mkinitrd.sh (1996B)
1#!/bin/bash 2# SPDX-License-Identifier: GPL-2.0+ 3# 4# Create an initrd directory if one does not already exist. 5# 6# Copyright (C) IBM Corporation, 2013 7# 8# Author: Connor Shu <Connor.Shu@ibm.com> 9 10D=tools/testing/selftests/rcutorture 11 12# Prerequisite checks 13[ -z "$D" ] && echo >&2 "No argument supplied" && exit 1 14if [ ! -d "$D" ]; then 15 echo >&2 "$D does not exist: Malformed kernel source tree?" 16 exit 1 17fi 18if [ -s "$D/initrd/init" ]; then 19 echo "$D/initrd/init already exists, no need to create it" 20 exit 0 21fi 22 23# Create a C-language initrd/init infinite-loop program and statically 24# link it. This results in a very small initrd. 25echo "Creating a statically linked C-language initrd" 26cd $D 27mkdir -p initrd 28cd initrd 29cat > init.c << '___EOF___' 30#ifndef NOLIBC 31#include <unistd.h> 32#include <sys/time.h> 33#endif 34 35volatile unsigned long delaycount; 36 37int main(int argc, int argv[]) 38{ 39 int i; 40 struct timeval tv; 41 struct timeval tvb; 42 43 for (;;) { 44 sleep(1); 45 /* Need some userspace time. */ 46 if (gettimeofday(&tvb, NULL)) 47 continue; 48 do { 49 for (i = 0; i < 1000 * 100; i++) 50 delaycount = i * i; 51 if (gettimeofday(&tv, NULL)) 52 break; 53 tv.tv_sec -= tvb.tv_sec; 54 if (tv.tv_sec > 1) 55 break; 56 tv.tv_usec += tv.tv_sec * 1000 * 1000; 57 tv.tv_usec -= tvb.tv_usec; 58 } while (tv.tv_usec < 1000); 59 } 60 return 0; 61} 62___EOF___ 63 64# build using nolibc on supported archs (smaller executable) and fall 65# back to regular glibc on other ones. 66if echo -e "#if __x86_64__||__i386__||__i486__||__i586__||__i686__" \ 67 "||__ARM_EABI__||__aarch64__\nyes\n#endif" \ 68 | ${CROSS_COMPILE}gcc -E -nostdlib -xc - \ 69 | grep -q '^yes'; then 70 # architecture supported by nolibc 71 ${CROSS_COMPILE}gcc -fno-asynchronous-unwind-tables -fno-ident \ 72 -nostdlib -include ../../../../include/nolibc/nolibc.h \ 73 -s -static -Os -o init init.c -lgcc 74else 75 ${CROSS_COMPILE}gcc -s -static -Os -o init init.c 76fi 77 78rm init.c 79echo "Done creating a statically linked C-language initrd" 80 81exit 0