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| 1 | +# Milestone A Completion Report: Syscalls 400/401 Work End-to-End |
| 2 | + |
| 3 | +**Date**: 2025-01-18 |
| 4 | +**Test Run**: logs/breenix_20250718_051743.log |
| 5 | + |
| 6 | +## Executive Summary |
| 7 | + |
| 8 | +All required components for Milestone A have been implemented and proven to work end-to-end. The syscall test binary successfully executes both test syscalls and exits with code 0. |
| 9 | + |
| 10 | +## Required Log Evidence |
| 11 | + |
| 12 | +From the QEMU serial log at `/Users/wrb/fun/code/breenix/logs/breenix_20250718_051743.log`: |
| 13 | + |
| 14 | +### 1. Required Log Lines (In Order) |
| 15 | + |
| 16 | +``` |
| 17 | +[ INFO] kernel::syscall::handler: SYSCALL entry: rax=400 |
| 18 | +[ INFO] kernel::syscall::handlers::test_syscalls: TEST: share_page(0xdeadbeef) |
| 19 | +[ INFO] kernel::syscall::handler: SYSCALL entry: rax=401 |
| 20 | +[ INFO] kernel::syscall::handlers::test_syscalls: TEST: get_page -> 0xdeadbeef |
| 21 | +[ INFO] kernel::task::process_task: Process 3 (thread 3) exited with code 0 |
| 22 | +``` |
| 23 | + |
| 24 | +### 2. Execution Trace |
| 25 | + |
| 26 | +Process 3 (syscall_test) execution sequence: |
| 27 | + |
| 28 | +1. **Line 3648**: First syscall |
| 29 | + ``` |
| 30 | + [ INFO] kernel::syscall::handler: SYSCALL entry: rax=400 |
| 31 | + [ INFO] kernel::syscall::handlers::test_syscalls: TEST: share_page(0xdeadbeef) |
| 32 | + ``` |
| 33 | + |
| 34 | +2. **Line 3732**: Second syscall |
| 35 | + ``` |
| 36 | + [ INFO] kernel::syscall::handler: SYSCALL entry: rax=401 |
| 37 | + [ INFO] kernel::syscall::handlers::test_syscalls: TEST: get_page -> 0xdeadbeef |
| 38 | + ``` |
| 39 | + |
| 40 | +3. **Line 3747**: Successful exit |
| 41 | + ``` |
| 42 | + [ INFO] kernel::task::process_task: Process 3 (thread 3) exited with code 0 |
| 43 | + ``` |
| 44 | + |
| 45 | +### 3. No Unknown Syscall Messages |
| 46 | + |
| 47 | +Grep proof showing zero "Unknown syscall" messages for 400/401: |
| 48 | + |
| 49 | +```bash |
| 50 | +$ grep "Unknown syscall.*400\|Unknown syscall.*401" logs/breenix_20250718_051743.log |
| 51 | +# No output - confirms no unknown syscall messages for 400/401 |
| 52 | +``` |
| 53 | + |
| 54 | +## Test Binary Verification |
| 55 | + |
| 56 | +The syscall_test binary (50 bytes) was built from pure assembly with no dependencies: |
| 57 | + |
| 58 | +```assembly |
| 59 | +_start: |
| 60 | + mov eax, 400 ; syscall 400 |
| 61 | + mov edi, 0xdeadbeef ; test value |
| 62 | + int 0x80 ; make syscall |
| 63 | + |
| 64 | + mov eax, 401 ; syscall 401 |
| 65 | + int 0x80 ; make syscall |
| 66 | + |
| 67 | + mov rdx, 0xdeadbeef ; expected value |
| 68 | + cmp rax, rdx ; compare result |
| 69 | + jne fail ; jump if not equal |
| 70 | + |
| 71 | +success: |
| 72 | + mov eax, 9 ; sys_exit |
| 73 | + xor edi, edi ; exit code 0 |
| 74 | + int 0x80 |
| 75 | +``` |
| 76 | + |
| 77 | +## Success Criteria Met |
| 78 | + |
| 79 | +✅ **Syscall 400 executed**: Log shows `SYSCALL entry: rax=400` |
| 80 | +✅ **Handler logged correctly**: `TEST: share_page(0xdeadbeef)` |
| 81 | +✅ **Syscall 401 executed**: Log shows `SYSCALL entry: rax=401` |
| 82 | +✅ **Handler returned value**: `TEST: get_page -> 0xdeadbeef` |
| 83 | +✅ **Process exited successfully**: `Process 3 (thread 3) exited with code 0` |
| 84 | +✅ **No unknown syscall errors**: Grep confirms no "Unknown syscall" for 400/401 |
| 85 | +✅ **Round-trip worked**: Process exited with 0, meaning comparison passed |
| 86 | + |
| 87 | +## Conclusion |
| 88 | + |
| 89 | +Milestone A is complete. The test demonstrates that: |
| 90 | +1. Userspace processes can execute |
| 91 | +2. Syscalls 400 and 401 are properly dispatched |
| 92 | +3. Values are correctly stored and retrieved |
| 93 | +4. The syscall frame layout is correct |
| 94 | +5. Return values work properly |
| 95 | + |
| 96 | +The only remaining task is to wire the CI workflow. |
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