Dualbooting with Windows
This guide aims to make it easy to dual-boot MassOS and Windows on the same system. It includes answers to common questions regarding dual-booting, and how to fix common issues that are experienced when setting up a dual-boot.
There exists a known bug with the os-prober package, whereby it is unable to detect a UEFI Windows installation while in a chroot environment (Legacy BIOS installations are unaffected). As a result, Windows does not get added as a boot entry to the GRUB menu like it should. This is not a bug specific to MassOS, and in fact it has been reported on many distros, including the following:
- https://www.reddit.com/r/archlinux/comments/10gyqjs/osprober_wont_detect_windows/
- https://www.reddit.com/r/artixlinux/comments/ldg00f/osprober_not_detecting_windows_in_the_chroot/
Since a chroot environment has to be used during the installation process (as the system is not fully installed at that point), there is no way to solve this problem. However, you can simply re-run the GRUB bootloader configuration command after the installation has finished and once you are booted into your new MassOS installation:
sudo grub-mkconfig -o /boot/grub/grub.cfg
After doing so, Windows will be correctly detected by os-prober, and the Windows boot entry will appear as Windows Boot Manager (on /dev/<XYZ>).
Optionally, if you wish to make Windows the "default" boot option in GRUB, instead of MassOS, then you can do so by editing the file /etc/default/grub, and changing the following line:
GRUB_DEFAULT=0
Change it to:
GRUB_DEFAULT=2
Save the changes to the file and exit the editor, and then re-generate your GRUB configuration file with the following command:
sudo grub-mkconfig -o /boot/grub/grub.cfg
After you reboot, the Windows boot option should be highlighted by default, and will boot automatically when the menu timer reaches 0 if you do not interrupt it using the arrow keys.
You must disable fast startup under Windows, to ensure that your Windows NTFS partition can be properly accessed from within MassOS. This is because, when fast startup is enabled, the volume is put into a "hibernated" state. While the newer kernel-based NTFS3 driver does support hibernated NTFS partitions, the older FUSE-based ntfs-3g driver does not. Nonetheless, even if you are using the kernel-based NTFS3 driver, disabling fast startup under Windows can still improve system stability in your dual-boot environment. To do this, enter the Windows control panel by pressing Windows Key + R, and type control in the box.
Select Hardware and Sound.
Under Power Options, select Change what the power buttons do.
Select Change settings that are currently unavailable.
Uncheck Turn on fast start-up.
Select Save changes and then restart your system. Fast startup will no longer be enabled, and your Windows NTFS volume should have full functionality under MassOS.
This is a known problem that can occur when dual-booting Windows with a Unix-like operating system (including MassOS, which is a GNU/Linux distribution). The problem occurs because Windows expects the system's hardware clock to be set to local time, whereas Unix expects the system's hardware clock to be set to UTC (and will automatically adjust the software clock based on your timezone).
When you install MassOS, it will set the hardware clock to UTC if it was previously set to local time. While it is possible to make GNU/Linux work with local time, it is strongly preferable (for reasons discussed below) to instead make Windows work with UTC. This can be done by creating a registry entry. In Windows, press Windows Key + R, and type regedit in the box, to open the registry editor.
Now head to the following location:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation
Create a new DWORD value in this location, named RealTimeIsUniversal, and give it the value of 1.
Save and exit the registry, then restart your computer. Windows should now display the time correctly.
NOTE: On Windows versions older than Windows 10, the above registry entry may not work. If this is the case, then re-create it as a QWORD value instead of a DWORD. However, this should not be needed on Windows 10 and newer, and the DWORD should work fine here.
Ubuntu and Fedora, two widely-recognised and commercially-backed distributions, do configure themselves to use local time if they detect Windows to be installed on the system. While in the short term this could be considered more "convenient", it causes numerous problems in the long run, especially if your country/region observes daylight saving time, and can cause time syncing issues under GNU/Linux, and can harm portability. Creating a registry entry is not difficult, however, as shown above, so is recommended to be done. Ubuntu and Fedora deviate from the norm in the name of "user convenience", yet in doing so, they completely disregard safety and compatibility issues which can arise from making GNU/Linux work with local time. If you are running one of these distros, you can force them switch to UTC by the running the following command:
sudo timedatectl set-local-rtc 0