hujun260 opened a new pull request, #17963:
URL: https://github.com/apache/nuttx/pull/17963
## Summary
Add AMP (Asymmetric MultiProcessing) mode support with GIC SGI (Software
Generated Interrupts) for inter-core communication. In AMP mode, multiple
independent OS instances run on different CPU cores, and each core needs SGI
capability for inter-core synchronization. This change enables SGI usage in AMP
configurations and ensures GIC CPU0-specific initialization occurs only once
per system, supporting both SMP and AMP architectures.
## Changes
- **arch/arm/src/armv7-r/gic.h**:
- Remove CONFIG_SMP conditional in arm_cpu_sgi() function
- Always use SGI_TGTFILTER_LIST targeting mode for SGI dispatch
- Enable SGI-based inter-core interrupts for both SMP and AMP modes
- **arch/arm/src/goldfish/goldfish_irq.c**:
- Add CPU0 check using sched_getcpu() before calling arm_gic0_initialize()
- Ensure arm_gic0_initialize() executes only on CPU0 during system startup
- Prevents duplicate GIC CPU0-specific initialization in AMP mode
- **arch/arm/src/imx6/imx_irq.c**:
- Add CPU0 check using sched_getcpu() before calling arm_gic0_initialize()
- Ensure arm_gic0_initialize() executes only on CPU0 during system startup
- Prevents duplicate GIC CPU0-specific initialization in AMP mode
- **arch/arm64/src/common/arm64_gicv2.c**:
- Add CPU0 check using sched_getcpu() before calling arm_gic0_initialize()
- Ensure arm_gic0_initialize() executes only on CPU0 during system startup
- Maintains consistent initialization behavior across ARM64 GIC
configurations
## Benefits & Technical Details
- **AMP support**: Enables inter-core SGI communication in AMP
configurations where each core runs independently
- **Correct initialization**: CPU0-only initialization prevents race
conditions and duplicate setup in multi-core boot
- **Architecture consistency**: Both ARM and ARM64 platforms now use same
SGI and initialization pattern
- **Flexible target mode**: Using SGI_TGTFILTER_LIST allows targeting
specific CPU cores in both SMP and AMP modes
- **Boot robustness**: sched_getcpu() check ensures safe execution during
system initialization
## Testing
- Verified SGI signals can be sent between CPU cores in both SMP and AMP
modes
- Confirmed arm_gic0_initialize() executes exactly once on CPU0 in
multi-core startup
- Tested GIC functionality with both single and multi-core configurations
- Validated Goldfish and IMX6 platforms with AMP mode enabled
- Confirmed ARM64 GICv2 initialization works correctly with CPU0 guard
## Impact
- **Functionality**: Enables AMP mode support with inter-core communication
via SGI
- **Compatibility**: Fully backward compatible with existing SMP
configurations
- **Scope**: Affects ARM (ARMv7-R, ARMv8-R), Goldfish, IMX6, and ARM64 GIC
implementations
- **Architecture**: Multi-core systems using Asymmetric MultiProcessing mode
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