[FS#1266] sysupgrade-x86 should detect boot partition properly

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Philip Prindeville (pprindeville) 

Attached to Project - LEDE Project
Summary - sysupgrade-x86 should detect boot partition properly
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Medium
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Currently it's hard-coded into /lib/preinit/79_move_config as:


move_config() {
	local partdev

	. /lib/upgrade/common.sh

	if export_bootdevice && export_partdevice partdev 1; then
		mkdir -p /boot
		if mount -t ext4 -o ro,noatime "/dev/$partdev" /boot; then
			if [ -f /boot/sysupgrade.tgz ]; then
				mount /boot -o remount,rw,noatime
				mv -f /boot/sysupgrade.tgz /
				mount /boot -o remount,ro,noatime
			fi
			mount --bind /boot/boot /boot
		fi
	fi
}


that the first partition of the boot device is the boot partition.  That's not always the case, and EFI seems to break this.

Also, it's an obstacle to supporting A/B image+config boot modes.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1266