hypersolid hybrid uefi/bios bootloader for baremetal systems

boot hypersolid via syslinux efi+mbr

Use syslinux/syslinux as bootloader to load hypersolid from removable devices.

Features

• hybrid boot support
• legacy/mbr mode
• efi mode
• dual system partitions (primary and backup)

How to deploy

Write the image directly to the device via dd

# extract image and write to disk
gzip -d -c boot.img.gz | dd bs=4M status=progress of=/dev/sdX

# create new uuid's and rewrite secondary GPT table to the end of the disk
sgdisk -G /dev/sdX && sync

Add system image

You can directly add the hypersolid kernel/initramfs/system images to the build by adding them into the image/ directory. They are automatically copied into the final partition image.

It can be used to create a rescue image.

image/
├── initramfs.img
├── kernel.img
└── system.img

Partition layout

The following GPT based partition layout is used (of course, syslinux can handle ext2 on gpt including legacy/mbr mode).

• Partition 1 "bootloader" - 50MB | FAT32 | syslinux efi+legacy loader ons esp partition including kernel+initramfs(1)
• Partition 2 "system0" - 2GB | EXT4 | hypersolid system0 partition including system.img
• Partition 3 "system1" - 2GB | EXT4 | hypersolid system1 partition including system.img
• Partition 4 "conf" - 512MB | EXT4 | hypersolid persistent storage
• Partition 5 "swap" - 4GB | EXT4 | swap (optional)
• Partition 6 "data" - XGB | EXT4 | persistent storage (optional)

Build the image

This bootloader-generator creates a raw GPT disk image with 4 paritions (boot, config) including all required bootloader files + configs. The build environment is isolated within a docker container but requires full system access (privileged mode) due to the use of loop devices.

Just run build.sh to build the docker image and trigger the image build script. The disk image will be copied into the dist/ directory.

 $ ./build.sh 

Boot stages

legacy bios/mbr

0. host system loads the initial bootloader (e.g. SeaBIOS) | hostsystem
1. BIOS loads the MBR bootcode (gptmbr.bin) at the start of the root disk | syslinux-stage1
2. syslinux mbr code searches for the first active partition | syslinux-stage1
3. syslinux mbr code executes the volume boot records of the active partition (contains the inode address of ldlinux.sys) | syslinux-stage2
4. syslinux loads the rest of ldlinux.sys | syslinux-stage3
5. syslinux loads ldlinux.c32 core bootloader module | syslinux-stage4
6. syslinux core module searches for the configuration file syslinux/syslinux.cfg and loads it | syslinux-stage5
7. syslinux loads kernel.img and initramfs.ing into ramdisk | syslinux-stage6
8. syslinux executes the kernel.img code | kernel-stage1

efi

0. host system loads the initial UEFI bootloader | hostsystem
1. EFI loader loads+executes syslinux image efi/boot/bootx64.efi | hostsystem
2. syslinux loads ldlinux.e64 core bootloader module | syslinux-stage1
3. syslinux core module searches for the configuration file efi/boot/syslinux.cfg and loads it | syslinux-stage2
4. syslinux loads kernel.img and initramfs.ing into ramdisk | syslinux-stage3
5. syslinux executes the kernel.img code | kernel-stage1

Serial Console

To enable the serial console (syslinux bootloader + kernel) just add the SERIAL directive as first line to your syslinux config and append the console option the kernel options.

Example

SERIAL 0 115200
DEFAULT linux
    SAY [BIOS/MBR] - booting debian kernel from SYSLINUX...
LABEL linux
    KERNEL ../kernel.img
    APPEND root=PARTLABEL=system0 pstorage=PARTLABEL=rescue-conf ro console=tty0 console=ttyS0,115200n8
    INITRD ../initramfs.img

License

hypersolid is OpenSource and licensed under the Terms of GNU General Public Licence v2. You're welcome to contribute!