Claude
37b1527279
Captain Bob, 2026-11-12: "Build an appropriate test harness! Love the idea." The kernel had no tests below the boots, so defects QEMU cannot provoke could not be tested first. Plan: docs/v4.0.0/plans/2026-11-12-kernel-host-tests.md. kernel/tests/: one host program per kernel source, built with that source as it is, the kernel's flags (-std=c99 -Wall -Wextra -Werror), and fakes -- the console captured line by line, a deterministic RNG that can fail, and a RAM disk whose reads, writes or flushes fail at chosen 1 KiB blocks. make -C kernel/tests test runs them; SRC_<test>= runs a test against other code, which is how a test is seen to fail against the code before a fix. test_gpt.c, 12 checks: a table written and read back; 16, 17 and 18 used entries against max 16 and an entry out of range after the 16th (#180); the RNG, the first write, a later write and a flush failing (#168). Against gpt.c before #168 and #180: 4 failures, each defect caught. Now: 0. Both runs in logs/.../kernel-tests/. Not yet a protocol stage: to rule (the plan, step 5). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_017RzZgrf7V7Zk2iczBXDRbm
38 lines
2.5 KiB
Markdown
38 lines
2.5 KiB
Markdown
# Kernel host tests -- plan and progress (kept current, one line per increment)
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Captain Bob, 2026-11-12: "Build an appropriate test harness! Love the idea." -- for the kernel's own
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C code, so that a defect QEMU cannot provoke (a USB descriptor no emulated device sends, a write that
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fails half-way, a stop that spins) is still tested first and seen to fail. v4 has had this since step
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1 (`make -C v4 test`); the kernel had none.
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## The design (my calls, open to a ruling)
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- **`kernel/tests/`**, one program per kernel source under test: `test_<unit>.c` compiled on the
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host with the kernel's own source file, `-std=c99 -Wall -Wextra -Werror`, and nothing else of the
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kernel. `make -C kernel/tests test` builds and runs them all; each prints `N checks, M failures`
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as v4's do, and the run fails if any does.
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- **Fakes, not mocks** (`kernel/tests/fakes.[ch]`): the console captured line by line (so a test
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reads what the kernel said), a deterministic RNG, and a RAM disk whose reads or writes fail at the
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1 KiB blocks a test chooses -- the disk faults QEMU's blkdebug gives the boots, here per block and
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without a boot.
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- **Code is moved only to be testable, never changed in the move.** Where a unit is buried in a
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larger function (the xHCI configuration-descriptor walk inside the event loop), it is moved out
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into a function of its own in one commit, the boots and the tests unchanged, and then tested.
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- **Not a substitute for acceptance.** The boots stay the only acceptance of the kernel; these run
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beside them. Whether they become a stage of the protocol and the PR's gate (`nightly.sh
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kernel-tests`, after test-32) is **to rule** -- proposed once there are enough tests to matter.
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## Increments
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- [x] 1. The harness (`Makefile`, `harness.h`, `fakes.[ch]`) and `test_gpt.c`: `gpt_read` and
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`gpt_write_one` against a RAM disk -- a valid table; more used entries than `max` (#180); an
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entry out of range past `max` (#180); the first write failing and a later one failing (#168).
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Seen to fail against `gpt.c` as it was before #168 and #180 (`54311be1~1`): 12 checks, 4
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failures -- each of the two defects caught. Now: 0 failures.
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- [ ] 2. The xHCI configuration-descriptor walk moved out of the event loop, then #170 and #171
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tested first and fixed.
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- [ ] 3. #176 (seeds wiped on every exit), #177 (the fatal stops halt), #178 (the slot array) --
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each with what it needs moved or faked.
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- [ ] 4. #179 once #187 is ruled (the block layer's header read).
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- [ ] 5. To rule: the kernel tests as a protocol stage and in the gate.
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