kbuild: collect minimum tool versions into scripts/min-tool-version.sh

The kernel build uses various tools, many of which are provided by the
same software suite, for example, LLVM and Binutils.

When you raise the minimum version of Clang/LLVM, you need to update
clang_min_version in scripts/cc-version.sh and also lld_min_version in
scripts/ld-version.sh.

Kbuild can handle CC=clang and LD=ld.lld independently, but it does not
make much sense to maintain their versions separately.

Let's create a central place of minimum tool versions so you do not need
to touch multiple files. scripts/min-tool-version.sh prints the minimum
version of the given tool.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>

scripts/min-tool-version.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Print the minimum supported version of the given tool.
+# When you raise the minimum version, please update
+# Documentation/process/changes.rst as well.
+
+set -e
+
+if [ $# != 1 ]; then
+	echo "Usage: $0 toolname" >&2
+	exit 1
+fi
+
+case "$1" in
+binutils)
+	echo 2.23.0
+	;;
+gcc)
+	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
+	# https://lore.kernel.org/r/20210107111841.GN1551@shell.armlinux.org.uk
+	if [ "$SRCARCH" = arm64 ]; then
+		echo 5.1.0
+	else
+		echo 4.9.0
+	fi
+	;;
+icc)
+	# temporary
+	echo 16.0.3
+	;;
+llvm)
+	echo 10.0.1
+	;;
+*)
+	echo "$1: unknown tool" >&2
+	exit 1
+	;;
+esac