Installing next to Windows or Linux

What it is

Install Alongside puts WolOS on the same disk as Windows or another Linux. It makes the other system's partition smaller (you drag a slider to split the room), adds WolOS's partitions in the freed space, and leaves every file of the other system where it was. At start you choose which system to run.

Why

Sharing a disk is risky when a tool guesses. WolOS reads the disk first (which systems are on it, whether Windows is hibernated or uses BitLocker), shows exactly what changes in the summary, and refuses the cases where shrinking could damage files. The plan names the partitions it may touch; if anything else moves, the install stops (ADR 0023).

How

Before you start

1. Back up what matters. As with any change to a disk, back up first. The installer says so on the Alongside page.
2. Shut Windows down fully. A Windows that is hibernated or was shut down with Fast Startup is refused, so its files cannot be damaged. In Windows turn off Fast Startup, choose Shut down (not Restart), then start the stick.
3. Know your BitLocker state. The installer cannot shrink a BitLocker-protected partition ("BitLocker protects Windows here"). Turn BitLocker off in Windows for that partition, then try again. If Windows keeps BitLocker on and Secure Boot changes, Windows asks once for its recovery key (see below).
4. macOS is not shrunk by the installer. Make room with Disk Utility in macOS, then start the installer again.

In the installer

1. Choose the disk, then Install Alongside. You see "Drag to choose how much room each system gets." The page names each system found on the disk.
2. Drag the slider to split the room. The other system only gets smaller; its files stay. If a partition cannot be shrunk, the page says why in one sentence (see the table below).
3. Continue through encryption, Secure Boot, account and modules as in Installing WolOS.
4. Read the summary. You see "Nothing has changed yet. This is exactly what will happen." It lists what is kept, what is shrunk and what is created. If Windows stays with BitLocker and Secure Boot is on, it also tells you about the BitLocker recovery key.
5. Click Install, wait, and read the last page. You see how to start the other system, for example "To start Windows, open your computer's startup menu while it starts, often with F12, F9 or Esc."

If the disk already holds an earlier WolOS, you can install again over it: the old WolOS's startup files are cleared first and the rest of the disk stays.

Choosing a system at start

• When another system stays on the disk, WolOS's boot menu waits a moment so you can choose.
• When WolOS gets its own startup partition next to Windows', the WolOS menu lists WolOS only, because it cannot reach the other partition. Start Windows from your computer's startup menu, which you open while the computer starts, often with F12, F9 or Esc. The installer's last page says the same, with the other system's name.
• Another system's boot manager can start WolOS too. Most find it on their own; for one that builds its menu from scripts, copy /usr/share/wolos/boot/41_wolos into its menu-script folder and run its menu update. See Boot.

The clock

WolOS keeps the clock in local time when Windows stays, as Windows does, so neither system shows the wrong time after the other has run.

Secure Boot and BitLocker

Secure Boot changes can make Windows ask once for its BitLocker recovery key. When Windows stays with BitLocker on, the Secure Boot page and the Summary tell you before it happens:

• Have the key ready; it is saved at account.microsoft.com/devices/recoverykey.
• To avoid the prompt on a computer in Setup Mode, restore the factory Secure Boot keys in the startup settings first; WolOS then uses a one-time key screen instead.
• On a computer whose Secure Boot trusts only Windows, suspend BitLocker in Windows before you change the startup setting.
• Or leave Secure Boot off in the installer; Windows' keys are then untouched. You can turn it on later (Secure Boot).

If something goes wrong