Setting up GRUB2

Install

warning // lessons learned

that part is a bit tricky

http://gnu.org/software/grub/manual/grub/html_node/Serial-terminal.html

http://gnu.org/software/grub/manual/grub/html_node/serial.html#serial

Casual F2FS sample

this is for hp proliant COM2 (virtual serial port) – unit=1 and ttyS1

    serial --unit=1 --speed=115200 --word=8 --parity=no --stop=1
terminal_input serial console
terminal_output serial console

set timeout=3

menuentry "Linux" {
    insmod f2fs
    set root=(hd0,msdos1)
    linux /boot/vmlinuz root=/dev/sda1 ro console=tty0 console=ttyS1,115200n8 mitigations=off
}

GNU/Linux dom0 sample

assuming serial console

grub-file --is-x86-multiboot /xen.gz && echo YES
cat /proc/cmdline
    vi /boot/grub/grub.cfg # new file

serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
# first terminal takes precedence when timeout expires
terminal --timeout=1 serial console
# --silent

set default=2
set timeout=3

# last console takes over /dev/console
menuentry "linux" {
    insmod ext2
    set root=(hd0,msdos1)
    linux /vmlinuz root=/dev/nvme0n1p1 ro console=tty0 console=ttyS0,115200n8 mitigations=off
}

menuentry "xen/pv" {
    insmod ext2
    set root=(hd0,msdos1)
    multiboot /xen.gz loglvl=info guest_loglvl=info noreboot=true smt=1 ept=exec-sp com1=115200,8n1 console=com1,vga
    module /vmlinuz root=/dev/nvme0n1p1 ro console=hvc0 earlyprintk=xen mitigations=off
}

menuentry "xen/pvh" {
    insmod ext2
    set root=(hd0,msdos1)
    multiboot /xen.gz dom0=pvh dom0_mem=1024M,max:2048M loglvl=info guest_loglvl=info noreboot=true smt=1 ept=exec-sp com1=115200,8n1 console=com1,vga
    module /vmlinuz root=/dev/nvme0n1p1 ro console=hvc0 earlyprintk=xen mitigations=off
}

more grub arguments

# insmod xfs
# set root=(hd0,gpt1)

more xen arguments

# pv-linear-pt=true

more kernel arguments

# root=/dev/nvme0n1p1
# root=/dev/sda1
# nomodeset
# vt.default_utf8=0
# ipv6.disable=1

NetBSD & dom0 setup

dos/ext2

menuentry "netbsd" {
        insmod ext2
        set root=(hd0,msdos1)
        knetbsd /netbsd --root=ld0e
}

gpt/ffs

menuentry "netbsd" {
        insmod ufs2
        set root=(hd0,gpt2)
        knetbsd /netbsd
}

gpt/ffs for XEN dom0

assuming serial console

THAT IS A DRAFT - UNTESTED

menuentry "XEN" {
    insmod ufs2
    set root=(hd0,gpt2)
    multiboot /xen.gz loglvl=info guest_loglvl=info noreboot=true smt=1 ept=exec-sp com1=115200,8n1 console=com1,vga
    module /netbsd bootdev=... ro console=...
}

Resources

https://www.gnu.org/software/grub/manual/grub/grub.html