Make `hiffy_decode` return a non-nested error by mkeeter · Pull Request #661 · oxidecomputer/humility

mkeeter · 2026-05-12T21:46:22Z

(staged on #660)

hiffy_decode returns a Result<std::result::Result<T, String>>, which is an awkward type.

We can instead use the HiffyCallError (renamed HiffyError), which distinguishes between internal errors (returned by the HIF program) and external errors (which occur when calling hiffy).

This simplifies most cases (where we want to return both inner and outer error), and adds a tiny bit of boilerplate to cases where we care about the difference – but that boilerplate is more clear than the nested type.

labbott

Minor question about performance but it looks correct

labbott · 2026-05-20T16:55:52Z

+                    let cfg = s.field::<Struct>("cfg")?;
+                    assert_eq!(cfg.name(), "PortConfig");
+                    let dev = decode_dev(&cfg.field("dev")?)?;
+                    let serdes = decode_dev(&cfg.field("serdes")?)?;
+                    let (mode, speed) = decode_mode(&cfg["mode"]);
+                    (
+                        dev.replace("DEV", ""),
+                        serdes.replace("SERDES", ""),
+                        mode,
+                        speed,
+                    )


How expensive is each .field call?

It's a lookup in a hashmap and then a Load call (basically the same as before, the hashmap lookup was previously hidden in the indexing operation).

mkeeter · 2026-05-21T20:29:46Z

Quick test sweep over affected commands:

matt@niles ~ () $ pfexec ./humility -t cosmo-b host cosmo last-post-code
humility: attached to 0483:374f:002A001C4D46500F20373033 via ST-Link V3
Bootloader Code: 0xed80000f
  Source:  ASP TEE
  Status:  BL_ERR_BOUNDARY_CHECK (0x0f)
  Detail:  Out of Boundary Condition Reached
matt@niles ~ () $ pfexec ./humility -t cosmo-b host cosmo post-codes | head -n10
humility: attached to 0483:374f:002A001C4D46500F20373033 via ST-Link V3
Bootloader Code: 0xee1000b3
  Source:  ASP BL2
  Status:  BL_SUCCESS_BYPASS_IDEVID_CHECK (0xb3)
  Detail:  IDEVID validation failed but bypassed (unsecure)
Bootloader Code: 0xee1000a0
  Source:  ASP BL2
  Status:  BL_SUCCESS_C_MAIN (0xa0)
  Detail:  Successfully entered C Main
Bootloader Code: 0xee1000a3
  Source:  ASP BL2

matt@niles ~ () $ pfexec ./humility -t sidecar-b monorail dump DEV1G[0]
humility: attached to 0483:3754:002600184D4B500E20373831 via ST-Link V3
Dumping target DEV1G[0] (0x71040000 -> 0x710400a0)
DEV1G[0]:DEV_CFG_STATUS:DEV_RST_CTRL    0x00100000
DEV1G[0]:DEV_CFG_STATUS:DEV_STICKY    0x00004000
DEV1G[0]:DEV_CFG_STATUS:DEV_DBG_CFG    0x00000800
DEV1G[0]:DEV_CFG_STATUS:DEV_PORT_PROTECT    0x00000000
DEV1G[0]:DEV_CFG_STATUS:EEE_CFG    0x0011940a
DEV1G[0]:DEV_CFG_STATUS:PTP_CFG    0x00400000
DEV1G[0]:DEV_CFG_STATUS:PTP_EVENTS    0x00000000
DEV1G[0]:MAC_CFG_STATUS:MAC_ENA_CFG    0x00000011
DEV1G[0]:MAC_CFG_STATUS:MAC_MODE_CFG    0x00000001
DEV1G[0]:MAC_CFG_STATUS:MAC_MAXLEN_CFG    0x000005ee
DEV1G[0]:MAC_CFG_STATUS:MAC_TAGS_CFG    0x88a80008
DEV1G[0]:MAC_CFG_STATUS:MAC_TAGS_CFG2    0x88a888a8
DEV1G[0]:MAC_CFG_STATUS:MAC_ADV_CHK_CFG    0x00000000
DEV1G[0]:MAC_CFG_STATUS:MAC_IFG_CFG    0x00000641
DEV1G[0]:MAC_CFG_STATUS:MAC_HDX_CFG    0x00000043
DEV1G[0]:MAC_CFG_STATUS:MAC_STICKY    0x00000000

matt@niles ~ () $ pfexec ./humility -t sidecar-b monorail status
humility: attached to 0483:3754:002600184D4B500E20373831 via ST-Link V3
PORT | MODE    SPEED  DEV     SERDES  LINK |   PHY    MAC LINK  MEDIA LINK
-----|-------------------------------------|-------------------------------
 0   | SGMII   100M   1G_0    1G_1    down | --       --         --
 1   | SGMII   100M   1G_1    1G_2    down | --       --         --
 2   | SGMII   100M   1G_2    1G_3    down | --       --         --
 3   | SGMII   100M   1G_3    1G_4    down | --       --         --
 4   | SGMII   100M   1G_4    1G_5    down | --       --         --
 5   | SGMII   100M   1G_5    1G_6    down | --       --         --
 6   | SGMII   100M   1G_6    1G_7    down | --       --         --
 7   | SGMII   100M   1G_7    1G_8    down | --       --         --
 8   | SGMII   100M   2G5_0   6G_0    down | --       --         --
 9   | SGMII   100M   2G5_1   6G_1    down | --       --         --
 10  | SGMII   100M   2G5_2   6G_2    down | --       --         --
 11  | SGMII   100M   2G5_3   6G_3    down | --       --         --
 12  | SGMII   100M   2G5_4   6G_4    down | --       --         --
 13  | SGMII   100M   2G5_5   6G_5    up   | --       --         --
 14  | SGMII   100M   2G5_6   6G_6    up   | --       --         --
 15  | SGMII   100M   2G5_7   6G_7    up   | --       --         --
 16  | SGMII   100M   2G5_8   6G_8    down | --       --         --
 17  | SGMII   100M   2G5_9   6G_9    down | --       --         --
 18  | SGMII   100M   2G5_10  6G_10   down | --       --         --
 19  | SGMII   100M   2G5_11  6G_11   down | --       --         --
 20  | SGMII   100M   2G5_12  6G_12   down | --       --         --
 21  | SGMII   100M   2G5_13  6G_13   down | --       --         --
 22  | --      --     --      --      --   | --       --         --
 23  | --      --     --      --      --   | --       --         --
 24  | SGMII   100M   2G5_16  6G_16   down | --       --         --
 25  | SGMII   100M   2G5_17  6G_17   down | --       --         --
 26  | SGMII   100M   2G5_18  6G_18   down | --       --         --
 27  | SGMII   100M   2G5_19  6G_19   down | --       --         --
 28  | SGMII   100M   2G5_20  6G_20   down | --       --         --
 29  | SGMII   100M   2G5_21  6G_21   down | --       --         --
 30  | SGMII   100M   2G5_22  6G_22   down | --       --         --
 31  | SGMII   100M   2G5_23  6G_23   down | --       --         --
 32  | --      --     --      --      --   | --       --         --
 33  | --      --     --      --      --   | --       --         --
 34  | --      --     --      --      --   | --       --         --
 35  | --      --     --      --      --   | --       --         --
 36  | --      --     --      --      --   | --       --         --
 37  | --      --     --      --      --   | --       --         --
 38  | --      --     --      --      --   | --       --         --
 39  | --      --     --      --      --   | --       --         --
 40  | QSGMII  100M   1G_16   6G_14   up   | VSC8504  up        up
 41  | QSGMII  100M   1G_17   6G_14   up   | VSC8504  up        down
 42  | QSGMII  100M   1G_18   6G_14   up   | VSC8504  up        down
 43  | QSGMII  100M   1G_19   6G_14   up   | VSC8504  up        down
 44  | QSGMII  1G     1G_20   6G_15   up   | VSC8562  err       up
 45  | QSGMII  1G     1G_21   6G_15   up   | VSC8562  err       down
 46  | --      --     --      --      --   | --       --         --
 47  | --      --     --      --      --   | --       --         --
 48  | SGMII   100M   2G5_24  1G_0    up   | --       --         --
 49  | BASEKR  --     10G_0   10G_0   down | --       --         --
 50  | --      --     --      --      --   | --       --         --
 51  | SGMII   100M   2G5_27  10G_2   down | --       --         --
 52  | SGMII   100M   2G5_28  10G_3   down | --       --         --

matt@niles ~ () $ pfexec ./humility -t sidecar-b net mac
humility: attached to 0483:3754:002600184D4B500E20373831 via ST-Link V3
humility: Reading 7 MAC addresses...
 PORT |        MAC
------|-------------------
    1 | 00:0e:c6:2c:bb:12
      | 1c:61:b4:19:39:40
      | e8:ea:6a:09:ca:3d
    3 | a8:40:25:05:ff:00
      | a8:40:25:05:ff:00
      | a8:40:25:05:ff:00
      | a8:40:25:05:ff:01

mkeeter requested a review from labbott May 12, 2026 21:46

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mkeeter mentioned this pull request May 14, 2026

Switch subcommand parsing to an enum Subcommand #666

Merged

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labbott approved these changes May 20, 2026

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Make hiffy_decode return a non-nested error

24d7716

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mkeeter merged commit f679141 into master May 21, 2026
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mkeeter deleted the mkeeter/hiffy-decode-flat branch May 21, 2026 20:50

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Make `hiffy_decode` return a non-nested error#661

Make `hiffy_decode` return a non-nested error#661
mkeeter merged 1 commit into
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mkeeter/hiffy-decode-flat

mkeeter commented May 12, 2026 •

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mkeeter commented May 12, 2026 •

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