Monday, November 27, 2017

grub2 - Dual-Boot: Win7 partition loads without error, but display doesn't work


I am having a strange dual-boot issue that I haven't been able to find an answer for anywhere. I have an Ubuntu 14.04 box, which I have created a secondary partition on for Win7. My setup process:



  • Boot to Ubuntu USB drive trial, shrink the Ubuntu partition and create NTFS partition, restart

  • Boot to Win7 CD, install, reboot, log into Win7 fine, restart

  • Boot to Ubuntu USB drive trial, run Boot-Repair, restart


Now I get a Grub menu on startup, and can get into Ubuntu no problem. However, trying to access Win7 results in a blank 'purple' screen (color of Grub screen), although I can hear the 'startup music' of Windows 7.


If I boot off the Windows CD again, and run "bootrec /fixboot" from the command line, then I am able to reboot, choose Win7 in Grub, and get into it correctly. HOWEVER, if at any point I go back into Ubuntu, then afterwards I run into the same problem above when trying to access Win7 unless I repeat the CD boot/bootrec step first.


Any ideas as to why accessing my Ubuntu partition keeps rendering my Win7 partition non-accessible?


FURTHER INFO: I tested, and it is not the selection to boot from Ubuntu that causes the subsequent Windows boot to fail. If I do two back-to-back Windows boots, the one after the CD boot/bootrec works (via a "Boot to safe mode or normally" menu), and then the next one fails.



As it turns out on further experimentation, the problem was that I had not yet installed the official graphics drivers for Windows 7 after the initial install. As far as I can tell, the handoff from GRUB to Windows 7 screws up the use of the very basic default graphic drivers to display.


But, as it turns out, if I did anything that would result in the system displaying the "Boot from Safe Mode or Normally" menu, or if I powered off and powered back on and then re-accessed Windows, prompting it to try and resume its previous session, the default graphics drivers were able to take over and work. I was able to use this to get in long enough to install the system-specific graphics drivers, after which it booted repeatedly with no problems.


I'm leaving this here for anyone who has the same problem (or wants to investigate why this happens in the GRUB-Win7 handoff).


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