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Description: Anti-aliasing is implemented along the horizontal raster line
with fractional pixels at the ends of each line. There is no
accounting for fractional pixels in the vertical direction.
As a result lines closer to vertical receive better anti-
aliasing than lines closer to horizontal.
Status: Open
Priority: Low, not a serious issue but worth noting. There is no plan
to change this behavior.
Title: REMOVE SINGLE USER MODE
Description: NX graphics supports two modes: A simple single user mode and
more complex multi-user mode selected with CONFIG_NX_MULTIUSER=y.
In this configuration, an application can start the NX server
with boardctrl(BOARDIOC_NX_START); After that, all graphic
interactions are via a thin layer in libnx/. The OS
interface is only via messages sent and received using POSIX
message queues. So this is good code and respects all of the
POSIX interfacing rules. Hence, it works well in all build
modes (FLAT, PROTECTED, and KERNEL builds).
But without CONFIG_NX_MULTIUSER, the single user applications
violate all of the rules and calls internal NX functions
directly. This includes all calls to internal OSfunctions
with names like, nx_open, up_fbinitialize, board_lcd_*, and
others. This is a violation of interfacing standard in all
cases and can only be made to work in the FLAT build mode.
The single user mode does have some desirable properties: It
is lighter weight and so more suitable for very resource limited
platforms. But I think that in the long run the only reasonable
solution is to eliminate the single user mode and provide only
the multi-user mode with the message queue interface.
Status: Open
Priority: Low-Medium, not a serious issue but worth noting. Single user
mode is a blemish on the OS and not compatible with the RTOS
roadmap. But neither is there any critical necessity to
remove the offending code immediately. Be aware: If you use
the single user mode, it will be yanked out from under your
feet in the not-so-distant future.
Gregory Nutt
committed
Title: WIDE-FOUNT SUPPORT
Description: Wide fonts are not currently supported by the NuttX graphics sub-
system. There is some discussion here:
https://groups.yahoo.com/neo/groups/nuttx/conversations/topics/3507
http://www.nuttx.org/doku.php?id=wiki:graphics:wide-fonts
Status: Open
Priority: Low for many, but I imagine higher in countries that use wide fonts
Title: MAKE EXPORT LIMITATIONS
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: CONTROL-C CAN BREAK DEPENDENCIES
Description: If you control C out of a make, then there are things that can go
wrong. For one, you can break the dependencies in this scenario:
- The build in a given directory begins with all of the compilations.
On terminal, this the long phase with CC: on each line. As each
.o file is created, it is timestamped with the current time.
- The dependencies on each .o are such that the C file will be re-
compile if the .o file is OLDER that the corresponding .a archive
file.
- The compilation phase is followed by a single, relatively short
AR: phase that adds each of the file to the .a archive file. As
each file is added to archive, the timestamp of the of archive is
updated to the current time. After the first .o file has been
added, then archive file will have a newer timestamp than any of
the newly compiled .o file.
- If the user aborts with control-C during this AR: phase, then we
are left with: (1) not all of the files have bee added to the
archive, and (2) the archive file has a newer timestamp than any
of the .o file.
So when the make is restarted after a control, the dependencies will
see that the .a archive file has the newer time stamp and those .o
file will never be added to the archive until the directory is cleaned
or some other dependency changes.
Gregory Nutt
committed
NOTE: This may not really be an issue because the the timestamp on
libapps.a is not really used but rather the timestamp on an empty
file:
.built: $(OBJS)
$(call ARCHIVE, $(BIN), $(OBJS))
$(Q) touch $@
UPDATE: But there is another way that Control-C can break dependencies:
Gregory Nutt
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If you control-c out of the make during the apps/ part of the build,
the archive at apps/libapps.a is deleted (but all of the .built files
remain in place). You can see this in the make outout, for example:
CC: ieee802154_getsaddr.c
make[2]: *** [Makefile:104: ieee802154_getsaddr.o] Interrupt
make: *** Deleting file '../apps/libapps.a'
When you rebuild the system, the first file archived will recreate
libapps.a and set the timestamp to the current time. Then, none of
the other object files will be added to the archive because they are
all older.. or, more correctly, none of the other object files will
be addred because .built files remained and say that there is no
need to update the libapps.a file.
Gregory Nutt
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The typical symptom of such an issue is a link time error like:
LD: nuttx libsched.a(os_bringup.o): In function `os_bringup':
os_bringup.c:(.text+0x34): undefined reference to `nsh_main'
This is becuase the libapps.a file was deleted and an new empty
libapps.a file was created (which the object containing nsh_main()).
The object containing nsh_main() will not be added because the
.built file exists and says that there is not need to add the
nsh_main() object to libapps.a.
The work-around for now is:
$ make apps_distclean
One solution to this might be to making the special target
.PRECIOUS depend on apps/libapps.a. Then if make receives a
signal, it will not delete apps/libapps.a. This would have to
be done in all Makefiles.
Status Open
Priority: Medium-High. It is a rare event that control-C happens at just the
point in time. However, when it does occur the resulting code may
have binary incompatiblies in the code taken from the out-of-sync
archives and cost a lot of debug time before you realize the issue.
The first stated problem is not really an issue: There is already
the spurious .built file that should handle the described case:
If you control-C out of the build then the timestamp on the .built
file will not be updated and the archiving should be okay on the
next build.
A work-around for the second stated problem is to do 'make clean'
if you ever decide to control-C out of a make and see that the
libapps.a file was deleted.
Gregory Nutt
committed
UPDATE: This is a potential fix for the second problem in place
in in all Makefiles under apps/. This fix adds
to all Makefiles. It has not yet been confirmed that this fix
eliminates the dependency issue or not.
Title: DEPENDENCIES OBJECT SUB-DIRECTORIES
Descripton: Dependencies do not work in directories that keep binaries in
a sub-directory like bin, ubin, kbin.
Status: Open
Priority: Medium-Low. Definitely a build issue once in awhile.
o Other drivers (drivers/)
^^^^^^^^^^^^^^^^^^^^^^^^
o Linux/Cywgin simulation (arch/sim)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Title: SIMULATOR HAS NO INTERRUPTS (NON-PREMPTIBLE)
Description: The current simulator implementation is has no interrupts and, hence,
is non-preemptible. Also, without simulated interrupt, there can
be no high-fidelity simulated device drivers.
Currently, all timing and serial input is simulated in the IDLE loop:
When nothing is going on in the simulation, the IDLE loop runs and
fakes timer and UART events.
Status: Open
Priority: Low, unless there is a need for developing a higher fidelity simulation
I have been thinking about how to implement simulated interrupts in
the simulation. I think a solution would work like this:
http://www.nuttx.org/doku.php?id=wiki:nxinternal:simulator
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 asynchronous events. This could
probably be fixed if the "timer interrupt" were driver by Linux
signals. NOTE: You would also have to implement up_irq_save() and
up_irq_restore() to block and (conditionally) unblock the signal.
Gregory Nutt
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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.
At present, the SMP simulation is not fully functional: It does
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. I have seen similar such strange behavior
other times that I have tried to use setjmp/longmp from a signal
handler! Like when I tried to implement simulated interrupts
using signals.
Apparently, if longjmp is invoked from the context of a signal
handler, the result is undefined:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1318.htm
Gregory Nutt
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Gregory Nutt
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-# CONFIG_EXPERIMENTAL is not set
+CONFIG_EXPERIMENTAL=y
+CONFIG_SPINLOCK=y
+CONFIG_SMP=y
+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
Gregory Nutt
committed
And you can enable some additional debug output with:
-# CONFIG_DEBUG_SCHED is not set
+CONFIG_DEBUG_SCHED=y
-# CONFIG_SCHED_INSTRUMENTATION is not set
+CONFIG_SCHED_INSTRUMENTATION=y
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.
But for example, this command:
nsh> sleep 1 &
will execute the sleep command on CPU1 which has worked
every time that I have tried it (which is not too many
times).
Status: Open
Priority: Low, SMP is important, but SMP on the simulator is not
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
area in g_current_regs instead of using up_copystate so much.
This approach is already implemented for the ARM Cortex-M0,
Cortex-M3, Cortex-M4, and Cortex-A5 families. But still needs
to be back-ported to the ARM7 and ARM9 (which are nearly
identical to the Cortex-A5 in this regard). The change is
*very* simple for this architecture, but not implemented.
Status: Open. But complete on all ARM platforms except ARM7 and ARM9.
Priority: Low.
Title: IMPROVED ARM INTERRUPT HANDLING
Description: The ARM and Cortex-M3 interrupt handlers restores all registers
upon return. This could be improved as well: If there is no
context switch, then the static registers need not be restored
(see arch/renesas/src/sh1/sh1_vector.S for example)
Title: CORTEX-M3 STACK OVERFLOW
Gregory Nutt
committed
Description: There is bit bit logic in 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 excessively high interrupt conditions, many
nested interrupts can occur 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: https://groups.yahoo.com/neo/groups/nuttx/conversations/messages/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.
UPDATE: Other ARM architectures have a similar issue.
Priority: Low. The conditions of continuous interrupts is really the problem.
If your design needs continuous interrupts like this, please try
the above change and, please, submit a patch with the working fix.
patacongo
committed
Title: IMPROVED TASK START-UP AND SYSCALL RETURN
Description: Couldn't up_start_task and up_start_pthread syscalls be
eliminated. Wouldn't this work to get us from kernel-
to user-mode with a system trap:
lda r13, #address
str rn, [r13]
msr spsr_SVC, rm
ld r13,{r15}^
Would also need to set r13_USER and r14_USER. For new
SYS_context_switch... couldn't we do he same thing?
Also... System calls use traps to get from user- to kernel-
mode to perform OS services. That is necessary to get from
user- to kernel-mode. But then another trap is used to get
from kernel- back to user-mode. It seems like this second
trap should be unnecessary. We should be able to do the
same kind of logic to do this.
Status: Open
Priority: Low-ish, but a good opportunity for performance improvement.
Title: UNVERIFIED THTTPD FEATURES
Gregory Nutt
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Description: Not all THTTPD features/options have been verified. In
particular, there is no test case of a CGI program receiving
POST input. Only the configuration of apps/examples/thttpd
has been tested.
Status: Open
Priority: Medium
Description: The NSH network management logic has general applicability
but is currently useful only because it is embedded in the NSH
module. It should be moved to apps/system or, better,
apps/netutils.
Status: Open
Priority: Low
o NuttShell (NSH) (apps/nshlib)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Title: IFCONFIG AND MULTIPLE NETWORK INTERFACES
Description: The ifconfig command will not behave correctly if an interface
is provided and there are multiple interfaces. It should only
show status for the single interface on the command line; it will
still show status for all interfaces.
Status: Open
Priority: Low
o System libraries apps/system (apps/system)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Title: READLINE IMPLEMENTATION
Description: readline implementation does not use C-buffered I/O, but rather
talks to serial driver directly via read(). It includes VT-100
specific editing commands. A more generic readline() should be
implemented using termios' tcsetattr() to put the serial driver
into a "raw" mode.
Status: Open
Priority: Low (unless you are using mixed C-buffered I/O with readline and
fgetc, for example).
Gregory Nutt
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o Modbus (apps/modbus)
^^^^^^^^^^^^^^^^^^^^
Title: MODBUS NOT USABLE WITH USB SERIAL
Description: Modbus can be used with USB serial, however, if the USB
serial connectiont is lost, Modbus will hang in an infinite
loop.
This is a problem in the handling of select() and read()
and could probabaly resolved by studying the Modbus error
handling.
A more USB-friendly solution would be to: (1) Re-connect and
(2) re-open the serial drviers. That is what is done is NSH.
When the serial USB device is removed, this terminates the
session and NSH will then try to re-open the USB device. See
the function nsh_waitusbready() in the file
apps/nshlib/nsh_usbconsole.c. When the USB serial is
reconnected the open() in the function will succeed and a new
session will be started.
Status: Open
Priority: Low. This is really an enhancement request: Modbus was never
designed to work with removable serial devices.
o Pascal Add-On (pcode/)
^^^^^^^^^^^^^^^^^^^^^^
Title: P-CODES IN MEMORY UNTESTED
Description: Need APIs to verify execution of P-Code from memory buffer.
Status: Open
Priority: Low
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.
Status: Open
Priority: Medium
Title: PDBG
Gregory Nutt
committed
Description: Move the pascal p-code debugger into the NuttX apps/ tree
where it can be used from the NSH command line.
Status: Open
Priority: Low
o Other Applications & Tests (apps/examples/)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Title: EXAMPLES/PIPE ON CYGWIN
Description: The redirection test (part of examples/pipe) terminates
incorrectly on the Cywgin-based simulation platform (but works
fine on the Linux-based simulation platform).
Status: Open
Priority: Low
Title: EXAMPLES/SENDMAIL UNTESTED
Description: examples/sendmail is untested on the target (it has been tested
on the host, but not on the target).
Title: EXAMPLES/NX FONT CACHING
Description: The font caching logic in examples/nx is incomplete. Fonts are
added to the cache, but never removed. When the cache is full
it stops rendering. This is not a problem for the examples/nx
code because it uses so few fonts, but if the logic were
leveraged for more general purposes, it would be a problem.
Update: see examples/nxtext for some improved font cache handling.
Update: The NXTERM font cache has been generalized and is now
offered as the standard, common font cache for all applications.
both the nx and nxtext examples should be modified to use this
common font cache. See interfaces defined in nxfonts.h.
Status: Open
Priority: Low. This is not really a problem because examples/nx works
fine with its bogus font caching.
Title: EXAMPLES/NXTEXT ARTIFACTS
Description: examples/nxtext. Artifacts when the pop-up window is opened.
There are some artifacts that appear in the upper left hand
corner. These seems to be related to window creation. At
tiny artifact would not be surprising (the initial window
should like at (0,0) and be of size (1,1)), but sometimes
the artifact is larger.
Status: Open
Priority: Medium.