build system: make compiler names configurable

The top-level Makefile hardcoded the host and cross compiler name
to "gcc".  Make it possible to set different values either on the
command line (make CROSS_COMPILER=clang) or in the configuration
file.

6 files changed, 48 insertions, 6 deletions

diff --git a/Config.in b/Config.in
index 0a6d57327..f6159b30b 100644
--- a/Config.in
+++ b/Config.in
@@ -689,6 +689,18 @@ config CROSS_COMPILER_PREFIX
 
         Native builds leave this empty.
 
+config HOST_COMPILER
+        string "Host compiler"
+        default "gcc"
+        help
+        Name of the compiler to use for host binaries.
+
+config CROSS_COMPILER
+        string "Cross compiler"
+        default "gcc"
+        help
+        Name of the compiler to use for cross compilation.
+
 config SYSROOT
         string "Path to sysroot"
         default ""
diff --git a/Makefile b/Makefile
index f1d6b20b4..51f460583 100644
--- a/Makefile
+++ b/Makefile
@@ -196,6 +196,28 @@ ARCH ?= $(SUBARCH)
 # Architecture as present in compile.h
 UTS_MACHINE := $(ARCH)
 
+HOST_COMPILER ?=
+ifeq ($(HOST_COMPILER),)
+HOST_COMPILER := $(shell grep ^CONFIG_HOST_COMPILER= .config 2>/dev/null)
+HOST_COMPILER := $(subst CONFIG_HOST_COMPILER=,,$(HOST_COMPILER))
+HOST_COMPILER := $(subst ",,$(HOST_COMPILER))
+#")
+endif
+ifeq ($(HOST_COMPILER),)
+HOST_COMPILER := gcc
+endif
+
+CROSS_COMPILER ?=
+ifeq ($(CROSS_COMPILER),)
+CROSS_COMPILER := $(shell grep ^CONFIG_CROSS_COMPILER= .config 2>/dev/null)
+CROSS_COMPILER := $(subst CONFIG_CROSS_COMPILER=,,$(CROSS_COMPILER))
+CROSS_COMPILER := $(subst ",,$(CROSS_COMPILER))
+#")
+endif
+ifeq ($(CROSS_COMPILER),)
+CROSS_COMPILER := gcc
+endif
+
 # SHELL used by kbuild
 CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
           else if [ -x /bin/bash ]; then echo /bin/bash; \
@@ -275,7 +297,7 @@ export quiet Q KBUILD_VERBOSE
 # Look for make include files relative to root of kernel src
 MAKEFLAGS += --include-dir=$(srctree)
 
-HOSTCC          = gcc
+HOSTCC          = $(HOST_COMPILER)
 HOSTCXX         = g++
 HOSTCFLAGS      :=
 HOSTCXXFLAGS    :=
@@ -293,7 +315,7 @@ MAKEFLAGS += -rR
 # Make variables (CC, etc...)
 
 AS              = $(CROSS_COMPILE)as
-CC              = $(CROSS_COMPILE)gcc
+CC              = $(CROSS_COMPILE)$(CROSS_COMPILER)
 LD              = $(CC) -nostdlib
 CPP             = $(CC) -E
 AR              = $(CROSS_COMPILE)ar
diff --git a/configs/mingw32_defconfig b/configs/mingw32_defconfig
index 0f674d45c..c5e108a30 100644
--- a/configs/mingw32_defconfig
+++ b/configs/mingw32_defconfig
@@ -1,7 +1,7 @@
 #
 # Automatically generated make config: don't edit
 # Busybox version: 1.37.0.git
-# Wed Dec 20 13:23:38 2023
+# Sat Jan 20 09:32:45 2024
 #
 CONFIG_HAVE_DOT_CONFIG=y
 # CONFIG_PLATFORM_POSIX is not set
@@ -74,6 +74,8 @@ CONFIG_OVERRIDE_APPLETS=""
 # CONFIG_FEATURE_INDIVIDUAL is not set
 # CONFIG_FEATURE_SHARED_BUSYBOX is not set
 CONFIG_CROSS_COMPILER_PREFIX="i686-w64-mingw32-"
+CONFIG_HOST_COMPILER="gcc"
+CONFIG_CROSS_COMPILER="gcc"
 CONFIG_SYSROOT=""
 CONFIG_EXTRA_CFLAGS=""
 CONFIG_EXTRA_LDFLAGS=""
diff --git a/configs/mingw64_defconfig b/configs/mingw64_defconfig
index 37f95f4c8..341da22d6 100644
--- a/configs/mingw64_defconfig
+++ b/configs/mingw64_defconfig
@@ -1,7 +1,7 @@
 #
 # Automatically generated make config: don't edit
 # Busybox version: 1.37.0.git
-# Wed Dec 20 13:23:38 2023
+# Sat Jan 20 09:32:45 2024
 #
 CONFIG_HAVE_DOT_CONFIG=y
 # CONFIG_PLATFORM_POSIX is not set
@@ -74,6 +74,8 @@ CONFIG_OVERRIDE_APPLETS=""
 # CONFIG_FEATURE_INDIVIDUAL is not set
 # CONFIG_FEATURE_SHARED_BUSYBOX is not set
 CONFIG_CROSS_COMPILER_PREFIX="x86_64-w64-mingw32-"
+CONFIG_HOST_COMPILER="gcc"
+CONFIG_CROSS_COMPILER="gcc"
 CONFIG_SYSROOT=""
 CONFIG_EXTRA_CFLAGS=""
 CONFIG_EXTRA_LDFLAGS=""
diff --git a/configs/mingw64a_defconfig b/configs/mingw64a_defconfig
index 0ee83fe11..8eb8bbcfa 100644
--- a/configs/mingw64a_defconfig
+++ b/configs/mingw64a_defconfig
@@ -1,7 +1,7 @@
 #
 # Automatically generated make config: don't edit
 # Busybox version: 1.37.0.git
-# Wed Dec 20 13:23:38 2023
+# Sat Jan 20 09:32:45 2024
 #
 CONFIG_HAVE_DOT_CONFIG=y
 # CONFIG_PLATFORM_POSIX is not set
@@ -74,6 +74,8 @@ CONFIG_OVERRIDE_APPLETS=""
 # CONFIG_FEATURE_INDIVIDUAL is not set
 # CONFIG_FEATURE_SHARED_BUSYBOX is not set
 CONFIG_CROSS_COMPILER_PREFIX="aarch64-w64-mingw32-"
+CONFIG_HOST_COMPILER="clang"
+CONFIG_CROSS_COMPILER="clang"
 CONFIG_SYSROOT=""
 CONFIG_EXTRA_CFLAGS=""
 CONFIG_EXTRA_LDFLAGS=""
diff --git a/configs/mingw64u_defconfig b/configs/mingw64u_defconfig
index f26b17ec9..4218c57a5 100644
--- a/configs/mingw64u_defconfig
+++ b/configs/mingw64u_defconfig
@@ -1,7 +1,7 @@
 #
 # Automatically generated make config: don't edit
 # Busybox version: 1.37.0.git
-# Wed Dec 20 13:23:38 2023
+# Sat Jan 20 09:32:45 2024
 #
 CONFIG_HAVE_DOT_CONFIG=y
 # CONFIG_PLATFORM_POSIX is not set
@@ -74,6 +74,8 @@ CONFIG_OVERRIDE_APPLETS=""
 # CONFIG_FEATURE_INDIVIDUAL is not set
 # CONFIG_FEATURE_SHARED_BUSYBOX is not set
 CONFIG_CROSS_COMPILER_PREFIX="x86_64-w64-mingw32-"
+CONFIG_HOST_COMPILER="gcc"
+CONFIG_CROSS_COMPILER="gcc"
 CONFIG_SYSROOT=""
 CONFIG_EXTRA_CFLAGS=""
 CONFIG_EXTRA_LDFLAGS=""