| 1 |
27 |
unneback |
<!-- Copyright (C) 2002 Red Hat, Inc. -->
|
| 2 |
|
|
<!-- This material may be distributed only subject to the terms -->
|
| 3 |
|
|
<!-- and conditions set forth in the Open Publication License, v1.0 -->
|
| 4 |
|
|
<!-- or later (the latest version is presently available at -->
|
| 5 |
|
|
<!-- http://www.opencontent.org/openpub/). -->
|
| 6 |
|
|
<!-- Distribution of the work or derivative of the work in any -->
|
| 7 |
|
|
<!-- standard (paper) book form is prohibited unless prior -->
|
| 8 |
|
|
<!-- permission is obtained from the copyright holder. -->
|
| 9 |
|
|
<HTML
|
| 10 |
|
|
><HEAD
|
| 11 |
|
|
><TITLE
|
| 12 |
|
|
>Synthetic Target Watchdog Device</TITLE
|
| 13 |
|
|
><meta name="MSSmartTagsPreventParsing" content="TRUE">
|
| 14 |
|
|
<META
|
| 15 |
|
|
NAME="GENERATOR"
|
| 16 |
|
|
CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
|
| 17 |
|
|
"></HEAD
|
| 18 |
|
|
><BODY
|
| 19 |
|
|
CLASS="REFENTRY"
|
| 20 |
|
|
BGCOLOR="#FFFFFF"
|
| 21 |
|
|
TEXT="#000000"
|
| 22 |
|
|
LINK="#0000FF"
|
| 23 |
|
|
VLINK="#840084"
|
| 24 |
|
|
ALINK="#0000FF"
|
| 25 |
|
|
><H1
|
| 26 |
|
|
><A
|
| 27 |
|
|
NAME="DEVS-WATCHDOG-SYNTH">Synthetic Target Watchdog Device</H1
|
| 28 |
|
|
><DIV
|
| 29 |
|
|
CLASS="REFNAMEDIV"
|
| 30 |
|
|
><A
|
| 31 |
|
|
NAME="AEN4"
|
| 32 |
|
|
></A
|
| 33 |
|
|
><H2
|
| 34 |
|
|
>Name</H2
|
| 35 |
|
|
>Synthetic Target Watchdog Device -- Emulate watchdog hardware in the synthetic target</DIV
|
| 36 |
|
|
><DIV
|
| 37 |
|
|
CLASS="REFSECT1"
|
| 38 |
|
|
><A
|
| 39 |
|
|
NAME="AEN7"
|
| 40 |
|
|
></A
|
| 41 |
|
|
><H2
|
| 42 |
|
|
>Overview</H2
|
| 43 |
|
|
><P
|
| 44 |
|
|
>Some target hardware comes equipped with a watchdog timer. Application
|
| 45 |
|
|
code can start this timer and after a certain period of time,
|
| 46 |
|
|
typically a second, the watchdog will trigger. Usually this causes the
|
| 47 |
|
|
hardware to reboot. The application can prevent this by regularly
|
| 48 |
|
|
resetting the watchdog. An automatic reboot can be very useful when
|
| 49 |
|
|
deploying hardware in the field: a hardware glitch could cause the
|
| 50 |
|
|
unit to hang; or the software could receive an unexpected sequence of
|
| 51 |
|
|
inputs, never seen in the laboratory, causing the system to lock up.
|
| 52 |
|
|
Often the hardware is still functional, and a reboot sorts out the
|
| 53 |
|
|
problem with only a brief interruption in service.
|
| 54 |
|
|
</P
|
| 55 |
|
|
><P
|
| 56 |
|
|
>The synthetic target watchdog package emulates watchdog hardware.
|
| 57 |
|
|
During system initialization watchdog device will be instantiated,
|
| 58 |
|
|
and the <TT
|
| 59 |
|
|
CLASS="FILENAME"
|
| 60 |
|
|
>watchdog.tcl</TT
|
| 61 |
|
|
> script will be loaded by the
|
| 62 |
|
|
I/O auxiliary. When the eCos application starts the watchdog device,
|
| 63 |
|
|
the <TT
|
| 64 |
|
|
CLASS="FILENAME"
|
| 65 |
|
|
>watchdog.tcl</TT
|
| 66 |
|
|
> script will start checking the
|
| 67 |
|
|
state of the eCos application at one second intervals. A watchdog
|
| 68 |
|
|
reset call simply involves a message to the I/O auxiliary. If the
|
| 69 |
|
|
<TT
|
| 70 |
|
|
CLASS="FILENAME"
|
| 71 |
|
|
>watchdog.tcl</TT
|
| 72 |
|
|
> script detects that a second has
|
| 73 |
|
|
<A
|
| 74 |
|
|
HREF="devs-watchdog-synth.html#SYNTH-WATCHDOG-WALLCLOCK-ELAPSED"
|
| 75 |
|
|
>elapsed</A
|
| 76 |
|
|
>
|
| 77 |
|
|
without a reset then it will send a <TT
|
| 78 |
|
|
CLASS="LITERAL"
|
| 79 |
|
|
>SIGPWR</TT
|
| 80 |
|
|
> signal
|
| 81 |
|
|
to the eCos application, causing the latter to terminate. If gdb is
|
| 82 |
|
|
being used to run the application, the user will get a chance to
|
| 83 |
|
|
investigate what is happening. This behaviour is different from real
|
| 84 |
|
|
hardware in that there is no automatic reboot, but the synthetic
|
| 85 |
|
|
target is used only for development purposes, not deployment in the
|
| 86 |
|
|
field: if a reboot is desired then this can be achieved very easily
|
| 87 |
|
|
by using gdb commands to run another instance of the application.
|
| 88 |
|
|
</P
|
| 89 |
|
|
></DIV
|
| 90 |
|
|
><DIV
|
| 91 |
|
|
CLASS="REFSECT1"
|
| 92 |
|
|
><A
|
| 93 |
|
|
NAME="DEVS-WATCHDOG-SYNTH-INSTALL"
|
| 94 |
|
|
></A
|
| 95 |
|
|
><H2
|
| 96 |
|
|
>Installation</H2
|
| 97 |
|
|
><P
|
| 98 |
|
|
>Before a synthetic target eCos application can use a watchdog device
|
| 99 |
|
|
it is necessary to build and install host-side support. The relevant
|
| 100 |
|
|
code resides in the <TT
|
| 101 |
|
|
CLASS="FILENAME"
|
| 102 |
|
|
>host</TT
|
| 103 |
|
|
>
|
| 104 |
|
|
subdirectory of the synthetic target watchdog package, and building it
|
| 105 |
|
|
involves the standard <B
|
| 106 |
|
|
CLASS="COMMAND"
|
| 107 |
|
|
>configure</B
|
| 108 |
|
|
>,
|
| 109 |
|
|
<B
|
| 110 |
|
|
CLASS="COMMAND"
|
| 111 |
|
|
>make</B
|
| 112 |
|
|
> and <B
|
| 113 |
|
|
CLASS="COMMAND"
|
| 114 |
|
|
>make install</B
|
| 115 |
|
|
> steps. The
|
| 116 |
|
|
implementation of the watchdog support does not require any
|
| 117 |
|
|
executables, just a Tcl script <TT
|
| 118 |
|
|
CLASS="FILENAME"
|
| 119 |
|
|
>watchdog.tcl</TT
|
| 120 |
|
|
> and
|
| 121 |
|
|
some support files, so the <B
|
| 122 |
|
|
CLASS="COMMAND"
|
| 123 |
|
|
>make</B
|
| 124 |
|
|
> step is a no-op.
|
| 125 |
|
|
</P
|
| 126 |
|
|
><P
|
| 127 |
|
|
>There are two main ways of building the host-side software. It is
|
| 128 |
|
|
possible to build both the generic host-side software and all
|
| 129 |
|
|
package-specific host-side software, including the watchdog support,
|
| 130 |
|
|
in a single build tree. This involves using the
|
| 131 |
|
|
<B
|
| 132 |
|
|
CLASS="COMMAND"
|
| 133 |
|
|
>configure</B
|
| 134 |
|
|
> script at the toplevel of the eCos
|
| 135 |
|
|
repository. For more information on this, see the
|
| 136 |
|
|
<TT
|
| 137 |
|
|
CLASS="FILENAME"
|
| 138 |
|
|
>README.host</TT
|
| 139 |
|
|
> file at the top of the repository.
|
| 140 |
|
|
Note that if you have an existing build tree which does not include
|
| 141 |
|
|
the synthetic target watchdog support then it will be necessary to
|
| 142 |
|
|
rerun the toplevel configure script: the search for appropriate
|
| 143 |
|
|
packages happens at configure time.
|
| 144 |
|
|
</P
|
| 145 |
|
|
><P
|
| 146 |
|
|
>The alternative is to build just the host-side for this package.
|
| 147 |
|
|
This requires a separate build directory, building directly in the
|
| 148 |
|
|
source tree is disallowed. The <B
|
| 149 |
|
|
CLASS="COMMAND"
|
| 150 |
|
|
>configure</B
|
| 151 |
|
|
> options
|
| 152 |
|
|
are much the same as for a build from the toplevel, and the
|
| 153 |
|
|
<TT
|
| 154 |
|
|
CLASS="FILENAME"
|
| 155 |
|
|
>README.host</TT
|
| 156 |
|
|
> file can be consulted for more
|
| 157 |
|
|
details. It is essential that the watchdog support be configured with
|
| 158 |
|
|
the same <TT
|
| 159 |
|
|
CLASS="OPTION"
|
| 160 |
|
|
>--prefix</TT
|
| 161 |
|
|
> option as other eCos host-side
|
| 162 |
|
|
software, especially the I/O auxiliary provided by the architectural
|
| 163 |
|
|
synthetic target HAL package, otherwise the I/O auxiliary will be
|
| 164 |
|
|
unable to locate the watchdog support.
|
| 165 |
|
|
</P
|
| 166 |
|
|
></DIV
|
| 167 |
|
|
><DIV
|
| 168 |
|
|
CLASS="REFSECT1"
|
| 169 |
|
|
><A
|
| 170 |
|
|
NAME="SYNTH-WATCHDOG-TARGET-CONFIG"
|
| 171 |
|
|
></A
|
| 172 |
|
|
><H2
|
| 173 |
|
|
>Target-side
|
| 174 |
|
|
Configuration</H2
|
| 175 |
|
|
><P
|
| 176 |
|
|
>The watchdog device depends on the generic watchdog support,
|
| 177 |
|
|
<TT
|
| 178 |
|
|
CLASS="VARNAME"
|
| 179 |
|
|
>CYGPKG_IO_WATCHDOG</TT
|
| 180 |
|
|
>: if the generic support is
|
| 181 |
|
|
absent then the watchdog device will be inactive. Some templates
|
| 182 |
|
|
include this generic package by default, but not all. If the
|
| 183 |
|
|
configuration does not include the generic package then it can be
|
| 184 |
|
|
added using the eCos configuration tools, for example:
|
| 185 |
|
|
</P
|
| 186 |
|
|
><TABLE
|
| 187 |
|
|
BORDER="5"
|
| 188 |
|
|
BGCOLOR="#E0E0F0"
|
| 189 |
|
|
WIDTH="70%"
|
| 190 |
|
|
><TR
|
| 191 |
|
|
><TD
|
| 192 |
|
|
><PRE
|
| 193 |
|
|
CLASS="SCREEN"
|
| 194 |
|
|
>$ ecosconfig add CYGPKG_IO_WATCHDOG</PRE
|
| 195 |
|
|
></TD
|
| 196 |
|
|
></TR
|
| 197 |
|
|
></TABLE
|
| 198 |
|
|
><P
|
| 199 |
|
|
>By default the configuration will use the hardware-specific support,
|
| 200 |
|
|
i.e. this package. However the generic watchdog package contains an
|
| 201 |
|
|
alternative implementation using the kernel alarm facility, and that
|
| 202 |
|
|
implementation can be selected if desired. However usually it will be
|
| 203 |
|
|
better to rely on an external watchdog facility as provided by the I/O
|
| 204 |
|
|
auxiliary and the <TT
|
| 205 |
|
|
CLASS="FILENAME"
|
| 206 |
|
|
>watchdog.tcl</TT
|
| 207 |
|
|
> script: if there
|
| 208 |
|
|
are serious problems within the application, for example memory
|
| 209 |
|
|
corruption, then an internal software-only implementation will not be
|
| 210 |
|
|
reliable.
|
| 211 |
|
|
</P
|
| 212 |
|
|
><P
|
| 213 |
|
|
>The watchdog resolution is currently fixed to one second: if the
|
| 214 |
|
|
device does not receive a reset signal at least once a second then
|
| 215 |
|
|
the watchdog will trigger and the eCos application will be terminated
|
| 216 |
|
|
with a <TT
|
| 217 |
|
|
CLASS="LITERAL"
|
| 218 |
|
|
>SIGPWR</TT
|
| 219 |
|
|
> signal. The current implementation
|
| 220 |
|
|
does not allow this resolution to be changed.
|
| 221 |
|
|
</P
|
| 222 |
|
|
><P
|
| 223 |
|
|
>On some targets the watchdog device does not perform a hard reset.
|
| 224 |
|
|
Instead the device works more or less via the interrupt subsystem,
|
| 225 |
|
|
allowing application code to install action routines that will be
|
| 226 |
|
|
called when the watchdog triggers. The synthetic target watchdog
|
| 227 |
|
|
support effectively does perform a hard reset, by sending a
|
| 228 |
|
|
<TT
|
| 229 |
|
|
CLASS="LITERAL"
|
| 230 |
|
|
>SIGPWR</TT
|
| 231 |
|
|
> signal to the eCos application, and there is
|
| 232 |
|
|
no support for action routines.
|
| 233 |
|
|
</P
|
| 234 |
|
|
><P
|
| 235 |
|
|
>The synthetic target watchdog package provides some configuration
|
| 236 |
|
|
options for manipulating the compiler flags used for building the
|
| 237 |
|
|
target-side code. That code is fairly simple, so for nearly all
|
| 238 |
|
|
applications the default flags will suffice.
|
| 239 |
|
|
</P
|
| 240 |
|
|
><P
|
| 241 |
|
|
>It should be noted that the watchdog device is subject to selective
|
| 242 |
|
|
linking. Unless some code explicitly references the device, for
|
| 243 |
|
|
example by calling the start and reset functions, the watchdog support
|
| 244 |
|
|
will not appear in the final executable. This is desirable because a
|
| 245 |
|
|
watchdog device has no effect until started.
|
| 246 |
|
|
</P
|
| 247 |
|
|
></DIV
|
| 248 |
|
|
><DIV
|
| 249 |
|
|
CLASS="REFSECT1"
|
| 250 |
|
|
><A
|
| 251 |
|
|
NAME="SYNTH-WATCHDOG-WALLCLOCK-ELAPSED"
|
| 252 |
|
|
></A
|
| 253 |
|
|
><H2
|
| 254 |
|
|
>Wallclock versus Elapsed Time</H2
|
| 255 |
|
|
><P
|
| 256 |
|
|
>On real hardware the watchdog device uses wallclock time: if the
|
| 257 |
|
|
device does not receive a reset signal within a set period of time
|
| 258 |
|
|
then the watchdog will trigger. When developing for the synthetic
|
| 259 |
|
|
target this is not always appropriate. There may be other processes
|
| 260 |
|
|
running, using up some or most of the cpu time. For example, the
|
| 261 |
|
|
application may be written such that it will issue a reset after some
|
| 262 |
|
|
calculations which are known to complete within half a second, well
|
| 263 |
|
|
within the one-second resolution of the watchdog device. However if
|
| 264 |
|
|
other Linux processes are running then the synthetic target
|
| 265 |
|
|
application may get timesliced, and half a second of computation may
|
| 266 |
|
|
take several seconds of wallclock time.
|
| 267 |
|
|
</P
|
| 268 |
|
|
><P
|
| 269 |
|
|
>Another problem with using wallclock time is that it interferes with
|
| 270 |
|
|
debugging: if the application hits a breakpoint then it is unlikely
|
| 271 |
|
|
that the user will manage to restart it in less than a second, and the
|
| 272 |
|
|
watchdog will not get reset in time.
|
| 273 |
|
|
</P
|
| 274 |
|
|
><P
|
| 275 |
|
|
>To avoid these problems the synthetic target watchdog normally uses
|
| 276 |
|
|
consumed cpu time rather than wallclock time. If the application is
|
| 277 |
|
|
timesliced or if it is halted inside gdb then it does not consume any
|
| 278 |
|
|
cpu time. The application actually has to spend a whole second's worth
|
| 279 |
|
|
of cpu cycles without issuing a reset before the watchdog triggers.
|
| 280 |
|
|
</P
|
| 281 |
|
|
><P
|
| 282 |
|
|
>However using consumed cpu time is not a perfect solution either. If
|
| 283 |
|
|
the application makes blocking system calls then it is not using cpu
|
| 284 |
|
|
time. Interaction with the I/O auxiliary involves system calls, but
|
| 285 |
|
|
these should take only a short amount of time so their effects can be
|
| 286 |
|
|
ignored. If the application makes direct system calls such as
|
| 287 |
|
|
<TT
|
| 288 |
|
|
CLASS="FUNCTION"
|
| 289 |
|
|
>cyg_hal_sys_read</TT
|
| 290 |
|
|
> then the system behaviour
|
| 291 |
|
|
becomes undefined. In addition by default the idle thread will make
|
| 292 |
|
|
blocking <TT
|
| 293 |
|
|
CLASS="FUNCTION"
|
| 294 |
|
|
>select</TT
|
| 295 |
|
|
> system calls, effectively waiting
|
| 296 |
|
|
until an interrupt occurs. If an application spends much of its time
|
| 297 |
|
|
idle then the watchdog device may take much longer to trigger than
|
| 298 |
|
|
expected. It may be desirable to enable the synthetic target HAL
|
| 299 |
|
|
configuration option <TT
|
| 300 |
|
|
CLASS="VARNAME"
|
| 301 |
|
|
>CYGIMP_HAL_IDLE_THREAD_SPIN</TT
|
| 302 |
|
|
>,
|
| 303 |
|
|
causing the idle thread to spin rather than block, at the cost of
|
| 304 |
|
|
wasted cpu cycles.
|
| 305 |
|
|
</P
|
| 306 |
|
|
><P
|
| 307 |
|
|
>The default is to use consumed cpu time, but this can be changed in
|
| 308 |
|
|
the target definition file:
|
| 309 |
|
|
</P
|
| 310 |
|
|
><TABLE
|
| 311 |
|
|
BORDER="5"
|
| 312 |
|
|
BGCOLOR="#E0E0F0"
|
| 313 |
|
|
WIDTH="70%"
|
| 314 |
|
|
><TR
|
| 315 |
|
|
><TD
|
| 316 |
|
|
><PRE
|
| 317 |
|
|
CLASS="PROGRAMLISTING"
|
| 318 |
|
|
>synth_device watchdog {
|
| 319 |
|
|
use wallclock_time
|
| 320 |
|
|
…
|
| 321 |
|
|
}</PRE
|
| 322 |
|
|
></TD
|
| 323 |
|
|
></TR
|
| 324 |
|
|
></TABLE
|
| 325 |
|
|
></DIV
|
| 326 |
|
|
><DIV
|
| 327 |
|
|
CLASS="REFSECT1"
|
| 328 |
|
|
><A
|
| 329 |
|
|
NAME="SYNTH-WATCHDOG-GUI"
|
| 330 |
|
|
></A
|
| 331 |
|
|
><H2
|
| 332 |
|
|
>User Interface</H2
|
| 333 |
|
|
><P
|
| 334 |
|
|
>When the synthetic target is run in graphical mode the watchdog device
|
| 335 |
|
|
extends the user interface in two ways. The <SPAN
|
| 336 |
|
|
CLASS="GUIMENU"
|
| 337 |
|
|
>Help</SPAN
|
| 338 |
|
|
>
|
| 339 |
|
|
menu is extended with an entry for the watchdog-specific
|
| 340 |
|
|
documentation. There is also a graphical display of the current state
|
| 341 |
|
|
of the watchdog. Initially the watchdog is asleep:
|
| 342 |
|
|
</P
|
| 343 |
|
|
><DIV
|
| 344 |
|
|
CLASS="INFORMALFIGURE"
|
| 345 |
|
|
><A
|
| 346 |
|
|
NAME="AEN60"><P
|
| 347 |
|
|
></P
|
| 348 |
|
|
><DIV
|
| 349 |
|
|
CLASS="MEDIAOBJECT"
|
| 350 |
|
|
><P
|
| 351 |
|
|
><IMG
|
| 352 |
|
|
SRC="asleep.gif"
|
| 353 |
|
|
ALIGN="CENTER"></P
|
| 354 |
|
|
></DIV
|
| 355 |
|
|
><P
|
| 356 |
|
|
></P
|
| 357 |
|
|
></DIV
|
| 358 |
|
|
><P
|
| 359 |
|
|
>When application code starts the device the watchdog will begin to
|
| 360 |
|
|
keep an eye on things (or occasionally both eyes).
|
| 361 |
|
|
</P
|
| 362 |
|
|
><DIV
|
| 363 |
|
|
CLASS="INFORMALFIGURE"
|
| 364 |
|
|
><A
|
| 365 |
|
|
NAME="AEN65"><P
|
| 366 |
|
|
></P
|
| 367 |
|
|
><DIV
|
| 368 |
|
|
CLASS="MEDIAOBJECT"
|
| 369 |
|
|
><P
|
| 370 |
|
|
><IMG
|
| 371 |
|
|
SRC="awake.gif"
|
| 372 |
|
|
ALIGN="CENTER"></P
|
| 373 |
|
|
></DIV
|
| 374 |
|
|
><P
|
| 375 |
|
|
></P
|
| 376 |
|
|
></DIV
|
| 377 |
|
|
><P
|
| 378 |
|
|
>If the watchdog triggers the display will change again, and optionally
|
| 379 |
|
|
the user can receive an audible alert. The location of the watchdog
|
| 380 |
|
|
display within the I/O auxiliary's window can be controlled via
|
| 381 |
|
|
a <B
|
| 382 |
|
|
CLASS="COMMAND"
|
| 383 |
|
|
>watchdog_pack</B
|
| 384 |
|
|
> entry in the target definition
|
| 385 |
|
|
file. For example the following can be used to put the watchdog
|
| 386 |
|
|
display to the right of the central text window:
|
| 387 |
|
|
</P
|
| 388 |
|
|
><TABLE
|
| 389 |
|
|
BORDER="5"
|
| 390 |
|
|
BGCOLOR="#E0E0F0"
|
| 391 |
|
|
WIDTH="70%"
|
| 392 |
|
|
><TR
|
| 393 |
|
|
><TD
|
| 394 |
|
|
><PRE
|
| 395 |
|
|
CLASS="PROGRAMLISTING"
|
| 396 |
|
|
>synth_device watchdog {
|
| 397 |
|
|
watchdog_pack -in .main.e -side top
|
| 398 |
|
|
…
|
| 399 |
|
|
}</PRE
|
| 400 |
|
|
></TD
|
| 401 |
|
|
></TR
|
| 402 |
|
|
></TABLE
|
| 403 |
|
|
><P
|
| 404 |
|
|
>The user interface section of the generic synthetic target HAL
|
| 405 |
|
|
documentation can be consulted for more information on window packing.
|
| 406 |
|
|
</P
|
| 407 |
|
|
><P
|
| 408 |
|
|
>By default the watchdog support will not generate an audible alert
|
| 409 |
|
|
when the watchdog triggers, to avoid annoying colleagues. Sound can be
|
| 410 |
|
|
enabled in the target definition file, and two suitable files
|
| 411 |
|
|
<TT
|
| 412 |
|
|
CLASS="FILENAME"
|
| 413 |
|
|
>sound1.au</TT
|
| 414 |
|
|
> and <TT
|
| 415 |
|
|
CLASS="FILENAME"
|
| 416 |
|
|
>sound2.au</TT
|
| 417 |
|
|
> are
|
| 418 |
|
|
supplied as standard:
|
| 419 |
|
|
</P
|
| 420 |
|
|
><TABLE
|
| 421 |
|
|
BORDER="5"
|
| 422 |
|
|
BGCOLOR="#E0E0F0"
|
| 423 |
|
|
WIDTH="70%"
|
| 424 |
|
|
><TR
|
| 425 |
|
|
><TD
|
| 426 |
|
|
><PRE
|
| 427 |
|
|
CLASS="PROGRAMLISTING"
|
| 428 |
|
|
>synth_device watchdog {
|
| 429 |
|
|
sound sound1.au
|
| 430 |
|
|
…
|
| 431 |
|
|
}</PRE
|
| 432 |
|
|
></TD
|
| 433 |
|
|
></TR
|
| 434 |
|
|
></TABLE
|
| 435 |
|
|
><P
|
| 436 |
|
|
>An absolute path can be specified if desired:
|
| 437 |
|
|
</P
|
| 438 |
|
|
><TABLE
|
| 439 |
|
|
BORDER="5"
|
| 440 |
|
|
BGCOLOR="#E0E0F0"
|
| 441 |
|
|
WIDTH="70%"
|
| 442 |
|
|
><TR
|
| 443 |
|
|
><TD
|
| 444 |
|
|
><PRE
|
| 445 |
|
|
CLASS="PROGRAMLISTING"
|
| 446 |
|
|
>synth_device watchdog {
|
| 447 |
|
|
sound /usr/share/emacs/site-lisp/emacspeak/sounds/default-8k/alarm.au
|
| 448 |
|
|
…
|
| 449 |
|
|
}</PRE
|
| 450 |
|
|
></TD
|
| 451 |
|
|
></TR
|
| 452 |
|
|
></TABLE
|
| 453 |
|
|
><P
|
| 454 |
|
|
>Sound facilities are not built into the I/O auxiliary itself, instead
|
| 455 |
|
|
an external program is used. The default player is
|
| 456 |
|
|
<B
|
| 457 |
|
|
CLASS="COMMAND"
|
| 458 |
|
|
>play</B
|
| 459 |
|
|
>, a front-end to the
|
| 460 |
|
|
<SPAN
|
| 461 |
|
|
CLASS="APPLICATION"
|
| 462 |
|
|
>sox</SPAN
|
| 463 |
|
|
> application shipped with some Linux
|
| 464 |
|
|
distributions. If another player should be used then this can be
|
| 465 |
|
|
specified in the target definition file:
|
| 466 |
|
|
</P
|
| 467 |
|
|
><TABLE
|
| 468 |
|
|
BORDER="5"
|
| 469 |
|
|
BGCOLOR="#E0E0F0"
|
| 470 |
|
|
WIDTH="70%"
|
| 471 |
|
|
><TR
|
| 472 |
|
|
><TD
|
| 473 |
|
|
><PRE
|
| 474 |
|
|
CLASS="PROGRAMLISTING"
|
| 475 |
|
|
>synth_device watchdog {
|
| 476 |
|
|
…
|
| 477 |
|
|
sound_player my_sound_player</PRE
|
| 478 |
|
|
></TD
|
| 479 |
|
|
></TR
|
| 480 |
|
|
></TABLE
|
| 481 |
|
|
><P
|
| 482 |
|
|
>The specified program will be run in the background with a single
|
| 483 |
|
|
argument, the sound file.
|
| 484 |
|
|
</P
|
| 485 |
|
|
></DIV
|
| 486 |
|
|
><DIV
|
| 487 |
|
|
CLASS="REFSECT1"
|
| 488 |
|
|
><A
|
| 489 |
|
|
NAME="DEVS-WATCHDOG-SYNTH-ARGS"
|
| 490 |
|
|
></A
|
| 491 |
|
|
><H2
|
| 492 |
|
|
>Command Line Arguments</H2
|
| 493 |
|
|
><P
|
| 494 |
|
|
>The watchdog support does not use any command line arguments. All
|
| 495 |
|
|
configuration is handled through the target definition file.
|
| 496 |
|
|
</P
|
| 497 |
|
|
></DIV
|
| 498 |
|
|
><DIV
|
| 499 |
|
|
CLASS="REFSECT1"
|
| 500 |
|
|
><A
|
| 501 |
|
|
NAME="DEVS-WATCHDOG-SYNTH-HOOKS"
|
| 502 |
|
|
></A
|
| 503 |
|
|
><H2
|
| 504 |
|
|
>Hooks</H2
|
| 505 |
|
|
><P
|
| 506 |
|
|
>The watchdog support does not provide any hooks for use by other
|
| 507 |
|
|
scripts. There is rarely any need for customizing the system's
|
| 508 |
|
|
behaviour when a watchdog triggers because those should be rare
|
| 509 |
|
|
events, even during application development.
|
| 510 |
|
|
</P
|
| 511 |
|
|
></DIV
|
| 512 |
|
|
><DIV
|
| 513 |
|
|
CLASS="REFSECT1"
|
| 514 |
|
|
><A
|
| 515 |
|
|
NAME="DEVS-WATCHDOG-SYNTH-TCL"
|
| 516 |
|
|
></A
|
| 517 |
|
|
><H2
|
| 518 |
|
|
>Additional Tcl Procedures</H2
|
| 519 |
|
|
><P
|
| 520 |
|
|
>The watchdog support does not provide any additional Tcl procedures or
|
| 521 |
|
|
variables for use by other scripts.
|
| 522 |
|
|
</P
|
| 523 |
|
|
></DIV
|
| 524 |
|
|
></BODY
|
| 525 |
|
|
></HTML
|
| 526 |
|
|
>
|
