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Looking for a way to get Windows to boot from the GRUB Windows menu. It may have to do with re-running the MOK menu or tool.

  • I can boot to either O/S but must use UEFI option rather than GRUB Menu option for Windows
  • When booting Windows off the GRUB menu, I get the blue screen stating "no more bitlocker recovery options" and prompting to press the Windows key to return to UEFI options. Reboot follows, I can get to Windows 10 via Boot configuration menu, but unable via GRUB

I may have taken some wrong turns after installing Ubuntu with the Secure Boot options, choosing a password in the installation screen, and finishing up ("remove installation media and press Enter") with the MOK manager dialog appearing once -- I may have chosen "Continue boot" rather than "Enroll MOK"? Perhaps this is causing the issue.

It's not a major deal to dual-boot this way (every time a trip to the UEFI boot config screen). This is a Surface Pro 4 with Windows 10 Pro latest/greatest.

TIA, Alex

AlMo320
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1 Answers1

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The question was asked and correctly answered here: there's no good way to chainload Windows Partitions protected by Bitlocker, because GRUB hasn't learned how to read decryption keys from TPM firmware. That's probably how it needs to stay, and for me it's not a big deal, just a press of the Volume Down key at boot time to access UEFI, getting me into whichever OS I set in Boot configuration in this Surface Pro 4 as default.

AlMo320
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  • Note that his is not about "learning" to read keys. Those keys are not accessible and will never be. The very purpose of the TPM is precisely to prevent accessing keys from a different environment. – spectras Jun 08 '23 at 22:03