• Is it possible to dual-boot both MBR & GPT without changing BIOS setti

    From Java Jive@2:250/1 to All on Friday, October 31, 2025 12:56:49
    Subject: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    As per subject, as I now have on the same PC some OSs - Ubuntu24, Windows7/10 - installed on an MBR disk and Windows 11 installed on a GPT/UEFI disk, I'd like if possible to find a way of booting any of
    them, and MBR/GPT USB sticks, without constantly having to change the
    BIOS settings on the PC.

    Research into whether this is possible seems to produce mixed results,
    mostly not, but a few suggesting it's possible, but I haven't yet found anything with clear and understandable instructions on how to achieve it.

    My own gut feeling is that it should be possible, but, while I have a
    good understanding of how a PC boots an MBR disk, I have less
    understanding how one boots a GPT/UEFI disk.

    Has anyone here been able to achieve this? Does anyone know of good
    reliable sources of information about this?

    --

    Fake news kills!

    I may be contacted via the contact address given on my website: www.macfh.co.uk

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Carlos E.R.@2:250/1 to All on Friday, October 31, 2025 13:26:35
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 2025-10-31 13:56, Java Jive wrote:
    As per subject, as I now have on the same PC some OSs  -  Ubuntu24, Windows7/10  -  installed on an MBR disk and Windows 11 installed on a GPT/UEFI disk, I'd like if possible to find a way of booting any of
    them, and MBR/GPT USB sticks, without constantly having to change the
    BIOS settings on the PC.

    Research into whether this is possible seems to produce mixed results, mostly not, but a few suggesting it's possible, but I haven't yet found anything with clear and understandable instructions on how to achieve it.

    My own gut feeling is that it should be possible, but, while I have a
    good understanding of how a PC boots an MBR disk, I have less
    understanding how one boots a GPT/UEFI disk.

    Has anyone here been able to achieve this?  Does anyone know of good reliable sources of information about this?

    I think it might work if the system is UEFI with GPT disks, if you put
    the other system in a partition, with boot code in the start record of
    that partition. You would then need "something" in /boot/EFI to load
    that boot code in that partition.

    --
    Cheers, Carlos.
    ES🇪🇸, EU🇪🇺;

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: Air Applewood, The Linux Gateway to the UK & Eire (2:250/1@fidonet)
  • From Windows Elf@2:250/1 to All on Friday, October 31, 2025 14:57:33
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 31/10/2025 12:56, Java Jive wrote:
    As per subject, as I now have on the same PC some OSs  -  Ubuntu24, Windows7/10  -  installed on an MBR disk and Windows 11 installed on a GPT/UEFI disk, I'd like if possible to find a way of booting any of
    them, and MBR/GPT USB sticks, without constantly having to change the
    BIOS settings on the PC.



    Have you considered running Windows 10 and Ubuntu in UEFI mode to
    achieve the desired result? It's time to abandon Windows 7. There's
    nothing you can do in Windows 7 that you can't do in Windows 10 or 11. I
    know I am talking to a concrete wall which can't b

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: To protect and to server (2:250/1@fidonet)
  • From Paul@2:250/1 to All on Friday, October 31, 2025 16:04:27
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On Fri, 10/31/2025 8:56 AM, Java Jive wrote:
    As per subject, as I now have on the same PC some OSs  -  Ubuntu24, Windows7/10  -  installed on an MBR disk and Windows 11 installed on a GPT/UEFI disk, I'd like if possible to find a way of booting any of them, and MBR/GPT USB sticks, without constantly having to change the BIOS settings on the PC.

    Research into whether this is possible seems to produce mixed results, mostly not, but a few suggesting it's possible, but I haven't yet found anything with clear and understandable instructions on how to achieve it.

    My own gut feeling is that it should be possible, but, while I have a good understanding of how a PC boots an MBR disk, I have less understanding how one boots a GPT/UEFI disk.

    Has anyone here been able to achieve this?  Does anyone know of good reliable sources of information about this?


    It depends on whether this is a BIOS-mediated plan or a Pop-Up Boot
    mediated plan.

    The BIOS has a list of hard drives. If a drive
    was not plugged in, maybe the BIOS moves on to
    a new disk menu entry and considers it. But this does not
    give much in the way of control, except if the user
    is very confident that they know which disk
    would be selected by the automation.

    Whereas the Popup boot key, offers everything, on a UEFI/CSM BIOS.
    The menu contents are determined by the ~25 second scan (for an HGST boot drive which is slow).

    I press F11 on this MSI motherboard computer, to access PopUp Boot. When the scan is finished.
    I press F8 on the Asus motherboqrd computer, to access PopUp Boot. When the scan is finished.

    CSM First disk

    UEFI Second disk # This could be a hybrid entry, or a hybrid DVD
    CSM Second disk

    UEFI Third disk

    Windows Boot Manager # That's a UEFI, and it lists some sort of disk identifier
    # The BIOS does not like multiple Windows Boot Managers, and
    # it especially does not like them, if on TWO IDENTICAL DISKS :-)
    # You can cursor one drive, and it selects the other drive.

    UEFI USB stick

    I don't know if Secure Boot can be enabled, without forcing the menu
    to only consider UEFI disks. UEFI/CSM mode might be with no Secure Boot.
    Once Secure Boot is enabled, only the UEFI disks should be listed (two entries in example).

    In the PopUp Boot, you can cursor down to the item desired, and hit <Enter>

    This situation is most likely to occur, when the disks don't
    know anything about one another, and you have slid the drive in
    as desired to achieve a result. The BIOS scans the drive set it finds at startup and puts entries for everything it finds. An entry that
    hides a multiboot GRUB or Windows menu, would only occupy
    one slot at this level, and once in a Windows tile menu, you could
    select from a set of Windows OS partitions. Some of the partitions,
    could even be on the other disk drives. If a disk drive is missing
    and a Windows multiboot has entries, it is not fussed about a disk
    drive gone missing... unless you hit <Enter> there and there is
    no disk fitting that description present. The boot sub-menu in that
    case is not validated on the fly.

    I could see a boot sequence, using as many as three levels of menu.
    For those of us who must be different. BIOS --> GRUB --> WindowsTiles
    I think I accidentally did that at least once (not intentional).

    *******

    If you have a "control disk" that directs all booting on subtending
    disks, then GRUB would be best for that, as it handles both its
    own kind of OS, plus using OS-Prober it can include Windows OSes.
    That's why the last paragraph has that example. I know I can get
    an additional menu level, but putting the GRUB in the middle
    of the sandwich.

    *******

    Ubuntu24, Windows7/10 - installed on an MBR disk
    Windows 11 GPT/UEFI disk

    USB Stick ???

    OK, how I'd do that, is I make the first disk the "control disk".
    As you likely installed Ubuntu24043 as a GRUB item and it was
    installed second and GRUB now shows this when we perpetually
    select the first disk so it steers the boot of other disks.

    Ubuntu2404
    Windows7
    Windows10

    If I do a sudo update-grub and OS-Prober is present while
    Ubuntu2404 is running, and the Windows 11 disk drive is present,
    then the GRUB may add the Windows to the menu during the update-grub run.
    Now my control disk (the first disk) controls two disk drives.

    Ubuntu2404
    Windows7
    Windows10
    Windows11

    In the BIOS, I set the BIOS to boot from the first (MBR) disk.
    The GRUB comes up, I cursor down and select one of the four targets.

    To launch the USB stick, I use the PopUp Boot key, and I select

    UEFI USB # some of mine are showing up without the namestring
    USB # for the USB hardware. The second one is CSM.

    <ControlDisk1> # I would select this to get to the four entry GRUB menu

    Some BIOS designs are just plain nasty, and follow no rules at all.
    I've even had one report of a BIOS "that went nuts". I could not
    make any sense whatsoever, out of the symptom description. The description makes as much sense as my mall elevator (I pressed "5" yesterday, the door closed, the elevator didn't move -- I pressed the "5" again, even though the "5" was already lit, and... off we went).

    While you can wave hands about these things, YMMV.

    Just a guess,
    Paul

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Theo@2:250/1 to All on Friday, October 31, 2025 16:06:44
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS settings on laptop

    In uk.comp.os.linux Java Jive <java@evij.com.invalid> wrote:
    As per subject, as I now have on the same PC some OSs - Ubuntu24, Windows7/10 - installed on an MBR disk and Windows 11 installed on a GPT/UEFI disk, I'd like if possible to find a way of booting any of
    them, and MBR/GPT USB sticks, without constantly having to change the
    BIOS settings on the PC.

    I think that should work without changing settings, although I haven't tried it.

    You need to ensure CSM is turned on, that's support for legacy BIOS boot.
    Then select which disc to boot from at boot time and it'll use UEFI if available and BIOS if not. You probably want Secure Boot turned off as that only works in UEFI mode.

    Theo

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: University of Cambridge, England (2:250/1@fidonet)
  • From Java Jive@2:250/1 to All on Sunday, November 02, 2025 14:12:26
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 2025-10-31 12:56, Java Jive wrote:

    As per subject, as I now have on the same PC some OSs  -  Ubuntu24, Windows7/10  -  installed on an MBR disk and Windows 11 installed on a GPT/UEFI disk, I'd like if possible to find a way of booting any of
    them, and MBR/GPT USB sticks, without constantly having to change the
    BIOS settings on the PC.

    Research into whether this is possible seems to produce mixed results, mostly not, but a few suggesting it's possible, but I haven't yet found anything with clear and understandable instructions on how to achieve it.

    My own gut feeling is that it should be possible, but, while I have a
    good understanding of how a PC boots an MBR disk, I have less
    understanding how one boots a GPT/UEFI disk.

    Has anyone here been able to achieve this?  Does anyone know of good reliable sources of information about this?

    Please all respondents accept my apologies for not replying sooner.
    I've read all the replies and am trying some things, but being delayed
    by problems with the Win11 image I have, so am constantly having to
    retrace steps to remake, all of which is wasting a great deal of time.
    I'll report back after I'm in a position to try some things out, in the meantime, the answer given here seems quite a good, and encouraging,
    summary:

    https://superuser.com/questions/1165557/how-grub2-works-on-a-mbr-partitioned-disk-and-gpt-partitioned-disk

    --

    Fake news kills!

    I may be contacted via the contact address given on my website: www.macfh.co.uk


    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Java Jive@2:250/1 to All on Tuesday, November 11, 2025 00:27:44
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 2025-10-31 12:56, Java Jive wrote:

    As per subject, as I now have on the same PC some OSs  -  Ubuntu24, Windows7/10  -  installed on an MBR disk and Windows 11 installed on a GPT/UEFI disk, I'd like if possible to find a way of booting any of
    them, and MBR/GPT USB sticks, without constantly having to change the
    BIOS settings on the PC.

    Research into whether this is possible seems to produce mixed results, mostly not, but a few suggesting it's possible, but I haven't yet found anything with clear and understandable instructions on how to achieve it.

    My own gut feeling is that it should be possible, but, while I have a
    good understanding of how a PC boots an MBR disk, I have less
    understanding how one boots a GPT/UEFI disk.

    Has anyone here been able to achieve this?  Does anyone know of good reliable sources of information about this?

    Thanks for the earlier responses, I have now some success to report ...

    You may recall the disk layout I was trying to achieve success with:

    Disk 1: 256GB (nominal) SSD - MBR partitioning
    P1: Win 7 Pro, NTFS
    P2: Win 10 Pro, NTFS
    P3: Win 7 32-Bit Pro, NTFS
    (for old scanner with only 32-bit drivers)
    P4: Ubuntu 24, ext4

    Disk 2: 2TB (nominal) HD - MBR partitioning
    P1: Windows Data, NTFS
    P2: Linux Data, ext4

    Disk 3: 128GB (nominal) MiniSSD - GPT partitioning
    P1: 128MB UEFI Boot, FAT32
    P2: Win 11 Pro, NTFS

    Before I started this work, when booted via MBR and Disk 1, Grub gave
    access to all the OSs except W11P, while when booted via UEFI/GPT and
    Disk 3, only W11P could be booted, whereas obviously I wanted to have
    just one method of booting every OS.

    Therefore the question was, should I try to find a way of booting W11P
    via UEFI from the legacy Grub installation on D1, which would have
    required some sort of forward compatibility of the legacy MBR
    installation, or should I attempt to load all the other OSs via UEFI via
    a new Grub installation on D3, which would require backward
    compatibility? I felt the chances of forward compatibility were less
    than the chances of backward compatibility, so, despite the extra work involved, and certainly it was a great deal of work, I chose the latter.

    However, as it has turned out, I've only been able to achieve partial
    backward compatibility in that all the 64-bit OSs can now be booted from
    D3, but not the 32-bit OS, I've not been able to find a way of booting
    Win 7 Pro 32-Bit from UEFI. Further, I have not been able to find a way
    of booting *ANY* 32-Bit OS, not even a UEFI boot Win 8 Pro 32-Bit
    installation USB, when using UEFI on that particular PC (so probably
    none of the others either, because they're all identical or nearly so),
    so I suspect that this is a firmware limitation with this range of PCs.

    FTR, this is how I got the other 64-Bit OSs to boot from Grub on the GPT
    disk, even though they themselves are on an MBR disk ...

    1) I renamed MS' D3P1:/Boot folder to 'boot', ie all lower case.

    2) I copied the previous MBR grub installation from D1P4:/boot/grub to D3P1:/boot/grub.

    3) Similarly, I copied the UEFI grub installation from an Ubuntu 24 installation USB over the previously copied files in D3P1:/boot/grub.

    4) In the PC's firmware, I set up a new boot option named 'Grub' to
    boot ...
    D3P1:/EFI/Boot/grubx64.efi

    As as result I was now able to boot into Grub displaying the previous
    menu from the MBR disk (because in step 2 I'd copied the grub.cfg across
    with everything else and taken steps to prevent it being lost in step
    3), but of course most of the options didn't work.

    However, the existing Ubuntu 24 installation was able to boot from this
    new Grub menu, the only discernible difference being that an additional initial message is displayed briefly, it reads ...

    EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path

    .... and thereafter the boot proceeds apparently as normal.

    5) Next, I thought it should be possible somehow to boot via UEFI into
    Ubuntu and simply run 'update-grub' to complete the setup, as per this
    advice ...

    https://askubuntu.com/questions/831216/how-can-i-reinstall-grub-to-the-efi-partition

    .... but this proved a complete waste of time. First I tried doing it
    from the existing Ubuntu 24 installation; when booted via UEFI, the EFI
    system is available, but when doing a chroot to perform update-grub, the
    EFI subsystem and its associated variables were lost. So next I tried
    booting via EFI from an Ubuntu 24 installation USB, but the same thing happened. Finally, after much machination I installed a separate UEFI
    Ubuntu 24 on a spare disk and booted from that, and finally succeeded in getting the EFI subsystem available within the chroot, but update-grub
    didn't find the other OSs on the MBR disk anyway, although it did now
    complete without error and so create a working entry for the W11P
    installation on the GPT disk, which reads (beware unintended line-wrap):

    5a) menuentry 'Windows Boot Manager (on /dev/sdc1)' --class windows
    --class os $menuentry_id_option 'osprober-efi-1043-DB71' {
    savedefault
    insmod part_gpt
    insmod fat
    set root='hd2,gpt1'
    if [ x$feature_platform_search_hint = xy ]; then
    search --no-floppy --fs-uuid --set=root --hint-bios=hd2,gpt1 --hint-efi=hd2,gpt1 --hint-baremetal=ahci2,gpt1 1043-DB71
    else
    search --no-floppy --fs-uuid --set=root 1043-DB71
    fi
    chainloader /EFI/Microsoft/Boot/bootmgfw.efi
    }

    But for the others I had to wing it, using little clues from various researches online, none of which gave a complete template or revealed a crucial extra step to get Windows 7 & 10 to boot, which is that you need
    to load the module 'ntfscomp' - I guess comp is short for 'compatible'
    or some related word. Also, you can't use drivemap but anyway don't
    need to, and you have to change the 'chainloader' command, like so ...

    6) Change a current MBR menu item of this form ...

    menuentry "Windows ... {
    ...
    insmod ntfs
    ...
    drivemap ...
    chainloader +1
    }

    .... to a GPT equivalent of this form ...

    menuentry "Windows ... {
    ...
    insmod ntfs
    insmod ntfscomp
    ...
    chainloader /Windows/Boot/EFI/bootmgfw.efi
    }

    7) The next thing to be done is to create the BCD files within the
    relevant Windows installation(s). This can be done by booting into a PE environment, most probably from an installation media and then choosing
    Repair ... Command Console.

    7a) First check the drive letters associated with the various partitions
    on the various disks, and adjust the one you want to work with to be C:

    DISKPART
    LIST VOL

    If a different volume than the one you want to work with is C:, first temporarily assign it a different letter, say T:, then assign the volume
    you want to work with, here assumed to be 2, to C: ...

    SELECT VOL 1
    ASSIGN LETTER=T:
    SELECT VOL 2
    ASSIGN LETTER=C:
    EXIT

    7b) Then, back in the console, give the following command ...

    BCDBoot C:\Windows /s C: /f ALL

    .... the 'ALL' parameter of which instructs BCDBoot to copy new BCD files
    into both ...

    C:\Boot\

    .... and (you might have to create the following parent directory chains before running the above command) ...

    C:\EFI\Microsoft\Boot\
    C:\EFI\Microsoft\Recovery\

    Repeat 7a and 7b for any other Windows installations.

    When complete, though I'm not sure that it's actually necessary, on the principle of being better safe than sorry I use DISKPART to reassign the
    drive letters back to what originally they were.

    Then reboot, and it all works.

    It's annoying about the 32-Bit problem, though of course I can still
    boot it via MBR - I need to use that for one particular old scanner
    for which I cannot get 64-bit drivers; it's useful to keep it going
    because it's quite suited to old gritty material which might scratch the
    glass of the new one, and also it's the only one I have with an
    Automatic Document Feeder.

    Perhaps next I might try seeing if I can boot W11P from the original MBR
    menu, which would achieve the desired state of only needing one boot menu.

    --

    Fake news kills!

    I may be contacted via the contact address given on my website: www.macfh.co.uk


    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Paul@2:250/1 to All on Tuesday, November 11, 2025 03:45:06
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On Mon, 11/10/2025 7:27 PM, Java Jive wrote:
    On 2025-10-31 12:56, Java Jive wrote:

    As per subject, as I now have on the same PC some OSs  -  Ubuntu24, Windows7/10  -  installed on an MBR disk and Windows 11 installed on a GPT/UEFI disk, I'd like if possible to find a way of booting any of them, and MBR/GPT USB sticks, without constantly having to change the BIOS settings on the PC.

    Research into whether this is possible seems to produce mixed results, mostly not, but a few suggesting it's possible, but I haven't yet found anything with clear and understandable instructions on how to achieve it.

    My own gut feeling is that it should be possible, but, while I have a good understanding of how a PC boots an MBR disk, I have less understanding how one boots a GPT/UEFI disk.

    Has anyone here been able to achieve this?  Does anyone know of good reliable sources of information about this?

    Thanks for the earlier responses, I have now some success to report ...

    You may recall the disk layout I was trying to achieve success with:

    Disk 1:  256GB (nominal) SSD - MBR partitioning
        P1:  Win  7 Pro, NTFS
        P2:  Win 10 Pro, NTFS
        P3:  Win  7 32-Bit Pro, NTFS
                (for old scanner with only 32-bit drivers)
        P4:  Ubuntu 24, ext4

    Disk 2:  2TB (nominal) HD - MBR partitioning
        P1:  Windows Data, NTFS
        P2:  Linux Data, ext4

    Disk 3:  128GB (nominal) MiniSSD - GPT partitioning
        P1:  128MB UEFI Boot, FAT32
        P2:  Win 11 Pro, NTFS

    Before I started this work, when booted via MBR and Disk 1, Grub gave access to all the OSs except W11P, while when booted via UEFI/GPT and Disk 3, only W11P could be booted, whereas obviously I wanted to have just one method of booting every OS.

    Therefore the question was, should I try to find a way of booting W11P via UEFI from the legacy Grub installation on D1, which would have required some sort of forward compatibility of the legacy MBR installation, or should I attempt to load all the other OSs via UEFI via a new Grub installation on D3, which would require backward compatibility?  I felt the chances of forward compatibility were less than the chances of backward compatibility, so, despite the extra work involved, and certainly it was a great deal of work, I chose the latter.

    However, as it has turned out, I've only been able to achieve partial backward compatibility in that all the 64-bit OSs can now be booted from D3, but not the 32-bit OS, I've not been able to find a way of booting Win 7 Pro 32-Bit from UEFI.  Further, I have not been able to find a way of booting *ANY* 32-Bit OS, not even a UEFI boot Win 8 Pro 32-Bit installation USB, when using UEFI on that particular PC (so probably none of the others either, because they're all identical or nearly so), so I suspect that this is a firmware limitation with this range of PCs.

    FTR, this is how I got the other 64-Bit OSs to boot from Grub on the GPT disk, even though they themselves are on an MBR disk ...

    1)  I renamed MS' D3P1:/Boot folder to 'boot', ie all lower case.

    2)  I copied the previous MBR grub installation from D1P4:/boot/grub to D3P1:/boot/grub.

    3)  Similarly, I copied the UEFI grub installation from an Ubuntu 24 installation USB over the previously copied files in D3P1:/boot/grub.

    4)  In the PC's firmware, I set up a new boot option named 'Grub' to boot ...
        D3P1:/EFI/Boot/grubx64.efi

    As as result I was now able to boot into Grub displaying the previous menu from the MBR disk (because in step 2 I'd copied the grub.cfg across with everything else and taken steps to prevent it being lost in step 3), but of course most of the options didn't work.

    However, the existing Ubuntu 24 installation was able to boot from this new Grub menu, the only discernible difference being that an additional initial message is displayed briefly, it reads ...

    EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path

    ... and thereafter the boot proceeds apparently as normal.

    5) Next, I thought it should be possible somehow to boot via UEFI into Ubuntu and simply run 'update-grub' to complete the setup, as per this advice ...

    https://askubuntu.com/questions/831216/how-can-i-reinstall-grub-to-the-efi-partition

    ... but this proved a complete waste of time.  First I tried doing it from the existing Ubuntu 24 installation; when booted via UEFI, the EFI system is available, but when doing a chroot to perform update-grub, the EFI subsystem and its associated variables were lost.  So next I tried booting via EFI from an Ubuntu 24 installation USB, but the same thing happened.  Finally, after much machination I installed a separate UEFI Ubuntu 24 on a spare disk and booted from that, and finally succeeded in getting the EFI subsystem available within the chroot, but update-grub didn't find the other OSs on the MBR disk anyway, although it did now complete without error and so create a working entry for the W11P installation on the GPT disk, which reads (beware unintended line-wrap):

    5a) menuentry 'Windows Boot Manager (on /dev/sdc1)' --class windows --class os $menuentry_id_option 'osprober-efi-1043-DB71' {
        savedefault
        insmod part_gpt
        insmod fat
        set root='hd2,gpt1'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd2,gpt1 --hint-efi=hd2,gpt1 --hint-baremetal=ahci2,gpt1 1043-DB71
        else
          search --no-floppy --fs-uuid --set=root 1043-DB71
        fi
        chainloader /EFI/Microsoft/Boot/bootmgfw.efi
    }

    But for the others I had to wing it, using little clues from various researches online, none of which gave a complete template or revealed a crucial extra step to get Windows 7 & 10 to boot, which is that you need to load the module 'ntfscomp'  -  I guess comp is short for 'compatible' or some related word.  Also, you can't use drivemap but anyway don't need to, and you have to change the 'chainloader' command, like so ...

    6)  Change a current MBR menu item of this form ...

    menuentry "Windows ... {
        ...
        insmod ntfs
        ...
        drivemap ...
        chainloader +1
    }

    ... to a GPT equivalent of this form ...

    menuentry "Windows ... {
        ...
        insmod ntfs
        insmod ntfscomp
        ...
        chainloader /Windows/Boot/EFI/bootmgfw.efi
    }

    7)  The next thing to be done is to create the BCD files within the relevant Windows installation(s).  This can be done by booting into a PE environment, most probably from an installation media and then choosing Repair ... Command Console.

    7a) First check the drive letters associated with the various partitions on the various disks, and adjust the one you want to work with to be C:

        DISKPART
        LIST VOL

    If a different volume than the one you want to work with is C:, first temporarily assign it a different letter, say T:, then assign the volume you want to work with, here assumed to be 2, to C: ...

        SELECT VOL 1
        ASSIGN LETTER=T:
        SELECT VOL 2
        ASSIGN LETTER=C:
        EXIT

    7b) Then, back in the console, give the following command ...

        BCDBoot C:\Windows /s C: /f ALL

    ... the 'ALL' parameter of which instructs BCDBoot to copy new BCD files into both ...

        C:\Boot\

    ... and (you might have to create the following parent directory chains before running the above command) ...

        C:\EFI\Microsoft\Boot\
        C:\EFI\Microsoft\Recovery\

    Repeat 7a and 7b for any other Windows installations.

    When complete, though I'm not sure that it's actually necessary, on the principle of being better safe than sorry I use DISKPART to reassign the drive letters back to what originally they were.

    Then reboot, and it all works.

    It's annoying about the 32-Bit problem, though of course I can still boot it via MBR  -  I need to use that for one particular old scanner for which I cannot get 64-bit drivers; it's useful to keep it going because it's quite suited to old gritty material which might scratch the glass of the new one, and also it's the only one I have with an Automatic Document Feeder.

    Perhaps next I might try seeing if I can boot W11P from the original MBR menu, which would achieve the desired state of only needing one boot menu.


    But for the others I had to wing it, using little clues from various researches online,
    none of which gave a complete template or revealed a crucial extra step to get
    Windows 7 & 10 to boot, which is that you need to load the module 'ntfscomp'

    "ntfscomp - GRUB is able to support the compression commonly used in NTFS with this module"

    That could be Old Compression (an ATTRIB applied to a file), versus New Compression
    (a custom Reparse Point invented by Microsoft to annoy Linux users).

    Regarding scanners, there is the commercial scanner driver package for old scanners.
    That could allow you to access the old scanner from a 64-bit OS, for a price. (hamrick.com VueScan). The main concern for old scanner users, is whether all the capabilities of the scanner are available, when a novel driver is used.

    Paul




    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Java Jive@2:250/1 to All on Tuesday, November 11, 2025 13:19:22
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 2025-11-11 03:45, Paul wrote:

    On Mon, 11/10/2025 7:27 PM, Java Jive wrote:

    Then reboot, and it all works.

    Except, I've discovered, OSs won't hibernate, all that happens is that
    the screen locks, the PC doesn't even sleep, let alone hibernate.

    It's annoying about the 32-Bit problem, though of course I can still boot it via MBR  -  I need to use that for one particular old scanner for which I cannot get 64-bit drivers; it's useful to keep it going because it's quite suited to old gritty material which might scratch the glass of the new one, and also it's the only one I have with an Automatic Document Feeder.

    Perhaps next I might try seeing if I can boot W11P from the original MBR menu, which would achieve the desired state of only needing one boot menu.

    Had a go at that meantime, couldn't get it to work.

    But for the others I had to wing it, using little clues from various researches online,
    none of which gave a complete template or revealed a crucial extra step to get
    Windows 7 & 10 to boot, which is that you need to load the module 'ntfscomp'

    "ntfscomp - GRUB is able to support the compression commonly used in NTFS with this module"

    Ah! So 'comp' is 'compression', not 'compatibility'.

    That could be Old Compression (an ATTRIB applied to a file), versus New Compression
    (a custom Reparse Point invented by Microsoft to annoy Linux users).

    Some folders are compressed in my setups - Recycle Bins, foreign
    language subdirs ar-SA to zh-TW, etc.

    Regarding scanners, there is the commercial scanner driver package for old scanners.
    That could allow you to access the old scanner from a 64-bit OS, for a price. (hamrick.com VueScan). The main concern for old scanner users, is whether all the capabilities of the scanner are available, when a novel driver is used.

    Yes, I've heard that mentioned before.

    Tx.

    --

    Fake news kills!

    I may be contacted via the contact address given on my website: www.macfh.co.uk


    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Paul@2:250/1 to All on Tuesday, November 11, 2025 15:13:48
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On Tue, 11/11/2025 8:19 AM, Java Jive wrote:
    On 2025-11-11 03:45, Paul wrote:


    Regarding scanners, there is the commercial scanner driver package for old scanners.
    That could allow you to access the old scanner from a 64-bit OS, for a price.
    (hamrick.com VueScan). The main concern for old scanner users, is whether all
    the capabilities of the scanner are available, when a novel driver is used.

    Yes, I've heard that mentioned before.

    Tx.


    See if there is a Trial Version.

    One of the main benefits of old scanners, is the CCD based
    ones (instead of CMOS sensor) have better depth of field
    and most of the scans done on them will be in focus.
    I have trouble on my CMOS based scanner, getting
    the paper pressed hard enough to the screen for
    a focused copy.

    Paul

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Carlos E.R.@2:250/1 to All on Friday, November 14, 2025 12:24:37
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 2025-11-11 16:13, Paul wrote:
    On Tue, 11/11/2025 8:19 AM, Java Jive wrote:
    On 2025-11-11 03:45, Paul wrote:


    Regarding scanners, there is the commercial scanner driver package for old scanners.
    That could allow you to access the old scanner from a 64-bit OS, for a price.
    (hamrick.com VueScan). The main concern for old scanner users, is whether all
    the capabilities of the scanner are available, when a novel driver is used. >>
    Yes, I've heard that mentioned before.

    Tx.


    See if there is a Trial Version.

    One of the main benefits of old scanners, is the CCD based
    ones (instead of CMOS sensor) have better depth of field
    and most of the scans done on them will be in focus.
    I have trouble on my CMOS based scanner, getting
    the paper pressed hard enough to the screen for
    a focused copy.

    Interesting. I have scanned some flat objects in the scanner, with some relief, worked really well.

    --
    Cheers, Carlos.
    ES🇪🇸, EU🇪🇺;

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: Air Applewood, The Linux Gateway to the UK & Eire (2:250/1@fidonet)
  • From Paul@2:250/1 to All on Friday, November 14, 2025 18:03:31
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On Fri, 11/14/2025 7:24 AM, Carlos E.R. wrote:
    On 2025-11-11 16:13, Paul wrote:
    On Tue, 11/11/2025 8:19 AM, Java Jive wrote:
    On 2025-11-11 03:45, Paul wrote:


    Regarding scanners, there is the commercial scanner driver package for old scanners.
    That could allow you to access the old scanner from a 64-bit OS, for a price.
    (hamrick.com VueScan). The main concern for old scanner users, is whether all
    the capabilities of the scanner are available, when a novel driver is used.

    Yes, I've heard that mentioned before.

    Tx.


    See if there is a Trial Version.

    One of the main benefits of old scanners, is the CCD based
    ones (instead of CMOS sensor) have better depth of field
    and most of the scans done on them will be in focus.
    I have trouble on my CMOS based scanner, getting
    the paper pressed hard enough to the screen for
    a focused copy.

    Interesting. I have scanned some flat objects in the scanner, with some relief, worked really well.


    I scanned a sheet the other day, that had been folded
    in a box. It's a sample sheet for testing scanners.

    The text right next to the fold is in focus,
    the text further from the fold is not. And it
    is an appreciable degradation. It could affect
    the accuracy of an OCR done on it. That is a CMOS
    sensor, which is cheaper to make as the materials
    are not as obscure as CCD sensor materials.

    This is why I would recommend finding a scanner
    with a CCD (charge-coupled device) sensor. Those don't
    have the depth-of-field problem. That's what my old
    scanner used.

    In the picture here, you can see an "exaggeration"
    of the value of a CCD sensor :-) The book shown would
    be perfectly reproduced because the spine on the source
    there is unrealistically compliant. You couldn't lay
    War&Peace on the scanner and get the spine to lay that flat.
    This is only 800DPI. But the scan surface is pretty large.

    https://www.thescannershop.com/plustek-opticpro-a320e-flatbed-scanner/

    Paul

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Carlos E.R.@2:250/1 to All on Friday, November 14, 2025 19:31:39
    On 2025-11-14 19:03, Paul wrote:
    On Fri, 11/14/2025 7:24 AM, Carlos E.R. wrote:
    On 2025-11-11 16:13, Paul wrote:
    On Tue, 11/11/2025 8:19 AM, Java Jive wrote:
    On 2025-11-11 03:45, Paul wrote:


    Regarding scanners, there is the commercial scanner driver package for old scanners.
    That could allow you to access the old scanner from a 64-bit OS, for a price.
    (hamrick.com VueScan). The main concern for old scanner users, is whether all
    the capabilities of the scanner are available, when a novel driver is used.

    Yes, I've heard that mentioned before.

    Tx.


    See if there is a Trial Version.

    One of the main benefits of old scanners, is the CCD based
    ones (instead of CMOS sensor) have better depth of field
    and most of the scans done on them will be in focus.
    I have trouble on my CMOS based scanner, getting
    the paper pressed hard enough to the screen for
    a focused copy.

    Interesting. I have scanned some flat objects in the scanner, with some relief, worked really well.

    Or scanned a "page" of on ebook; the display is depressed about 1 mm
    from the edge. It came out perfect.

    I know that there was a setting in xsane to change the focus to some
    small distance, or to the glass surface. I can not find it now, though.
    Ah! Show advanced options. "Focus 2.5 mm above glass".

    Means that if I buy a scanner, it has to be CCD. Good to know.




    I scanned a sheet the other day, that had been folded
    in a box. It's a sample sheet for testing scanners.

    The text right next to the fold is in focus,
    the text further from the fold is not. And it
    is an appreciable degradation. It could affect
    the accuracy of an OCR done on it. That is a CMOS
    sensor, which is cheaper to make as the materials
    are not as obscure as CCD sensor materials.

    This is why I would recommend finding a scanner
    with a CCD (charge-coupled device) sensor. Those don't
    have the depth-of-field problem. That's what my old
    scanner used.

    In the picture here, you can see an "exaggeration"
    of the value of a CCD sensor :-) The book shown would
    be perfectly reproduced because the spine on the source
    there is unrealistically compliant. You couldn't lay
    War&Peace on the scanner and get the spine to lay that flat.
    This is only 800DPI. But the scan surface is pretty large.

    https://www.thescannershop.com/plustek-opticpro-a320e-flatbed-scanner/

    Yeah, that book has been domesticated :-D


    I have a low priority project, from an idea I got in one usenet
    conversation, which is scan my magazines and notes, to save space in the house. That person used an automatic feed scanner, double side pages,
    coupled with cutting magazines in half first with a big guillotine cutter.


    --
    Cheers, Carlos.
    ES🇪🇸, EU🇪🇺;

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: Air Applewood, The Linux Gateway to the UK & Eire (2:250/1@fidonet)
  • From Paul@2:250/1 to All on Friday, November 14, 2025 22:52:37
    On Fri, 11/14/2025 2:31 PM, Carlos E.R. wrote:
    On 2025-11-14 19:03, Paul wrote:

    https://www.thescannershop.com/plustek-opticpro-a320e-flatbed-scanner/

    Yeah, that book has been domesticated :-D


    I have a low priority project, from an idea I got in one usenet conversation,
    which is scan my magazines and notes, to save space in the house. That person
    used an automatic feed scanner, double side pages, coupled with cutting magazines
    in half first with a big guillotine cutter.

    There are book scanning devices, that flip the pages
    on the book, and they use a camera method for capture.
    You don't have to cut the binding off to capture.

    At least in this one, you can see the cameras used.
    (The site is a bit slow, move your mouse around while waiting)

    https://diybookscanner.org/forum/viewtopic.php?t=3125

    Paul

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Java Jive@2:250/1 to All on Saturday, November 15, 2025 01:57:05
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 2025-11-11 13:19, Java Jive wrote:

    On 2025-11-11 03:45, Paul wrote:

    On Mon, 11/10/2025 7:27 PM, Java Jive wrote:

    Perhaps next I might try seeing if I can boot W11P from the original
    MBR menu, which would achieve the desired state of only needing one
    boot menu.

    Had a go at that meantime, couldn't get it to work.

    Still no success with this business of trying to boot Win11P on a GPT
    disk from Grub launched from an MBR disk. This is what I've tried ...

    menuentry 'Windows 11 Professional (on /dev/sdc2)' --class windows
    --class os $menuentry_id_option 'osprober-chain-65153A0C0A7F9BDA' {
    savedefault
    insmod part_gpt
    insmod ntfs
    set root='hd2,gpt2'
    if [ x$feature_platform_search_hint = xy ]; then
    search --no-floppy --fs-uuid --set=root --hint-bios=hd2,gpt2 --hint-efi=hd2,gpt2 --hint-baremetal=ahci2,gpt2 65153A0C0A7F9BDA
    else
    search --no-floppy --fs-uuid --set=root 65153A0C0A7F9BDA
    fi
    chainloader /BOOTMGR
    }

    The above is what seems to get slightly furthest, but it fails with ...

    error: invalid signature
    Press any key to continue...

    I've also tried both of the following ...

    chainloader +1
    chainloader /BOOTSECT.BIN

    .... where /BOOTSECT.BIN is a dd dump of the first sector of the Win11P partition, but both simply end up with the PC rebooting.

    --

    Fake news kills!

    I may be contacted via the contact address given on my website: www.macfh.co.uk


    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Carlos E.R.@2:250/1 to All on Saturday, November 15, 2025 03:06:00
    On 2025-11-14 23:52, Paul wrote:
    On Fri, 11/14/2025 2:31 PM, Carlos E.R. wrote:
    On 2025-11-14 19:03, Paul wrote:

    https://www.thescannershop.com/plustek-opticpro-a320e-flatbed-scanner/

    Yeah, that book has been domesticated :-D


    I have a low priority project, from an idea I got in one usenet conversation,
    which is scan my magazines and notes, to save space in the house. That person
    used an automatic feed scanner, double side pages, coupled with cutting magazines
    in half first with a big guillotine cutter.

    There are book scanning devices, that flip the pages
    on the book, and they use a camera method for capture.
    You don't have to cut the binding off to capture.

    Yes, I saw a video once, but that will be too big and expensive for a
    home user.


    At least in this one, you can see the cameras used.
    (The site is a bit slow, move your mouse around while waiting)

    https://diybookscanner.org/forum/viewtopic.php?t=3125

    Yes, similar to the one I saw years ago.

    --
    Cheers, Carlos.
    ES🇪🇸, EU🇪🇺;

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: Air Applewood, The Linux Gateway to the UK & Eire (2:250/1@fidonet)
  • From Carlos E.R.@2:250/1 to All on Saturday, November 15, 2025 13:51:36
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 2025-11-15 02:57, Java Jive wrote:
    On 2025-11-11 13:19, Java Jive wrote:

    On 2025-11-11 03:45, Paul wrote:

    On Mon, 11/10/2025 7:27 PM, Java Jive wrote:

    Perhaps next I might try seeing if I can boot W11P from the original
    MBR menu, which would achieve the desired state of only needing one
    boot menu.

    Had a go at that meantime, couldn't get it to work.

    Still no success with this business of trying to boot Win11P on a GPT
    disk from Grub launched from an MBR disk.  This is what I've tried ...

    Maybe using os-probe from the first disk, it would find the W11 and
    create an stanza.


    --
    Cheers, Carlos.
    ES🇪🇸, EU🇪🇺;

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: Air Applewood, The Linux Gateway to the UK & Eire (2:250/1@fidonet)
  • From Java Jive@2:250/1 to All on Saturday, November 15, 2025 15:01:36
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 2025-11-15 13:51, Carlos E.R. wrote:
    On 2025-11-15 02:57, Java Jive wrote:
    On 2025-11-11 13:19, Java Jive wrote:

    On 2025-11-11 03:45, Paul wrote:

    On Mon, 11/10/2025 7:27 PM, Java Jive wrote:

    Perhaps next I might try seeing if I can boot W11P from the
    original MBR menu, which would achieve the desired state of only
    needing one boot menu.

    Had a go at that meantime, couldn't get it to work.

    Still no success with this business of trying to boot Win11P on a GPT
    disk from Grub launched from an MBR disk.  This is what I've tried ...

    Maybe using os-probe from the first disk, it would find the W11 and
    create an stanza.

    Running 'update-grub' produces two entries, one for each set of UEFI
    boot files in /dev/sdc{1,2}, and both entries are similar to the one
    already quoted, except that both insert a drivemap command and use
    chainloader +1, so both reboot the PC.

    --

    Fake news kills!

    I may be contacted via the contact address given on my website: www.macfh.co.uk


    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Paul@2:250/1 to All on Saturday, November 15, 2025 16:54:17
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On Sat, 11/15/2025 10:01 AM, Java Jive wrote:
    On 2025-11-15 13:51, Carlos E.R. wrote:
    On 2025-11-15 02:57, Java Jive wrote:
    On 2025-11-11 13:19, Java Jive wrote:

    On 2025-11-11 03:45, Paul wrote:

    On Mon, 11/10/2025 7:27 PM, Java Jive wrote:

    Perhaps next I might try seeing if I can boot W11P from the original MBR menu, which would achieve the desired state of only needing one boot menu.

    Had a go at that meantime, couldn't get it to work.

    Still no success with this business of trying to boot Win11P on a GPT disk from Grub launched from an MBR disk.  This is what I've tried ...

    Maybe using os-probe from the first disk, it would find the W11 and create an stanza.

    Running 'update-grub' produces two entries, one for each set of UEFI boot files in /dev/sdc{1,2}, and both entries are similar to the one already quoted, except that both insert a drivemap command and use chainloader +1, so both reboot the PC.


    Would this process go any easier, if the controlling disk was
    a UEFI one, and the only tricky chainloading it had to do was
    an MBR one ?

    I have a copy of the Supergrub disc, and it appears to only
    support UEFI booting, as if MBR booting would not be sufficient.

    Name: supergrub2-2.06s4-multiarch-USB.img.zip
    Size: 24206301 bytes (23 MiB)
    SHA256: 3F690588C5DBE80A9186818F5AA7B7566D4F2DC079F0FD9D06961F62DE0D7A0D

    Paul

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From TJ@2:250/1 to All on Sunday, November 16, 2025 18:58:46
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 2025-11-10 19:27, Java Jive wrote:
    You may recall the disk layout I was trying to achieve success with:

    Disk 1:  256GB (nominal) SSD - MBR partitioning
        P1:  Win  7 Pro, NTFS
        P2:  Win 10 Pro, NTFS
        P3:  Win  7 32-Bit Pro, NTFS
                (for old scanner with only 32-bit drivers)
        P4:  Ubuntu 24, ext4

    Disk 2:  2TB (nominal) HD - MBR partitioning
        P1:  Windows Data, NTFS
        P2:  Linux Data, ext4

    Disk 3:  128GB (nominal) MiniSSD - GPT partitioning
        P1:  128MB UEFI Boot, FAT32
        P2:  Win 11 Pro, NTFS


    FWIW, I multi-boot on my UEFI-capable machines using the rEFInd boot
    manager. https://www.rodsbooks.com/refind/ IIRC, I believe it can boot
    either an EFI or a BIOS OS, but you might want to read the website
    carefully to confirm that. Seems to me that I was able to boot a legacy
    usb stick once, but it's been a couple of years since I tried it.

    While it works for me, there are several differences between my machines
    and yours. I'm using Mageia 9 Linux, for one thing, and it will install
    rEFInd on your UEFI machine for you if requested.

    I do not have separate Windows partitions. For the very few things I
    need Windows to do I have a Windows 7 and Windows 10 guests in
    VirtualBox. At this time I have zero interest in Windows 11.

    I also have a relatively new scanner, part of an HP Envy Photo 7858
    printer. My old scanner died a few years back, and while looking for a stand-alone model to replace it I discovered that the most economical
    way to get one was to buy one with a printer attached. The scanner, as
    well as my color Laserjet m254dw, can be connected via wifi or Ethernet
    and both work well with both Mageia and the Windows guests.

    TJ

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: A noiseless patient Spider (2:250/1@fidonet)
  • From Adrian Caspersz@2:250/1 to All on Saturday, November 22, 2025 18:22:16
    Subject: Re: Is it possible to dual-boot both MBR & GPT without changing BIOS
    settings on laptop

    On 31/10/2025 12:56, Java Jive wrote:
    As per subject, as I now have on the same PC some OSs  -  Ubuntu24, Windows7/10  -  installed on an MBR disk and Windows 11 installed on a GPT/UEFI disk, I'd like if possible to find a way of booting any of
    them, and MBR/GPT USB sticks, without constantly having to change the
    BIOS settings on the PC.

    Unless playing games, Decent secondhand ex-business laptops are so cheap
    (< £100*), and so are their docking stations. Plus, Remmina works
    decently enough for Windows Remote Desktop, which means you can mix OS environments at will.

    Dual booting is a bit of a faff?


    * - HP EliteBook, 840 G5 8th Gen i7

    --
    Adrian C

    --- MBSE BBS v1.1.1 (Linux-x86_64)
    * Origin: Air Applewood, The Linux Gateway to the UK & Eire (2:250/1@fidonet)