that event. The write_index returned must be at the start
of the data, then the remaining data is treated as the payload of the event.”h]”hŒéAfter registering an event the same fd that was used to register can be used
to write an entry for that event. The write_index returned must be at the start
of the data, then the remaining data is treated as the payload of the event.”…””}”(hjØ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´MhjÇ  h²hubhì)”}”(hX  For example, if write_index returned was 1 and I wanted to write out an int
payload of the event. Then the data would have to be 8 bytes (2 ints) in size,
with the first 4 bytes being equal to 1 and the last 4 bytes being equal to the
value I want as the payload.”h]”hX  For example, if write_index returned was 1 and I wanted to write out an int
payload of the event. Then the data would have to be 8 bytes (2 ints) in size,
with the first 4 bytes being equal to 1 and the last 4 bytes being equal to the
value I want as the payload.”…””}”(hjæ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´M
hjÇ  h²hubhì)”}”(hŒ%In memory this would look like this::”h]”hŒ$In memory this would look like this:”…””}”(hjô  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´MhjÇ  h²hubjÈ  )”}”(hŒint index;
int payload;”h]”hŒint index;
int payload;”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´MhjÇ  h²hubhì)”}”(hŒáUser programs might have well known structs that they wish to use to emit out
as payloads. In those cases writev() can be used, with the first vector being
the index and the following vector(s) being the actual event payload.”h]”hŒáUser programs might have well known structs that they wish to use to emit out
as payloads. In those cases writev() can be used, with the first vector being
the index and the following vector(s) being the actual event payload.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´MhjÇ  h²hubhì)”}”(hŒ+For example, if I have a struct like this::”h]”hŒ*For example, if I have a struct like this:”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´MhjÇ  h²hubjÈ  )”}”(hŒ^struct payload {
      int src;
      int dst;
      int flags;
} __attribute__((__packed__));”h]”hŒ^struct payload {
      int src;
      int dst;
      int flags;
} __attribute__((__packed__));”…””}”hj,  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´MhjÇ  h²hubhì)”}”(hŒ4It's advised for user programs to do the following::”h]”hŒ5Itâ€™s advised for user programs to do the following:”…””}”(hj:  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´M hjÇ  h²hubjÈ  )”}”(hŒÃstruct iovec io[2];
struct payload e;

io[0].iov_base = &write_index;
io[0].iov_len = sizeof(write_index);
io[1].iov_base = &e;
io[1].iov_len = sizeof(e);

writev(fd, (const struct iovec*)io, 2);”h]”hŒÃstruct iovec io[2];
struct payload e;

io[0].iov_base = &write_index;
io[0].iov_len = sizeof(write_index);
io[1].iov_base = &e;
io[1].iov_len = sizeof(e);

writev(fd, (const struct iovec*)io, 2);”…””}”hjH  sbah}”(h]”h ]”h"]”h$]”h&]”j×  jØ  uh1jÇ  h³hÊh´M"hjÇ  h²hubhì)”}”(hŒM**NOTE:** *The write_index is not emitted out into the trace being recorded.*”h]”(ji  )”}”(hŒ	**NOTE:**”h]”hŒNOTE:”…””}”(hjZ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jh  hjV  ubhŒ ”…””}”(hjV  h²hh³Nh´Nubj}  )”}”(hŒC*The write_index is not emitted out into the trace being recorded.*”h]”hŒAThe write_index is not emitted out into the trace being recorded.”…””}”(hjl  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j|  hjV  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´M,hjÇ  h²hubeh}”(h]”Œwriting-data”ah ]”h"]”Œwriting data”ah$]”h&]”uh1hµhh·h²hh³hÊh´Mubh¶)”}”(hhh]”(h»)”}”(hŒExample Code”h]”hŒExample Code”…””}”(hj‹  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjˆ  h²hh³hÊh´M/ubhì)”}”(hŒ'See sample code in samples/user_events.”h]”hŒ'See sample code in samples/user_events.”…””}”(hj™  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hëh³hÊh´M0hjˆ  h²hubeh}”(h]”Œexample-code”ah ]”h"]”Œexample code”ah$]”h&]”uh1hµhh·h²hh³hÊh´M/ubeh}”(h]”Œ$user-events-user-based-event-tracing”ah ]”h"]”Œ%user_events: user-based event tracing”ah$]”h&]”uh1hµhhh²hh³hÊh´Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”hÊuh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(hºNŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”jÚ  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”hÊŒ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(j´  j±  j—  j”  j,  j)  jX  jU  j  j|  j$  j!  j}  jz  j;  j8  jÄ  jÁ  j…  j‚  j¬  j©  uŒ	nametypes”}”(j´  ‰j—  ‰j,  ‰jX  ‰j  ‰j$  ‰j}  ‰j;  ‰jÄ  ‰j…  ‰j¬  ‰uh}”(j±  h·j”  j  j)  jš  jU  j&  j|  j[  j!  j‚  jz  j/  j8  j€  jÁ  j>  j‚  jÇ  j©  jˆ  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nh²hub.