This commit addresses the following issues:
1. Add a new Kconfig configuration for specifying Dual-redundant Core
Lock-step (DCLS) processor topology.
2. Register initialisation is only required when Dual-redundant Core
Lock-step (DCLS) is implemented in hardware. This initialisation is
required on DCLS only because the architectural registers are in an
indeterminate state after reset and therefore the initial register
state of the two parallel executing cores are not guaranteed to be
identical, which can lead to DCCM detecting it as a hardware fault.
A conditional compilation check for this hardware configuration
using the newly added CONFIG_CPU_HAS_DCLS flag has been added.
3. The existing CPU register initialisation code did not take into
account the banked registers for every execution mode. The new
implementation ensures that all architectural registers of every
mode are initialised.
4. Add VFP register initialisation for when floating-point support is
enabled and the core is configured in DCLS topology. This
initialisation sequence is required for the same reason given in
the first issue.
5. Add provision for platform-specific initialisation on Cortex-R
using PLATFORM_SPECIFIC_INIT config and z_platform_init function.
6. Remove seemingly pointless and inadequately defined STACK_MARGIN.
Not only does it violate the 8-byte stack alignment rule, it does
not provide any form of real stack protection.
Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
bc8524eb82