kernel-xen.sh: This script builds the Linux Kernel for a Xen Hypervisor.

* Kernel config files found here are based on generic Slackware ones with
  some Xen settings enabled to get it going. Only x86_64 architecture is now
  supported because Xen no longer builds a 32-bit VMM image. This readme is
  by no means complete or a replacement for Linux Kernel and Xen docs.

* To run "make menuconfig" before compiling Xen kernel, use:

  MENUCONFIG=yes ./kernel-xen.sh

* This script will also create an initrd image, with the following defaults:

  ROOTMOD=ext4 ROOTFS=ext4 ROOTDEV=/dev/sda2 ./kernel-xen.sh

* Booting LILO with mbootpack has shown to be unreliable, and the easiest
  method is to use EXTLINUX from Syslinux package. In this example, device
  /dev/sda1 would have an ext2 filesystem mounted to /boot.

  !!! Make sure to understand what are you doing at this point, you could
      easily lose your data. Always create backups !!!

  * To check and set the legacy BIOS bootable flag (bit 2 attribute):

    sgdisk /dev/sda --attributes=1:show
    sgdisk /dev/sda --attributes=1:set:2

  * Install the binary:

    mkdir /boot/extlinux
    extlinux --install /boot/extlinux
    dd if=/usr/share/syslinux/gptmbr.bin of=/dev/sda
    cp -a /usr/share/syslinux/mboot.c32 /boot/extlinux/

  * Edit the /boot/extlinux/extlinux.conf file:

    default XenLinux
    prompt 1
    timeout 50
    label XenLinux
      kernel mboot.c32
      append /xen.gz --- /vmlinuz-xen root=/dev/sda2 nomodeset --- /initrd-xen.gz

* When using GRUB, /boot/grub/menu.lst should looks something like this:

  title Slackware XenLinux 15.0
    root (hd0,0)
    kernel /boot/xen.gz dom0_mem=524288 console=vga
    module /boot/vmlinuz-xen root=/dev/sda2 ro console=tty0 nomodeset
    module /boot/initrd-xen.gz

* Booting Xen on a native EFI system (non-BIOS legacy mode) is probably the
  best option, but the only clean solution at this time requires a modified
  binutils package. More experienced user can add "x86_64-pep" to the list of
  enabled targets and build/replace binutils on their system. Subsequently,
  building Xen will then also create a Xen EFI binary.

  * To make things a bit easier, a copy of Xen EFI binary can be found here:

    http://slackware.hr/~mario/xen/xen-4.16.1.efi.gz

  !!! Make sure to understand what are you doing at this point, you could
      easily lose your data. Always create backups !!!

  * In this example, partition /dev/sda1 with EF or EF00 type, and do:

    mkfs.vfat /dev/sda1
    mkdir /boot/efi
    mount /dev/sda1 /boot/efi

  * Copy/unpack EFI binary to /boot/efi/EFI/BOOT/bootx64.efi and edit
    /boot/efi/EFI/BOOT/bootx64.cfg file to add these:

    [global]
    default=XenLinux
    [XenLinux]
    options=dom0_mem=min:512M,max:512M,512M
    kernel=vmlinuz-xen root=/dev/sda2 ro console=tty0 nomodeset
    ramdisk=initrd-xen.gz

* Many more boot options are supported, this readme covers only some examples!

* Troubleshooting dom0 crashes, freezes, blank screen at boot, etc:

  * Set an out-of-range device id, eg. fbcon=map:9 (Look for more in /proc/fb)
  * Blacklist framebuffer devices (Look in dmesg/lsmod)
  * Compile Linux kernel with CONFIG_FB=n
  * Use a serial cable to see early boot messages
  * Use another VGA card :-)