Update TODO

TODO

@@ -1609,26 +1609,19 @@ o Linux/Cywgin simulation (arch/sim)
   Status:      Open
   Priority:    Low
 
-  Title:       SMP SIMULATION INCOMPLETE
+  Title:       SMP SIMULATION ISSUES
   Description: The configuration has basic support SMP testing.  The simulation
                supports the emulation of multiple CPUs by creating multiple
                pthreads, each run a copy of the simulation in the same process
                address space.
 
-               The simulation SMP implemention is incomplete, however.  Two
+               At present, the SMP simulation is not fully functional:  It does
-               critical SMP functions are not implemented:
+               operate on the simulated CPU threads for a few context switches
+               then fails during a setjmp() operation.  I suspect that this is
+               not an issue with the NuttX SMP logic but more likely some chaos
+               in the pthread controls.
 
-                 - int up_cpu_pause(void)
+               You can enable SMP for ostest configuration by enabling:
-                 - int up_cpu_resume(void)
-
-               These are used to start a new task on a different CPU:  (1)
-               the other CPU is stopped or paused, (2) the OS datastructures
-               for that CPU are modified, then (2) the other CPU is resumed.
-               Unfortunately, I have not yet thought of a way to implement
-               them in the simulation.
-
-               Currently, for example, you can enable SMP for ostest
-               configuration by enabling:
 
                  -# CONFIG_EXPERIMENTAL is not set
                  +CONFIG_EXPERIMENTAL=y
@@ -1638,6 +1631,13 @@ o Linux/Cywgin simulation (arch/sim)
                  +CONFIG_SMP_NCPUS=2
                  +CONFIG_SMP_IDLETHREAD_STACKSIZE=2048
 
+               You also must enable near-realtime-performance otherwise even long
+               timeouts will expire before a CPU thread even has a chance to
+               execute.
+
+                 -# CONFIG_SIM_WALLTIME is not set
+                 +CONFIG_SIM_WALLTIME=y
+
                And you can enable some additional debug output with:
 
                  -# CONFIG_DEBUG_SCHED is not set
@@ -1646,73 +1646,24 @@ o Linux/Cywgin simulation (arch/sim)
                  -# CONFIG_SCHED_INSTRUMENTATION is not set
                  +CONFIG_SCHED_INSTRUMENTATION=y
 
-               The result should be as follows:
+               The NSH configuration can also be forced to run SMP, but
+               suffers from the same quirky behavior.  I can be made
+               reliable if you modify arch/sim/src/up_idle.c so that
+               the IDLE loop only runs for CPU0.  Otherwise, often
+               simuart_post() will be called from CPU1 and it will try
+               to restart NSH on CPU0 and, again, the same quirkiness
+               occurs.
 
-                 - CPU0 initializes and starts CPU1.  CPU1 is running an
+               But for example, this command:
-                   executing the IDLE task.
 
-                   os_start: Entry
+                 nsh> sleep 1 &
-                   os_idletask: CPU1: Beginning Idle Loop
 
-                 - CPU0 brings up the the OS test application on CPU0
+               will execute the sleep command on CPU1 which has worked
+               every time that I have tried it (which is not too many
+               times).
 
-                   os_do_appstart: Starting init thread
+  Status:      Open
-                   CPU0: Start init, TCB@42f490, state=5
+  Priority:    Low, SMP is important, but SMP on the simulator is not
-                   up_unblock_task: Unblocking TCB=42f490
-                   CPU0: Suspend CPU0 IDLE, TCB@42c180, state=4
-                   CPU0: Resume init, TCB@42f490, state=0
-                   up_unblock_task: New Active Task TCB=42f490
-
-                 - OS test runs and performs some basic checks.
-
-                   stdio_test: write fd=1
-                   stdio_test: Standard I/O Check: printf
-                   stdio_test: write fd=2
-                   stdio_test: Standard I/O Check: fprintf to stderr
-                   ostest_main: putenv(Variable1=BadValue3)
-
-                   up_block_task: Blocking TCB=42f490
-                   CPU0: Suspend init, TCB@42f490, state=4
-                   CPU0: Resume CPU0 IDLE, TCB@42c180, state=3
-                   up_block_task: New Active Task TCB=42c180
-                   up_unblock_task: Unblocking TCB=42f490
-                   CPU0: Suspend CPU0 IDLE, TCB@42c180, state=4
-                   CPU0: Resume init, TCB@42f490, state=0
-                   up_unblock_task: New Active Task TCB=42f490
-
-                   ostest_main: setenv(Variable1, GoodValue1, TRUE)
-                   ostest_main: setenv(Variable2, BadValue1, FALSE)
-                   ostest_main: setenv(Variable2, GoodValue2, TRUE)
-                   ostest_main: setenv(Variable3, Variable3, FALSE)
-                   ostest_main: setenv(Variable3, Variable3, FALSE)
-                   show_variable: Variable=Variable1 has value=GoodValue1
-                   show_variable: Variable=Variable2 has value=GoodValue2
-                   show_variable: Variable=Variable3 has value=GoodValue3
-
-                 - Then OS test tries to start the task ostest on CPU1
-
-                   CPU0: Start ostest, TCB@430e90, state=5
-                   up_unblock_task: Unblocking TCB=430e90
-                   CPU1: Suspend CPU1 IDLE, TCB@42c2c0, state=4
-                   CPU0: Resume ostest, TCB@430e90, state=0
-                   ostest_main: Started user_main at PID=4
-
-               There is no failure but, of course, the task on CPU1 does not
-               run, i.e., it does not replace the IDLE task running on CPU1.
-
-               2016-02-16: The NSH configuration can be forced to run, but
-               only if (1) You don't try to execute built-in commands or to
-               execute commands in the background.  Those thoses cases, it
-               will try to start the command on CPU1 and the same problem
-               as for the ostest case occurs.
-
-               Also, for NSH you have to modify arch/sim/src/up_idle.c so
-               that the IDLE loop only runfs for CPU0.  Otherwise, often
-               simuart_post() will be called from CPU1 and it will try to
-               restart NSH on CPU0 and, again, the same problem occurs.
-
-               2016-02-18:  There is an initial implementation based on
-               signals and signal handling, but this is not yet functional.
 
 o ARM (arch/arm/)
   ^^^^^^^^^^^^^^^