Rather than putting the kernel images for the other distro on OW's /boot partition, I would like to have grub use them in the target partition. I know this works, as I triple boot my work station like this (other distros do not write to the primary /boot at all).
I'd like to modify the default grub.cfg generated by the OW image to boot into it. I tried modifying it as follows but it did not work:
serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1 --rtscts=off
terminal_input console serial; terminal_output console serial
set default="0"
set timeout="1"
search -l kernel -s root
menuentry "OpenWrt" {
linux /boot/vmlinuz root=PARTUUID=7fe1d9bc-6bf4-44dc-b869-b213c3af5102 rootwait amd-pstate=passive console=tty0 console=ttyS0,115200n8 noinitrd
}
menuentry "OpenWrt (failsafe)" {
linux /boot/vmlinuz failsafe=true root=PARTUUID=7fe1d9bc-6bf4-44dc-b869-b213c3af5102 rootwait amd-pstate=passive console=tty0 console=ttyS0,115200n8 noinitrd
}
menuentry "Arch" {
search --no-floppy --fs-uuid --set=root 06834425-8796-4bfe-b2ec-23d551c8f78d
echo 'Loading Linux ...'
linux /boot/vmlinuz-linux root=/dev/nvme0n1p3 rw audit=0
echo 'Loading initial ramdisk ...'
initrd /boot/amd-ucode.img /boot/initramfs-linux.img
}
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#
### BEGIN /etc/grub.d/00_header ###
insmod part_gpt
insmod part_msdos
if [ -s $prefix/grubenv ]; then
load_env
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="0"
fi
if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi
export menuentry_id_option
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi
function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}
if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_gpt
insmod ext2
set root='hd0,gpt3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3 0abc5c57-d62c-311c-9ad4-2571a788ff95
else
search --no-floppy --fs-uuid --set=root 0abc5c57-d62c-311c-9ad4-2571a788ff95
fi
font="/usr/share/grub/unicode.pf2"
fi
if loadfont $font ; then
set gfxmode=auto
load_video
insmod gfxterm
fi
terminal_input console
terminal_output gfxterm
insmod part_gpt
insmod ext2
set root='hd0,gpt3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3 0abc5c57-d62c-311c-9ad4-2571a788ff95
else
search --no-floppy --fs-uuid --set=root 0abc5c57-d62c-311c-9ad4-2571a788ff95
fi
insmod png
background_image -m stretch /boot/grub/arch.png
if [ x$feature_timeout_style = xy ] ; then
set timeout_style=menu
set timeout=1
# Fallback normal timeout code in case the timeout_style feature is
# unavailable.
else
set timeout=1
fi
### END /etc/grub.d/00_header ###
### BEGIN /etc/grub.d/10_linux ###
menuentry 'Arch Linux, with Linux linux' --class arch --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-linux-advanced-0abc5c57-d62c-311c-9ad4-2571a788ff95' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_gpt
insmod ext2
set root='hd0,gpt3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3 0abc5c57-d62c-311c-9ad4-2571a788ff95
else
search --no-floppy --fs-uuid --set=root 0abc5c57-d62c-311c-9ad4-2571a788ff95
fi
echo 'Loading Linux linux ...'
linux /boot/vmlinuz-linux root=UUID=0ebc5c57-0abc5c57-d62c-311c-9ad4-2571a788ff95 rw audit=0 loglevel=3 quiet
echo 'Loading initial ramdisk ...'
initrd /boot/intel-ucode.img /boot/initramfs-linux.img
}
menuentry 'Arch Linux, with Linux linux (fallback initramfs)' --class arch --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-linux-fallback-0abc5c57-d62c-311c-9ad4-2571a788ff95' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_gpt
insmod ext2
set root='hd0,gpt3'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt3 --hint-efi=hd0,gpt3 --hint-baremetal=ahci0,gpt3 0abc5c57-d62c-311c-9ad4-2571a788ff95
else
search --no-floppy --fs-uuid --set=root 0abc5c57-d62c-311c-9ad4-2571a788ff95
fi
echo 'Loading Linux linux ...'
linux /boot/vmlinuz-linux root=UUID=0abc5c57-d62c-311c-9ad4-2571a788ff95 rw audit=0 loglevel=3 quiet
echo 'Loading initial ramdisk ...'
initrd /boot/intel-ucode.img /boot/initramfs-linux-fallback.img
}
### END /etc/grub.d/10_linux ###
### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###
### BEGIN /etc/grub.d/25_bli ###
if [ "$grub_platform" = "efi" ]; then
insmod bli
fi
### END /etc/grub.d/25_bli ###
### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###
### BEGIN /etc/grub.d/30_uefi-firmware ###
if [ "$grub_platform" = "efi" ]; then
fwsetup --is-supported
if [ "$?" = 0 ]; then
menuentry 'UEFI Firmware Settings' $menuentry_id_option 'uefi-firmware' {
fwsetup
}
fi
fi
### END /etc/grub.d/30_uefi-firmware ###
EDIT: I figured it out:
Needed some grub modules so I copied /boot/grub/x86_64-efi over to OpenWrt's /boot partition
Used this grub stanza and it booted successfully
menuentry "arch1" {
set root='hd0,gpt3'
insmod gzio
insmod part_gpt
insmod ext2
linux /boot/vmlinuz-linux root=UUID=06834425-8796-4bfe-b2ec-23d551c8f78d rw audit=0
initrd /boot/amd-ucode.img /boot/initramfs-linux.img
}
i am not a grub expert, so maybe it is totally wrong, but:
according
it is missing this file, did you copy to owrt /boot next to arch linux kernel?
as far as i understand grub loads the kernel from a location grub can read from, then kernel reads all the other stuff. if your arch kernel is installed to partition which is using a filesystem grub does know it will unable to load it obviously. not sure if owrt grub can read other than fat partition but i think by default /boot is not ext3/4 for a reason.
personally i think uuid partition naming is a confusing overkill in a likely static environment, i.e. it is probably unlikely you are going to change disks very often, so easier to reference to /dev/<partition id> imho.
EDIT: oh, meanwhile you came to the same conclusion, ie. you need extra modules to be able to read from arch partition.