Howto boot Alpine Xen dom0 with EFI¶

This guide will create an installation of diskless Alpine with Xen dom0 support, bootable with EFI.

Create EFI bootable dom0 medium¶

NOTE: the official Alpine installation medium doesn't support EFI, so create the installed medium by booting it with BIOS/compatibility mode.

This guide assumes alpine-xen-3.6.2-x86_64.iso is used as boot medium, and is booted before continuing.

Partition disk¶

Set up internet connectivity and configure to use an Alpine repository mirror:

$ ifconfig eth0 up
$ udhcpc eth0
$ setup-apkrepos
$ apk update

Assumptions:

1. The destination disk is at /dev/sda.
2. The size of the dom0 disk is 1GiB.
3. The dom0 disk and EFI ESP is the same partition.

$ modprobe vfat
$ apk add parted dosfstools
$ parted /dev/sda
(parted) mklabel gpt
(parted) mkpart ESP fat32 1MiB 1GiB
(parted) set 1 boot on
(parted) quit
$ mkfs.vfat /dev/sda1

Setup diskless Alpine¶

$ apk add syslinux
$ setup-bootable /dev/cdrom /dev/sda1

Install EFI bootloader¶

This uses Gummiboot as bootloader, which is deprecated but the only way with Xen 4.8. Xen 4.9 supports multiboot2, making it possible to use GRUB2 instead, and avoiding creating the configuration for xen.efi.

$ apk add gummiboot
$ mount -t vfat /dev/sda1 /media/sda1
$ mkdir -p /media/sda1/EFI/boot /media/sda1/loader/entries
$ cp /usr/lib/gummiboot/gummibootx64.efi /media/sda1/EFI/boot/bootx64.efi

Configure gummiboot¶

Gummiboot will be configured with two boot options: linux-hardened (without Xen) and xen.

TODO: The options below could be read from /etc/update-extlinux.conf

Create file /media/sda1/loader/entries/linux-hardened.conf:

linux /boot/vmlinuz-hardened
initrd /boot/initramfs-hardened
options modules=loop,squashfs,sd-mod,usb-storage quiet nomodeset

Create file /media/sda1/loader/entries/xen.conf:

efi /boot/xen.efi

NOTE: The first boot will be without Xen, to setup Xen properly first.

Create file /media/sda1/loader/loader.conf:

default linux-hardened
timeout 5

Reboot into UEFI¶

Reboot the machine and make sure it boots via UEFI and not BIOS.

Setup Xen dom0¶

Refer to the base dom0 guide: alpine_dom0

Setup base system¶

$ setup-alpine
$ lbu commit

Install Xen¶

$ apk add xen xen-hypervisor
$ lbu commit

Copy Xen boot files¶

NOTE: due to a bug in current Xen APKBUILD, the Xen efi files are stored in /usr/lib64/efi/xen. See PR aports#1513 for discussion.

NOTE: since symlinks isn't supported on vfat, this wastes quite some space...

TODO: this needs to be run upon Xen updates, so should be put in a script and run with update-kernel.

$ mount -o remount,rw /media/sda1
$ cp -f /usr/lib64/efi/xen* /media/sda1/boot/

Configure Xen EFI bootloader¶

The xen.efi is a bootloader itself, which requires a configuration file. This is easier with Xen 4.9 which has multiboot2 support, but for now it needs to be configured.

TODO: kernel options should also be read from /etc/update-extlinux.conf instead.

Create /media/sda1/boot/xen.cfg:

[global]
default=XEN-linux-hardened

[XEN-linux-hardened]
options=dom0_mem=1024M
kernel=vmlinuz-hardened modules=loop,squashfs,sd-mod,usb-storage quiet nomodeset
ramdisk=initramfs-hardened

Set Xen as default boot¶

Set Xen as the default Gummiboot target.

In /media/sda1/loader/loader.conf:

default xen
timeout 5

Reboot into Xen¶

$ reboot

Setup Xen dom0 essentials¶

The system is now like a Xen dom0 system booted with BIOS.

$ setup-xen-dom0
$ lbu commit