UEFI "Other OS" option

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mike acker
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UEFI "Other OS" option

Post by mike acker » Mon Jun 17, 2019 8:24 pm

Today I ran the LMDE3 installer on a LMDE/2 system disk.

The system is using an ASUS A88X-Pro MoBo which has extensive UEFI options.

The LMDE/3 install seems to insist on UEFI mode. So, I went ahead and deleted my extended partition (which had noting in it ) and created the 100Mb FAT32 partition. This partition had to have a boot flag set -- and THEN formatted as FAT32 before the installer would accept it at the recommended mount point.

As soon as I got past fussing over all of that the LMDE3 installer finished properly although the automatic restart at the end didn't work: I had to pull the USB live stick and hit the reset key -- which restarts the system from POST on the MoBo

getting it to boot was tricky: I had to set the UEFI compatibility mode to AUTO and change the OS Type from Windows to "Other OS"

and I had to select LINUXMINT from the boot drive offerings -- rather than the disc drive name.

the key question though is: will setting the OS Type to "Other OS" prevent Windows-10 from booting? I'm thinking: most likely.

I was working with the "Research Box" today which does not boot any Windows system -- it has Straight Debian(Stretch) with Oracle VirtualBox for that.

But the next machine has Windows 10 on a separate drive; I'd hate for the user to have to keep changing the "OS Type".

I wonder if I let the machine start LMDE/3 if I can interrupt and get into GRUB and then direct GRUB to load the Win10 machine ?

p.s. the data from the LMDE/2 /home directory -- was all preserved properly.
¡Viva la Resistencia!

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administrollaattori
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Re: UEFI "Other OS" option

Post by administrollaattori » Tue Jun 18, 2019 12:41 am

UEFI requires a GPT partition table for working, so are the bootable drive GPT?

Code: Select all

sudo parted -l

mike acker
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Re: UEFI "Other OS" option

Post by mike acker » Tue Jun 18, 2019 7:48 am

administrollaattori wrote:
Tue Jun 18, 2019 12:41 am
UEFI requires a GPT partition table for working, so are the bootable drive GPT?

Code: Select all

sudo parted -l
No: the partition table is still MSDOS(MBR). This project was an attempt to see if I could update the old LMDE2 system to LMDE3.

Code: Select all

Model: ATA WDC WD1002FAEX-0 (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system     Flags
 1      1049kB  33.6GB  33.6GB  primary  ext4            boot
 2      33.6GB  67.1GB  33.6GB  primary  linux-swap(v1)
 3      67.1GB  1000GB  933GB   primary  ext4


Model: ATA ST31000524AS (scsi)
Disk /dev/sdb: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system     Flags
 1      1049kB  45.0GB  45.0GB  primary  ext4
 2      45.0GB  989GB   944GB   primary  ext4
 3      989GB   994GB   5000MB  primary  linux-swap(v1)
 4      994GB   994GB   105MB   primary  fat32           boot


Model: ATA ST31000524AS (scsi)
Disk /dev/sdc: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  1000GB  1000GB  primary  ntfs

the LMDE3 system is mounted on sdb

in order to change the partition table to GPT I would have lost the complete content of the existing disc. To prevent that I could have installed a new disc in the machine and formatted that as GPT and then added the FAT32/UEFI partition, followed by a new partition to become root.

Using GPARTED I might have been able to then copy the /home partition from the existing system to the new GPT formatted disc and then added another partition to become swap

then on running the LMDE3 installer I might have directed it to use this new set of partitions

that option is still open as the /home partition of the earlier LMDE2 system -- while now in the the LMDE3 system -- seems to have survived OK

this work was all done on the Research box so it's OK to play with it a bit more. It's probably worth doing as using GPARTED to copy the home partition of an earlier system based on MSDOS/MBR partitions is probably "the right thing to do ".

thoughts -- anyone ?
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AndyMH
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Re: UEFI "Other OS" option

Post by AndyMH » Tue Jun 18, 2019 9:23 am

You could try gdisk to convert mbr to gpt without losing your data. Not done it myself (and if I did, I'd still back it up), but a bit more here and the man pages are reasonable.
http://www.rodsbooks.com/gdisk/mbr2gpt.html

If you do, report back here on how it went :)
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mike acker
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Re: UEFI "Other OS" option

Post by mike acker » Tue Jun 18, 2019 9:29 am

AndyMH wrote:
Tue Jun 18, 2019 9:23 am
<snip> (and if I did, I'd still back it up)<snip>
thanks for the tip. I'd be much more inclined to use gparted and copy the partition to a new GPT disc though -- that leaves the original as the backup :D
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Re: UEFI "Other OS" option

Post by Nuts2u » Wed Jun 19, 2019 5:51 pm

I convert my mbr partition to a GPT partition on the fly with no loss of data. The first thing to do is using gparted, create a 10 meg parition, format it as ext2 or whatever it does not matter, and set the flag as bios_grub. That is where grub will be installed after conversion from mbr. I moved it to the front of my ssd using gparted. Then using gdisk program perform the conversion, which takes 1 sec litterally, write the changes to disk, the update grub using grub customizer or from the command line, whichever is easiest for you, then reinstall grub. I used grub customizer, clicked on file, then install to mbr, it recognized it was now GPT partition and installed grub in the new 10 meg biod_grub partition. I did have a backup in case anything went wrong. This whole operation took less than 5 mins.
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mike acker
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Re: UEFI "Other OS" option

Post by mike acker » Fri Jun 21, 2019 8:11 am

administrollaattori wrote:
Tue Jun 18, 2019 12:41 am
UEFI requires a GPT partition table for working, so are the bootable drive GPT?

Code: Select all

sudo parted -l
a few quick thoughts ( have I got this stuff right ?? )

when the MBR partition table is used the Master Boot Record is the first sector on the disk ( ? ) and contains some of the boot text -- followed by the MSDOS version partition table -- which has space for just four partition descriptors....... the boot text can then search the partition table for the partition to mount at root, and from that source it can continue into the startup text for the target O/S

switching to GPT gets away from that -- the MBR does not exist. The result being that the FAT32 partition has to be defined as a place for the boot text. UEFI then becomes required because only that system is able to identify the FAT32 boot partition and continue the boot process from the MoBo firmware into the OpSys boot text

it seems to me then that using the GPT partition table is going to require the use of UEFI -- not vv

interestingly, when I switched my Research box LMDE/2 system to LMDE/3 the installer insisted that I create the FAT32 partition -- and mount it accordingly

on system startup where I would usually select a drive a new option appeared labeled simply "LINUXMINT". The MoBo firmware (ASUS/A88X-Pro) allowed me to select the LINUXMINT as the boot device -- and fired up LMDE/3 "Cindy". Hopefully, I might have assigned a label to that FAT32 partition while gparted was running,..... this will be critical if there is more than one sysres disk in the box......
¡Viva la Resistencia!

gm10
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Re: UEFI "Other OS" option

Post by gm10 » Fri Jun 21, 2019 9:11 am

If you installed in UEFI mode then the system boots in UEFI mode, no matter your partition table. Your UEFI doesn't care whether your partition table is MBR or GPT, it can boot from either. It's only Windows that refuse to install to an MBR disk in UEFI mode by default (it can be made to though).

In a multi-boot situation LMDE3's GRUB boot loader should automatically detect and add the Windows install to its boot menu when you run sudo update-grub and you can then choose which OS to boot without having to change the UEFI boot device.

If you install Windows after LMDE then it is possible that WIndows will overwrite the MBR and point it to its own boot loader instead. This is easily fixed by installing GRUB again.
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mike acker
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Re: UEFI "Other OS" option

Post by mike acker » Sun Jun 23, 2019 10:22 am

gm10 wrote:
Fri Jun 21, 2019 9:11 am
If you installed in UEFI mode then the system boots in UEFI mode, no matter your partition table. Your UEFI doesn't care whether your partition table is MBR or GPT, it can boot from either. It's only Windows that refuse to install to an MBR disk in UEFI mode by default (it can be made to though).

In a multi-boot situation LMDE3's GRUB boot loader should automatically detect and add the Windows install to its boot menu when you run sudo update-grub and you can then choose which OS to boot without having to change the UEFI boot device.

If you install Windows after LMDE then it is possible that WIndows will overwrite the MBR and point it to its own boot loader instead. This is easily fixed by installing GRUB again.
thanks; this clears thing up!!
¡Viva la Resistencia!

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