Notepads where a feature of RTEMS' tasks that simply functioned in
the same way as POSIX keys or threaded local storage (TLS). They were
introduced well before per task variables, which are also deprecated,
and were barely used in favor of their POSIX alternatives.
In addition to their scarce usage, Notepads took up unnecessary memory.
For each task:
- 16 32-bit integers were allocated.
- A total of 64 bytes per task per thread.
This is especially critical in low memory and safety-critical applications.
They are also defined as uint32_t, and therefore are not guaranteed to
hold a pointer.
Lastly, they are not portable solutions for SMP and uniprocessor systems,
like POSIX keys and TLS.
updates #2493.
Make rtems_initialize_data_structures(),
rtems_initialize_before_drivers() and rtems_initialize_device_drivers()
static. Rename rtems_initialize_start_multitasking() to
rtems_initialize_executive() and call the registered system
initialization handlers in this function. Add system initialization API
available via #include <rtems/sysinit.h>. Update the documentation
accordingly.
This is no functional change, only the method to call the existing
initialization routines changes. Instead of direct function calls a
table of function pointers contained in the new RTEMS system
initialization linker set is used. This table looks like this (the
actual addresses depend on the target).
nm *.exe | grep _Linker | sort
0201a2d0 D _Linker_set__Sysinit_begin
0201a2d0 D _Linker_set__Sysinit_bsp_work_area_initialize
0201a2d4 D _Linker_set__Sysinit_bsp_start
0201a2d8 D _Linker_set__Sysinit_rtems_initialize_data_structures
0201a2dc D _Linker_set__Sysinit_bsp_libc_init
0201a2e0 D _Linker_set__Sysinit_rtems_initialize_before_drivers
0201a2e4 D _Linker_set__Sysinit_bsp_predriver_hook
0201a2e8 D _Linker_set__Sysinit_rtems_initialize_device_drivers
0201a2ec D _Linker_set__Sysinit_bsp_postdriver_hook
0201a2f0 D _Linker_set__Sysinit_end
Add test sptests/spsysinit01.
Update #2408.
Call bsp_work_area_initialize() before bsp_start(). This allows
bsp_start() to use malloc() etc. which is beneficial for systems with a
plug-and-play hardware enumeration.
Update #2408.
Add rtems_interrupt_local_disable|enable() as suggested by Pavel Pisa to
emphasize that interrupts are only disabled on the current processor.
Do not define the rtems_interrupt_disable|enable|flash() macros and
functions on SMP configurations since they don't ensure system wide
mutual exclusion.
Aggregate several critical sections into a bigger one. Sending and
receiving messages is now protected by an ISR lock. Thread dispatching
is only disabled in case a blocking operation is necessary. The message
copy procedure is done inside the critical section (interrupts
disabled). Thus this change may have a negative impact on the interrupt
latency in case very large messages are transferred.
Update #2273.
