Hi

I am new to this forum and new to Linux (Cinnamon Mint 21.1).


I have successfully dual boot Mint 21.1 with MS-DOS 7.1, i.e., grub-update Menu allows choice between (Mint + DOS).

On the same disc, later on, in later unallocated partition, (no changes to existing MS-DOS and Mint partitions), installed Windows 10 x64 21H2 and update-grub Menu allows choice only between (Mint + Windows 10).

I wish to have triple boot (Mint + DOS + Win).

With permission, I attempted to sudoedit /etc/default/grub to add back the DOS menuentry but get a sudo update-grub error


$ sudo update-grub
[sudo] password for r...
Sourcing file '/etc/default/grub'
/usr/sbin/grub-mkconfig: 38: /etc/default/grub: menuentry: not found
$





The offending line 38 is

menuentry 'MS-DOS 5.x/6.x/Win3.1 (on /dev/sda2)' --class ms_dos --class os $menuentry_id_option 'osprober-chain-5230-F0FE' {



I also tried simplifying the line to 'MS-DOS' and also 'MS-DOS (on /dev/sda2)' leaving the rest of the line intact (--class ms dos ...) but get the same update-grub error as above.



The complete listing for /etc/default/grub I have tried is below




# TEST FOR EDIT_CHANGE
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'

GRUB_DEFAULT="0"
GRUB_TIMEOUT_STYLE="hidden"
GRUB_TIMEOUT="10"
GRUB_DISTRIBUTOR="`lsb_release -i -s 2> /dev/null || echo Debian`"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL="console"

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE="640x480"

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID="true"

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"


### BEGIN /etc/grub.d/30_os-prober ###
menuentry 'MS-DOS 5.x/6.x/Win3.1 (on /dev/sda2)' --class ms_dos --class os $menuentry_id_option 'osprober-chain-5230-F0FE' {
insmod part_gpt
insmod fat
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 5230-F0FE
else
search --no-floppy --fs-uuid --set=root 5230-F0FE
fi
drivemap -s (hd0) ${root}
chainloader +1
}
set timeout_style=menu
if [ "${timeout}" = 0 ]; then
set timeout=10
fi
### END /etc/grub.d/30_os-prober ###




According to Gparted, my MS-DOS partition is /dev/sda2





Summary

At first, I had dual boot (Mint + DOS), then added Windows, update-grub and now only dual boot (Mint + Win).

Question - how to have triple boot (Mint + DOS + Win) - assuming that I only have to edit /etc/default/grub correctly to achieve this?

It should be this in /etc/default/grub to activate os-prober:

Please post output from either sudo parted -l and/or sudo fdisk -l, from sudo lsblk -f and from sudo efibootmgr.

Attn MRMAZDA

Info as requested




sudo parted -l

r@HP:~$ sudo parted -l
[sudo] password for r:
Model: ATA WDC WDS400T1R0A (scsi)
Disk /dev/sda: 4001GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number Start End Size File system Name Flags
1 17.4kB 16.8MB 16.8MB Microsoft reserved partition msftres
2 16.8MB 8607MB 8590MB fat32 Basic data partition msftdata
3 8607MB 17.2GB 8590MB fat32 Basic data partition msftdata
4 17.2GB 1091GB 1074GB ntfs Basic data partition msftdata
5 1091GB 1091GB 105MB fat32 EFI system partition boot, esp
7 1091GB 1091GB 1049kB bios_grub
8 1091GB 1628GB 537GB ext4
6 1628GB 4001GB 2373GB ntfs Basic data partition msftdata


Model: Verbatim STORE N GO (scsi)
Disk /dev/sdb: 31.0GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:

Number Start End Size Type File system Flags
1 32.3kB 537MB 537MB primary fat32 boot
2 538MB 31.0GB 30.4GB primary fat32 lba


r@HP:~$ ^C
r@HP:~$






sudo fdisk -l

r@HP:~$ sudo fdisk -l
Disk /dev/sda: 3.64 TiB, 4000787030016 bytes, 7814037168 sectors
Disk model: WDC WDS400T1R0A
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 4A521CCC-5630-4D13-A207-67287FC9DE43

Device Start End Sectors Size Type
/dev/sda1 34 32767 32734 16M Microsoft reserved
/dev/sda2 32768 16809983 16777216 8G Microsoft basic data
/dev/sda3 16809984 33587199 16777216 8G Microsoft basic data
/dev/sda4 33587200 2130739199 2097152000 1000G Microsoft basic data
/dev/sda5 2130739200 2130943999 204800 100M EFI System
/dev/sda6 3179520000 7814033407 4634513408 2.2T Microsoft basic data
/dev/sda7 2130944000 2130946047 2048 1M BIOS boot
/dev/sda8 2130946048 3179519999 1048573952 500G Linux filesystem

Partition table entries are not in disk order.


Disk /dev/sdb: 28.85 GiB, 30972837888 bytes, 60493824 sectors
Disk model: STORE N GO
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xc198e76a

Device Boot Start End Sectors Size Id Type
/dev/sdb1 * 63 1048638 1048576 512M b W95 FAT32
/dev/sdb2 1050624 60491775 59441152 28.3G c W95 FAT32 (LBA)
r@HP:~$






sudo lsblk -f

r@HP:~$ sudo lsblk -f
NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
sda
├─sda1
│
├─sda2
│ vfat FAT32 GPT_D71
│ 5230-F0FE
├─sda3
│ vfat FAT32 GPT_FD
│ A251-6A08
├─sda4
│ ntfs F8AAC911AAC8CCF6
├─sda5
│ vfat FAT32 202E-600C 65.7M 32% /boot/efi
├─sda6
│ ntfs New Volume
│ BC1CC62B1CC5E10E
├─sda7
│
└─sda8
ext4 1.0 f19f7536-4cd7-40d4-b785-1ed717ec0ccf 455.1G 2% /
sdb
├─sdb1
│ vfat FAT32 DOS71 EC01-CEA4 189.6M 63% /media/r/DOS71
└─sdb2
vfat FAT32 DOS71_DATA
4E94-A524 24.6G 13% /media/r/DOS71_DATA
r@HP:~$






sudo efibootmgr

r@HP:~$ sudo efibootmgr
BootCurrent: 0002
Timeout: 20 seconds
BootOrder: 0001,3001,0002,2001,2002,2004
Boot0001* Windows Boot Manager
Boot0002* ubuntu
Boot2001* EFI USB Device
Boot2002* EFI DVD/CDROM
Boot3001* Internal Hard Disk or Solid State Disk
r@HP:~$









and some other files, not re-modified yet


/boot/grub/grub.cfg

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
if [ "${initrdfail}" = 2 ]; then
set initrdfail=
elif [ "${initrdfail}" = 1 ]; then
set next_entry="${prev_entry}"
set prev_entry=
save_env prev_entry
if [ "${next_entry}" ]; then
set initrdfail=2
fi
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="0"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function initrdfail {
if [ -n "${have_grubenv}" ]; then if [ -n "${partuuid}" ]; then
if [ -z "${initrdfail}" ]; then
set initrdfail=1
if [ -n "${boot_once}" ]; then
set prev_entry="${default}"
save_env prev_entry
fi
fi
save_env initrdfail
fi; fi
}
function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}

if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_gpt
insmod ext2
set root='hd0,gpt8'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt8 --hint-efi=hd0,gpt8 --hint-baremetal=ahci0,gpt8 f19f7536-4cd7-40d4-b785-1ed717ec0ccf
else
search --no-floppy --fs-uuid --set=root f19f7536-4cd7-40d4-b785-1ed717ec0ccf
fi
font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
set gfxmode=auto
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=en_AU
insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ] ; then
set timeout=30
else
if [ x$feature_timeout_style = xy ] ; then
set timeout_style=hidden
set timeout=10
# Fallback hidden-timeout code in case the timeout_style feature is
# unavailable.
elif sleep --interruptible 10 ; then
set timeout=0
fi
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
set gfxpayload="${1}"
if [ "${1}" = "keep" ]; then
set vt_handoff=vt.handoff=7
else
set vt_handoff=
fi
}
if [ "${recordfail}" != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if [ ${grub_platform} != pc ]; then
set linux_gfx_mode=keep
elif hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode
menuentry 'Linux Mint 21.1 Cinnamon' --class linuxmint --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-f19f7536-4cd7-40d4-b785-1ed717ec0ccf' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
set root='hd0,gpt8'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt8 --hint-efi=hd0,gpt8 --hint-baremetal=ahci0,gpt8 f19f7536-4cd7-40d4-b785-1ed717ec0ccf
else
search --no-floppy --fs-uuid --set=root f19f7536-4cd7-40d4-b785-1ed717ec0ccf
fi
linux /boot/vmlinuz-5.15.0-56-generic root=UUID=f19f7536-4cd7-40d4-b785-1ed717ec0ccf ro quiet splash
initrd /boot/initrd.img-5.15.0-56-generic
}
submenu 'Advanced options for Linux Mint 21.1 Cinnamon' $menuentry_id_option 'gnulinux-advanced-f19f7536-4cd7-40d4-b785-1ed717ec0ccf' {
menuentry 'Linux Mint 21.1 Cinnamon, with Linux 5.15.0-56-generic' --class linuxmint --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.15.0-56-generic-advanced-f19f7536-4cd7-40d4-b785-1ed717ec0ccf' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
set root='hd0,gpt8'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt8 --hint-efi=hd0,gpt8 --hint-baremetal=ahci0,gpt8 f19f7536-4cd7-40d4-b785-1ed717ec0ccf
else
search --no-floppy --fs-uuid --set=root f19f7536-4cd7-40d4-b785-1ed717ec0ccf
fi
echo 'Loading Linux 5.15.0-56-generic ...'
linux /boot/vmlinuz-5.15.0-56-generic root=UUID=f19f7536-4cd7-40d4-b785-1ed717ec0ccf ro quiet splash
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.15.0-56-generic
}
menuentry 'Linux Mint 21.1 Cinnamon, with Linux 5.15.0-56-generic (recovery mode)' --class linuxmint --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.15.0-56-generic-recovery-f19f7536-4cd7-40d4-b785-1ed717ec0ccf' {
recordfail
load_video
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
set root='hd0,gpt8'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt8 --hint-efi=hd0,gpt8 --hint-baremetal=ahci0,gpt8 f19f7536-4cd7-40d4-b785-1ed717ec0ccf
else
search --no-floppy --fs-uuid --set=root f19f7536-4cd7-40d4-b785-1ed717ec0ccf
fi
echo 'Loading Linux 5.15.0-56-generic ...'
linux /boot/vmlinuz-5.15.0-56-generic root=UUID=f19f7536-4cd7-40d4-b785-1ed717ec0ccf ro recovery nomodeset dis_ucode_ldr
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.15.0-56-generic
}
}

### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/11_linux_zfs ###
### END /etc/grub.d/11_linux_zfs ###

### BEGIN /etc/grub.d/20_linux_xen ###

### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/30_os-prober_proxy ###


set timeout_style=menu
if [ "${timeout}" = 0 ]; then
set timeout=10
fi
### END /etc/grub.d/30_os-prober_proxy ###

### BEGIN /etc/grub.d/40_custom_proxy ###
menuentry "Windows Boot Manager (on /dev/sda5)" --class windows --class os $menuentry_id_option 'osprober-efi-202E-600C' {
insmod part_gpt
insmod fat
set root='hd0,gpt5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt5 --hint-efi=hd0,gpt5 --hint-baremetal=ahci0,gpt5 202E-600C
else
search --no-floppy --fs-uuid --set=root 202E-600C
fi
chainloader /EFI/Microsoft/Boot/bootmgfw.efi
}
### END /etc/grub.d/40_custom_proxy ###

### BEGIN /etc/grub.d/41_os-prober_proxy ###
### END /etc/grub.d/41_os-prober_proxy ###

### BEGIN /etc/grub.d/42_uefi-firmware ###
menuentry 'UEFI Firmware Settings' $menuentry_id_option 'uefi-firmware' {
fwsetup
}
### END /etc/grub.d/42_uefi-firmware ###

### BEGIN /etc/grub.d/43_fwupd ###
### END /etc/grub.d/43_fwupd ###

### BEGIN /etc/grub.d/44_custom_proxy ###

# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.

### END /etc/grub.d/44_custom_proxy ###

### BEGIN /etc/grub.d/45_custom ###
if [ -f ${config_directory}/custom.cfg ]; then
source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg
fi
### END /etc/grub.d/45_custom ###





/etc/default/grub

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'

GRUB_DEFAULT="0"
GRUB_TIMEOUT_STYLE="hidden"
GRUB_TIMEOUT="10"
GRUB_DISTRIBUTOR="`lsb_release -i -s 2> /dev/null || echo Debian`"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL="console"

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE="640x480"

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID="true"

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

# Addition to /etc/default/grub
# via sudo -i [Enter]
# sudoedit /etc/default/grub

### BEGIN /etc/grub.d/30_os-prober ###
# DELETED 'MS-DOS 5.x/6.x/Win3.1 (on /dev/sda2)' --class ms_dos --class os $menuentry_id_option 'osprober-chain-5230-FDFE'{

menuentry 'MS-DOS (on /dev/sda2)' --class ms_dos --class os $menuentry_id_option 'osprober-chain-5230-F0FE' {

insmod part_gpt
insmod fat
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 5230-F0FE
else
search --no-floppy --fs-uuid --set=root 5230-F0FE
fi
drivemap -s (hd0) ${root}
chainloader +1
}
set timeout_style=menu
if [ "${timeout}" = 0 ]; then
set timeout=10
fi
### END /etc/grub.d/30_os-prober ###





/boot/grub/grubenv

# GRUB Environment Block
# WARNING: Do not edit this file by tools other than grub-editenv!!!
#################################################################################################### #################################################################################################### #################################################################################################### #################################################################################################### #################################################################################################### #################################################################################################### #################################################################################################### #################################################################################################### #################################################################################################### ##############################




using grub 2.06 on MINT 21.1 beta cinnamon

Attn ColorPurple21859

result with trying your suggestion


r@HP:~$ sudo update-grub
[sudo] password for r:
Sourcing file `/etc/default/grub'
/usr/sbin/grub-mkconfig: 47: /etc/default/grub: menuentry: not found
r@HP:~$





/etc/default/grub at present now

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'

GRUB_DEFAULT="0"
GRUB_TIMEOUT_STYLE="hidden"
GRUB_TIMEOUT="10"
GRUB_DISTRIBUTOR="`lsb_release -i -s 2> /dev/null || echo Debian`"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

#
GRUB_DISABLE_OS_PROBER=false
#

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL="console"

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE="640x480"

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID="true"

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

# Addition to /etc/default/grub
# via sudo -i [Enter]
# sudoedit /etc/default/grub



#
### BEGIN /etc/grub.d/30_os-prober ###
menuentry 'MS-DOS 5.x/6.x/Win3.1 (on /dev/sda2)' --class ms_dos --class os $menuentry_id_option 'osprober-chain-5230-FDFE'{

insmod part_gpt
insmod fat
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 5230-F0FE
else
search --no-floppy --fs-uuid --set=root 5230-F0FE
fi
drivemap -s (hd0) ${root}
chainloader +1
}
set timeout_style=menu
if [ "${timeout}" = 0 ]; then
set timeout=10
fi
### END /etc/grub.d/30_os-prober ###
#

My take on this is at one time you was using legacy mode to multiboot windows 7 and linux, When windows 10 was installed the boot mode was changed to uefi mode. You are attempting to chainload windows 7 in legacy mode from grub efi bootloader which won't work. If windows 7 is 32bit you will have to boot windows 7 in legacy mode from the firmware/bios boot menu. It is possible to boot windows 7 64bit by adding windows 7 to windows 10 boot menu using bcdedit tools.

Delete all this from /etc/default/grub, It should be put in /etc/grub.d/40_custom, however it won't work.

I agree in principle with colorpurple21859 that boot mode was changed to UEFI, with the result that DOS 7.1 (Win98SE) could not be bootable via BIOS from the same disk, though I would expect it to be bootable installed as a virtual machine.

I've never tried putting DOS on a PC with UEFI BIOS, but I would expect you could add a small MBR partitioned disk for booting FreeDOS, and boot from it either chainloaded from EFI Grub, or directly from BIOS by an appropriate BIOS setting change when needed. You might do well to check on the FreeDOS website and/or ask FreeDOS users.

QUOTE]with MS-DOS 7.1[/QUOTE]I was thinking of windows 7, not MS-DOS-7.1 in my earlier post. I don't think with MS-DOS 7.1 will boot from a gpt disk and agree with mrmazda a virtual machine would be the way to go.

re: "I don't think with MS-DOS 7.1 will boot from a gpt disk..."

Normally, you would be right.

But, _now_ it is possible to boot DOS from a GPT partition. ;-)

http://www.bttr-software.de/forum/fo...y.php?id=19502

Could someone please provide a suitable link for a feature request for Mint 21.1 developers to consider?


Googling seems to come up with vastly different web pages.



Briefly, I wish a feature to allow multiple booting by essentially a MANUAL technique.


It appears to me that if have a triple boot (Mint + DOS + Windows) on GPT style disk, Windows "kicks out" MS-DOS 7.1
and so the Grub 2.06 BOOT MENU does not list MSDOS (and so cannot boot DOS).



By MANUAL technique, I mean do not do the auto-stuff by say OS-prober and the like.


Instead, suppose I supply relevant numbers for all partitions on the GPT disk, e.g.,



DOS info 8 GB partition

Type: {ebd0a0a2-b9e5-4433-87c0-68b6b72699c7}
First LBA: 32768 Last LBA: 16809983
Size: 8192 MB Flags: 0
Name: Basic data partition



MINT 21.1 info 500 GB partition

Type: {0fc63daf-8483-4772-8e79-3d69d8477de4}
First LBA: 2130946048 Last LBA: 3179519999
Size: 511999 MB Flags: 0




WIN info 1000 GB partition

Type: {ebd0a0a2-b9e5-4433-87c0-68b6b72699c7}
First LBA: 33587200 Last LBA: 2130739199
Size: 1024000 MB Flags: 0
Name: Basic data partition



and similarly, for any other required data partition.


As I see it, the GRUB Menu needs relevant numbers (addresses, etc.) - irrespective of
method to obtain same.


Thanks

What you would propose isn't about Mint. It's about Grub, or bootloaders in general. But, what you seem to want is already possible via Grub, via files in /etc/grub.d/ and/or /boot/grub/custom.cfg. You simply create the stanzas you need manually, and place them in /etc/grub.d/ and/or in /boot/grub/custom.cfg. Grub's normal menu presentation will then include your custom stanzas in its own menu, either before, and/or after, those it creates, according to where you place them. Of course for this to work, you need a configuration that includes OSes able to be booted from the same BIOS mode and disk partition configuration. IOW, all must be either in legacy/BIOS/CSM mode, or in UEFI mode, unless you don't mind booting from the other mode via BBS hotkey for any exception(s).

Since MS-DOS 7.1 predates UEFI & GPT by a lot of years, good luck getting it to boot conveniently in a PC cohabiting with Win11 in UEFI mode. Mint developers are all but certain to have neither interest nor talent to facilitate any such compatibility. They're primarily packagers who reconfigure some of the Debian and Ubuntu packages on which Mint is based, package some of their own, and provide some customization. Grub ultimately comes from upstream, like most software.

https://github.com/linuxmint/linuxmint/issues/new is where to report a general issue about Mint rather than some specific package or system that has its own tracker.

The link refers to hacking the protective mbr of the gpt drive and should be done by one someone who understands what they are doing, otherwise there is a good chance to break the drive.

Yes, as is stated by the folks who developed this 'system'...
it's most certainly for experts and if just one byte is done
incorrectly... all data on that drive will be trashed.

So as the old saying goes... "Do not attempt this at home." ;-)