starnight / build-image

Build a Linux distribution based on Alpine

build-image

Build a Linux distribution based on Alpine with GitHub CI

This is mentioned in the talk Launch the First Process in Linux System.

Use the QEMU image for Example

1. Download the compressed image & checksum from the Releases and verify the image with the checksum.

$ ls simple-alpine-qemu_aarch64.img.xz*
simple-alpine-qemu_aarch64.img.xz  simple-alpine-qemu_aarch64.img.xz.sha512
$ sha512sum -c simple-alpine-qemu_aarch64.img.xz.sha512
simple-alpine-qemu_aarch64.img.xz: OK

2. Decompress the image as the RAW disk image.

$ unxz simple-alpine-qemu_aarch64.img.xz
$ ls simple-alpine-qemu_aarch64.img
simple-alpine-qemu_aarch64.img

3. List the partitions of the RAW disk image.

$ fdisk -l simple-alpine-qemu_aarch64.img
Disk simple-alpine-qemu_aarch64.img: 256 MiB, 268435456 bytes, 524288 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x69aba5f7

Device                          Boot  Start    End Sectors  Size Id Type
simple-alpine-qemu_aarch64.img1 *      2048 206847  204800  100M  c W95 FAT32 (LBA)
simple-alpine-qemu_aarch64.img2      206848 524287  317440  155M 83 Linux

The 1st partition is the boot partition, but not used. The 2nd partition holds Root Filesystem. The layout is according to the platform and case by case actually. 4. Run a QEMU aarch64 VM with the RAW disk image and the built kernel image.

$ qemu-system-aarch64 \
	-smp 2 \
	-M virt \
	-cpu cortex-a57 \
	-m 1G \
	-kernel <built aarch64 kernel> \
	--append "console=ttyAMA0 root=/dev/vda2 rw rootfstype=ext4" \
	-hda simple-alpine-qemu_aarch64.img \
	-serial stdio

The RISC-V 64 bits image can be used in the same way:

$ qemu-system-riscv64 -smp 4 \
    -M virt \
    -m 2G \
    -kernel <built riscv64 kernel> \
    -append "root=/dev/vda2 rw rootfstype=ext4" \
    -drive file=simple-alpine-qemu_riscv64.img,format=raw,id=hd0 \
    -device virtio-blk-device,drive=hd0 \
    -netdev user,id=eth0 \
    -device virtio-net-device,netdev=eth0 \
    -serial stdio