Booting the Installation
This chapter will explain how to boot the installer from local media or a network server as well as how to navigate the boot menu and use custom options.
Preparing to Boot
After you have made a bootable USB flash drive or a CD or DVD using the steps described in xref:install/Preparing_for_Installation.adoc#sect-preparing-boot-media[Preparing Boot Media], you are ready to boot the installation. Note that the steps described below are generic and the exact steps will vary somewhat depending on your system - particularly on your motherboard manufacturer.
There are no separate media provided for BIOS and UEFI systems; all of them can boot from the same ISO image. However, once you install {PRODUCT}, you cannot switch between UEFI and BIOS. The system must run on the same firmware it was installed on; if you, for example, perform the installation on an UEFI system in UEFI mode, and then switch it to BIOS compatibility mode, {PRODUCT} will no longer boot and will require a reinstallation.
{PRODUCT} does not support UEFI booting for 32-bit x86 systems. Only BIOS boot is supported on these systems.
Also note that {PRODUCT} only fully supports version 2.2 of the UEFI specification. Hardware that supports version 2.3 or later will boot and work normally, but the additional functionality defined by these later specifications will not be available. The UEFI specifications are available from link:++https://www.uefi.org/specs/agreement/++[].
To boot the {PRODUCT} installer, follow these steps:
Booting the {PRODUCT} Installer
Plug in the boot USB drive, or insert the boot CD or DVD into your computer's optical disc drive. Alternatively, if you plan on booting from a network boot (PXE) server, make sure that the network cable is plugged in.
Restart the system. Once it starts rebooting, it should display a prompt similar to the following (usually at the bottom of the screen):
Press F12 to select boot device, or Del to enter SETUP
Follow the on-screen instructions to access the boot menu. If no instructions are displayed (some systems only display a graphical logo during early stages of boot), try pressing kbd:[F12], kbd:[F11], kbd:[F10] or kbd:[Del] several times; these are most commonly used keys. Note that there is usually a very short time window provided to access the menu; once it passes, you need to restart the system and try again.
Some older systems may not support choosing a boot device at startup. In that case, enter the system's SETUP (BIOS), and change the default boot order so that your boot media (CD, DVD, USB or network) has higher priority than internal hard drives.
On Mac hardware, hold down the kbd:[Option] key to enter the boot media selection menu.
When your system's boot menu opens, select an entry such as `Boot from USB` if you created a bootable USB drive, `Boot from CD/DVD` if you are using an optical disc to install {PRODUCT}, or `Boot from PXE` if you want to boot from a network location.
Wait until the boot menu is displayed. The boot menu is described further in this chapter.
The Boot Menu
In most cases, when you boot the {PRODUCT} installer from your prepared boot media or server, the boot menu will be the first thing that appears. From this menu, you can either start the actual installation, or you can use the boot media to rescue an existing system.
The way the boot menu will look and function will vary somewhat depending on your system's firmware - BIOS systems use the [application]*SYSLINUX* boot loader, and UEFI systems use [application]*GRUB2*. However, both of the menus described below function very similarly from a user's point of view.