Windows 10 Technical Preview is the beta version of what will become Windows 10, a major revision of Microsoft’s operating system.
It is being planned for release in the second quarter of this year, but if you sign up as a Windows Insider Program, you can download an ISO image, which weighs in at about 3.9 GB, transfer it to a USB stick or burn it to a suitably-sized DVD disc and install it on a desktop or laptop computer. NOTE: After signing up for that program, I found out that the ISO images can be downloaded without signing up.
I have no interest in using a beta version of a Microsoft’s operating system, but it seems that many people are already downloading and attempting to dual-boot it with their favorite Linux distribution. That got me interested so I joined the Microsoft Insider program, downloaded it and transferred it to a USB stick.
Now, initial attempts to transfer the ISO image to a USB stick on Linux did not produce a bootable USB stick. So I actually had to copy the ISO image from my Linux computer to another computer running Windows 7. From there I used Rufus to transfer it to a USB stick. That minor adventure led to the publication of How to install the latest OpenSSH on Windows 7 and Windows 8.
The whole point of the exercise was to determine if attempting to dual-boot Windows 10 Technical Preview and a Linux distribution on a computer with UEFI firmware will be just as painful as doing so with Windows 8. The rest of this article shows what I found and I offers a tip for those who might want to dual-boot Windows 10 Technical Preview and their favorite Linux distribution.
For whatever reason, the ISO image I downloaded does not have a UEFI-aware installer, so even when it’s installed on a computer with UEFI firmware, the installer does not create GTP partitions. Figure 1 shows the partitions created by the installer. If it had created UEFI/GPT partitions, there would have been a EFI partition of about 135 MB.
And this code block provides confirming evidence that the partitioning scheme used by the Windows 10 Technical Preview installer is MBR. The Disklabel type: dos line (line 10) is the pertinent line. If it where GPT, that line would have read Disklabel type: gpt.
sudo fdisk -l Disk /dev/loop0: 1 GiB, 1115594752 bytes, 2178896 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0xfa766b3a Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 718847 716800 350M 7 HPFS/NTFS/exFAT /dev/sda2 718848 307202047 306483200 146.1G 7 HPFS/NTFS/exFAT
From the Advanced partitioning tool of Ubuntu 14.10, you could clearly see that default Windows 10 partitions – a System partition of about 350 MB and a C drive. Both are, of course, NTFS partitions.
So when I created partitions to use for installing Ubuntu 14.10 alongside Windows 10 Technical Preview on the same hard drive, one of the Ubuntu 14.10 partitions had to be a (extended) logical partition. And the boot loader had to be installed in the Master Boot Record (MBR) of the target hard drive.
So the big tip is this: If you want to dual-boot your favorite Linux distribution and Windows 10 Technical Preview on any computer, whether the computer has UEFI firmware or not, the Windows 10 Technical Preview installer is only capable of creating partitions using an MBR partitioning scheme. And so you should be aware of that when creating partitions for installing any Linux distribution.
Note that this might not necessarily be the case when the final edition of Windows 10 is released. But just something you have to keep in mind before then. If you want to test-drive Windows 10 Technical Preview, ISO images are available for download here.