The title basically says it all. Windows 10 (and 8 and 7) all really don’t play nice with Dual Boot – despite what Microsoft claims.
First, the failure of Windows 7 to handle dual-boot nicely caused some (many) Windows 7 updates to fail on my Lenovo Y480. I kept getting the error where the updates would try to apply, then fail, then roll back and (after a few reboots) Windows 7 would finally start. This in-turn caused the my Windows 7 system to never receive the Windows 10 update notification – which was actually a bit of a blessing.
But finally, in June 2016 I wanted Windows 10. And the Upgrade wouldn’t work; and it would fail if I tried from USB. The installer indicated I would have to start over and would wipe the disk! I even took this computer to the Microsoft Store – where I was promised a free laptop if they couldn’t complete the upgrade in one day (I whined about it on HN). Well, the of course the Microsoft Store couldn’t figure it out – and weaselled out of the free laptop deal.
After I discovered the Windows failure to handle dual boot issue I was able to get my Windows 7 updated. Then I was able to complete the Windows 10 upgrade as well. But, Windows 10 updates still fail – unless one makes special accommodations for Microsoft’s Developer Arrogance.
Dual Boot Fails
What Microsoft understands as “dual boot” means Windows is the Active Partition and nothing else can claim this. A problem for me; see I use syslinux as my bootloader, /dev/sda1 is the bootable partition and it’s formatted with ext2 (yes 2). Windows 7 (and 10) have updates that, for some reason, need to Windows on the bootable partition. Not all updates; only some. On Windows 7 the blocker was some patch to SHA2 and I’m not sure about what causes the issues on Windows 10 – probably all of them.
How to Get Updates to Work
First, at your boot prompt choose Windows. Then in Windows open the Disk Manager and set the Windows partition (/dev/sda3) to be the bootable one (aka: Active Partition). Then reboot, Windows should automatically start. Then wait for the updates and the requisite reboot. Now your Windows 10 is updated! To switch back to your desired bootloader you must boot from some external media, then configure your preferred bootable partition – Windows cannot change the Active Partition back to /dev/sda1 because the Disk Manager is a broken pile of garbage. This was a frustrating path.
Magic MBR from Syslinux
The above process sucks. If you are missing your bootable USB tool then you’ll not be able to switch partitions until you can boot from something smarter than Windows. There is a chain loader in Syslinux but I’ve not been able to get that to work – and trick Windows.
Windows as VM Only
But, if you use a toolkit like VirtualBox or KVM to boot Windows from it’s own partition then everything is great. However, now you cannot go back to booting Windows direct anymore – because Windows is hyper-sensitive to hardware changes.
Windows does not play well with others – NEWS! The work-around is basically allocating dedicated time & resources to running a simple update – or run Windows in a VM – or figure out some bootload trick.