Libraries: link CHGfx, CHGame and CHSd from archives

platform/README.md

@@ -211,6 +211,22 @@ list builds stayed byte-identical. Not yet run on a board.
 
 ## Changes since the copies were taken
 
+- 2026-10-08: the three libraries link from archives (`dot_a_linkage=true`
+  in CHGfx's, CHGame's and CHSd's `library.properties`). A developer using
+  only `audio::` and the buttons, with their own display code, found every
+  sketch that includes `CHGame.h` carrying CHGfx's framebuffer: Arduino
+  links a library's objects whole, and the DMA interrupt handler in
+  `CHGfx.cpp` (a strong `DMA1_Channel3_IRQHandler` over the core's weak
+  one) keeps `gfx_fb`, the chunk buffers and the SRAM converters with it.
+  From an archive an object is linked only when something calls into it,
+  so that sketch is 352 B of RAM instead of 9,712 B, and the two hooks the
+  libraries override (that handler, and `osSystickHandler` in `Audio.cpp`)
+  sit in the same objects as `gfx_begin()` and `audio::begin()`, so a
+  sketch that uses the feature always gets them. Plain `riscv-none-embed-ar`
+  indexes GCC 8's slim LTO objects, so the `-Os -flto` builds need no
+  `gcc-ar`. All 23 examples' release images are byte-identical
+  (board/CHANGELOG.md, "Unreleased"). The simulator does not read the flag.
+
 - 2026-10-07: an API reference for every library the board package ships.
   The public headers of CHGame, CHGfx, CHSd, SPI, Wire and EEPROM carry
   Doxygen comments (a brief, every parameter, the return value, and the

platform/board/CHANGELOG.md

@@ -14,6 +14,19 @@ file as the GitHub release notes.
   function, class and constant of CHGame, CHGfx, CHSd, SPI, Wire and EEPROM,
   documented in their headers with Doxygen.
 
+### Changed
+
+- **CHGfx, CHGame and CHSd link from archives** (`dot_a_linkage=true` in
+  their `library.properties`), so an object of theirs is linked only when
+  the sketch calls into it. Arduino otherwise links every object of an
+  included library whole, and CHGfx's DMA interrupt handler (its
+  `DMA1_Channel3_IRQHandler` replaces the core's weak default) kept the 8 KB
+  framebuffer, the 1 KB chunk buffers and the SRAM converters alive in any
+  sketch that included `CHGame.h`, drawing with it or not. A sketch that
+  uses `audio::` and `chgame_readButtons()` and draws through its own code
+  now takes 352 B of static RAM instead of 9,712 B. The 20 games' and the
+  3 apps' release images are byte-identical. (Reported by a developer.)
+
 ### Fixed
 
 - **EEPROM no longer writes the CH32X035's option bytes.** The library is

platform/board/arduino/CHGame/libraries/CHGame/README.md

@@ -99,7 +99,10 @@ include just the one it needs, e.g. `<chgame/Fmt.h>`.
   what fills it. Unused parts of the library cost nothing (link-time optimisation
   drops them).
 - **RAM is 18,416 B** for statics, plus a 2 KB stack. The framebuffer takes
-  8 KB of it.
+  8 KB of it when the sketch draws with CHGfx. A sketch that includes
+  `CHGame.h` for its sound, buttons or saves and draws through its own code
+  does not carry it: the libraries link from archives, so an object is
+  linked only when something calls into it.
 - **`static const` tables of 8 bytes or less** are copied into SRAM by this
   core's link script; sound steps use `AUDIO_STEPS` to stay in flash.
 - **Integer maths only.** Soft-float costs kilobytes and frame rate.

platform/board/arduino/CHGame/libraries/CHGame/library.properties

@@ -9,3 +9,4 @@ url=https://github.com/bateske/CHGame
 architectures=ch32v
 includes=CHGame.h
 depends=CHGfx
+dot_a_linkage=true

platform/board/arduino/CHGame/libraries/CHGame/src/CHGame.h

@@ -21,7 +21,10 @@
 /// | chgame/Debug.h   | dbg:: the serial debug protocol the simulator and the tools drive a game through (CHGAME_DEBUG builds) |
 /// | chgame/Config.h  | the library's build switches (CHGAME_DEBUG ...) |
 ///
-/// The casino games in this library's examples are built from these.
+/// The casino games in this library's examples are built from these. Only
+/// what a sketch calls is linked: CHGfx's framebuffer and DMA handler come
+/// with the first drawing call, not with the include, so a sketch that uses
+/// this library for its sound, buttons or saves alone pays nothing for them.
 /// chgame/Sizzle.h (particles, banners, floating texts) is not included
 /// here: a game configures and compiles it itself.
 #pragma once

platform/board/arduino/CHGame/libraries/CHGfx/library.properties

@@ -8,3 +8,4 @@ category=Display
 url=https://github.com/bateske/CHGame
 architectures=ch32v
 includes=CHGfx.h
+dot_a_linkage=true

platform/board/arduino/CHGame/libraries/CHSd/library.properties

@@ -9,3 +9,4 @@ url=https://github.com/bateske/CHGame
 architectures=ch32v
 includes=Fat.h,SdSpi.h
 depends=
+dot_a_linkage=true