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Gregory Nutt 2017-04-12 07:28:11 -06:00
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@ -1,4 +1,4 @@
NuttX TODO List (Last updated April 10, 2017)
NuttX TODO List (Last updated April 12, 2017)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This file summarizes known NuttX bugs, limitations, inconsistencies with
@ -9,7 +9,7 @@ issues related to each board port.
nuttx/:
(10) Task/Scheduler (sched/)
(11) Task/Scheduler (sched/)
(1) SMP
(1) Memory Management (mm/)
(0) Power Management (drivers/pm)
@ -186,6 +186,47 @@ o Task/Scheduler (sched/)
Priority: Low. Things are just the way that we want them for the way
that NuttX is used today.
Title: INTERNAL VERSIONS OF USER FUNCTIONS
Description: The internal NuttX logic uses the same interfaces as does
the application. That sometime produces a problem because
there is "overloaded" functionality in those user interfaces
that are not desireable.
For example, having cancellation points hidden inside of the
OS can cause non-cancellation point interfaces to behave
strangely. There was a change recently in pthread_cond_wait()
and pthread_cond_timedwait() recently to effectively disable
the cancellation point behavior of sem_init(). This was
accomplished with two functions: pthread_disable_cancel()
and pthread_enable_cancel()
Here is another issue:  Internal OS functions should not set
errno and should never have to look at the errno value to
determine the cause of the failure.  The errno is provided
for compatibility with POSIX application interface
requirements and really doesn't need to be used within the
OS.
Both of these could be fixed if there were special internal
versions these functions.  For example, there could be a an
nx_sem_wait() that does all of the same things as sem_wait()
was does not create a cancellation point and does not set
the errno value on failures.
Everything inside the OS would use nx_sem_wait().
Applications would call sem_wait() which would just be a
wrapper around nx_sem_wait() that adds the cancellation point
and that sets the errno value on failures.
Changes like that could clean up some of this internal
craziness.  The condition variable change described above is
really a "bandaid" to handle the case that sem_wait() is a
cancellation point.
Status: Open
Priority: Low. Things are working OK the way they are. But the design
could be improved and made a little more efficient with this
change.
o SMP
^^^