kumquat-buildroot/board/pc/post-image-efi-gpt.sh
Carlos Santos fee29b05bb configs/pc_x86_64_efi: use a GPT partition table
Since all EFI-based systems support GPT, this commit changes
pc_x86_64_efi to use a GPT partition table. It shows an example of how
to craft a disk image with GPT partitioning instead of MBR. This is
achieved by means of a post-image script which uses
mkdosfs+mcopy+sfdisk, since genimage is unable to deal with GPT. Long
term, it would be ideal if genimage had GPT support, but until then,
this script shows how to achieve creating a GPT-based disk image.

The script was kept as simple as possible to make it easy to understand
and adapt for other purposes.

The root filesystem location is passed to the kernel by a partition
UUID, so it is possible to boot on QEMU, directly from the disk image,
or dump the image to a physical device.

Signed-off-by: Carlos Santos <casantos@datacom.com.br>
Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
2019-02-06 17:40:28 +01:00

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#!/bin/sh
set -e
cd ${BINARIES_DIR}
# GPT partition type UUIDs
esp_type=c12a7328-f81f-11d2-ba4b-00a0c93ec93b
linux_type=44479540-f297-41b2-9af7-d131d5f0458a
# Partition UUIDs
efi_part_uuid=$(uuidgen)
root_part_uuid=$(uuidgen)
# Boot partition offset and size, in 512-byte sectors
efi_part_start=64
efi_part_size=32768
# Rootfs partition offset and size, in 512-byte sectors
root_part_start=$(( efi_part_start + efi_part_size ))
root_part_size=$(( $(stat -c %s rootfs.ext2) / 512 ))
first_lba=34
last_lba=$(( root_part_start + root_part_size ))
# Disk image size in 512-byte sectors
image_size=$(( last_lba + first_lba ))
cat > efi-part/EFI/BOOT/grub.cfg <<EOF
set default="0"
set timeout="5"
menuentry "Buildroot" {
linux /bzImage root=PARTUUID=$root_part_uuid rootwait console=tty1
}
EOF
# Create EFI system partition
rm -f efi-part.vfat
dd if=/dev/zero of=efi-part.vfat bs=512 count=0 seek=$efi_part_size
mkdosfs efi-part.vfat
mcopy -bsp -i efi-part.vfat efi-part/startup.nsh ::startup.nsh
mcopy -bsp -i efi-part.vfat efi-part/EFI ::EFI
mcopy -bsp -i efi-part.vfat bzImage ::bzImage
rm -f disk.img
dd if=/dev/zero of=disk.img bs=512 count=0 seek=$image_size
sfdisk disk.img <<EOF
label: gpt
label-id: $(uuidgen)
device: /dev/foobar0
unit: sectors
first-lba: $first_lba
last-lba: $last_lba
/dev/foobar0p1 : start=$efi_part_start, size=$efi_part_size, type=$esp_type, uuid=$efi_part_uuid, name="efi-part.vfat"
/dev/foobar0p2 : start=$root_part_start, size=$root_part_size, type=$linux_type, uuid=$root_part_uuid, name="rootfs.ext2"
EOF
dd if=efi-part.vfat of=disk.img bs=512 count=$efi_part_size seek=$efi_part_start conv=notrunc
dd if=rootfs.ext2 of=disk.img bs=512 count=$root_part_size seek=$root_part_start conv=notrunc