This commit resolves issue #620:
Remove CONFIG_CAN_PASS_STRUCTS #620
The configuration option CONFIG_CAN_PASS_STRUCTS was added many years ago to support an old version of the SDCC compiler. That compiler is currently used only with the Z80 and Z180 targets. The limitation of that old compiler was that it could not pass structures or unions as either inputs or outputs. For example:
#ifdef CONFIG_CAN_PASS_STRUCTS
struct mallinfo mallinfo(void);
#else
int mallinfo(FAR struct mallinfo *info);
#endif
And even leads to violation of a few POSIX interfaces like:
#ifdef CONFIG_CAN_PASS_STRUCTS
int sigqueue(int pid, int signo, union sigval value);
#else
int sigqueue(int pid, int signo, FAR void *sival_ptr);
#endif
This breaks the 1st INVIOLABLES rule:
Strict POSIX compliance
-----------------------
o Strict conformance to the portable standard OS interface as defined at
OpenGroup.org.
o A deeply embedded system requires some special support. Special
support must be minimized.
o The portable interface must never be compromised only for the sake of
expediency.
o Expediency or even improved performance are not justifications for
violation of the strict POSIX interface
Also, it appears that the current SDCC compilers have resolve this issue and so, perhaps, this is no longer a problem: z88dk/z88dk#1132
NOTE: This commit cannot pass the PR checks because it depends on matching changes to the apps/ directory.
Squashed commit of the following:
mm/iob: The IOB available notifier is now just a wrapper around the common signal notifier.
sched/signal: Add a generic signal notification facility.
sched/signal/sig_evthread.c: More trivial naming changes.
sched/signal: Rename nxsig_notification() to nxsig_evthread() to make forthcoming naming additions more consistent.
Replace all calls to sigqueue() in the OS proper with calls to nxsig_queue() to avoid accessing the errno variable.
sched/signal: Add nxsig_queue() which is functionally equivalent to sigqueue() except that it does not modify the errno variable.
This is analogous to similar renaming that was done previously for semaphores.
Squashed commit of the following:
sched/signal: Fix a few compile warnings introduced by naming changes.
sched/signal: Rename all private, internal signl functions to use the nxsig_ prefix.
sched/signal: Rename sig_removependingsignal, sig_unmaskpendingsignal, and sig_mqnotempty to nxsig_remove_pendingsignal, nxsig_unmask_pendingsignal, and nxsig_mqnotempty to make it clear that these are OS internal interfaces.
sched/signal: Rename sig_findaction and sig_lowest to nxsig_find_action and nxsig_lowest to make it clear that these are OS internal interfaces.
sched/signal: Rename sig_allocatepingsigaction and sig_deliver to nxsig_alloc_pendingsigaction and nxsig_deliver to make it clear that these are OS internal interfaces.
sched/signal: Rename sig_cleanup, sig_release, sig_releasependingaction, and sig_releasependingsignal to nxsig_cleanup, nxsig_release, nxsig_release_pendingaction, and nxsig_release_pendingsignal to make it clear that these are OS internal interfaces.
sched/signal: Rename sig_tcbdispatch and sig_dispatch to nxsig_tcbdispatch and nxsig_dispatch to make it clear that these are OS internal interfaces.
sched/signal: Rename sig_releaseaction and sig_pendingset to nxsig_release_action and nxsig_pendingset to make it clear that these are OS internal interfaces.
sched/signal: Rename sig_initialize and sig_allocateactionblock to nxsig_initialize and nxsig_alloc_actionblock to make it clear that these are OS internal interfaces.
