rtos/hwthread: add hardware-thread pseudo rtos

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>

Source: http://openocd.zylin.com/#/c/3999

1 files changed, 67 insertions, 51 deletions

diff --git a/doc/openocd.texi b/doc/openocd.texi
index 5992320..d79664f 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -9858,55 +9858,6 @@ 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}
@@ -9937,12 +9888,11 @@ 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
@@ -9989,6 +9939,72 @@ 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