On Thu, Jan 21, 2021 at 10:02 AM Dan Ritter <d...@randomstring.org> wrote:
> Dan Hitt wrote:
> > On Thu, Jan 21, 2021 at 3:33 AM Brian <a...@cityscape.co.uk> wrote:
> >
> > >
> > > menuentry 'Debian 10' {
> > > linux /boot/vmlinuz
> > > initrd /boot/initrd.gz
> > > }
> > >
> > > --
> > > Brian.
> > >
> > >
> > Brian, thanks so much for your advice. Thank you also Felix, David, and
> > Bastien --- i need to study what you have all written.
> >
> > However, Brian's final stanza is so simple that i can ask a question
> about
> > it immediately.
> >
> > And that is: how can grub2 or any other software know what partition
> > '/boot' refers to?
> >
> > So i presume that in this very very short stanza you provide, there will
> > also have to be a search line like David has (search --no-floppy ......)
> to
> > identify just where '/boot' is (???).
>
>
> https://en.wikipedia.org/wiki/GNU_GRUB#Startup_on_systems_using_BIOS_firmware
>
> stage 2: core.img loads /boot/grub/i386-pc/normal.mod from the
> partition configured by grub-install. If the partition index has
> changed, GRUB will be unable to find the normal.mod, and
> presents the user with the GRUB Rescue prompt.
>
> So the answer to your question is, it's been configured at
> install time, not discovered at runtime.
>
> -dsr-
>
Thanks Dan for your mail, and for the reference to the wikipedia article.
When you say 'configured at install time', does that refer to the time at
which i run 'sudo update-grub' (on my mint host)?
(I presume that it is impossible that this refers to the time when grub
itself was last installed on the box, several years ago.)
Anyhow, i added an entry to /etc/grub.d just to see what would happen if i
took the simple menu entry quite literally:
menuentry "simple-test" {
linux /boot/vmlinuz
initrd /boot/initrd.gz
}
I ran 'sudo update-grub', and the entry was copied into /boot/grub/grub.cfg
without modification. And then i tried booting into it, just to see what
grub would do. And, it did what i think was the only thing it possibly
could: it reported:
error: file `/boot/vmlinuz' not found.
error: you need to load the kernel first.
Press any key to continue...
Now, Brian said that "the installer's initrd does not contain a loop
module", so that would indicate that if i want to use
debian-10.7.0-amd64-xfce-CD-1.iso, i'll need to get it on the disk
(presumably by just unpacking it somewhere --- prior to booting, i can loop
mount it and copy it to a 'real' directory), and then modifying
/boot/vmlinuz and /boot/initrd.gz to be paths that grub understands. Or,
maybe the debootstrap method Bastien suggests would be good.
Anyhow, thanks for your message, and thanks everybody else for these
important pieces of knowledge that i need to learn.
dan
