oxidecomputer / oxidecomputer/quartz
Gimlet Sequencer doesn't correctly snapshot fault state/pg
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Gimlet Sequencer
- Dominant language
- VHDL
- Stars
- 22
- Forks
- 2
- Avg merge
- 9h 38m
- Merged PRs (30d)
- 1
Description
While debugging a unit that fails to sequence, the logic for when to snap FLT_A0_SMSTATUS, FLT_GROUPB_PG, and FLT_GROUPC_PG appears to be incorrect as they stay at zero. We can see that the watermark (MAX) registers are latched, but not the fault ones
$ humility ringbuf gimlet_seq
...
42 950 1 1 A0Failed(A0Timeout)
43 940 1 1 A0FailureDetails(IFR, 0x0)
44 940 1 1 A0FailureDetails(DBG_MAX_A0SMSTATUS, 0xa)
45 940 1 1 A0FailureDetails(MAX_GROUPB_PG, 0xff)
46 940 1 1 A0FailureDetails(MAX_GROUPC_PG, 0x3)
47 940 1 1 A0FailureDetails(FLT_A0_SMSTATUS, 0x0)
48 940 1 1 A0FailureDetails(FLT_GROUPB_PG, 0x0)
49 940 1 1 A0FailureDetails(FLT_GROUPC_PG, 0x0)
...
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
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- Open a pull request that references the issue number.
Research direction
Start by tracing the Gimlet sequencer logic responsible for snapshotting FLT_A0_SMSTATUS, FLT_GROUPB_PG, and FLT_GROUPC_PG, using the humility ringbuf gimlet_seq output as the observed failure. Compare that path with the working MAX register latching, then verify that the fault entries capture the relevant values during a failed sequence.
Written by the indexing model from the issue text.
Assessment
- Domain
- embedded-iot
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100