How to Install OpenWrt on Linksys WRT3200ACM & WRT1900ACS

The Dual-Partition Architecture of Linksys WRT

The Linksys WRT3200ACM and WRT1900ACS feature a dual NAND flash layout (mtd3 and mtd4). This allows you to flash OpenWrt onto Partition 1 while keeping stock firmware on Partition 2 as an instant hardware fallback.

Initial Flash from Stock Linksys Firmware

1. Download openwrt-mvebu-cortexa9-linksys_wrt3200acm-squashfs-factory.img.
2. Log into Linksys Smart Wi-Fi GUI (192.168.1.1).
3. Go to Connectivity > Basic > Router Firmware Update > Manual.
4. Select the factory.img file and click Start. Wait for the reboot cycle.

Switching Between Partitions via SSH

If you need to flip between alternate boot partitions:

# Check currently active boot partition
cat /proc/sys/kernel/sysrq
# Toggle active partition to the alternate bank
/usr/sbin/advanced_reboot