// ** The above line should force tbl to be a preprocessor **
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// Man page for slackspot
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//
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// Copyright (C) 2014 Philippe Gerum <rpm@xenomai.org>
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//
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// You may distribute under the terms of the GNU General Public
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// License as specified in the file COPYING that comes with the
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// Xenomai distribution.
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//
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//
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SLACKSPOT(1)
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==========
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:doctype: manpage
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:revdate: 2014/06/26
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:man source: Xenomai
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:man version: {xenover}
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:man manual: Xenomai Manual
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NAME
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----
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slackspot - Trace secondary mode switches
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SYNOPSIS
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---------
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*slackspot* [ options ]
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DESCRIPTION
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------------
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*slackspot* is a utility to decode the trace data collected by the
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Cobalt core when CONFIG_XENO_OPT_DEBUG_TRACE_RELAX is enabled in the
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kernel configuration.
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This data describes each call hierarchy causing migration to secondary
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mode (i.e. _relaxes_) within the application. *slackspot* presents
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such data in a human-readable format as symbolic stack backtraces, for
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helping in debugging spurious relaxes.
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OPTIONS
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--------
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*slackspot* accepts the following options:
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*--file <trace-file>*::
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Read the trace information to decode from _trace-file_. By default,
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trace data is read from +/proc/xenomai/debug/relax+ unless the
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standard input stream was redirected, in which case +stdin+ is read.
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In addition, the dash character "-" is interpreted as a placeholder
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for +stdin+.
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*--path <dir[:dir...]>*::
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Search directory list for executables and dynamic
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libraries. Directories are separatared by a semi-colon within the
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list. Each directory may be scanned for binary executables when
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resolving symbols found in stack backtraces.
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*--filter-in <name=exp[,name=...]>*::
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Only retain backtraces matching the given filters in the output. Each
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filter is specified by a _name=<expr>_ pair, where _name_ identifies
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the information field to be matched in the backtrace, and _expr_ is a
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regular expression which should match such data. Filters are separated
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by a comma within the list. The available filters are as follows:
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* _thread_ matches the thread name.
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* _pid_ matches the kernel task identifier, i.e. per-task _pid_.
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* _exe_ matches the name of the main executable being traced.
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* _function_ matches the name of the function being traced.
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* _file_ matches the path of the source file being traced.
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* _map_ matches the path of the mapped executable being traced.
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*--filter <name=exp[,name=...]>*::
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A shorthand for *--filter-in*.
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*--filter-out <name=exp[,name=...]>*::
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Only retain backtraces NOT matching the given filters in the
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output. This option inverts the sense of matching defined by
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*--filter-in*.
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*CROSS_COMPILE=<toolchain-prefix>*::
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A cross-compilation toolchain prefix should be specified for decoding
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the data obtained from a target system, on a build/development
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machine. When present, the value of CROSS_COMPILE will be prepended to
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+gcc+ and +addr2line+ for running the corresponding utilities on the
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development system.
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VERSIONS
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--------
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*slackspot* appeared in Xenomai 3.0 for the _Cobalt_ real-time core.
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EXAMPLE
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-------
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In the following scenario, the _target_ system built with the
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CONFIG_XENO_OPT_DEBUG_TRACE_RELAX feature enabled in the kernel
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configuration, just ran the _/bin/relax_ program.
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This program caused a transition to secondary mode switch of the
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current task (_Task 2_) as a result of calling +putchar()+. The Cobalt
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core saved the corresponding backtrace information, which is now
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available from +/proc/xenomai/debug/relax+ on the target system.
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Since the target system has limited horsepower, and doesn't have
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access to the binary utilities required for decoding the trace data,
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we will send such data over the network to the _host_ system, in order
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for the latter to do the decoding and display the call stacks.
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We use the standard +netcat+ utility to send and receive the contents
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of +/proc/xenomai/debug/relax+ over the wire between the target and
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host systems. The host will also have to mention where the
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cross-compilation toolchain can be found, by setting the CROSS_COMPILE
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variable appropriately. The example assumes that
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+/opt/rootfs/MPC5200/lib+ is the host-based location of the system
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libraries mounted over NFS onto the target file hierarchy.
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.On the target system:
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---------------------------------------------------------------------------
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target> netcat -l -p 67676 -c < /proc/xenomai/debug/relax
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---------------------------------------------------------------------------
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.On the host system:
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---------------------------------------------------------------------------
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host> netcat target 67676 | CROSS_COMPILE=ppc_6xx- slackspot
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--path=/opt/rootfs/MPC5200/lib:$HOME/frags/relax --filter thread=Task*
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Thread[828] "Task 2" started by /bin/relax:
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#0 0xfff00000 ???
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#1 0x000001bb ???
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#2 0x00064393 _IO_file_doallocate() in ??:?
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#3 0x00073d6f _IO_doallocbuf() in ??:?
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#4 0x00072d87 _IO_file_overflow() in ??:?
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#5 0x00075f83 __overflow() in ??:?
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#6 0x0006997b putchar() in ??:?
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#7 0x100017db task2_func() in /home/rpm/frags/relax/relax.c:23
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#8 0x000078d7 task_entry() in /home/rpm/git/xenomai-forge/lib/alchemy/task.c:235
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#9 0x00005a6b start_thread() in pthread_create.c:?
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#10 0x000d389f __clone() in ??:?
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---------------------------------------------------------------------------
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AUTHOR
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-------
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*slackspot* was written by Philippe Gerum <rpm@xenomai.org>.
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