InfiniTimeOrg · mark9064 · Jan 10, 2026 · Jan 10, 2026 · NeroBurner · Jan 10, 2026
diff --git a/.vscode/c_cpp_properties.json b/.vscode/c_cpp_properties.json
@@ -2,7 +2,7 @@
     "env": {
         // TODO: This is a duplication of the configuration set in /docker/build.sh!
         "TOOLS_DIR": "/opt",
-        "GCC_ARM_PATH": "gcc-arm-none-eabi-10.3-2021.10"
+        "GCC_ARM_PATH": "arm-gnu-toolchain-15.2.rel1-x86_64-arm-none-eabi"
     },
     "configurations": [
         {

diff --git a/.vscode/launch.json b/.vscode/launch.json
@@ -53,7 +53,7 @@
                 "continue"
             ],
             // Only use armToolchainPath if your arm-none-eabi-gdb is not in your path (some GCC packages does not contain arm-none-eabi-gdb)
-            "armToolchainPath": "${workspaceRoot}/../gcc-arm-none-eabi-10.3-2021.10/bin",
+            "armToolchainPath": "${workspaceRoot}/../arm-gnu-toolchain-15.2.rel1-x86_64-arm-none-eabi/bin",
             "svdFile": "${workspaceRoot}/nrf52.svd",
             "configFiles": [
                 "interface/stlink.cfg",
@@ -68,7 +68,7 @@
             "request": "launch",
             "servertype": "external",
             // FIXME: This is hardcoded. I have no idea how to use the values set in build.sh here
-            "gdbPath": "/opt/gcc-arm-none-eabi-10.3-2021.10/bin/arm-none-eabi-gdb",
+            "gdbPath": "/opt/arm-gnu-toolchain-15.2.rel1-x86_64-arm-none-eabi/bin/arm-none-eabi-gdb",
             // Connect to an already running OpenOCD instance
             "gdbTarget": "host.docker.internal:3333",
             "svdFile": "${workspaceRoot}/nrf52.svd",

diff --git a/doc/buildAndProgram.md b/doc/buildAndProgram.md
@@ -4,7 +4,7 @@
 
 To build this project, you'll need:
 
-- A cross-compiler : [ARM-GCC (10.3-2021.10)](https://developer.arm.com/downloads/-/gnu-rm)
+- A cross-compiler : [ARM-GCC 15.2-Rel1 from December 17, 2025 (AArch32 bare-metal target (arm-none-eabi))](https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads)
 - The NRF52 SDK 15.3.0 : [nRF-SDK v15.3.0](https://nsscprodmedia.blob.core.windows.net/prod/software-and-other-downloads/sdks/nrf5/binaries/nrf5sdk153059ac345.zip)
 - The Python 3 modules `cbor`, `intelhex`, `click` and `cryptography` modules for the `mcuboot` tool (see [requirements.txt](../tools/mcuboot/requirements.txt))
   - To keep the system clean, you can install python modules into a python virtual environment (`venv`)
@@ -38,7 +38,7 @@ CMake configures the project according to variables you specify the command line
 
  Variable | Description | Example|
 ----------|-------------|--------|
-**ARM_NONE_EABI_TOOLCHAIN_PATH**|path to the toolchain directory|`-DARM_NONE_EABI_TOOLCHAIN_PATH=/home/jf/nrf52/gcc-arm-none-eabi-10.3-2021.10/`|
+**ARM_NONE_EABI_TOOLCHAIN_PATH**|path to the toolchain directory|`-DARM_NONE_EABI_TOOLCHAIN_PATH=/home/jf/nrf52/arm-gnu-toolchain-15.2.rel1-x86_64-arm-none-eabi/`|
 **NRF5_SDK_PATH**|path to the NRF52 SDK|`-DNRF5_SDK_PATH=/home/jf/nrf52/Pinetime/sdk`|
 **CMAKE_BUILD_TYPE (\*)**| Build type (Release or Debug). Release is applied by default if this variable is not specified.|`-DCMAKE_BUILD_TYPE=Debug`
 **BUILD_DFU (\*\*)**|Build DFU files while building (needs [adafruit-nrfutil](https://github.com/adafruit/Adafruit_nRF52_nrfutil)).|`-DBUILD_DFU=1`

diff --git a/doc/buildWithVScode.md b/doc/buildWithVScode.md
@@ -8,7 +8,7 @@ To support as many setups as possible the VS Code configuration files expect the
 
  Variable | Description | Example
 ----------|-------------|--------
-**ARM_NONE_EABI_TOOLCHAIN_PATH**|path to the toolchain directory|`export ARM_NONE_EABI_TOOLCHAIN_PATH=/opt/gcc-arm-none-eabi-10.3-2021.10`
+**ARM_NONE_EABI_TOOLCHAIN_PATH**|path to the toolchain directory|`export ARM_NONE_EABI_TOOLCHAIN_PATH=/opt/arm-gnu-toolchain-15.2.rel1-x86_64-arm-none-eabi`
 **NRF5_SDK_PATH**|path to the NRF52 SDK|`export NRF5_SDK_PATH=/opt/nRF5_SDK_15.3.0_59ac345`
 
 ## VS Code Extensions

diff --git a/docker/build.sh b/docker/build.sh
@@ -16,7 +16,7 @@ export NPM_DIR="$BUILD_DIR/npm"
 export npm_config_cache="${NPM_DIR}"
 
 export BUILD_TYPE=${BUILD_TYPE:=Release}
-export GCC_ARM_VER=${GCC_ARM_VER:="10.3-2021.10"}
+export GCC_ARM_VER=${GCC_ARM_VER:="15.2.rel1"}
 export NRF_SDK_VER=${NRF_SDK_VER:="nRF5_SDK_15.3.0_59ac345"}
 # convert to lower case and remove _ and . character
 # the download URL uses the SLUG, but the extracted folder is named like the original value
@@ -26,7 +26,7 @@ export NRF_SDK_VER_SLUG=${NRF_SDK_VER_SLUG//[_.]/}
 MACHINE="$(uname -m)"
 [ "$MACHINE" = "arm64" ] && MACHINE="aarch64"
 
-export GCC_ARM_PATH="gcc-arm-none-eabi-$GCC_ARM_VER"
+export GCC_ARM_PATH="arm-gnu-toolchain-$GCC_ARM_VER-$MACHINE-arm-none-eabi"
 
 main() {
   local target="$1"
@@ -50,7 +50,7 @@ main() {
 }
 
 GetGcc() {
-  wget -q https://developer.arm.com/-/media/Files/downloads/gnu-rm/$GCC_ARM_VER/$GCC_ARM_PATH-$MACHINE-linux.tar.bz2 -O - | tar -xj -C $TOOLS_DIR/
+  wget -q https://developer.arm.com/-/media/Files/downloads/gnu/$GCC_ARM_VER/binrel/$GCC_ARM_PATH.tar.xz -O - | tar -xJ -C $TOOLS_DIR/
   if [ ! -d "$TOOLS_DIR/$GCC_ARM_PATH" ]; then
     echo "missing GCC path: $TOOLS_DIR/$GCC_ARM_PATH"
     return 1

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
@@ -930,7 +930,7 @@ target_compile_options(${EXECUTABLE_NAME} PUBLIC
 
 set_target_properties(${EXECUTABLE_NAME} PROPERTIES
         SUFFIX ".out"
-        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT} --specs=nosys.specs -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_FILE_NAME}.map"
+        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT} -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_FILE_NAME}.map"
         )
 
 add_custom_command(TARGET ${EXECUTABLE_NAME}
@@ -965,7 +965,7 @@ target_compile_options(${EXECUTABLE_MCUBOOT_NAME} PUBLIC
 
 set_target_properties(${EXECUTABLE_MCUBOOT_NAME} PROPERTIES
         SUFFIX ".out"
-        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT_MCUBOOT} --specs=nosys.specs -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_MCUBOOT_FILE_NAME}.map"
+        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT_MCUBOOT} -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_MCUBOOT_FILE_NAME}.map"
         )
 
 add_custom_command(TARGET ${EXECUTABLE_MCUBOOT_NAME}
@@ -1008,7 +1008,7 @@ target_compile_options(${EXECUTABLE_RECOVERY_NAME} PUBLIC
 
 set_target_properties(${EXECUTABLE_RECOVERY_NAME} PROPERTIES
         SUFFIX ".out"
-        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT} --specs=nosys.specs -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_RECOVERY_FILE_NAME}.map"
+        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT} -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_RECOVERY_FILE_NAME}.map"
         )
 
 add_custom_command(TARGET ${EXECUTABLE_RECOVERY_NAME}
@@ -1040,7 +1040,7 @@ target_compile_options(${EXECUTABLE_RECOVERY_MCUBOOT_NAME} PUBLIC
 
 set_target_properties(${EXECUTABLE_RECOVERY_MCUBOOT_NAME} PROPERTIES
         SUFFIX ".out"
-        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT_MCUBOOT} --specs=nosys.specs -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_GRAPHICS_FILE_NAME}.map"
+        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT_MCUBOOT} -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_GRAPHICS_FILE_NAME}.map"
         )
 
 add_custom_command(TARGET ${EXECUTABLE_RECOVERY_MCUBOOT_NAME}
@@ -1083,7 +1083,7 @@ add_dependencies(${EXECUTABLE_RECOVERYLOADER_NAME} ${EXECUTABLE_RECOVERY_MCUBOOT
 
 set_target_properties(${EXECUTABLE_RECOVERYLOADER_NAME} PROPERTIES
         SUFFIX ".out"
-        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT} --specs=nosys.specs -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_RECOVERYLOADER_FILE_NAME}.map"
+        LINK_FLAGS "-mthumb -mabi=aapcs -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT} -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_RECOVERYLOADER_FILE_NAME}.map"
         )
 
 add_custom_command(TARGET ${EXECUTABLE_RECOVERYLOADER_NAME}
@@ -1118,7 +1118,7 @@ add_dependencies(${EXECUTABLE_MCUBOOT_RECOVERYLOADER_NAME} ${EXECUTABLE_RECOVERY
 
 set_target_properties(${EXECUTABLE_MCUBOOT_RECOVERYLOADER_NAME} PROPERTIES
         SUFFIX ".out"
-        LINK_FLAGS "-mthumb -mabi=aapcs -std=gnu++98 -std=c99 -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT_MCUBOOT} --specs=nosys.specs -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_MCUBOOT_RECOVERYLOADER_FILE_NAME}.map"
+        LINK_FLAGS "-mthumb -mabi=aapcs -std=gnu++98 -std=c99 -L ${NRF5_SDK_PATH}/modules/nrfx/mdk -T${NRF5_LINKER_SCRIPT_MCUBOOT} -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -Wl,--gc-sections -Wl,--print-memory-usage --specs=nano.specs -Wl,-Map=${EXECUTABLE_MCUBOOT_RECOVERYLOADER_FILE_NAME}.map"
         )
 
 add_custom_command(TARGET ${EXECUTABLE_MCUBOOT_RECOVERYLOADER_NAME}

diff --git a/src/stdlib.c b/src/stdlib.c
@@ -1,6 +1,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <FreeRTOS.h>
+#include <sys/stat.h>
+#include <unistd.h>
 
 // Override malloc() and free() to use the memory manager from FreeRTOS.
 // According to the documentation of libc, we also need to override
@@ -29,7 +31,7 @@ void __wrap_free(void* ptr) {
 }
 
 void* calloc(size_t num, size_t size) {
-  void *ptr = malloc(num * size);
+  void* ptr = malloc(num * size);
   if (ptr) {
     memset(ptr, 0, num * size);
   }
@@ -49,3 +51,58 @@ void* realloc(void* ptr, size_t newSize) {
 void* __wrap_realloc(void* ptr, size_t newSize) {
   return realloc(ptr, newSize);
 }
+
+// Implement functions required by libc as stubs
+// These functions aren't linked into the final binary
+
+__attribute__((error("stub"))) void _close(int fp) {
+  __builtin_trap();
+  (void) fp;
+}
+
+__attribute__((error("stub"))) void _fstat(int fildes, struct stat* buf) {
+  __builtin_trap();
+  (void) fildes;
+  (void) buf;
+}
+
+__attribute__((error("stub"))) pid_t _getpid() {
+  __builtin_trap();
+}
+
+__attribute__((error("stub"))) int _isatty(int fd) {
+  __builtin_trap();
+  (void) fd;
+}
+
+__attribute__((error("stub"))) int _kill(pid_t pid, int sig) {
+  __builtin_trap();
+  (void) pid;
+  (void) sig;
+}
+
+__attribute__((error("stub"))) off_t _lseek(int fd, off_t offset, int whence) {
+  __builtin_trap();
+  (void) fd;
+  (void) offset;
+  (void) whence;
+}
+
+__attribute__((error("stub"))) ssize_t _read(int fd, void* buf, size_t count) {
+  __builtin_trap();
+  (void) fd;
+  (void) buf;
+  (void) count;
+}
+
+__attribute__((error("stub"))) ssize_t _write(int fd, void* buf, size_t count) {
+  __builtin_trap();
+  (void) fd;
+  (void) buf;
+  (void) count;
+}
+
+__attribute__((error("stub"))) void _exit(int status) {
+  __builtin_trap();
+  (void) status;
+}