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Setting up grub4dos for dual-boot Win8.1/Win7 after installing Win8.1


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#1 doveman

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Posted 13 July 2014 - 11:43 PM

I did a fresh install of Win8.1 onto a new system and it's created a 350MB partition before the actual Win8.1 one, which I've never had before when installing Win7.

 

I've then created another partition and restored a Win7 True Image to that.

 

I now want to setup grub4dos to choose which to boot but I'm worried about messing things up because of this strange 350MB partition. So if someone could advise what I need to do to make it work and avoid causing any problems, I'd be grateful.



#2 cdob

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Posted 17 July 2014 - 08:45 PM

I wonder:
what about adding Windows 7 to Windows 8 \boot\bcd ?

#3 doveman

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Posted 17 July 2014 - 09:05 PM

I guess I could but I like to have grub4dos to use for other stuff and that would mean having to go through two boot screens, rather than choosing Win7 or Win8 directly from g4d.



#4 cdob

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Posted 19 July 2014 - 03:47 PM

Which partition does exists? Does Windows 7 matches (hd0,2) ?

Does Windows 7 partition contains the file \bootmgr and the directory \boot ?
 
tile Windows 7 (hd0,2)
root (hd0,2)
chainloader /bootmgr


#5 doveman

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Posted 19 July 2014 - 08:06 PM

Thanks cdob, that's right for Win7. I should have been clearer that I'm more concerned about breaking the Win8.1 boot by installing g4d, as I have no idea what this extra 350MB partition (shown as System Reserved, Active in Win8.1 but no drive letter assigned) is for.

 

I guess what I could do is use a USB stick with g4d on to boot from using g4d before I install the g4d MBR to the HDD though.



#6 erwan.l

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Posted 19 July 2014 - 09:00 PM

I'll assume you have a MBR (i.e not GPT) partition scheme.

In which case this "hidden" partition holds the Boot Manager code and the Boot Configuration Database.

You could unhide it if you wanted and this without harming your system boot and you could even assign a drive letter to it but it is not what you are looking for.

You could even delete it, provided you move you boot manager and bcd to the system partition before doing that (you would also need to set the system partition as active then) but again this is not what you are after.

 

Regarding G4D, if you want to use it as your boot manager, as is, you would need to install it on the current active / hidden partition.

From G4D, you could decide then on which partition to boot : the win7 one or the win8 one.



#7 doveman

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Posted 19 July 2014 - 09:27 PM

Yep, only using MBR on a 256GB SSD.

 

Thanks for the explanation, I understand now. How much of that 350MB does the boot partition actually use? My Win7 Boot folder is only about 20MB, so if it only uses a similar amount, it might make sense to move everything to the system partition and expand it to merge the two partitions.



#8 doveman

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Posted 20 July 2014 - 12:17 AM

Hmm, I can't seem to get the PC to boot g4d from my USB stick. I tested it in Virtualbox on my other PC and that works fine and shows the g4d menu. In my Intel PC though, if I choose the UEFI boot option it just boots to the Win8.1 installer bootmgr that's on there and if I choose the non-UEFI option it just boots Win8.1 installed on the HDD.

 

I tried setting the Secure Boot option to Other OS instead of UEFI as well, in case that was preventing it from booting the USB stick but that didn't help. Secure Bpot isn't disabled as such though. I'm not sure how to do that, maybe by Clear Secure Boot Keys but I don't want to do that in case it breaks Win8.1 (the Save Secure Boot Keys option just gives a 'Error whilst writing to file dbs' message whichever of the drive options I select. 



#9 cdob

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Posted 20 July 2014 - 05:46 AM

I'm more concerned about breaking the Win8.1 boot by installing g4d, as I have no idea what this extra 350MB partition (shown as System Reserved, Active in Win8.1 but no drive letter assigned) is for.

That's the Win8.1 boot files and recovery Winre.wim, about 260MB data occupied.

Chainload the bootmgr from this partition at grub4dos.
tile Windows 8 (hd0,0)
root (hd0,0)
chainloader /bootmgr


#10 doveman

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Posted 20 July 2014 - 08:03 AM

That's the Win8.1 boot files and recovery Winre.wim, about 260MB data occupied.

Chainload the bootmgr from this partition at grub4dos.

Ah, in that case it's not worth messing with the partitions if I'll only gain about 90MB.

 

I still want to get it booting from USB though, before I install G4D to the HDD, so that I have a backup route in case things go wrong.



#11 doveman

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Posted 20 July 2014 - 11:11 AM

Cool, managed to get it to boot from the USB by setting Boot #1 to the stick and Boot #2 to the UEFI version of the stick. It probably means it won't boot to the SSD when I remove the stick but I can change the settings back to fix that quite easily.



#12 doveman

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Posted 23 July 2014 - 04:33 PM

I've got it booting from g4d from the HDD now :)

 

I've actually copied the boot files from the Reserved partition to the main Win8.1 partition and am booting from there (hd0,1) now, as I figured it's easier to have all the files on one partition for making system images, so I ought to wipe the Reserved partition and give the space to the other partition sometime, even if it is only 350MB.






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