bochs.bochsrc

romimage: file=BIOS-bochs-latest, options=fastboot

vgaromimage: file=VGABIOS-lgpl-latest

cpu: count=1, ips=10000000, model=corei5_arrandale_m520
  
megs: 256

display_library: sdl2

ata0-master: type=disk, mode=flat, biosdetect=auto, translation=auto, path="disk.img", cylinders=0, heads=0, spt=0

boot: disk

log: bochsout.txt

mouse: enabled=0

create-min-linux-disk-image.sh

#!/usr/bin/bash
# create disk image that could be used with qemu or written to real hardware. No efi, MBR only
set -e
if [ $(id -u) -ne 0 ]; then
    echo run as root
    exit -1
fi
#set -x #echo commands as they executing
DISK_SIZE_BYTES=$((1024 * 1024 * 32)) #32MB total image sizes
DISK_FILE_NAME=disk.img
LODEVICE=$(losetup -f)
SYS_MOUNTPOINT=$(mktemp -d)
BUSYBOX_PATH=busybox/busybox-1.37.0/busybox
LINUX_KERN_PATH=linux/linux-6.18.1/arch/x86/boot/bzImage

function cleanup {
  set +e
  # unmount everything
  umount $SYS_MOUNTPOINT 2> /dev/null
  losetup -d $LODEVICE
  chmod 775 $DISK_FILE_NAME
  if [[ -v SUDO_USER ]]; then
    chown $SUDO_USER:$SUDO_USER $DISK_FILE_NAME
  fi
}

trap cleanup EXIT

dd if=/dev/zero of=$DISK_FILE_NAME bs=512 count=$((($DISK_SIZE_BYTES + 511) / 512)) status=none # create empty file which size is a multiple of 512
losetup $LODEVICE $DISK_FILE_NAME # mount image to loop dev
parted $LODEVICE mktable msdos --script #create mbr partition table
parted $LODEVICE mkpart primary fat32 512KB 100% --script #create system partition
parted $LODEVICE set 1 boot on --script #mark bootpartition
mkfs.vfat $LODEVICE"p1" > /dev/null #format sys partition
mount $LODEVICE"p1" $SYS_MOUNTPOINT
grub-install --target=i386-pc --modules="part_msdos fat" --install-modules="search linux echo halt" --boot-directory $SYS_MOUNTPOINT/boot --fonts="ascii" $LODEVICE > /dev/null

ROOT_FS_UUID=$(blkid -s UUID -o value $LODEVICE"p1")

#copy kernel
cp $LINUX_KERN_PATH $SYS_MOUNTPOINT/boot

#create+copy ramdisk
RAMDISK_TMPDIR=$(mktemp -d)

cat << INIT > $RAMDISK_TMPDIR/init
#! /bin/sh
mount -t sysfs sysfs /sys
mount -t proc proc /proc
mount -t devtmpfs udev /dev
sysctl -w kernel.printk="2 4 1 7"
/bin/sh
poweroff -f
INIT

chmod 777 $RAMDISK_TMPDIR/init
mkdir -p $RAMDISK_TMPDIR/bin
mkdir -p $RAMDISK_TMPDIR/dev
mkdir -p $RAMDISK_TMPDIR/proc
mkdir -p $RAMDISK_TMPDIR/sys
cp $BUSYBOX_PATH $RAMDISK_TMPDIR/bin/busybox
for prog in $($RAMDISK_TMPDIR/bin/busybox --list); do
	ln -s /bin/busybox $RAMDISK_TMPDIR/bin/$prog;
done

(cd $RAMDISK_TMPDIR && find .) | cpio -D $RAMDISK_TMPDIR -o -H newc | xz -9 --check=crc32 > $SYS_MOUNTPOINT/boot/initrd.img
cp $SYS_MOUNTPOINT/boot/initrd.img .
#create grub config
cat << GRUB > $SYS_MOUNTPOINT/boot/grub/grub.cfg
set timeout=5
menuentry "Boot this linux" {
	search --no-floppy --set=root --fs-uuid $ROOT_FS_UUID
	linux /boot/$(basename $LINUX_KERN_PATH)
	initrd /boot/initrd.img
}

menuentry "System shutdown" {
	echo "System shutting down..."
	halt
}
GRUB