This commit enables Cortex-M CPU interrupt sub-priorities
and allows the PendSV interrupt to have a priority different
from the default one. Together these two preprocessor
defines can be used to have PendSV always run as the last interrupt
before returning from the interrupt stack back to the user space.
Running PendSV as the last interrupt before returning to the
user space is recommended by ARM, as it increases efficiency.
Furthermore, that change enhances stability a lot with the
new nRF52 SoftDevice support, currently being worked in
PR #9473.
This commit merely enables sub-priorities and a separate
PendSV priority to be used without changing the default
RIOT behaviour.
- The __NOP() that was added in #8518 is now remooved.
- When DBG_STANDBY, DBG_STOP or DBG_SLEEP are set in DBG_CR a hardfault
occurs on wakeup from sleep. This was first diagnosed in #8518. When
enabled, a hardfault occured when returning from a branch to irq_restore()
we avoid the call by inlining the function call. See #11830 for more
details.
This new function allows to jump to another execution
environment (VTOR) located at a certain (aligned) address.
It's used to boot firmwares at another location than
`CPU_FLASH_BASE`.
The user needs to ensure that the CPU using this feature
is able to be initialised at least twice while jumping
to the RIOT `reset_handler_default` function, since it
initialises the CPU again (calls cpu_init()).
Co-authored-by: Kaspar Schleiser <kaspar@schleiser.de>
Refactor cortexm_init to allow bits and pieces of
it to be called separately, while retaining the
current API, too. Needed for non-standard
Cortex-M initialisation, such as with nRF52
SoftDevice.
Instead of using `weak` function definitions, this PR handles
default implementations using `PROVIDES_x` defines, allowing
for cpus/pm realted modules to use their own implementations.
register is deprecated when building C++11 code and removed in C++17,
using it will cause build failures with C++ and -Werror. The register
hint keyword is likely ignored in GCC anyway.
Fixes error on LLVM/Clang:
cpu/cortexm_common/vectors_cortexm.c:287:5: error: non-ASM statement in naked function is not supported
core_panic(PANIC_HARD_FAULT, "HARD FAULT HANDLER");
^
cpu/cortexm_common/include/vectors_cortexm.h:65:46: note: attribute is here
void hard_fault_default(void) __attribute__((naked));
^
1 error generated.
