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feat(kernel): Implement RFC-00C8 concurrent fault isolation test#503

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t81dev wants to merge 4 commits intomainfrom
rfc-00c8-concurrent-fault-isolation-8260938961588559707
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feat(kernel): Implement RFC-00C8 concurrent fault isolation test#503
t81dev wants to merge 4 commits intomainfrom
rfc-00c8-concurrent-fault-isolation-8260938961588559707

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@t81dev t81dev commented Mar 25, 2026

This pull request introduces the RFC-00C8 Phase 19 test to the Axion EL0 cooperative scheduler.

The test specifically exercises the fs_sched_fault_handler() path where a thread is marked Faulted, and instead of blindly returning to EL1, the scheduler finds the next Runnable thread, installs its L3 context, and context-switches to it.

Thread F (tid=7) is loaded from LBA 12 (el0_fault_test.bin) and configured to fault immediately.
Thread E (tid=6) is loaded from LBA 11 (el0_device_filter_test.bin) and set to do a normal WaitForDevice and exit.

We verify that the kGovThreadFault event is captured for Thread F and the kGovTimerDeviceWake event is captured for Thread E. This closes the last untested code path in the fault handler, demonstrating that an isolated EL0 thread fault does not crash its sibling threads.


PR created automatically by Jules for task 8260938961588559707 started by @t81dev

Implements the RFC-00C8 concurrent fault isolation test to validate
the context-switch path in `fs_sched_fault_handler()`. This proves
that a thread faulting immediately upon start does not crash the system
and the scheduler correctly switches to the next runnable thread.

Includes updates to:
- `canon_exec_loader.cpp`: Implements `canon_concurrent_fault_load_and_run`
- `qemu_slice6_cpp_bridge.cpp`: Wires up the execution and logs
- `qemu-boot.yml`: Adds the CI gate test string
- `PROGRESS.md`: Documentation for RFC-00C8

Co-authored-by: t81dev <207451414+t81dev@users.noreply.github.com>
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google-labs-jules bot and others added 3 commits March 25, 2026 10:17
Implements the RFC-00C8 concurrent fault isolation test to validate
the context-switch path in `fs_sched_fault_handler()`. This proves
that a thread faulting immediately upon start does not crash the system
and the scheduler correctly switches to the next runnable thread.

Includes updates to:
- `canon_exec_loader.cpp`: Implements `canon_concurrent_fault_load_and_run`
- `qemu_slice6_cpp_bridge.cpp`: Wires up the execution and logs
- `qemu-boot.yml`: Adds the CI gate test string
- `PROGRESS.md`: Documentation for RFC-00C8

Also fixes:
- `README.md` missing Determinism Surface Registry boundary language.
- `aarch64_trap_entry.cpp` missing `extern "C"` on `axion_exception_vector_base` causing linkage failures on Clang for Arm64.

Co-authored-by: t81dev <207451414+t81dev@users.noreply.github.com>
Moved `extern "C"` declaration of `axion_exception_vector_base`
outside of the function scope so it compiles properly on clang-18
for arm64.

Co-authored-by: t81dev <207451414+t81dev@users.noreply.github.com>
Moved `extern "C"` declaration of `axion_exception_vector_base`
outside of the function scope so it compiles properly on clang-18
for arm64. Also moved it outside the namespace to avoid any name
mangling problems during the linking phase.

Co-authored-by: t81dev <207451414+t81dev@users.noreply.github.com>
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