Minimal linux live iso creator

Makefile

#!/usr/bin/make -f
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 3 of the License, or (at your option)
# any later version.
#
KERNEL_VERSION=5.11.6
BUSYBOX_VERSION=1.33.0

help:
	: Usage: make [help/fetch/build/install/clean/reset/dist-clean]
	:   help: write this message
	:   fetch: download source archives
	:   build: build source
	:   install: install sources and create iso file
	:   clean: remove source files and installation
	:   reset: remove only installation
	:   dist-clean: remove all
	

all: fetch build
fetch: archives sources

# Fetch archice files
archives:
	mkdir archives
	wget -O archives/linux.tar.xz http://kernel.org/pub/linux/kernel/v5.x/linux-$(KERNEL_VERSION).tar.xz
	wget -O archives/busybox.tar.bz2 http://busybox.net/downloads/busybox-$(BUSYBOX_VERSION).tar.bz2

# Extract archive files
sources:
	mkdir sources
	cd sources ; tar -xvf ../archives/linux.tar.xz
	cd sources ; tar -xvf ../archives/busybox.tar.bz2
# Clean and dist-clean functions. 
clean: reset
	rm -rvf sources
reset:
	rm -rfv isowork rootfs initramfs
	make build_rootfs
dist-clean: clean
	rm -rvf archives

# Build functions
build: build_rootfs build_busybox build_linux 

build_initramfs:
	mkdir -p initramfs/bin initramfs/lib initramfs/hooks

build_rootfs: build_isowork build_initramfs
	mkdir -p rootfs/bin rootfs/lib rootfs/etc rootfs/dev rootfs/sys rootfs/proc rootfs/run rootfs/tmp

build_isowork:
	mkdir -p isowork/boot/grub/

build_busybox:
	make defconfig -C sources/busybox-$(BUSYBOX_VERSION)
	sed -i "s|.*CONFIG_STATIC.*|CONFIG_STATIC=y|" sources/busybox-$(BUSYBOX_VERSION)/.config
	make busybox install -C sources/busybox-$(BUSYBOX_VERSION)/ -j`nproc`

build_linux:
	# Enable all modules and embed into vmlinuz
	#make mrproper allyesconfig -C sources/linux-$(KERNEL_VERSION)/ -j`nproc`
	# Use defconfig
	make mrproper defconfig -C sources/linux-$(KERNEL_VERSION)/ -j`nproc`
	# enable some modules
	for config in CONFIG_OVERLAY_FS CONFIG_SQUASHFS CONFIG_HFSPLUS_FS ; do \
	sed -i "s/# $$config is not set/$$config=y/g" sources/linux-$(KERNEL_VERSION)/.config ; \
	done
	make bzImage -C sources/linux-$(KERNEL_VERSION)/ -j`nproc`
	make modules -C sources/linux-$(KERNEL_VERSION)/ -j`nproc`

# install_functions

install: install_busybox install_linux install_rootfs install_isowork

install_initramfs:
	echo '#!/bin/busybox ash' > initramfs/init
	echo '/bin/busybox --install -s /bin' >> initramfs/init
	echo 'set -xe' >> initramfs/init
	echo 'mkdir /dev /sys /proc /run /tmp || true' >> initramfs/init
	echo 'mount -t devtmpfs none /dev' >> initramfs/init
	echo 'mount -t proc none /proc' >> initramfs/init
	echo 'mount -t sysfs none /sys' >> initramfs/init
	echo 'for hook in $$(ls /hooks) ; do' >> initramfs/init
	echo '    ash /hooks/$$hook || true' >> initramfs/init
	echo 'done' >> initramfs/init
	echo 'setsid cttyhack /bin/sh' >> initramfs/init

install_busybox:
	install sources/busybox-$(BUSYBOX_VERSION)/busybox initramfs/bin/busybox
	install sources/busybox-$(BUSYBOX_VERSION)/busybox rootfs/bin/busybox
	rootfs/bin/busybox --list | grep -v busybox | while read applet ; do \
	  cp /bin/busybox rootfs/bin/$$applet ; \
	done

MODDIR=lib/modules/$(KERNEL_VERSION)
WORKDIR=initramfs/
install_linux:
	install sources/linux-$(KERNEL_VERSION)/arch/x86/boot/bzImage isowork/linux
	make -C sources/linux-$(KERNEL_VERSION) modules_install INSTALL_MOD_PATH="$$(pwd)/rootfs"  INSTALL_MOD_STRIP=1
	mkdir -p $(WORKDIR)/$(MODDIR) || true
	cp -prvf rootfs/$(MODDIR)/kernel/{crypto,fs,lib,block} $(WORKDIR)/$(MODDIR) || true
	cp -prvf rootfs/$(MODDIR)/kernel/drivers/input/{keyboard,serio} $(WORKDIR)/$(MODDIR) || true
	cp -prvf rootfs/$(MODDIR)/kernel/drivers/{ata,md,mmc,firewire} $(WORKDIR)/$(MODDIR) || true
	cp -prvf rootfs/$(MODDIR)/kernel/drivers/{scsi,pcmcia,virtio,cdrom} $(WORKDIR)/$(MODDIR) || true
	cp -prvf rootfs/$(MODDIR)/kernel/drivers/usb/ $(WORKDIR)/$(MODDIR) || true
	cp -prvf rootfs/$(MODDIR)/kernel/drivers/acpi/ $(WORKDIR)/$(MODDIR) || true
	# Some kernels not have this directories.
	cp -prvf ${MODDIR}/kernel/drivers/{block,cdrom}/ $(WORKDIR)/$(MODDIR) || true
	echo '#!/bin/busybox ash' > initramfs/hooks/00-modules
	echo 'find /lib/modules/*/fs/ -type f | sed "s/.*\///g" | sed "s/^/modprobe /g" | sed "s/\.ko//g" | sed "s/$$/ &/g" > /fs' >> initramfs/hooks/00-modules
	echo 'sh /fs &>/dev/null' >> initramfs/hooks/00-modules
	echo 'find /lib/modules/*/crypto/ -type f | sed "s/.*\///g" | sed "s/^/modprobe /g" | sed "s/\.ko//g" | sed "s/$$/ &/g" > /crypto' >> initramfs/hooks/00-modules
	echo 'sh /crypto &>/dev/null' >> initramfs/hooks/00-modules
	echo 'cd /$(MODDIR)' >> initramfs/hooks/00-modules
	echo 'find  crypto lib block ata md firewire scsi \' >> initramfs/hooks/00-modules
	echo 'message pcmcia virtio host storage \' >> initramfs/hooks/00-modules
	echo '-type f 2> /dev/null | sed "s/.*\///g" | grep "\.ko" | sed "s/.ko.*/ &/g" | sed "s/^/modprobe /g"> /load_modules.sh' >> initramfs/hooks/00-modules
	echo 'sh /load_modules.sh &>/dev/null' >> initramfs/hooks/00-modules
	echo 'mdev -s &>/dev/null' >> initramfs/hooks/00-modules



install_rootfs: install_initramfs
	# Live hook
	echo '#!/bin/busybox ash' > initramfs/hooks/99-live
	echo 'set -xe' >> initramfs/hooks/99-live
	echo 'mkdir /rootfs /source /a /b /live-root' >>  initramfs/hooks/99-live
	echo 'while [ "$$root" == "" ] ; do' >> initramfs/hooks/99-live
	echo '  for disk in $$(ls /sys/class/block/ | grep ".*[0-9]$$" | grep -v loop | grep -v ram | grep -v nbd | sed "s|^|/dev/|g") ; do' >>  initramfs/hooks/99-live
	echo '    mount -o ro $$disk /tmp || true' >>  initramfs/hooks/99-live
	echo '    [ -f /tmp/main.sfs ] && root=$$disk' >>  initramfs/hooks/99-live
	echo '    umount -lf /tmp || true' >>  initramfs/hooks/99-live
	echo '    sleep 0.3' >>  initramfs/hooks/99-live
	echo '  done' >>  initramfs/hooks/99-live
	echo 'done' >>  initramfs/hooks/99-live
	echo 'mount $$root /source' >>  initramfs/hooks/99-live
	echo 'mount /source/main.sfs /live-root' >>  initramfs/hooks/99-live
	echo 'mount -t overlay -o lowerdir=/live-root/,upperdir=/a/,workdir=/b overlay /rootfs' >> initramfs/hooks/99-live
	echo 'for dir in dev sys proc tmp run ; do' >> initramfs/hooks/99-live
	echo '  mount --bind $$dir /rootfs/$$dir' >> initramfs/hooks/99-live
	echo 'done' >> initramfs/hooks/99-live
	echo 'exec chroot /rootfs /bin/init' >> initramfs/hooks/99-live
	# profile file
	echo '#!/bin/ash' > rootfs/etc/profile
	echo 'echo -e "\033[32;1mWelcome to minimal linux-$$(uname -r) live\033[0m"' >> rootfs/etc/profile
	echo 'echo -e "Build source code: \033[31;1m/etc/build-live.mk\033[0m"' >> rootfs/etc/profile
	install Makefile rootfs/etc/build-live.mk
	
install_isowork:
	# fallback service manager
	echo "#!/bin/ash" > rootfs/bin/init
	echo "clear" >> rootfs/bin/init
	echo "source /etc/profile" >> rootfs/bin/init
	echo "setsid cttyhack /bin/sh" >> rootfs/bin/init
	chmod 755 rootfs/bin/init
	chmod 755 initramfs/hooks/*
	chmod 755  initramfs/init
	cd initramfs ; find . | cpio -R root:root -H newc -o > ../isowork/initramfs
	echo 'menuentry minimal {' > isowork/boot/grub/grub.cfg
	echo '  linux /linux quiet' >> isowork/boot/grub/grub.cfg
	echo '  initrd /initramfs' >> isowork/boot/grub/grub.cfg
	echo '}' >> isowork/boot/grub/grub.cfg
	# create sfs file
	mksquashfs rootfs isowork/main.sfs -comp gzip -wildcards
	grub-mkrescue isowork -o minimal.iso