I have a machine that currently has linux mint 16.04 on it.
I would like to install debian 10 on it, but the installer really wants
access to a cd drive, and one just isn't available.
However, the linux mint 16.04 system does have grub2 on it.
So it is possible for me to boot from an iso image stored in the filesystem
just like a regular file. It's just a matter of writing a menu entry in
/etc/grub/40_custom.
I know this works because i've booted into a live cd image of linux mint
20.1 (using the filesystem, not a cdrom), and started an installation
process. I backed out of it, because i would like to install debian 10,
not just a later version of mint.
When i do the same thing with debian, it starts off ok, doing some simple
things like setting the language and the keyboard layout, but then it
complains that it cannot find a cd rom. This is true with both the netinst
image, as well as with a jigdo xfce image which i think should have
everything necessary and not need a cd rom. For reference, my debian menu
entry is
menuentry "debian-10-iso" {
set isofile="/USER/iso/debian-10.7.0-amd64-xfce-CD-1.iso"
loopback loop (hd0,gptNN)$isofile
linux (loop)/install.amd/vmlinuz boot=install.amd
iso-scan/filename=$isofile noprompt noeject
initrd (loop)/install.amd/initrd.gz
}
Here, USER is the user name in whose account the iso image is, and gptNN
stands for the particular partition where home is mounted for the user USER.
So my first question is whether there's a better iso image i can use, or if
i can fix this up by giving more arguments to the linux invocation line or
something else in the menu entry.
The second question is whether there's a way, from grub (grub2, actually),
of dropping down to the bios. I imagine this is quite impossible, but if
i'm wrong, please let me know. The reason i would like to do this is that
it is very hard for me to interrupt the boot process fast enough to get to
the bios, and i've only managed to do it once or twice after many tries.
If i were in the bios, i might be able to figure out if it could boot from
usb, and i could set the boot order to do this, and make a bootable usb
version of netinst (perhaps).
Or perhaps there's some other way to approach the problem? For example,
i've already created a partition to hold the debian system i want to put on
the machine. Is there some way of hand-populating it? I do have a running
debian 10 system on another machine, and i suppose i could tar it up and
unpack it into the new partition on the mint machine. But i'm not sure if
there's something outside the filesystem but inside the partition which is
necessary for it to be bootable.
Thanks in advance for any advice!
dan
