After resizing the last partition to maximum, /boot is not mounted after booting

hgl · December 27, 2021, 9:17am

Thanks for the quick reply.

After some endeavor, I managed to locate the code that mounts /boot:

openwrt/openwrt/blob/v21.02.1/target/linux/x86/base-files/lib/preinit/79_move_config#L11

    
      
          # Copyright (C) 2012-2015 OpenWrt.org
          
          
move_config() {
          	local partdev parttype=ext4
          
          
	. /lib/upgrade/common.sh
          
          
	if export_bootdevice && export_partdevice partdev 1; then
          		mkdir -p /boot
          		part_magic_fat "/dev/$partdev" && parttype=vfat
          		mount -t $parttype -o rw,noatime "/dev/$partdev" /boot
          		if [ -f "/boot/$BACKUP_FILE" ]; then
          			mv -f "/boot/$BACKUP_FILE" /
          		fi
          		mount --bind /boot/boot /boot
          	fi
          }
          
          
boot_hook_add preinit_mount_root move_config

github.com

openwrt/openwrt/blob/v21.02.1/package/base-files/files/lib/upgrade/common.sh#L179

    
      
          				uuid="${rootpart#PARTUUID=}"
          				uuid="${uuid%-[a-f0-9][a-f0-9]}"
          				for blockdev in $(find /dev -type b); do
          					set -- $(dd if=$blockdev bs=1 skip=440 count=4 2>/dev/null | hexdump -v -e '4/1 "%02x "')
          					if [ "$4$3$2$1" = "$uuid" ]; then
          						uevent="/sys/class/block/${blockdev##*/}/uevent"
          						break
          					fi
          				done
          			;;
          			PARTUUID=????????-????-????-????-??????????02)
          				uuid="${rootpart#PARTUUID=}"
          				uuid="${uuid%02}00"
          				for disk in $(find /dev -type b); do
          					set -- $(dd if=$disk bs=1 skip=568 count=16 2>/dev/null | hexdump -v -e '8/1 "%02x "" "2/1 "%02x""-"6/1 "%02x"')
          					if [ "$4$3$2$1-$6$5-$8$7-$9" = "$uuid" ]; then
          						uevent="/sys/class/block/${disk##*/}/uevent"
          						break
          					fi
          				done
          			;;

It seems /boot will only be mounted, at lease in my case, if the partition (the one containing the root filesystem) ID is ended with 02, and I can confirm it works by changing the partition ID manually.

I wonder what's the significance of 02?

When one follows the doc, the partition ID is bound to change. Whether it ends with 02 is totally by chance IMO.