mirror of
https://github.com/linuxkit/linuxkit.git
synced 2025-07-19 09:16:29 +00:00
133 lines
4.0 KiB
Bash
Executable File
133 lines
4.0 KiB
Bash
Executable File
#!/bin/sh
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set -e
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# for debugging
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[ -n "$DEBUG" ] && set -x
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IMGFILE=$PWD/disk.img
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# we want everything except the final result to stderr
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( exec 1>&2;
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ESP_FILE=$PWD/boot.img
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# get the GRUB2 boot file name
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ARCH=${TARGETARCH:-`uname -m`}
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case $ARCH in
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x86_64)
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BOOTFILE=BOOTX64.EFI
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;;
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aarch64)
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BOOTFILE=BOOTAA64.EFI
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;;
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esac
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mkdir -p /tmp/efi
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cd /tmp/efi
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# input is a tarball on stdin with kernel and cmdline in /boot
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# output is an iso on stdout
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# extract. BSD tar auto recognises compression, unlike GNU tar
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# only if stdin is a tty, if so need files volume mounted...
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[ -t 0 ] || bsdtar xzf -
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INITRD="$(find . -name '*.img')"
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KERNEL="./kernel"
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CMDLINE_FILE="$(find . -name cmdline)"
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CMDLINE="$(cat $CMDLINE_FILE )"
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# PARTUUID for root
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PARTUUID=$(cat /proc/sys/kernel/random/uuid)
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cp /usr/local/share/$BOOTFILE .
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mkdir -p EFI/BOOT
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cat >> EFI/BOOT/grub.cfg <<EOF
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set timeout=0
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set gfxpayload=text
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menuentry 'LinuxKit ISO Image' {
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linux /kernel ${CMDLINE} text
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initrd /initrd.img
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}
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EOF
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# FAT filesystem config
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FAT_SIZE=32
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SECTOR_SIZE=512
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SECTORS_PER_CLUSTER=8
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# these always include the Boot Sector and FS Information Sector (sector 0 and 1) among others for FAT32
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RESERVED_SECTORS=32
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# calculate sizes
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KERNEL_FILE_SIZE=$(stat -c %s "$KERNEL")
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INITRD_FILE_SIZE=$(stat -c %s "$INITRD")
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EFI_FILE_SIZE=$(stat -c %s "$BOOTFILE")
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GRUB_FILE_SIZE=$(stat -c %s EFI/BOOT/grub.cfg)
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# this is the minimum size of our EFI System Partition
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ESP_DATA_SIZE=$(( $KERNEL_FILE_SIZE + $INITRD_FILE_SIZE + $EFI_FILE_SIZE + $GRUB_FILE_SIZE ))
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ESP_DATA_SECTORS=$(( $ESP_DATA_SIZE / $SECTOR_SIZE ))
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# File Allocation Table Sectors = (clusters + 2) * bytes per cluster / sector size
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FILE_ALLOCATION_TABLE_SECTORS=$(( ( $ESP_DATA_SECTORS / $SECTORS_PER_CLUSTER + 2 ) * ( $FAT_SIZE / 8 ) / $SECTOR_SIZE ))
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# there are two file allocation tables hence 2 * $FILE_ALLOCATION_TABLE_SECTORS
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FAT_OVERHEAD_SECTORS=$(( $RESERVED_SECTORS + ( 2 * $FILE_ALLOCATION_TABLE_SECTORS ) ))
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FAT_OVERHEAD_SIZE=$(( $FAT_OVERHEAD_SECTORS * $SECTOR_SIZE ))
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# (x+1024)/1024*1024 rounds up to multiple of 1024KB, or 2048 sectors
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# some firmwares get confused if the partitions are not aligned on 2048 blocks
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# we will round up to the nearest multiple of 2048 blocks
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# since each block is 512 bytes, we want the size to be a multiple of
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# 2048 blocks * 512 bytes = 1048576 bytes = 1024KB
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ESP_FILE_SIZE_KB=$(( ( ( ($ESP_DATA_SIZE + $FAT_OVERHEAD_SIZE + 1024 - 1) / 1024 ) + 1024 - 1) / 1024 * 1024 ))
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# and for sectors
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ESP_FILE_SIZE_SECTORS=$(( $ESP_FILE_SIZE_KB * 1024 / $SECTOR_SIZE ))
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# create a raw disk with an EFI boot partition
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# Stuff it into a FAT filesystem, making it as small as possible.
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mkfs.vfat -v -F $FAT_SIZE -S $SECTOR_SIZE -s $SECTORS_PER_CLUSTER -R $RESERVED_SECTORS -C $ESP_FILE $(( $ESP_FILE_SIZE_KB )) > /dev/null
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echo "mtools_skip_check=1" >> /etc/mtools.conf && \
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mmd -i $ESP_FILE ::/EFI
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mmd -i $ESP_FILE ::/EFI/BOOT
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mcopy -i $ESP_FILE $BOOTFILE ::/EFI/BOOT/
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mcopy -i $ESP_FILE EFI/BOOT/grub.cfg ::/EFI/BOOT/
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mcopy -i $ESP_FILE $KERNEL ::/
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mcopy -i $ESP_FILE $INITRD ::/
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# now make our actual filesystem image
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# how big an image do we want?
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# it should be the size of our ESP file+1MB for BIOS boot + 1MB for MBR + 1MB for GPT
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ONEMB=$(( 1024 * 1024 ))
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SIZE_IN_BYTES=$(( $(stat -c %s "$ESP_FILE") + 4*$ONEMB ))
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# and make sure the ESP is bootable for BIOS mode
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# settings
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BLKSIZE=512
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MB_BLOCKS=$(( $SIZE_IN_BYTES / $ONEMB ))
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# make the image
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dd if=/dev/zero of=$IMGFILE bs=1M count=$MB_BLOCKS
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ESP_SECTOR_START=2048
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ESP_SECTOR_END=$(( $ESP_SECTOR_START + $ESP_FILE_SIZE_SECTORS - 1 ))
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# create the partitions - size of the ESP must match our image
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# and make sure the ESP is bootable for BIOS mode
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sgdisk --clear \
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--new 1:$ESP_SECTOR_START:$ESP_SECTOR_END --typecode=1:ef00 --change-name=1:'EFI System' --partition-guid=1:$PARTUUID \
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--attributes 1:set:2 \
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$IMGFILE
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# copy in our EFI System Partition image
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dd if=$ESP_FILE of=$IMGFILE bs=$BLKSIZE count=$ESP_FILE_SIZE_SECTORS conv=notrunc seek=$ESP_SECTOR_START
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)
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cat $IMGFILE
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