Re: Dual booting problem
Van Snyder composed on 2025-06-30 14:46 (UTC-0700):
> On Mon, 2025-06-30 at 17:26 -0400, Felix Miata wrote:
>> Debian needs to be installed in UEFI mode for its Grub to be able to>> chain Win11's
>> bootloader.
> The netinst Debian 12 DVD I downloaded wouldn't boot in EFI mode. How
> do I install Debian 12 in EFI mode. Can I change it after it's
> installed?
AFAIK, Debian doesn't make any installation .isos for Stable amd64 that will not
boot in UEFI mode. What probably happened to you is one of two or more things:
1-incomplete burning of .iso to USB media. Just because the burner program claims
it's done doesn't necessarily mean the writing to the USB is complete. You must
ensure the OS reports safe first. I ensure this by issuing the sync command after
the write utility's claim of completion occurs. Only when sync returns is it sure
to be truly safe to "safely" remove the device, or to reboot. As USB sticks are
notoriously unreliable, I do my .iso writing to them using ddrescue instead of
plain dd or any of the GUI tools designed for the task.
2-you didn't try hard enough. One way to ensure you don't boot in CSM/legacy mode
is to disable it in the UEFI BIOS. Another way to be sure is to use the BBS hotkey
to select the boot device. UEFI capable media will normally show up in that menu
(at least) twice, once with, and once without, a UEFI moniker. Simply select that
which has a UEFI moniker included.
3-USB3 sticks can't be expected to work properly in USB2 ports.
If Fedora was installed in UEFI mode, you can use its bootloader to start a Debian
installation by loading the linux and initrd.gz taken either from the NET
installation media, or its mirrors counterpart:
<http://ftp.us.debian.org/debian/dists/bookworm/main/installer-amd64/current/images/netboot/debian-installer/amd64/>
Loading linux and initrd.gz with Grub is how most of my Linux installations begin.
The following is (approximately) an EFI Grub2 stanza I previously used for the
purpose:
menuentry "Install Debian via HTTP" {
search --no-floppy --label --set=root tm8p03res
linuxefi /deb/linux showopts vga=791 --- net.ifnames=0 ipv6.disable=1
netcfg/get_hostname=myhost netcfg/get_domain=mydomain.net
netcfg/disable_autoconfig=true netcfg/get_ipaddress=192.168.###.###/24
netcfg/get_gateway=192.168.###.### netcfg/get_nameservers=1.0.0.1
netcfg/confirm_static=true tasks=standard base-installer/install-recommends=false
GRUB_DISABLE_OS_PROBER=true
initrdefi /deb/initrd.gz
}
Most of those linu line options are not necessary, but simply those I prefer be
utilized to get a simple base installation working before adding selected
non-essentials.
--
Evolution as taught in public schools is, like religion,
based on faith, not based on science.
Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!
Felix Miata
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