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Observation of Grub2, Win7-10 upgrade in multiboot

Posted: Thu Jul 30, 2015 4:28 am
by wayne128
Just a record for reference.

System 1.
Multiboot Linux / Win7 on Single Hard Disk.
Grub2, V1.99-27+deb7u2, controlling MBR
Win7 has EasyBCD as boot manager, however, it does not control MBR.


Observation,
As Linux's grub2 is controlling MBR, each time when I need to run Win7 I would need to select Win7 from grub2 start menu, so as to continue upgrading process for Win10.

During Win7- Win10 upgrade, it has a few automatic resets which is part of the Win10 upgrade process.
On each automatic reset, grub2 start menu always appear, showing the same old configuration, indicating grub2 iscontrolling MBR.
After several resets, Win10 finally run, without any issue.

Upon resetting computer, grub2 retain control of MBR.
Multiboot grubs configuration remained unchanged.
All Win10, Linux OS can boot after selecting fromgrub2 start menu.

This is a little unexpected, I thought Windows boot manager to take over MBR but not on this multiboot computer.

This is a good news, if it repeat for other multiboot / dual boot system, it means users will have easier time on upgrading.

I personally clone Win7 OS so that in case there is a hiccup I simply restore from clone.

I summary of hard disk
# blkid -o list
device fs_type label mount point UUID
-------------------------------------------------------------------------------
/dev/sda1 ntfs Win7 (not mounted) B4409A7A409A42D2
/dev/sda5 ext4 debian8all (not mounted) e3de588a-379f-44c3-a5d3-d0e1c1f48bb9
/dev/sda6 ext4 xfce (not mounted) 28e9bff6-2f83-41a4-9d46-383d9e2aac8b
/dev/sda7 swap (not mounted) 9876b183-250b-4d88-8b43-2915698e1ae1
/dev/sda8 ext4 (not mounted) dc79cc49-82ad-44d3-b4b8-0c875856ff91
/dev/sda9 ext4 linux / 4dd44696-f6c4-4447-b163-df0c8bbadfc4
/dev/sda10 ext4 (not mounted) 38d686f2-217d-4923-bc93-537355f1d435
/dev/sda3 ntfs CoolMasterData (not mounted) 962CCC302CCC0CE5

Re: Observation of Grub2, Win7-10 upgrade in multiboot

Posted: Thu Jul 30, 2015 4:45 am
by wayne128
System 2.

Multiboot Win7 /Linux with two hard disks.
grub version : grub-install (GRUB) 2.02~beta2-23
Win7 boot manager: EasyBCD.
MBR controlled by EasyBCD.

Observation,
With MBR controlled by EasyBCD, each time when I boot computer, I would need to select a Linux OS to boot from Windows BCD like startup menu, this is a very old Win7's bcd style selection menu, just a few lines in black-white. No graphic.

I set EasyBCD default to boot Win7.

The upgrading process from Win7 to Win10 is quite automatic.
Each time when Win10 installer reset the computer, as EasyBCD is controlling the MBR, and default to 'old win7', the Win10 installer will boot itself and complete the installation, configuration, etc without a need for manually selecting 'win10' to boot.

This is good because I can multitask and leave it alone.

After Win10 completed configuration, upon reboot, I see the win8 like startup menu ( huge graphic icons+text lines to select OS to boot).

However here is the boot issue:
Previously on Win7, when I select Linux OS it will boot.
Now with Win10, when I select Linux OS, it gets grub rescue> and won't boot Linux OS.

Solution on the Linux boot issue is :
just boot from Linux OS from USB/DVD and repair grub.