pussuw opened a new pull request, #14329:
URL: https://github.com/apache/nuttx/pull/14329
## Summary
Implement hartid<->cpuid mapping for RISC-V. This is necessary for some
platforms which cannot use 1:1 mapping between logical and physical CPU /
core IDs. One example is MPFS where hart0 cannot be used for NuttX SMP as
it is a less capable "monitor" core (E51) compared to the application
cores hart1...3 (E54).
Why not just use a generic offset then? We also need the physical hart ID
for many things:
- Communication between harts (IPI)
- External interrupt acknowledgment (interrupt claim for specific CPU)
- Communication to SBI
Thus, create procedures that can do this translation:
- The default mapping is still logical=physical.
- Another flavor is to use the existing CONFIG_ARCH_RV_HARTID_BASE config
variable, which is just a simple offset
- The final flavor is to overload hartid<->cpuid on a per chip basis (no
example for this is provided yet)
To achieve this, a generic "up_this_cpu()" macro is introduced to the common
architecture layer. This macro
is activated by setting ARCH_HAVE_CPUID_MAPPING=y after which the arch/chip
must implement the CPUID mapping
function.
By default, the CPUID mapping is still logical=physical.
## Impact
Decouples physical and logical CPU ids from each other. Only the RISC-V
platform is affected.
## Testing
- rv-virt:knsh64
- rv-virt:ksmp64
- rv-virt:nsh64
- rv-virt:smp64
ostest pass
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