MicroPython: LVGL memory pools on ports without multi_heap

ports/micropython/micropython.cmake

@@ -25,6 +25,7 @@ file(GLOB_RECURSE SOURCES ${LVGL_DIR}/src/*.c)
 list(FILTER SOURCES EXCLUDE REGEX "/src/drivers/(opengles|sdl|glfw|x11|wayland|evdev|libinput|qnx|uefi|nuttx|windows)/")
 list(FILTER SOURCES EXCLUDE REGEX "/src/draw/opengles/")
 list(APPEND SOURCES ${LVMP_DIR}/src/lv_mem_core_micropython.c)
+list(APPEND SOURCES ${LVMP_DIR}/src/lvmp_tlsf.c)
 
 if(NOT EXISTS ${LVMP_C})
     message(FATAL_ERROR "${LVMP_C} not found. Run ${BINDINGS_DIR}/regenerate_all.sh --target micropython")

ports/micropython/micropython.mk

@@ -52,6 +52,7 @@ SOURCES := $(foreach s,$(SOURCES),$(if $(strip $(foreach d,$(LVMP_EXCLUDE_DIRS),
 endif
 
 SOURCES += $(LVMP_DIR)/src/lv_mem_core_micropython.c
+SOURCES += $(LVMP_DIR)/src/lvmp_tlsf.c
 
 $(if $(wildcard $(LVMP_C)),,$(error $(LVMP_C) not found. Run $(BINDINGS_DIR)/regenerate_all.sh --target micropython))
 

ports/micropython/src/lv_mem_core_micropython.c

@@ -28,22 +28,37 @@
 // callback that only lv_obj_t.user_data refers to stays alive, as with
 // gc_alloc(). Allocations of LVMP_POOL_BIG bytes or more, and anything that
 // does not fit, still go to gc_alloc().
-#if defined(ESP_PLATFORM) && MICROPY_MALLOC_USES_ALLOCATED_SIZE
-#define LVMP_POOL (1)
-#else
-#define LVMP_POOL (0)
-#endif
+//
+// Other ports: the same pools on LVGL's own TLSF (lv_tlsf.c, built for this in
+// lvmp_tlsf.c) when the board sets LVMP_POOL_TLSF=1. STM32H743 with a 28 MB
+// GC heap in SDRAM: a full-screen refresh of 48 buttons took 54 ms with a
+// fresh heap and 575 ms once 2 MB of bytearrays sat behind a free block, every
+// LVGL allocation walking the table past them (mpy-lvgl-boards, 2026-11-02).
+#include "lvmp_pool.h"
 
-#if LVMP_POOL
+#if LVMP_POOL && defined(ESP_PLATFORM)
 #include "multi_heap.h"
+#elif LVMP_POOL
+// lv_tlsf.h declares these only with LV_STDLIB_BUILTIN.
+typedef void * lv_tlsf_t;
+lv_tlsf_t lv_tlsf_create_with_pool(void * mem, size_t bytes);
+void * lv_tlsf_malloc(lv_tlsf_t tlsf, size_t bytes);
+void * lv_tlsf_realloc(lv_tlsf_t tlsf, void * ptr, size_t size);
+size_t lv_tlsf_free(lv_tlsf_t tlsf, const void * ptr);
+size_t lv_tlsf_block_size(void * ptr);
+typedef lv_tlsf_t multi_heap_handle_t;
+#define multi_heap_register(mem, bytes) lv_tlsf_create_with_pool((mem), (bytes))
+#define multi_heap_malloc lv_tlsf_malloc
+#define multi_heap_realloc lv_tlsf_realloc
+#define multi_heap_free(h, p) ((void)lv_tlsf_free((h), (p)))
+#define multi_heap_get_allocated_size(h, p) lv_tlsf_block_size(p)
+#endif
 
-#define LVMP_POOL_MAX   (8)
-#define LVMP_POOL_BYTES (256 * 1024)
-#define LVMP_POOL_BIG   (32 * 1024)
+#if LVMP_POOL
 
-// The pools' GC blocks: a root pointer keeps them (and so everything LVGL
-// stores in them) reachable.
-MP_REGISTER_ROOT_POINTER(void *lvmp_pool_mem[8]);
+// The pools' GC blocks are kept reachable (and so everything LVGL stores in
+// them) by the root pointer lvmp_pool_mem, registered in lvgl_micropython_build.c:
+// make builds do not scan this file (SRC_USERMOD_LIB_C) for root pointers.
 
 static multi_heap_handle_t lvmp_heaps[LVMP_POOL_MAX];
 static uint8_t *lvmp_start[LVMP_POOL_MAX];

ports/micropython/src/lvgl_micropython_build.c

@@ -6,6 +6,13 @@
 #include "py/obj.h"
 #include "py/objstr.h"
 #include "py/runtime.h"
+#include "lvmp_pool.h"
+
+#if LVMP_POOL
+// The GC blocks of lv_mem_core_micropython.c's pools: this root pointer keeps
+// them, and so everything LVGL stores in them, reachable.
+MP_REGISTER_ROOT_POINTER(void *lvmp_pool_mem[LVMP_POOL_MAX]);
+#endif
 
 #ifndef LVMP_REVISION
 #define LVMP_REVISION "unknown"

ports/micropython/src/lvmp_pool.h

@@ -0,0 +1,28 @@
+// SPDX-FileCopyrightText: 2026 Nunzio Raciti
+//
+// SPDX-License-Identifier: MIT
+
+// LVGL allocations from TLSF pools kept in GC blocks (lv_mem_core_micropython.c).
+// Shared with lvgl_micropython_build.c, which registers the pools' root pointer
+// (make builds scan only SRC_USERMOD_C for root pointers, not the LVGL sources),
+// and lvmp_tlsf.c, which sizes LVGL's TLSF for one pool.
+#ifndef LVMP_POOL_H
+#define LVMP_POOL_H
+
+#include "py/mpconfig.h"
+
+// ESP32: ESP-IDF's multi_heap. Other ports: LVGL's TLSF, when the board sets
+// LVMP_POOL_TLSF=1.
+#if defined(ESP_PLATFORM) && MICROPY_MALLOC_USES_ALLOCATED_SIZE
+#define LVMP_POOL (1)
+#elif defined(LVMP_POOL_TLSF) && LVMP_POOL_TLSF
+#define LVMP_POOL (1)
+#else
+#define LVMP_POOL (0)
+#endif
+
+#define LVMP_POOL_MAX   (8)
+#define LVMP_POOL_BYTES (256 * 1024)
+#define LVMP_POOL_BIG   (32 * 1024)
+
+#endif // LVMP_POOL_H

ports/micropython/src/lvmp_tlsf.c

@@ -0,0 +1,23 @@
+// SPDX-FileCopyrightText: 2026 Nunzio Raciti
+//
+// SPDX-License-Identifier: MIT
+
+/**
+ * @file lvmp_tlsf.c
+ *
+ * LVGL's TLSF allocator for the LVMP pools of lv_mem_core_micropython.c on
+ * ports without ESP-IDF's multi_heap (LVMP_POOL_TLSF=1). LVGL compiles
+ * lv_tlsf.c only with LV_STDLIB_BUILTIN, so it is built here, in a translation
+ * unit of its own, with that setting: nothing else in LVGL changes.
+ */
+#include "lvgl/src/lv_conf_internal.h"
+#if LV_USE_STDLIB_MALLOC == LV_STDLIB_MICROPYTHON_OVERRIDE && defined(LVMP_POOL_TLSF) && LVMP_POOL_TLSF
+#include "lvmp_pool.h"
+#undef LV_USE_STDLIB_MALLOC
+#define LV_USE_STDLIB_MALLOC LV_STDLIB_BUILTIN
+// lv_tlsf.c sizes its tables for LV_MEM_SIZE + LV_MEM_POOL_EXPAND_SIZE, which
+// lv_conf_internal.h defines only with LV_STDLIB_BUILTIN: one TLSF per pool.
+#define LV_MEM_SIZE LVMP_POOL_BYTES
+#define LV_MEM_POOL_EXPAND_SIZE 0
+#include "lvgl/src/stdlib/builtin/lv_tlsf.c"
+#endif