Sysupgrade on two partitions hardware


have the linksys ea8500 and I try to keep one partition with linksys oem firmware and run the other with openwrt, but everytime I sysupgrade, the upgrade goes on the second partition (linksys oem), so my two partitions become openwrt, is it possible to keep those intact?

Not easily. Both OpenWrt and the OEM firmware use strategy where the new version is flashed to the other partition, so that the current one remains as the known-to-work fallback alternative.

Easiest is to switch boot to OEM, and flash a new factory image from there.