A side project of OS/4 is the QSINIT loader, which is another replacement for OS2LDR. Newer versions of this loader allow 3.5GB of RAM to be used on certain systems where OS2LDR prevents using more than 512MB due to "memory holes". It also allows using memory above 4GB as a RAM disk, which otherwise is useless on a 32-bit operating system that does not support PAE (such as OS/2). Unfortunately, it is currently incompatible with the official ACPI drivers, due to some assumptions made in that code.
Source: OS/2 Warp News and Rumors