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NuttX TODO List (Last updated February 1, 2012)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This file summarizes known NuttX bugs, limitations, inconsistencies with
standards, things that could be improved, and ideas for enhancements.
(1) Memory Managment (mm/)
(2) USB (drivers/usbdev, drivers/usbhost)
(8) Libraries (lib/)
(10) File system/Generic drivers (fs/, drivers/)
(1) Graphics subystem (graphics/)
(5) Linux/Cywgin simulation (arch/sim)
(5) ARM (arch/arm/)
(2) ARM/i.MX (arch/arm/src/imx/)
(6) ARM/LPC214x (arch/arm/src/lpc214x/)
(3) ARM/LM3S6918 (arch/arm/src/lm3s/)
(1) Hitachi/Renesas SH-1 (arch/sh/src/sh1)
apps/
(5) Network Utilities (apps/netutils/)
(5) NuttShell (NSH) (apps/nshlib)
(1) System libraries apps/system (apps/system)
(5) Other Applications & Tests (apps/examples/)
Title: CHILD PTHREAD TERMINATION
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.
Title: MULTIPLE ATEXIT() FUNCTIONS
Description: atexit() supports registration of only single function called on
exit(). It should support multiple functions registered by atexit()
or onexit() and these should be called in reverse order of
registration when the task exits.
Priority: Low
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.
Update: A simple but usable version of waitpid() has been included.
This version is not compliant with all specifications and can be
enabled with CONFIG_SCHED_WAITPID.
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)
Title: TICKLESS OS
Description: On a side note, I have thought about a tick-less timer for the OS
for a long time. Basically we could replace the periodic system
timer interrupt with a one-shot interval timer programmed for the
next interesting event time. That is one way to both reduce the
timer interrupt overhead and also to increase the accuracy of
delays.
Current timer processing is in sched/sched_processtimer.c:
1) Calls clock_timer() which just increments a counter (the system
timer -- basically "up-time"). This is only used when code asks
for the current time. In a tickless OS, some substitute answer
for the question "What time is it?" would need to be developed.
You could use an RTC? Or maybe logic that gets the time until the
next interval expiration and computes the current time. The
solution is not too difficult, but depends on a hardware solution.
2) Calls wd_timer() which handles the link list of ordered events:
Each timer event is saved with the delta time to the next event
in the list. So an interval timer would be perfect to implement this.
3) sched_process_timeslice(). Then there is round-robin time-slicing.
o On-demand paging (sched/)
^^^^^^^^^^^^^^^^^^^^^^^^^
Title: ON-DEMAND PAGE INCOMPLETE
Description: On-demand paging has recently been incorporated into the RTOS.
The design of this feature is described here:
http://www.nuttx.org/NuttXDemandPaging.html.
As of this writing, the basic feature implementation is
complete and much of the logic has been verified. The test
harness for the feature exists only for the NXP LPC3131 (see
configs/ea3131/pgnsh and locked directories). There are
some limitations of this testing so I still cannot say that
the feature is fully functional.
Description: get_environ_ptr() (sched/sched_getenvironptr.c) is not implemented.
The representation of the the environment strings selected for
NutX is not compatible with the operation. Some significant
re-design would be required to implement this funcion and that
effort is thought to be not worth the result.
Status: Open
Priority: Low -- There is no plan to implement this.
Description: timer_getoverrun() (sched/timer_getoverrun.c) is not implemented.
Status: Open
Priority: Low -- There is no plan to implement this.
Title: FREE MEMORY ON TASK EXIT
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.
There would be complexities with this implementation as well
because often one task allocates memory and then passes the
memory to another: The task that "owns" the memory may not
be the same as the task that allocated the memory.
Status: Open
Priority: Medium/Low, a good feature to prevent memory leaks but would
have negative impact on memory usage and code size.
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.
Description: sig_notify() logic does not support SIGEV_THREAD; structure
struct sigevent does not provide required members sigev_notify_function
or sigev_notify_attributes.
Status: Low, there are alternative designs. However, these features
are required by the POSIX standard.
Priority: Low for now
Description: pthread_cancel(): Should implement cancellation points and
pthread_testcancel()
Status: Open
Priority: Low, probably not that useful
Title: USE OF SIZE_T IN NEW OPERATOR
Description: The argument of the 'new' operators should take a type of
size_t (see libxx/libxx_new.cxx and libxx/libxx_newa.cxx). But
size_t has an unknown underlying. In the nuttx sys/types.h
header file, size_t is typed as uint32_t (which is determined by
architecture-specific logic). But the C++ compiler may believe
that size_t is of a different type resulting in compilation errors
in the operator. Using the underlying integer type Instead of
size_t seems to resolve the compilation issues.
Status: Kind of open. There is a workaround. Setting CONFIG_CXX_NEWLONG=y
will define the operators with argument of type unsigned long;
Setting CONFIG_CXX_NEWLONG=n will define the operators with argument
of type unsigned int. But this is pretty ugly! A better solution
would be to get ahold of the compilers definition of size_t.
Priority: Low.
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().
Description: Not all of the NXFLAT test under apps/examples/nxflat are working.
Most simply do not compile yet. tests/mutex runs okay but
outputs garbage on completion.
Status: Open
Priority: High
Description: The ARM up_getpicbase() does not seem to work. This means
the some features like wdog's might not work in NXFLAT modules.
Status: Open
Priority: Medium-High
Description: At present, all .rodata must be put into RAM. There is a
tentative design change that might allow .rodata to be placed
in FLASH (see Documentation/NuttXNxFlat.html).
Status: Open
Priority: Medium
Title: GOT-RELATIVE FUNCTION POINTERS
Description: If the function pointer to a statically defined function is
taken, then GCC generates a relocation that cannot be handled
by NXFLAT. There is a solution described in Documentataion/NuttXNxFlat.html,
by that would require a compiler change (which we want to avoid).
The simple workaround is to make such functions global in scope.
Status: Open
Priority: Low (probably will not fix)
Title: USE A HASH INSTEAD OF A STRING IN SYMBOL TABLES
Description: In the NXFLAT symbol tables... Using a 32-bit hash value instead
of a string to identify a symbol should result in a smaller footprint.
Status: Open
Priority: Low
Title: WINDOWS-BASED TOOLCHAIN BUILD
Description: Windows build issue. Some of the configurations that use NXFLAT have
the linker script specified like this:
NXFLATLDFLAGS2 = $(NXFLATLDFLAGS1) -T$(TOPDIR)/binfmt/libnxflat/gnu-nxflat.ld -no-check-sections
That will not work for windows-based tools because they require Windows
style paths. The solution is to do something like this:
if ($(WINTOOL)y)
NXFLATLDSCRIPT=${cygpath -w $(TOPDIR)/binfmt/libnxflat/gnu-nxflat.ld}
else
NXFLATLDSCRIPT=$(TOPDIR)/binfmt/libnxflat/gnu-nxflat.ld
endif
Then use
NXFLATLDFLAGS2 = $(NXFLATLDFLAGS1) -T"$(NXFLATLDSCRIPT)" -no-check-sections
Status: Open
Priority: There are too many references like the above. They will have
to get fixed as needed for Windows native tool builds.
Description: Should implement SOCK_RAW, SOCK_PACKET
Status: Open
Priority: Low
Tile: MULTIPLE NETWORK INTERFACE SUPPORT
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.
Title: SENTDO() AND MULTIPLE NETWORK INTERFACE SUPPORT
Description: sendto() 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: IPv6 support is incomplete. Adam Dunkels has recently announced
IPv6 support for uIP (currently only as part of Contiki). Those
changes need to be ported to NuttX.
Title: LISTENING FOR UDP BROADCASTS
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
Title: STANDARDIZE ETHERNET DRIVER STATISTICS
Description: Need to standardize collection of statistics from network
drivers. apps/nshlib ifconfig command should present
Title: CONCURRENT TCP SEND OPERATIONS
Description: At present, there cannot be two concurrent active TCP send
operations in progress using the same socket. This is because
the uIP ACK logic will support only one transfer at a time. The
solution is simple: A mutex will be needed to make sure that each
send that is started is able to be the exclusive sender until all of
the data to be sent has been ACKed.
Status: Open. There is some temporary logic to apps/nshlib that does
this same fix and that temporary logic should be removed when
send() is fixed.
Priority: Medium-Low. This is an important issue for applications that
send on the same TCP socket from multiple threads.
Description: TCP supports read-ahead buffering to handle the receipt of
TCP/IP packets when there is no read() in place. Should such
capability be useful for UDP? PRO: Would reduce packet loss
and enable support for poll()/select(). CON: UDP is inherently
lossy so why waste memory footprint?
Status: Open
Priority: Medium
Title: NO POLL/SELECT ON UDP SOCKETS
Description: poll()/select() is not implemented for UDP sockets because they do
do not support read-ahead buffering. Therefore, there is never
a case where you can read from a UDP socket without blocking.
Status: Open, depends on UDP read-ahead support
Priority: Medium
Title: POLL/SELECT ON TCP SOCKETS NEEDS READ-AHEAD
Description: poll()/select() only works for availability of buffered TCP
read data (when read-ahead is enabled). The way writing is
handled in uIP, all sockets must wait when send and cannot
be notifiied when they can send without waiting.
Status: Open, probably will not be fixed.
Priority: Medium... this does effect porting of applications that expect
different behavior from poll()/select()
Title: SOCKETS DO NOT ALWAYS SUPPORT O_NONBLOCK
Description: sockets do not support all modes for O_NONBLOCK. Sockets
support only (1) TCP/IP non-blocking read operations when read-ahead
buffering is enabled, and (2) TCP/IP accept() operations when TCP/IP
connection backlog is enabled.
Status: Open
Priority: Low.
Title: UNFINISHED CRYSTALLAN CS89X0 DRIVER
Description: I started coding a CrystalLan CS89x0 driver (drivers/net/cs89x0.c),
but never finished it.
Status: Open
Priority: Low unless you need it.
Title: UNFINISHED ENC28J60 DRIVER
Description: So far, I have not come up with a usable hardware platform to
verify the ENC28J60 Ethernet driver (drivers/net/enc28j60.c).
So it is untested.
Status: Open
Priority: Low unless you need it.
Description: Support for client-side IGMPv2 multicast has been added but not yet
tested (because I don't have a proper environment for multicast testing).
There are most likely errors that need to be fixed at least in the
receipt of multicast packets.
In addition, an ethernet driver that needs to work with the IGMP logic
will have to include additional support for multicast MAC address tables.
Status: Open
Priority: Low unless you need it.
Title: INTERFACES TO LEAVE/JOIN IGMP MULTICAST GROUP
Description: The interfaces used to leave/join IGMP multicast groups is non-standard.
RFC3678 (IGMPv3) suggests ioctl() commands to do this (SIOCSIPMSFILTER) but
also status that those APIs are historic. NuttX implements these ioctl
commands, but is non-standard because: (1) It does not support IGMPv3, and
(2) it looks up drivers by their device name (eg., "eth0") vs IP address.
Linux uses setsockopt() to control multicast group membership using the
IP_ADD_MEMBERSHIP and IP_DROP_MEMBERSHIP options. It also looks up drivers
using IP addresses (It would require additional logic in NuttX to look up
drivers by IP address). See http://tldp.org/HOWTO/Multicast-HOWTO-6.html
Status: Open
Priority: Medium. All standards compatibility is important to NuttX. However, most
the mechanism for leaving and joining groups is hidden behind a wrapper
function so that little of this incompatibilities need be exposed.
Title: CONFIGURATIONS WITH TINY MTUS
Description: Many configurations have the MTU (CONFIG_NET_BUFSIZE) set to very small
numbers, less then the minimum MTU size that must be supported -- 576.
This can cause problems in some networks: CONFIG_NET_BUFSIZE should
be set to at least 576 in all defconfig files.
The symptoms of using very small MTU sizes can be very strange. With
Ubuntu 9.x and vsFtpd was that the total packet size did *not match* the
packet size in the IP header. This then caused a TCP checksum failure
and the packet was rejected.
Status: Open
Priority: Low... fix defconfig files as necessary.
o USB (drivers/usbdev, drivers/usbhost)
Title: USB STORAGE DRIVER DELAYS
Description: There is a workaround for a bug in drivers/usbdev/usbdev_storage.c.
that involves delays. This needs to be redesigned to eliminate these delays.
Status: Open
Priority: Medium
Title: RTL8187 DRIVER IS UNFINISHED
Description: misc/drivers/usbhost_rtl8187.c is a work in progress. There is no RTL8187
driver available yet. That is a work in progress it was abandoned because
it depends on having an 802.11g stack.
Status: Open
Priority: Low (Unless you need RTL8187 support).
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
Description: Need some minimal termios support... at a minimum, enough to
switch between raw and "normal" modes to support behavior like
that needed for readline().
Status: Open
Priority: Low
Description: strftime() and other timing functions do not handle days of the week.
Status: Open
Priority: Low
Description: There is an issue with the way that getopt() handles errors that
return '?'.
1. Does getopt() reset its global variables after returning '?' so
that it can be re-used? That would be required to support where
the caller terminates parsing before reaching the last parameter.
2. Or is the client expected to continue parsing after getopt()
returns '?' and parse until the final parameter?
The current getopt() implementation only supports #2.
Status: Open
Priority: Low
Description: Not implemented: ferror() and clearerr()
Status: Open
Priority: Low
Title: CONCURRENT STREAM READ/WRITE
Description: NuttX only supports a single file pointer so reads and writes
must be from the same position. This prohibits implementation
of behavior like that required for fopen() with the "a+" mode.
According to the fopen man page:
"a+ Open for reading and appending (writing at end of file).
The file is created if it does not exist. The initial file
position for reading is at the beginning of the file, but
output is always appended to the end of the file."
At present, the single NuttX file pointer is positioned to the
end of the file for both reading and writing.
Status: Open
Priority: Medium. This kind of operation is probably not very common in
deeply embedded systems but is required by standards.
Title: DIVIDE BY ZERO
Description: This is bug 3468949 on the SourceForge website (submitted by
Philipp Klaus Krause):
"lib_strtod.c does contain divisions by zero in lines 70 and 96.
AFAIK, unlike for Java, division by zero is not a reliable way to
get infinity in C. AFAIK compilers are allowed e.g. give a compile-
time error, and some, such as sdcc, do. AFAIK, C implementations
are not even required to support infinity. In C99 the macro isinf()
could replace the first use of division by zero. Unfortunately, the
macro INFINITY from math.h probably can't replce the second division
by zero, since it will result in a compile-time diagnostic, if the
implementation does not support infinity."
Status: Open
Priority:
Title: OLD dtoa NEEDS TO BE UPDATED
Description: This implementation of dtoa in lib/stdio is old and will not
work with some newer compilers. See
http://patrakov.blogspot.com/2009/03/dont-use-old-dtoac.html
Status: Open
Priority: ??
o File system / Generic drivers (fs/, drivers/)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
NOTE: The NXFFS file system has its own TODO list at nuttx/fs/nxffs/README.txt
Description: At present, the CAN driver does not support the poll() method.
Status: Open
Priority: Low
Title: REMOVING PIPES AND FIFOS
Description: There is no way to remove a FIFO or PIPE created in the
psuedo filesystem. Once created, they persist indefinitely
and cannot be unlinked. This is actually a more generic
issue: unlink does not work for anything in the psuedo-
filesystem.
Status: Open, but partially resolved: pipe buffer is at least freed
when there are not open references to the pipe/FIFO.
Description: The ROMFS file system does not verify checksums on either
volume header on on the individual files.
Status: Open
Priority: Low. I have mixed feelings about if NuttX should pay a
performance penalty for better data integrity.
Title: SPI-BASED SD MULTIPLE BLOCK TRANSFERS
Description: The simple SPI based MMCS/SD driver in fs/mmcsd does not
yet handle multiple block transfers.
Status: Open
Priority: Medium-Low
Title: READ-AHEAD/WRITE BUFFER UNTESTED
Description: Block driver read-ahead buffer and write buffer support is
implemented but not yet tested.
Status: Open
Priority: Low
Title: SDIO-BASED SD READ-AHEAD/WRITE BUFFERING INCOMPLETE
Description: The drivers/mmcsd/mmcsd_sdio.c driver has hooks in place to
support read-ahead buffering and write buffering, but the logic
is incomplete and untested.
Status: Open
Priority: Low
Title: ENC29J60 DRIVER UNTESTED
Description: ENC28J60 driver is complete, but untested (I still haven't got
a good ENC28J60 test platform).
Status: Open
Priority: Low
Title: SERIAL DRIVER DOES NOT RETURN WHEN SIGNAL RECEIVED
Description: The serial driver (drivers/serial) should return with an
error and errno=EINTR when an interrupt is received. However,
the serial driver just continues waiting:
static void uart_takesem(FAR sem_t *sem)
{
while (sem_wait(sem) != 0)
{
ASSERT(*get_errno_ptr() == EINTR);
}
}
Status: Open
Priority Medium
Description: All drivers that support the poll method should also report
POLLHUP event when the driver is closedd.
Status: Open
Priority: Medium-Low
o Graphics subystem (graphics/)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Description: Testing of all APIs is not complete. See
http://nuttx.sourceforge.net/NXGraphicsSubsystem.html#testcoverage
Status: Open
Priority: Medium
Title: ITALIC FONTS / NEGATIVE FONT OFFSETS
Description: Font metric structure (in include/nuttx/nx/nxfont.h) should allow
negative X offsets. Negative x-offsets are necessary for certain
glyphs (and is very common in italic fonts).
For example Eth, icircumflex, idieresis, and oslash should have
offset=1 in the 40x49b font (these missing negative offsets are
NOTE'ed in the font header files).
Status: Open. The problem is that the x-offset is an unsigned bitfield
in the current structure.
Priority: Low.
Title: P-CODES IN MEMORY UNTESTED
Description: Need APIs to verify execution of P-Code from memory buffer.
Status: Open
Title: SMALLER LOADER AND OBJECT FORMAT
Description: Loader and object format may be too large for some small
memory systems. Consider ways to reduce memory footprint.
o Documentation (Documentation/)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Title: DOCUMENT APIS USABLE FROM INTERRUPT HANDLERS
Description: Need to document which APIs can be used in interrupt
handlers (like mq_send and sem_post) and which cannot.
Status: Open
Priority: Low
Title: DEPENDENCIES IN THE BOARD DIRECTORY
Description: Dependencies do not work correctly under configs/<board>/src
UPDATE: Added the following to each arch/*/src/Makefile:
PHONY: board/libboard$(LIBEXT)
However, I have not confirmed that this a full-proof fix in
all cases -- still under test (thanks to Mike Smith).
Priority: Medium (maybe higher for z80 target)
Title: NUTTX CONFIGURATION TOOL
Description: Need a NuttX configuration tool. The number of configuration
settings has become quite large and difficult to manage manually.
Status: Open
Priority: Medium-low
Description: At present, NuttX builds only under Linux or Cygwin.
Investigate the possibility of a native Windows build using
something like the GNUWin32 tools (coreutils+make+grep+sed+uname).
Status: Open
Priority: Low
Title: WINDOWS DEPENDENCY GENERATION
Description: Dependency generation is currently disabled when a Windows native
toolchain is used. I think that the only issue is that all of the
Windows dependencies needed to be quoted in the Make.dep files.
Status: Open
Priority: Low -- unless some dependency-related build issues is discovered.
Title: SETENV.H
Description: Logic in most setenv.sh files can create the following problem
on many platforms:
$ . ./setenv.sh
basename: invalid option -- 'b'
Try `basename --help' for more information.
The problem is that $0 is the current running shell which may include
a dash in front:
$ echo $0
-bash
But often is just /bin/bash (and the problem does not occur. The fix
is:
-if [ "$(basename $0)" = "setenv.sh" ]; then
+if [ "$_" = "$0" ] ; then
Status: Open
Priority: Low. Use of setenv.sh is optional and most platforms do not have
this problem. Scripts will be fixed one-at-a-time as is appropropriate.
Description: The top-level Makefile 'export' target that will bundle up all of the
NuttX libraries, header files, and the startup object into an export-able
tarball. This target uses the tools/mkexport.sh script. Issues:
1. This script assumes the host archiver ar may not be appropriate for
non-GCC toolchains
2. For the kernel build, the user libraries should be built into some
libuser.a. The list of user libraries would have to accepted with
some new argument, perhaps -u.
Status: Open
Priority: Low.
Title: KERNEL BUILD MODE ISSUES
Description: In the kernel build mode (where NuttX is built as a monlithic
kernel and user code must trap into the protected kernel via
syscalls), the single user mode cannot be supported. In this
built configuration, only the multiple user mode can be supported
with the NX server residing inside of the kernel space. In
this case, most of the user end functions in graphics/nxmu
must be moved to lib/nx and those functions must be built into
libuser.a to be linked with the user-space code.
Status: Open
Priority: Low -- the kernel build configuration is not fully fielded
yet.
o Linux/Cywgin simulation (arch/sim)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Description: The simulated serial driver has some odd behavior. It
will stall for a long time on reads when the C stdio buffers are
being refilled. This only effects the behavior of things like
fgetc(). Workaround: Set CONFIG_STDIO_BUFFER_SIZE=0, suppressing
all C buffered I/O.
Status: Open
Priority: Low (because the simulator is only a test/development platform)
Title: SIMULATOR NETWORKING SUPPORT
Description: I never did get networking to work on the sim Linux target. On Linux,
it tries to use the tap device (/dev/net/tun) to emulate an Ethernet
NIC, but I never got it correctly integrated with the NuttX networking.
NOTE: On Cygwin, the build uses the Cygwin WPCAP library and is, at
least, partially functional (it has never been rigorously tested).
Status: Open
Priority: Low (unless you want to test networking features on the simulation).
Title: ROUND-ROBIN SCHEDULING IN THE SIMULATOR
Description: Since the simulation is not pre-emptible, you can't use round-robin
scheduling (no time slicing). Currently, the timer interrupts are
"faked" during IDLE loop processing and, as a result, there is no
task pre-emption because there are no asynchrous events. This could
probably be fixed if the "timer interrupt" were driver by Linux
signals. NOTE: You would also have to implement irqsave() and
irqrestore() to block and (conditionally) unblock the signal.
Status: Open
Priority: Low
Title: NSH ISSUES ON THE SIMULATOR
Descripion: The NSH example has some odd behaviors. Mult-tasking -- for example,
execution of commands in background -- does not work normally. This
is due to the fact that NSH uses the system standard input for the
console. This means that the simulation is actually "frozen" all of
the time when NSH is waiting for input and background commands never
get the chance to run.
Status: Open
Priority: This will not be fixed. This is the normal behavior in the current
design of the simulator. "Real" platforms will behave correctly
because NSH will "sleep" when it waits for console inpu and other
tasks can run freely.
Description: In the NSH example, the host HOST echoes each command so after you
you enter a command, the command is repeated on the next line. This
is an artifact of the simulator only.
Status: Open
Priority: This will not be fixed. This is the normal behavior in the current
design of the simulator. "Real" platforms will behave correctly.
Title: IMPROVED ARM INTERRUPT HANDLING
Description: ARM interrupt handling performance could be improved in some
ways. One easy way is to use a pointer to the context save
see handling of 'current_regs" in arch/arm/src/armv7-m/* for
Title: IMPROVED ARM INTERRUPT HANDLING
Description: The ARM and Cortex-M3 interrupt handlers restores all regisers
upon return. This could be improved as well: If there is no
context switch, then the static registers need not be restored
because they will not be modified by the called C code.
(see arch/sh/src/sh1/sh1_vector.S for example)
Status: Open
Priority: Low
Description: The Cortex-M3 user context switch logic uses SVCall instructions.
This user context switching time could be improved by eliminating
the SVCalls and developing assembly language implementations
of the context save and restore logic.
Also, because interrupts are always disabled when the SVCall is
executed, the SVC goes to the hard fault handler where it must
be handled as a special case. I recall seeing some controls
somewhere that will allow to suppress one hard fault. I don't
recall the control, but something like this should be used before
executing the SVCall so that it vectors directly to the SVC
handler.
Status: Open
Priority: Low
Title: ARM INTERRUPTS AND USER MODE
Description: The ARM interrupt handling (arch/arm/src/arm/up_vectors.S) returns
using 'ldmia sp, {r0-r15}^' My understanding is that this works
fine because everything is in kernel-mode. In an operating model
where applications run in user mode and interrupts/traps run in
kernel-mode, I think that there is a problem with this. This would
like be a problem, for example, if for a kernel build where NuttX
is built as a monolithic, protected kernel and user mode programs
trap into the kernel.
Priority: Low until I get around to implementng security or kernel mode for
the ARM platform.
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Title: CORTEX-M3 STACK OVERFLOW
Description: There is bit bit logic inf up_fullcontextrestore() that executes on
return from interrupts (and other context switches) that looks like:
ldr r1, [r0, #(4*REG_CPSR)] /* Fetch the stored CPSR value */
msr cpsr, r1 /* Set the CPSR */
/* Now recover r0 and r1 */
ldr r0, [sp]
ldr r1, [sp, #4]
add sp, sp, #(2*4)
/* Then return to the address at the stop of the stack,
* destroying the stack frame
*/
ldr pc, [sp], #4
Under conditions of excessivley high interrupt conditions, many
nested interrupts can oocur just after the 'msr cpsr' instruction.
At that time, there are 4 bytes on the stack and, with each
interrupt, the stack pointer may increment and possibly overflow.
This can happen only under conditions of continuous interrupts.
See this email thread: http://tech.groups.yahoo.com/group/nuttx/message/1261
On suggested change is:
ldr r1, [r0, #(4*REG_CPSR)] /* Fetch the stored CPSR value */
msr spsr_cxsf, r1 /* Set the CPSR */
ldmia r0, {r0-r15}^
But this has not been proven to be a solution.
Status: Open
Priority: Low. The conditions of continous interrupts is really the problem.
If your design needs continous interrupts like this, please try
the above change and, please, submit a patch with the working fix.
o ARM/C5471 (arch/arm/src/c5471/)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Description: UART re-configuration is untested and conditionally compiled out.
Status: Open
Priority: Medium. ttyS1 is not configured, but not used; ttyS0 is configured
by the bootloader
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
Title: USB DEVICE DRIVER UNTESTED
Description: A USB device controller driver was added but has never been tested.
Status: Open
Priority: Medium
Title: FRAMEBUFFER DRIVER UNTESTED
Description: A framebuffer "driver" was added, however, it remains untested.
Status: Open
Priority: Medium
Description: In order to use the framebuffer "driver" additional video encoder
logic is required to setupt composite video output or to interface
with an LCD.
Status: Open
Priority: Medium (high if you need to use the framebuffer driver)
Description: The basic port of the i.MX1 architecuture was never finished. The port
is incomplete (as of this writing, is still lacks a timer, interrupt
decoding, USB, network) and untested.
Title: SPI METHODS ARE NOT THREAD SAFE
Description: SPI methods are not thread safe. Needs a semaphore to protect from re-entrancy.
Status: Open
Priority: Medium -- Will be very high if you do SPI access from multiple threads.
o ARM/LPC17xx (arch/arm/src/lpc17xx/)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Description: USB DMA not fully implemented. Partial logic is in place but it is
fragmentary and bogus. (Leveraged from the lpc214x)
Description: a) At present the SSP driver is polled. Should it be interrupt driven?
Look at arch/arm/src/imx/imx_spi.c -- that is a good example of an
interrupt driven SPI driver. Should be very easy to part that architecture
to the LPC.
b) See other SSP (SPI) driver issues listed under ARM/LPC214x. The LPC17xx
driver is a port of the LPC214x driver and probably has the same issues.
b) Other SSP driver improvements: Add support for multiple devices on the
SSP bus, use DMA data transfers
Status: Open
Priority: Medium
Title: NOKIA LCD DRIVER NONFUNCTIONAL
Description: An LCD driver for the Olimex LPC1766STK has been developed. However, that
driver is not yet functional on the board: The backlight comes on, but
nothing is visible on the display.
Status: Open
Priority: Medium-Low (unless you need the display on the LPC1766STK!)
o ARM/LPC214x (arch/arm/src/lpc214x/)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Description: Should use Vector Interrupts
Status: Open
Priority: Low
Description: USB DMA not fully implemented. Partial logic is in place but it is
fragmentary and bogus.
Title: USB SERIAL DRIVER REPORTS WRONG ERROR
Description: USB Serial Driver reports wrong error when opened before the
USB is connected (reports EBADF instead of ENOTCONN)
Status: Open
Priority: Low
Description: At present the SPI driver is polled. Should it be interrupt driven?
Look at arch/arm/src/imx/imx_spi.c -- that is a good example of an
interrupt driven SPI driver. Should be very easy to part that architecture
to the LPC.
Title: SPI METHODS ARE NOT THREAD SAFE
Description: SPI methods are not thread safe. Needs a semaphore to protect from re-entrancy.
Status: Open
Priority: Medium -- Will be very high if you do SPI access from multiple threads.
Description: At present the SPI driver is polled -AND- there is a rather large, arbitrary,
delay in one of the block access routines. The purpose of the delay is to
avoid a race conditions. This begs for a re-design -OR- at a minimum, some
optimiation of the delay time.
Status: Open