In SMP, the system timer is used for timeslicing on auxiliary CPUs,
but the base system timekeeping via _nano_sys_clock_tick_announce() is
still done on CPU0 only (because the framework isn't prepared for
asynchronous notification yet). Skip processing on CPU1+.
Also, due to a hardware interaction* that is difficult to work around,
timer initialization on the auxiliary CPUs is done at the very end of
the CPU bringup, just before the swap into the scheduler. A
smp_timer_init() API has been added for this purpose.
* On ESP-32, enabling the timer seems to result in a near-synchronous
interrupt being delivered despite my best attempts to keep it
masked, then blowing things up because the CPU record isn't set up
to handle it yet.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Now that all the pieces are in place, enable SMP for real:
Initialize the CPU records, launch the CPUs at the end of kernel
initialization, have them wait for a flag to release them into the
scheduler, then enter into the runnable threads via _Swap().
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
The xtensa-asm2 work included a patch that added nano_internal.h
includes in lots of places that needed to have _Swap defined, because
it had to break a cycle and this no longer got pulled in from the arch
headers.
Unfortunately those new includes created new and more amusing cycles
elsewhere which led to breakage on other platforms.
Break out the _Swap definition (only) into a separate header and use
that instead. Cleaner. Seems not to have any more hidden gotchas.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
When using _arch_switch() context switching, the thread return value
is a generic hook and not provided by the architecture.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
The existing __swap() mechanism is too high level for some
applications because of its scheduler-awareness. This introduces a
new _arch_switch() mechanism, which is a simpler primitive that looks
like:
void _arch_switch(void *handle, void **old_handle_out);
The new thread handle (typically just a stack pointer) is specified
explicitly instead of being picked up from the scheduler by
per-architecture code, and on return the "old" thread handle that got
switched out is returned through the pointer.
The new primitive (currently available only on xtensa) is selected
when CONFIG_USE_SWITCH is "y". A new C _Swap() implementation based
on this primitive is then added which operates compatibly.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
K_NUM_PRIORITIES and K_NUM_PRIO_BITMAPS were defined in
nano_internal.h, but used in only a handful of places. Move to
kernel_structs.h (somewhat higher up in the hierarchy) to help with
include file cycle-breaking. Arguably they are a better fit there
anyway.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Rename the nano_internal.h to kernel_internal.h and modify the
header file name accordingly wherever it is used.
Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@intel.com>
