1#!/bin/sh 2# SPDX-License-Identifier: GPL-2.0-only 3# 4# Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG 5# options your compiler does not support. This works well if you configure and 6# build the kernel on the same host machine. 7# 8# It is inconvenient if you prepare the .config that is carried to a different 9# build environment (typically this happens when you package the kernel for 10# distros) because using a different compiler potentially produces different 11# CONFIG options than the real build environment. So, you probably want to make 12# as many options visible as possible. In other words, you need to create a 13# super-set of CONFIG options that cover any build environment. If some of the 14# CONFIG options turned out to be unsupported on the build machine, they are 15# automatically disabled by the nature of Kconfig. 16# 17# However, it is not feasible to get a full-featured compiler for every arch. 18# Hence these dummy toolchains to make all compiler tests pass. 19# 20# Usage: 21# 22# From the top directory of the source tree, run 23# 24# $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig 25# 26# Most of compiler features are tested by cc-option, which simply checks the 27# exit code of $(CC). This script does nothing and just exits with 0 in most 28# cases. So, $(cc-option, ...) is evaluated as 'y'. 29# 30# This scripts caters to more checks; handle --version and pre-process __GNUC__ 31# etc. to pretend to be GCC, and also do right things to satisfy some scripts. 32 33# Check if the first parameter appears in the rest. Succeeds if found. 34# This helper is useful if a particular option was passed to this script. 35# Typically used like this: 36# arg_contain <word-you-are-searching-for> "$@" 37arg_contain () 38{ 39 search="$1" 40 shift 41 42 while [ $# -gt 0 ] 43 do 44 if [ "$search" = "$1" ]; then 45 return 0 46 fi 47 shift 48 done 49 50 return 1 51} 52 53# To set CONFIG_CC_IS_GCC=y 54if arg_contain --version "$@"; then 55 echo "gcc (scripts/dummy-tools/gcc)" 56 exit 0 57fi 58 59if arg_contain -E "$@"; then 60 # For scripts/cc-version.sh; This emulates GCC 20.0.0 61 if arg_contain - "$@"; then 62 sed -n '/^GCC/{s/__GNUC__/20/; s/__GNUC_MINOR__/0/; s/__GNUC_PATCHLEVEL__/0/; p;}; s/__LONG_DOUBLE_128__/1/ p' 63 exit 0 64 else 65 echo "no input files" >&2 66 exit 1 67 fi 68fi 69 70# To set CONFIG_AS_IS_GNU 71if arg_contain -Wa,--version "$@"; then 72 echo "GNU assembler (scripts/dummy-tools) 2.50" 73 exit 0 74fi 75 76if arg_contain -S "$@"; then 77 # For scripts/gcc-x86-*-has-stack-protector.sh 78 if arg_contain -fstack-protector "$@"; then 79 if arg_contain -mstack-protector-guard-reg=fs "$@"; then 80 echo "%fs" 81 else 82 echo "%gs" 83 fi 84 exit 0 85 fi 86 87 # For arch/powerpc/tools/gcc-check-mprofile-kernel.sh 88 if arg_contain -m64 "$@" && arg_contain -mprofile-kernel "$@"; then 89 if ! test -t 0 && ! grep -q notrace; then 90 echo "_mcount" 91 fi 92 exit 0 93 fi 94 95 # For arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh 96 if arg_contain -m64 "$@" && arg_contain -fpatchable-function-entry=2 "$@"; then 97 echo "func:" 98 echo ".section __patchable_function_entries" 99 echo ".localentry" 100 echo " nop" 101 echo " nop" 102 exit 0 103 fi 104fi 105 106# To set GCC_PLUGINS 107if arg_contain -print-file-name=plugin "$@"; then 108 # Use $0 to find the in-tree dummy directory 109 echo "$(dirname "$(readlink -f "$0")")/dummy-plugin-dir" 110 exit 0 111fi 112 113# inverted return value 114if arg_contain -D__SIZEOF_INT128__=0 "$@"; then 115 exit 1 116fi 117