Xen

Options for config entries for a guest:

name - domain name
builder - the type of domain. generic uses the default, which is a PV domain, with hvm being the second option.
vcpus - number of virtual CPUs to start the guest with
memory - start with # MBs of RAM
on_poweroff - specifics on what to do when a domain shuts itself down:
- destroy - default
- restart
- rename-restart - rename the domain that was created, and create a new one with the same config
- preserve - keep the domain name that was created
on_reboot, on_crash - same options as before
uuid - specify a UUID for the domain; by default Xen creates one

Paravirtulized is the default type of guest emulation.

kernel - location of the kernel image on domain filesystem; this or bootloader must be used
ramdisk - location of the ramdisk on domain filesystem
bootloader - program to run to find the kernel image and ramdisk to use; normally would be pygrub, which is an emulation of either grub, grub2, and syslinux.
bootloader_args
root - value of root= to pass to kernel (fex: root /dev/xvda3 in Xen config becomes root=/dev/xvda3 in kernel command line)
extra - string to append to the kernel command line (fex: acpi=off)

Format: disk = [ “DISK_SPEC_STRING”, “DISK_SPEC_STRING”, … ]

Give the guest read-write access to a device, and set it as /dev/xvda:

disk= [ 'phy:/dev/sdc,xvda,rw' ]

Booting from CD

Same configuration as above, but with an ISO attached, as device /dev/hdc. Note that pygrub will boot from the first device in the list.

disk= [ 'file:/var/isos/gentoo.iso,hdc:cdrom,r', 'phy:/dev/sdc,xvda,rw' ]

If you'd like to boot from the ISO, add this to your Xen guest config:

boot = 'c'