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#!/bin/sh # SPDX-License-Identifier: GPL-2.0-only # # Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG # options your compiler does not support. This works well if you configure and # build the kernel on the same host machine. # # It is inconvenient if you prepare the .config that is carried to a different # build environment (typically this happens when you package the kernel for # distros) because using a different compiler potentially produces different # CONFIG options than the real build environment. So, you probably want to make # as many options visible as possible. In other words, you need to create a # super-set of CONFIG options that cover any build environment. If some of the # CONFIG options turned out to be unsupported on the build machine, they are # automatically disabled by the nature of Kconfig. # # However, it is not feasible to get a full-featured compiler for every arch. # Hence these dummy toolchains to make all compiler tests pass. # # Usage: # # From the top directory of the source tree, run # # $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig # # Most of compiler features are tested by cc-option, which simply checks the # exit code of $(CC). This script does nothing and just exits with 0 in most # cases. So, $(cc-option, ...) is evaluated as 'y'. # # This scripts caters to more checks; handle --version and pre-process __GNUC__ # etc. to pretend to be GCC, and also do right things to satisfy some scripts. # Check if the first parameter appears in the rest. Succeeds if found. # This helper is useful if a particular option was passed to this script. # Typically used like this: # arg_contain <word-you-are-searching-for> "$@" arg_contain () { search="$1" shift while [ $# -gt 0 ] do if [ "$search" = "$1" ]; then return 0 fi shift done return 1 } # To set CONFIG_CC_IS_GCC=y if arg_contain --version "$@"; then echo "gcc (scripts/dummy-tools/gcc)" exit 0 fi if arg_contain -E "$@"; then # For scripts/gcc-version.sh; This emulates GCC 20.0.0 if arg_contain - "$@"; then sed 's/^__GNUC__$/20/; s/^__GNUC_MINOR__$/0/; s/^__GNUC_PATCHLEVEL__$/0/' exit 0 else echo "no input files" >&2 exit 1 fi fi # To set CONFIG_AS_IS_GNU if arg_contain -Wa,--version "$@"; then echo "GNU assembler (scripts/dummy-tools) 2.50" exit 0 fi if arg_contain -S "$@"; then # For scripts/gcc-x86-*-has-stack-protector.sh if arg_contain -fstack-protector "$@"; then echo "%gs" exit 0 fi fi # To set GCC_PLUGINS if arg_contain -print-file-name=plugin "$@"; then # Use $0 to find the in-tree dummy directory echo "$(dirname "$(readlink -f "$0")")/dummy-plugin-dir" exit 0 fi # inverted return value if arg_contain -D__SIZEOF_INT128__=0 "$@"; then exit 1 fi |