On 5/24/22 6:28 PM, Gustavo Rios wrote:
May some one here suggest a documentation the explains this scenario ? I am
in needof this.
Thanks in advance!
I've actually been experimenting with the UEFI OpenBSD and Windows combo,
though I suspect it is applicable to Linux, as well.
Warning: I'm trying to avoid GRUB as my boot selector. UEFI is supposed
to be able to do this for us. So I would rather just use it. I don't
trust grub to do anything other than Windows and Linux (which is just
Windows re-invented badly).
Short version: wow...there's a lot variety out there on machines. If you
want one answer for all hardware, that's not gonna happen. :-/
That's about the only certainty I have at this point. Many UEFI systems
are only designed to boot Windows it seems, the idea of multiple OSs on
one disk didn't occur to some people..
I don't want to use the Windows 10 boot selection process IF I have
another option. Unlike Windows 7 and before, it seems to boot
95% of Windows, then gives you the menu. If you pick OpenBSD, it then
totally reboots the machine -- back to the firmware and back up, but
this time to OpenBSD. If you pick Windows, the last 5% loads in a couple
seconds.
IF you install OpenBSD first, you need to puff-out the GPT boot
partition before install. OpenBSD's default is really tiny, just
enough to boot OpenBSD (as you would expect). Boot bsd.rd, drop
to shell, MAKEDEV your disk, "fdisk -gb200000 sd0" or similar, iirc,
for a 100MB GPT UEFI boot partition. The default Windows one is
big enough for OpenBSD to share, I'm guessing Linux, as well.
A couple Dell laptops I have with UEFI actually don't suck. In the BIOS,
there's an option to select various boot targets. One is "Windows Boot
Manager" or something like that, the others can be loaders pulled out of
the UEFI boot partition. This ends up working really slickly for dual
booting, and it looks like it would easily extend to multiple OSs.
Basically put each option in your boot list, make the first one your
primary OS (the "no hands" boot). If you want to boot a different OS,
you hit the boot selection key at the right time (F12? I mark mine with
a bit of paint, so I can't remember what it is). This brings up a
menu, the menu selections can be readable to humans... May not be
the ultimate solution for all people, but ... works really well for
me.
I've got a couple older HP systems, not so impressive. If you to hit
the magic key (F9, iirc) at the right moment, you can poke around
in the boot partition. Otherwise, it wants to boot a particular OS, and
if I recall properly, I got one booting OpenBSD by default, the other
windows by default, and I have NO IDEA how the default was chosen (or
is it just the firmware on this machine prefers ...?). One one of them,
I found a 16MB (yes, MB, not GB) SD card, came with an old digicam
(flashback to 12 exposure rolls of film!). I dropped minirootXX.img
on it, created a /etc/boot.conf file that pointed to pulling the
kernel off hd1a:/bsd and called it done. Want to run OpenBSD, leave
the SD card in place, want to boot windows, eject the card a little, push
it back in when it's booted. This is cheesy, doesn't scale to a third OS,
but it works for me in this laptop.
I'm working on a better write-up (with fewer "IIRC"s :) ), but this might
be enough to get you started.
Nick.
