To use an ETM trace port it must be associated with a driver.
+@deffn {Trace Port Driver} dummy
+Use the @option{dummy} driver if you are configuring an ETM that's
+not connected to anything (on-chip ETB or off-chip trace connector).
+@emph{This driver lets OpenOCD talk to the ETM, but it does not expose
+any trace data collection.}
+@deffn {Config Command} {etm_dummy config} target
+Associates the ETM for @var{target} with a dummy driver.
+@end deffn
+@end deffn
+
@deffn {Trace Port Driver} etb
Use the @option{etb} driver if you are configuring an ETM
to use on-chip ETB memory.
@end deffn
@end deffn
-@deffn {Trace Port Driver} etm_dummy
-Use the @option{etm_dummy} driver if you are configuring an ETM that's
-not connected to anything (on-chip ETB or off-chip trace connector).
-@emph{This driver lets OpenOCD talk to the ETM, but it does not expose
-any trace data collection.}
-@deffn {Config Command} {etm_dummy config} target
-Associates the ETM for @var{target} with a dummy driver.
-@end deffn
-@end deffn
-
@deffn {Trace Port Driver} oocd_trace
This driver isn't available unless OpenOCD was explicitly configured
with the @option{--enable-oocd_trace} option. You probably don't want
@deffn Command {target_request debugmsgs} [enable|disable|charmsg]
Displays current handling of target DCC message requests.
These messages may be sent to the debugger while the target is running.
-The optional @option{enable} and @option{charmsg} parameters are
-equivalent; both enable the messages, @option{disable} disables them.
+The optional @option{enable} and @option{charmsg} parameters
+both enable the messages, while @option{disable} disables them.
+With @option{charmsg} the DCC words each contain one character,
+as used by Linux with CONFIG_DEBUG_ICEDCC;
+otherwise the libdcc format is used.
@end deffn
@node JTAG Commands