New install of win10 doesn't recognise older win7 drive for dual boot?

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  1. Posts : 6,247
    Windows 11 Pro - Windows 7 HP - Lubuntu
       #11

    NavyLCDR said:
    I guess you didn't believe my post #5.
    I don't know what the OP has so I'm always carefully before giving instructions, specially those that change system essential procedures.
    Better be safe than sorry.
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  2. Posts : 254
    Win 10, Win 7 & KDE Neon
    Thread Starter
       #12

    Thanks NavyLCDR and Megahertz

    I did believe you, I just need to research commands before applying them.

    Here is a screenshot of my drives. Win7 is on Disk1 and Win10 is on disk5 - if I right click on disk5 it showsConvert to MBR, the others show Convert to GPT greyed out. I put this in as it shows that Win10 is installed slightly differently.

    New install of win10 doesn't recognise older win7 drive for dual boot?-drives_uefi_and_legacy.jpg
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  3. Posts : 18,424
    Windows 11 Pro
       #13

    The bcdboot commands given are the way to set up the dual booting.
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  4. Posts : 254
    Win 10, Win 7 & KDE Neon
    Thread Starter
       #14

    NavyLCDR said:
    The bcdboot commands given are the way to set up the dual booting.
    Thanks NavyLCDR.

    I will try that.....Can it go wrong or be reversed? I like to be prepared just in case.
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  5. Posts : 18,424
    Windows 11 Pro
       #15

    farrellart said:
    Thanks NavyLCDR.

    I will try that.....Can it go wrong or be reversed? I like to be prepared just in case.
    It can't go wrong if you do both bcdboot commands. Make sure to change the drive letter in the first command to your windows 7 drive letter, it looks like I:\Windows. The second command stays at C:\Windows
    Last edited by NavyLCDR; 12 Jun 2019 at 10:05.
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  6. Posts : 18,424
    Windows 11 Pro
       #16

    Megahertz said:
    I don't know what the OP has so I'm always carefully before giving instructions, specially those that change system essential procedures.
    Better be safe than sorry.
    @farrellart provided all the information needed in the OP. The fact that Windows 7 disappeared from the boot menu when Windows 10 was installed indicates that Windows 10 created it's own system partition. It doesn't matter if it was created on the new GPT drive, or was created on the old MBR Windows 7 drive (the latter being pretty much impossible because of the way Windows setup works). The fact is clear that the system partition the computer boots into Windows 10 from was created by Windows 10. Therefore, the bcdboot commands are the appropriate command line commands run under Windows 10 to add the Windows 7 entry to the BCD contained in the newly created Windows 10 system partition.

    The first bcdboot command adds Windows 7 to the BCD in the Windows 10 system partition, but it also changes the boot menu to the Windows 7 text style boot menu. I've never known this cause an issue, other than aesthetics, but just in case something happened that caused it to remove Windows 10 from the BCD, the second bcdboot command will restore the Windows 10 graphical style boot menu and will all ensure the Windows 10 is present in the BCD.
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  7. Posts : 18,424
    Windows 11 Pro
       #17

    @farrellart could even make the computer boot from the Windows 7 hard drive in UEFI mode. He (and I am assuming he, I apologize if I am wrong) could delete the existing system reserved partition. Create a FAT32 primary partition in the empty space. Mark it as active. Use the bootsect command from a Windows 10 installation drive to write bootmgr to the MBR. Then use the bcdboot commands to create the BCD pointing to either and/or both Windows 7 and Windows 10. Now you have a hard drive that will boot in both UEFI modes (even with secure boot turned on) and legacy BIOS (CSM) modes and would be capable of booting both Windows 10 and Windows 7. Assuming the Windows 7 is SP1 or greater, because SP1 for Windows 7 was required to boot in UEFI mode.
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  8. Posts : 6,247
    Windows 11 Pro - Windows 7 HP - Lubuntu
       #18

    NavyLCDR said:
    @farrellart could even make the computer boot from the Windows 7 hard drive in UEFI mode. He (and I am assuming he, I apologize if I am wrong) could delete the existing system reserved partition. Create a FAT32 primary partition in the empty space. Mark it as active. Use the bootsect command from a Windows 10 installation drive to write bootmgr to the MBR. Then use the bcdboot commands to create the BCD pointing to either and/or both Windows 7 and Windows 10. Now you have a hard drive that will boot in both UEFI modes (even with secure boot turned on) and legacy BIOS (CSM) modes and would be capable of booting both Windows 10 and Windows 7. Assuming the Windows 7 is SP1 or greater, because SP1 for Windows 7 was required to boot in UEFI mode.
    You are right.
    - farrellart Installed win 7 as Legacy - MBR and Win 10 as UEFI-GPT. They have completely independent boot loaders and can work without depending from the other. You select witch one to boot from by BIOS priority or by Boot Menu.
    - Normally you will only see on a MBR disk a System Reserved partition on Win 7 OEM computers. They have the OEM tools and the boot loader (active). If there is no System Reserved partition, Windows partition will be set as active.
    - If you create a win 7 boot load option on the Win 10 boot loader on the EFI partition (bcdboot) you don't need the System Reserved partition or the Fat32 partition on the Win 7 disk. BIOS will take the boot sequence to the Win 10 EFI partition and from there it will take to Win 7 or Win 10.
    - EFI Fat32 partition can have many boot loaders that will take to different OS, on different partitions or different disks. My main disk EFI Fat32 partition has Windows and Linux boot loader.
    GPT disks don't have an active partition, Only MBR disks do. A active partition sets the MBR to take the boot sequence to the active partition where the boot loader is.

    I would leave Win 7 untouched. I would only add the Win 7 boot load option to the Win 10 as you instructed.

    With the bcdboot X:\Windows /d /addlast preserves the Win 10 and add Win 7 to last option.
    Navy, I know you can set timeout for the default (win10) but I don't remember if it's automatically set or it can be set with another cmd or msconfig - boot
    Last edited by Megahertz; 12 Jun 2019 at 11:44.
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  9. Posts : 18,424
    Windows 11 Pro
       #19

    Timeout defaults to 30 seconds. It can be changed in numerous ways, the command line option is bcdedit /timeout xx. xx being number of seconds desired. It can also be changed in the boot tab of msconfig.
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  10. Posts : 254
    Win 10, Win 7 & KDE Neon
    Thread Starter
       #20

    Thank you NavyLCDR, Megahertz and everyone.

    Bcdboot worked a treat......my heart did stop a little after I made a test run to select Win7 and the system rebooted, but all went well.

    Cheers

    Chris
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