[FifteenPen]

What and why

Symptom: Kirby and the Forgotten Land's Nintendo Switch 2 Edition (program 04004D300C5AE001, v65536, SDK 21) aborts at boot, connecting to pl:u.

Cause: it asks for its built-in fonts with nn::pl::GetBuiltInFontDataSet, the list form of GetBuiltInFontData, which the host already takes over. Unhooked, the SDK goes to pl:u, which the host does not serve.

What the SDK does (its own GetBuiltInFontDataSet, sdk+0x4fc780 in that build):

• It takes at most 6 types and sends them to pl:u as one byte each (an in-buffer of n bytes).
• It fills *count entries of 0x18 bytes (BuiltInFontDataOunce) in order.
• It returns whether the service answered (a bool, not a Result).

Change (dm/host/hle_sdk16.c): a takeover of the Switch 2 overload.

• Each type is filled as the GetBuiltInFontData takeover fills it, with the same stand-in fonts, in the order asked.
• A type with no stand-in font is left out of the count.
• The Switch 1 overload (BuiltInFontTypeNx) is not hooked: no game at hand imports it.

The reference entry Built-in fonts and the audio device notification of SDK 21 covers the new call. Kirby's game note links it under "Found on this game".

Checked

• Tests:
  • make -C dm/host/tests GAME=01004D300C5AE000 build/t_shared_font: 144 checks, 0 failed. The new checks cover the entries, their order, the limit of 6 and the case with no fonts.
  • dm/tools/tests/test_docs.py: OK.
• Games run: Kirby and the Forgotten Land Nintendo Switch 2 Edition (04004D300C5AE001, v65536). It reached play past frame 1800 with its fonts loaded (the log's shared font lines), and no abort. The text on screen was not compared with the console.
  • The build was main plus Super Mario Bros. Wonder Nintendo Switch 2 Edition (Program 1): boot, New Game, Continue and correct rendering on the Mac #1639 (Program 1 packing, which this program needs to be packed at all) plus this change.
  • It was not run on main alone, since main cannot pack Program 1 yet.
• Devices and OS: Apple M4 Pro, macOS 27.2.1.
• Regression check: none run. The takeover only runs in a game that imports GetBuiltInFontDataSet.
  • scripts/regress.py impact finds 0 profiled games that use it, and the 4 with usage manifests are not affected.
  • Of the game builds at hand, only this Switch 2 Edition imports it, and it has no profile on main.

Docs

• The finding is in its docs/reference/services.md entry and Kirby's game note, and python3 dm/tools/docs_symptoms.py was run (the symptom index did not change)
• A chain tool changed: not applicable
• No game files, keys or data extracted from a game in the change or the attachments

[seedds]

Landed as f0dba3b on main, with you credited as co-author. Thanks for the clear diagnosis. Two additions on top: the SDK's disassembly (Splatoon Raiders' SDK 21, sdk+0x59a3c0) shows the return value is whether the fonts are loaded (a failed request aborts), so the comment and services.md now say that; and the Switch 1 overload (sdk+0x59a720: at most 7 types, *count set only when the fonts are loaded) is taken over too, through a helper the two share, with checks in t_shared_font (146 pass).