In order for updates to work our own grub bootloader will need to be used, so you'll need to configure your primary bootloader to chainload the CoreOS one on the second disk. If booting in EFI mode that'll be (hd1,gpt1)/efi/boot/bootx64.efi or in legacy bios use (hd1) or (hd1,gpt2). You'll need to write your own menuentry by hand and add it to Ubuntu's /etc/grub.d/40_custom or similar.
If you don't care about working updates you may be able to skip our grub and boot using the default grub configuration as long as the kernel is given arguments like "root=/dev/sdb9 mount.usr=/dev/sdb3 rw" On Fri, Sep 23, 2016 at 8:41 AM, Gerald Talton <[email protected]> wrote: > I want to start experimenting with CoreOS. I did a bare metal install on a > second drive from Ubuntu just now and that worked just fine. > > The problem is this older motherboard doesn't allow selecting which SATA > drive to boot from so it always boots the lowest SATA drive first .. meaning > the Ubuntu. > > However I have grub on Ubuntu and I should be able to have grub .. boot the > second drive .. IF I can figure out the proper grub config. > > Using grub-customizer and os-prober .. they both see a Linux distro on > /dev/sdb3 .. however as I expected I see a "Legacy BIOS Bootable" partition > on /dev/sdb1. > > When I grub boot to /dev/sdb3 .. it seems CoreOS is in a > maintenance/recovery mode .. so .. not what I want. > > Should I try to configure grub to boot /dev/sdb1 like my instincts tell me? > > Thanks for any help and regards, > > Gerald Talton
