The final version doesn’t support Linux 2.4 because of which the distribution wouldn’t run on old router models, for example the Linksys WRT54G models, which have 16MB of RAM and CPUs clocked at 200MHz. The distribution is now based on Linux 3.3 and there is good news for the Raspberry Pi fans as the distribution now supports the credit card sized computer along with Ramips routers.
The OpenWRT 12.09 doesn’t use script-based network configuration system and has instead adopted network interface daemon (netifd). Some of the other enhancements include ext4 filesystem; shadow passwords; support for 6RD configuration; improved parallel building support; and various firewall enhancements among others. Experimental support for 5 and 10 MHz channels in Atheros wireless drivers ath5k and ath9k has also been added.