On 05/29/2017 07:17 PM, John Little wrote:
Richard Owlett asked for a grub2 customized to his wishes.
How to obtain and install?
(This from memory before I got an UEFI computer. Please, anyone,
criticize the following.)
I approve of trimming, BUT ;/
You trimmed one {perhaps poorly worded} sentence too much.
I had said:
> I am assuming a Grub2 executable conforming exactly to the
> official documentation.
In your first paragraph you alluded to a "can of worms" I'm trying to
avoid when you said:
> A lot of what people see as part of Grub, like the "OS prober",
> "update-grub", and custom entries in /etc/grub.d belong to
> debian, and grub is agnostic about them.
What I want "to obtain and install" is an "unadulterated canonical
Grub2". Does what I want even exist in the "www.gnu.org/software/grub/"
universe of discourse? Or is Grub2 itself only a set of building blocks
and intentionally not a complete entity {right word?}?
You also said:
> ... running several installs, reinstalling occasionally,...
and
> ... implies you haven't installed it yet.
That points out something I did not explicitly state in this thread.
My underlying motivation for the question is that I'm experimenting with
releases and configurations. I have a machine physically set aside for
my experiments. I have done as many as 15 installs from scratch in one
week. I've had as many as 5 fully functioning installs at one time.
I suppose the critical question is "does the Grub2 project have
functional equivalents of "OS prober" and "update-grub"?
I've not digested the remainder of your post yet.
Thank you for your time.
I think you're headed for a hand-coded grub.cfg. There's a learning
curve, but in the long run, say the life of a PC, if you're running
several installs, reinstalling occasionally, IMO it's easier that way.
A lot of what people see as part of Grub, like the "OS prober",
"update-grub", and custom entries in /etc/grub.d belong to debian, and
grub is agnostic about them.
The main trouble with the generated grub.cfg was that it would change
unpredictably, and not work sometimes; grub 2 was arriving during
those years. Or, I'd move a partition, add a disk, or do an install
and get the grub rescue prompt.
1) I imagine the default gap to the first partition (1 MiB less 1
sector) will be enough, as I'm not suggesting you add any modules to
what goes there. However, in 2017, perhaps more is needed now.
/boot/grub is 8.9 MiB on my system, but if you want background images
and fonts they'll need space. I suggest 100 MiB for /dev/sda1.
2) "will contain the default OS" implies you haven't installed it yet.
When you install it, if possible tell the installer to put grub on
/dev/sda3. (My installer is Ubuntu's one, ubiquity, and it asked that
question.) The grub code in the MBR and the gap will point to
/dev/sda3/boot. When your debian updates with a new kernel, you don't
want debian updating grub on /dev/sda1. When you install other OS's,
don't let them install grub to /dev/sda.
2) Boot that OS, then (as root) mount /dev/sda1, say on /mnt/grub,
mkdir /mnt/grun/boot, then run grub-install /dev/sda
--boot-directory=/mnt/grub/boot. The grub in the MBR and the gap will
now point to /dev/sda1/boot. Have bootable media handy, in case
something goes wrong.
3) Edit /dev/sda1/boot/grub.cfg. At the least change the first entry,
for your default OS, to search for the label you give it, not the
UUID, and to load /vmlinuz and /init.rd, some thing like:
search --no-floppy --label <your-label>
linux /vmlinuz
initrd /init.img
Those are symbolic links to the latest kernel and initrd; debian
updates them when getting a new kernel. Now, no need for grub.cfg to
be updated when a new kernel arrives.
4) I used to add an "others" menu entry:
menuentry "others" {
search --no-floppy --label --set=root <my-label>
configfile /boot/grub/grub.cfg
}
This just gets to debian's updated grub, with all it's bells and
whistles, memdisk, older kernels, and whatever annoying change would
arrive. I would also rip out most of the beginning of grub.cfg, and
refactor the insmod statements that appeared in every menuentry,
5) Every year or so, I'd have a look at where the debian grub.cfg had
got to, and see if I wanted the changes.
Regards, John Little
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