nuttx/TODO

NuttX TODO List (Last updated January 6, 2008)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  (6)  Task/Scheduler (sched/)
  (1)  Dynamic loader (N/A)
  (2)  Memory Managment (mm/)
  (1)  Signals (sched/, arch/)
  (1)  pthreads (sched/)
  (1)  C++ Support
  (10) Network (net/, netutils/)
  (2)  USB (drivers/usbdev)
  (3)  Libraries (lib/)
  (2)  File system (fs/, drivers/)
  (1)  Pascal add-on (pcode/)
  (2)  Documentation (Documentation/)
  (3)  Build system
  (0)  Applications & Tests (examples/)
  (1)  ARM (arch/arm/)
  (0)  ARM/C5471 (arch/arm/src/c5471/)
  (1)  ARM/DM320 (arch/arm/src/dm320/)
  (2)  ARM/LPC214x (arch/arm/src/lpc214x/)
  (4)  pjrc-8052 / MCS51 (arch/pjrc-8051/)
  (2)  z80 (arch/z80/)

o Task/Scheduler (sched/)
  ^^^^^^^^^^^^^^^^^^^^^^^

  Description: When a tasks exits, shouldn't all of its child pthreads also be
               terminated?
  Status:      Open
  Priority:    Medium, required for good emulation of process/pthread model.

  Description: atexit() supports registration of one function called on exit().
               Should task_delete() also cause atexit() function to be called?
  Status:      Open
  Priority:    Low, task_delete() is non-standard and its behavior is
               unspecified.

  Description: Implement sys/mman.h and functions
  Status:      Open
  Priority:    Low

  Description: Implement sys/wait.h and functions.  Consider implementing wait,
               waitpid, waitid.  At present, a parent has no information about
               child tasks.
  Status:      Open
  Priority:    Low

  Description: Implement priority inheritance
  Status:      Open
  Priority:    Medium, this is a good feature for realtime systems.

  Description: Several APIs do not set errno.  Need to review all APIs.
  Status:      Open
  Priority:    Medium, required for standard compliance (but makes the
               code bigger)

o Dynamic Loader
  ^^^^^^^^^^^^^^

  Description: At some point in the future, I intend to port the XFLAT
               dynamic loader into NuttX (see http://xflat.sourceforge.net/).
               That would allow NuttX to dynamically load and link
               external code in a mounted filesystem.
  Status:      Open
  Priority:    Low, Nice feature and I might do it someday

o Memory Managment (mm/)
  ^^^^^^^^^^^^^^^^^^^^^^

  Description: Add an option to free all memory allocated by a task when the
               task exits. This is probably not be worth the overhead for a
               deeply embedded system.
  Status:      Open
  Priority:    Medium/Low, a good feature to prevent memory leaks but would
               have negative impact on memory usage and code size.

  Description: Current logic adapts size_t for 16-bit address machines vs.
               32-bit address machines.  But a small memory option should also
               be provided so that the small offset option can be used with
               32-bit machines that have small RAM memories (like the lpc2148)
  Status:      Open
  Priority:    High, a good feature enhancement.

o Signals (sched/, arch/)
  ^^^^^^^^^^^^^^^^^^^^^^^

  Description: 'Standard' signals and signal actions are not supported.
               (e.g., SIGINT, SIGCHLD, SIGSEGV, etc).
  Status:      Open
  Priority:    Low, required by standards but not so critical for an
               embedded system.

o pthreads (sched/)
  ^^^^^^^^^^^^^^^^^

  Description: pthread_cancel():  Should implement cancellation points and
               pthread_testcancel()
  Status:      Open
  Priority:    Low, probably not that useful

o C++ Support
  ^^^^^^^^^^^

  Description: Need to call static constructors
  Status:      Open
  Priority:    Low, depends on toolchain.  Call to gcc's built-in static
               constructor logic will probably have to be performed by
               user logic in user_start().

o Network (net/, netutils/)
  ^^^^^^^^^^^^^^^^^^^^^^^^^

  Description: Several of the netutils/ apps are untested.  These include
               uIP's netutils/smtp, dhcpd, resolv, webclient.  Only minimal
               testing of the others has been performed.
  Status:      Open
  Priority:    Medium, Important but not core NuttX functionality

  Description: Should implement SOCK_RAW, SOCK_PACKET
  Status:      Open
  Priority:    Low

  Description: uIP polling issues / Multiple network interface support:
               (1) Current logic will not support multiple ethernet drivers.
                  Each driver should poll on TCP connections connect on the
                  network supported by the driver; UDP polling should respond
                  with TX data only if the UDP packet is intended for the
                  the network supported by the driver.
               (2) If there were multiple drivers, polling would occur at
                  double the rate.  Fix by using bound IP address in TCP
                  connection (lipaddr) and verifying that it is in the subnet
                  served by the driver.
  Status:      Open
  Priority:    Medium, The feature is not important, but it is important
               for NuttX to resolve the architectural issues.

  Description: Sendoto() and multiple network interface support:
               When polled, would have to assure that the destination IP
               is on the subnet served by the polling driver.
  Status:      Open
  Priority:    Medium, The feature is not important, but it is important
               for NuttX to resolve the architectural issues.

  Description: uIP/Socket callback logic is not thread safe. This means that
               a socket cannot be used concurrently by two threads.  Minimal
               fix:  Add mutex to support exclusion for protection.
  Status:      Open
  Priority:    Low.  The currently socket design cannot be use concurrently
               by threads with out a major redesign.  The feature is not
               of great value since the use model for multi-thread sockets
               is not common.  Adding mutex support would only mask the
               underlying issue.

  Description: IPv6 support is incomplete
  Status:      Open
  Priority:    Medium

  Description: Incoming UDP broadcast should only be accepted if listening on
               INADDR_ANY(?)
  Status:      Open
  Priority:    Low

  Description: Read-ahead buffers capture incoming TCP data when no user
               thread is recv-ing the data.  Should add some driver call to
               support throttling; when there is no listener for new data, the
               driver should be throttled.  Perhaps the driver should disable
               RX interrupts when throttled and re-anable on each poll time.
               recvfrom would, of course, have to un-throttle.
  Status:      Open
  Priority:    Medium

  Description: Need to standardize collection of statistics from network
               drivers.  examples/nsh ifconfig command should present
               statistics.
  Status:      Open
  Priority:    Low

  Description: Outgoing packets are dropped and overwritten by ARP packets
               if the destination IP has not been mapped to a MAC.  Could
               improve send() performance by explicitly performing ARP before
               sending the packet.
  Status:      Open
  Priority:    Medium

o USB (drivers/usbdev)
  ^^^^^^^^^^^^^^^^^^^^

  Description: Implement USB device support
  Status:      Open
  Priority:    High

  Description: Implement USB bulk / serial device support
  Status:      Open
  Priority:    High

o Libraries (lib/)
  ^^^^^^^^^^^^^^^^

  Description: sscanf() and lib_vsprintf() do not support floating point
               values.
  Status:      Open
  Priority:    Low

  Description: The definition of environ in stdlib.h is bogus and will not
               work as it should.  This is because the underlying
               representation of the environment is not an arry of pointers.
  Status:      Open
  Priority:    Medium

  Description: There are two different copies of getenv():  One in
               sched/env_getenv.c and one in lib/lib_getenv().  Keep one.
  Status:      Open
  Priority:    Low

o File system (fs/, drivers/)
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^

  Description: Add chmod(), truncate().
  Status:      Open
  Priority:    Low

  Description: FAT32: long file names
  Status:      Open
  Priority:    Medium

o Pascal Add-On (pcode/)
  ^^^^^^^^^^^^^^^^^^^^^^

  Description: Need a test to verify execution of P-Code from files.
               Need APIs to verify execution of P-Code from memory buffer.
  Status:      Open
  Priority:    Medium

o Documentation (Documentation/)
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  Description: Document driver/ logic
  Status:      Open
  Priority:    Low

  Description: Document C-library APIs
  Status:      Open
  Priority:    Low

o Build system
  ^^^^^^^^^^^^

  Description: Some names under arch are still incorrect.  These should be
               processor architecture names:  pjrc-8051 should be 805x
  Status:      Open
  Priority:    Low

  Description: configs/pjrc-8051 should be configs/pjrc-87c52
  Status:      Open
  Priority:    Low

  Description: Dependencies do not work correctly under configs/<board>/src
               (same as arch/<arch>/src/board).  Seems to be worse using SDCC.
  Status:      Open
  Priority:    Medium (maybe higher for z80 target)

o Applications & Tests (examples/)
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

o ARM (arch/arm/)
  ^^^^^^^^^^^^^^^

  Description: Add option to use a separate stack for interrupt handling.  At
               present, each interrupt executes on top of the user stack
               allocation making each user stack allocation larger than needed.
  Status:      Open
  Priority:    Medim

o ARM/C5471 (arch/arm/src/c5471/)
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

o ARM/DM320 (arch/arm/src/dm320/)
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  Description: config/ntos-dm320: It seems that when a lot of debug statements
               are added, the system no longer boots.  This is suspected to be
               a stack problem: Making the stack bigger or removing arrays on
               the stack seems to fix the problem (might also be the
               bootloader overwriting memory)
  Status:      Open
  Priority:    Mediam

o ARM/LPC214x (arch/arm/src/lpc214x/)
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  Description: Finish bringup
  Status:      Open
  Priority:    High

  Description: Add MMC and USB support
  Status:      Open
  Priority:    Mediam

o pjrc-8052 / MCS51 (arch/pjrc-8051/)
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

  Description: Current status:
               - Basic OS task management seems OK
               - Fails when interrupts enabled.  The stack pointer is around
                 0x6e before the failure occurs.  It looks like some issue
                 when the stack pointer moves from the directly to indirectly
                 addressable region (0x80 boundary).
               - Work on the 8052 is temporarily on hold
  Status:      Open
  Priority:    Low, 8051 is a tough platform because of the tiny stack.

  Description: Use timer 0 as system timer.  Timer 2 is needed for second UART.
               Logic is implemented, but there needs to be a system
               configuration to change the ticks-per-second value to match the
               timer interrupt rate
  Status:      Open
  Priority:    Low

  Description: During build, there are several integer overflows reported:
               sched/gmtime_r.c aroud lines 184 and 185
               sched/clock_initialize.c at line 107
               sched/pthread_create.c at 330
               examples/ostest/barrier.c around lines 53 and 74
               examples/ostest/sighand.c at 225 and 244
               driver/serial.c in usleep calls around 347 and 354
  Status:      Open
  Priority:    Medium

  Description  Global data is not being initialized.  Logic like that of SDCCs
               crt0*.s needs to be incorporated into the system boot logic
  Status:      Open
  Priority:    Low -- only because there as so many other issues with 8051

o z80 (arch/z80)
 ^^^^^^^^^^^^^^^

  Description: The Has the same problems with interger overflow during compilation
               as described for pjrc-8051.  At typical cause is code like
               usleep(500*1000) which exceeds the range of a 16-bit integer
  Status:      See pjrc-8051
  Priority:    See pjrc-8051

  Description: The simulated serial console (configs/z80sim/src/z80_serial.c +
               driver/serial.c) does not work.  This is because there are
               no interrupts in the simulation so there is never any serial
               traffic.
  Status:      Open
  Priority:    Low -- the simulated console is not critical path and the designs
               to solve the problem are complex.