[core] Specify toolchain prefix in board.json

arduino/descript.ion

@@ -1,2 +0,0 @@
-realtek-ambz Realtek AmebaZ Arduino Core
-libretuya Interfaces for LibreTuya Arduino cores

boards/_base/beken-72xx.json

@@ -1,6 +1,7 @@
 {
 	"build": {
-		"f_cpu": "120000000L"
+		"f_cpu": "120000000L",
+		"prefix": "arm-none-eabi-"
 	},
 	"connectivity": [
 		"wifi",

boards/_base/realtek-ambz.json

@@ -2,6 +2,7 @@
 	"build": {
 		"family": "RTL8710B",
 		"f_cpu": "125000000L",
+		"prefix": "arm-none-eabi-",
 		"amb_flash_addr": "0x08000000"
 	},
 	"connectivity": [

builder/main.py

@@ -28,18 +28,19 @@ if env.get("PROGNAME", "program") == "program":
 env.Replace(PROGSUFFIX=".elf")
 
 # Toolchain config - TODO multiple arch, specified in board.json
+prefix = board.get("build.prefix", "")
 env.Replace(
-    AR="arm-none-eabi-gcc-ar",
-    AS="arm-none-eabi-gcc",
-    CC="arm-none-eabi-gcc",
-    CXX="arm-none-eabi-g++",
-    GDB="arm-none-eabi-gdb",
-    NM="arm-none-eabi-gcc-nm",
-    LINK="arm-none-eabi-gcc",
-    OBJCOPY="arm-none-eabi-objcopy",
-    OBJDUMP="arm-none-eabi-objdump",
-    # RANLIB="arm-none-eabi-gcc-ranlib",
-    SIZETOOL="arm-none-eabi-size",
+    AR=prefix + "gcc-ar",
+    AS=prefix + "gcc",
+    CC=prefix + "gcc",
+    CXX=prefix + "g++",
+    GDB=prefix + "gdb",
+    NM=prefix + "gcc-nm",
+    LINK=prefix + "gcc",
+    OBJCOPY=prefix + "objcopy",
+    OBJDUMP=prefix + "objdump",
+    # RANLIB=prefix + "gcc-ranlib",
+    SIZETOOL=prefix + "size",
 )
 
 # Default environment options

builder/utils/libs.py

@@ -54,11 +54,12 @@ def env_add_library(
             srcs.append("-<" + expr + ">")
 
     # queue library for further env clone and build
-    env.Prepend(
-        LIBQUEUE=[
-            (join("$BUILD_DIR", name), base_dir, srcs, options),
-        ]
-    )
+    if srcs:
+        env.Prepend(
+            LIBQUEUE=[
+                (join("$BUILD_DIR", name), base_dir, srcs, options),
+            ]
+        )
 
     # search all include paths
     for dir, expr in iter_expressions(includes):