I attempted to setup dual boot on my PC, I've just been informed you cannot have UEFI & MBR OS's sharing the same GRUB menu (if anyone knows how feel free to share).

So I'm checking my DISKS in Windows, I have 2: an SSD and a HDD.
Under disk management, both appear as the Master Boot Record partition type.


However, I know for a fact that Manjaro is installed on DISK 0 as UEFI, which uses GPT right?
Therefore, even though Windows Disk Management is saying that DISK 0 is a MBR, is it possible that one partition on DISK 0 is MBR and it has another GPT?

Sorry if this is a noob question as I'm recently getting involved in the whole dual booting and it's a lot of new terminology to me and understanding consequences of using OS's with conflicting boot partition types.

UEFI can work with both GPT and MBR, it just needs it's own EFI partition (which is esentially FAT32 partition)


If you boot into a live iso. Some bios will give you the option to boot using uefi or not. MBR will tell the bios to boot using legacy style. It not really that big of a deal.

If you want you could run the following command in a terminal in Manjaro and post the ouput back here to give the forum more detailed info on yor disk set up:
sudo parted -l
(that is liwercase L)

There you go my good sir.

Model: ATA ST1000DX001-1NS1 (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size   Type     File system  Flags
 1      1049kB  525MB   524MB  primary  ntfs         boot
 4      525MB   105GB   104GB  primary  fat32
 2      105GB   686GB   581GB  primary  ntfs
 3      686GB   1000GB  315GB  primary  ext4

Model: ATA WDC WDS500G2B0B (scsi)
Disk /dev/sdb: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End    Size   Type     File system  Flags
 1      1049kB  608MB  607MB  primary  ntfs         boot
 2      608MB   500GB  499GB  primary  ntfs

Thank you so much for providing the requested info!

As your disk manager in Windows showed, the output of the parted -l confirms that you have msdos/mbr partition table on both of your disks.

For Manjaro to be installed in UEFI mode you would have needed a disk with Guid Partition Table (GPT). Also a Fat32-formatted partition, flagged as boot and esp and a couple of 100 MB in size, is required as the location for installation of the bootloader.

There is however a FAT32-partiton on your /dev/sda but that one is way too large and lacks the above mentioned flags. So I think this suggests that Manjaro is installed in Legacy/MBR mode which I am afraid contardicts:

To dissipate any shadows of doubt, once you are booted into your Manjaro, please open a terminal and run:

test -d /sys/firmware/efi && echo UEFI || echo BIOS

If ecohed BIOS then your Manjaro is installed in Legacy/MBR/BIOS mode, which is perfectly fine as long as everything is working fine.

Hi there! Thank you for the response.
I have executed the command and the echo back was UEFI.
Thank you for your time :smiley:

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Well then I have to admit that there must be something more to this that is beyond my level of understanding these matters. Perhaps some more knowledgeable community members would join to shed some light on this.


By the way, what would
findmnt /boot/efi
lsblk -f

You have an existing windows in bios-legacy (msdos disk).
Suggest you do not try to install manjaro in uefi {and convert the disk to gpt}
Best you stick to installing manjaro in bios-legacy without converting your disk to gpt.
There is no point in converting your disk to gpt and installing in bios-legacy (with the many constricts)

See this post, and the many links in that post.

Looking forward to a small fish. :wink:

When I execute the Command

test -d /sys/firmware/efi && echo UEFI || echo BIOS

It returns the value UEFI, so I believe I've already done so. Someone at the top of this thread mentioned that UEFI can be installed on both MBR and GPT partition tables provided it has its own FAT32 partition which is probably why my DISK is showing as MSDOS despite containing a UEFI system?

Do you believe the reason for Windows 10 not showing up on my Manjaro Boot Loader is due Windows being legacy and Manjaro being UEFI? This would really help me to make sense of the situation.

Also here is your fish for your troubles sir penguin.


The installation seems to be already in UEFI as per:

Doesn't this explain why Windows Boot Manager is not captured by Grub, since they are installed in different modes?

What I was unaware of was the fact that you could install in UEFI on a disk with MBR partition table which apparently is the case here.

To install in bios-legacy, you must boot the install media in bios-legacy.
You need to reboot install media in bios-legacy, not uefi.

That is not correct, you can install in bios-legacy in both msdos and in gpt, but to install in gpt, there's several things to watch out, also mentioned above. But you just cannot install uefi to a msdos disk. Just cannot, no way. Installation might complete but subsequent errors later on will occur.
Repeat, for uefi installation, it has to be a gpt disk.

Now...your case, what you should be looking out.
You have windows in bios-legacy in msdos disk.
In fact all your disks are now in msdos. Good.
If you read my links, you cannot use a uefi manjaro grub to boot bios-legacy windows.
The best for you to do, is to install manjaro in bios-legacy to the msdos disk.
Do not convert the msdos disk to gpt. There is no point. There is no advantage. There is nothing to gain and everything to lose.

Just install Manjaro in bios-legacy to that msdos disk.
Reminder, you must boot the install media in bios-legacy, that is all.

Thanks for the fish.
ps: anything bigger? :rofl:

I will give you this information when I'm back from work, currently on my work laptop at the moment!

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See this topic.
and the problems (in the links in that post) other users face. Still valid.
And still our installer allows installation to proceed. :zipper_mouth_face:

Here take it, you deserve it champ.
Feed the little ones.

Thank you very much for letting me pick your brain.
I will go ahead read those links and fix this!!!

Ah... now that's something.
Thanks... burp. :rofl:

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