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rtos/hwthread: add hardware-thread pseudo rtos

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This patch adds "hwthread", a pseudo rtos that represents cpu cores
in an SMP system as threads to gdb. This allows to debug SMP
system kernels in a more sensible manner and removes the current
atrocities of switching gdb manually between CPU cores to update
the context.

Change-Id: Ib781c6c34097689d21d9e02011e4d74a4a742379
Signed-off-by: Matthias Welwarsky <matthias.welwarsky@sysgo.com>
Reviewed-on: http://openocd.zylin.com/3999
Tested-by: jenkins
Reviewed-by: Tim Newsome <tim@sifive.com>
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>
Reviewed-by: Graham Sanderson <graham.sanderson@gmail.com>
This commit is contained in:
Matthias Welwarsky
2017-02-17 16:16:51 +01:00
committed by Matthias Welwarsky
parent 56568b7996
commit 85ba2dc4c6
4 changed files with 417 additions and 51 deletions
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doc/openocd.texi
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@@ -10199,55 +10199,6 @@ and GDB would require stopping the target to get the prompt back.
Do not use this mode under an IDE like Eclipse as it caches values of
previously shown varibles.
@anchor{usingopenocdsmpwithgdb}
@section Using OpenOCD SMP with GDB
@cindex SMP
For SMP support following GDB serial protocol packet have been defined :
@itemize @bullet
@item j - smp status request
@item J - smp set request
@end itemize
OpenOCD implements :
@itemize @bullet
@item @option{jc} packet for reading core id displayed by
GDB connection. Reply is @option{XXXXXXXX} (8 hex digits giving core id) or
@option{E01} for target not smp.
@item @option{JcXXXXXXXX} (8 hex digits) packet for setting core id displayed at next GDB continue
(core id -1 is reserved for returning to normal resume mode). Reply @option{E01}
for target not smp or @option{OK} on success.
@end itemize
Handling of this packet within GDB can be done :
@itemize @bullet
@item by the creation of an internal variable (i.e @option{_core}) by mean
of function allocate_computed_value allowing following GDB command.
@example
set $_core 1
#Jc01 packet is sent
print $_core
#jc packet is sent and result is affected in $
@end example
@item by the usage of GDB maintenance command as described in following example (2 cpus in SMP with
core id 0 and 1 @pxref{definecputargetsworkinginsmp,,Define CPU targets working in SMP}).
@example
# toggle0 : force display of coreid 0
define toggle0
maint packet Jc0
continue
main packet Jc-1
end
# toggle1 : force display of coreid 1
define toggle1
maint packet Jc1
continue
main packet Jc-1
end
@end example
@end itemize
@section RTOS Support
@cindex RTOS Support
@anchor{gdbrtossupport}
@@ -10278,12 +10229,11 @@ Currently supported rtos's include:
@item @option{mqx}
@item @option{uCOS-III}
@item @option{nuttx}
@item @option{hwthread} (This is not an actual RTOS. @xref{usingopenocdsmpwithgdb,,Using OpenOCD SMP with GDB}.)
@end itemize
@quotation Note
Before an RTOS can be detected, it must export certain symbols; otherwise, it cannot
be used by OpenOCD. Below is a list of the required symbols for each supported RTOS.
@end quotation
@table @code
@item eCos symbols
@@ -10330,6 +10280,72 @@ contrib/rtos-helpers/FreeRTOS-openocd.c
contrib/rtos-helpers/uCOS-III-openocd.c
@end table
@anchor{usingopenocdsmpwithgdb}
@section Using OpenOCD SMP with GDB
@cindex SMP
@cindex RTOS
@cindex hwthread
OpenOCD includes a pseudo RTOS called @emph{hwthread} that presents CPU cores
("hardware threads") in an SMP system as threads to GDB. With this extension,
GDB can be used to inspect the state of an SMP system in a natural way.
After halting the system, using the GDB command @command{info threads} will
list the context of each active CPU core in the system. GDB's @command{thread}
command can be used to switch the view to a different CPU core.
The @command{step} and @command{stepi} commands can be used to step a specific core
while other cores are free-running or remain halted, depending on the
scheduler-locking mode configured in GDB.
@section Legacy SMP core switching support
@quotation Note
This method is deprecated in favor of the @emph{hwthread} pseudo RTOS.
@end quotation
For SMP support following GDB serial protocol packet have been defined :
@itemize @bullet
@item j - smp status request
@item J - smp set request
@end itemize
OpenOCD implements :
@itemize @bullet
@item @option{jc} packet for reading core id displayed by
GDB connection. Reply is @option{XXXXXXXX} (8 hex digits giving core id) or
@option{E01} for target not smp.
@item @option{JcXXXXXXXX} (8 hex digits) packet for setting core id displayed at next GDB continue
(core id -1 is reserved for returning to normal resume mode). Reply @option{E01}
for target not smp or @option{OK} on success.
@end itemize
Handling of this packet within GDB can be done :
@itemize @bullet
@item by the creation of an internal variable (i.e @option{_core}) by mean
of function allocate_computed_value allowing following GDB command.
@example
set $_core 1
#Jc01 packet is sent
print $_core
#jc packet is sent and result is affected in $
@end example
@item by the usage of GDB maintenance command as described in following example (2 cpus in SMP with
core id 0 and 1 @pxref{definecputargetsworkinginsmp,,Define CPU targets working in SMP}).
@example
# toggle0 : force display of coreid 0
define toggle0
maint packet Jc0
continue
main packet Jc-1
end
# toggle1 : force display of coreid 1
define toggle1
maint packet Jc1
continue
main packet Jc-1
end
@end example
@end itemize
@node Tcl Scripting API
@chapter Tcl Scripting API
@cindex Tcl Scripting API