As of 2.2.4, I should be synchronized with the Sparc[64] and PPC ports,
which is the major reason why the patch is pretty huge. Apart from the
architecture synchronizations, 2.2.4 does:

 - dumping core over NFS could do bad things. Core-dumping cleaned up and
   fixed.

 - various small TCP/IP buglets fixed. Linux got confused by hosts that
   didn't report any mss, and had problems with zero-sized fragments, etc.

 - various small, often silly bugs fixed (PC BIOS PCI buglet, alpha
   semaphores, bottom half interrupts, fork() returns wrong error code).

 - tons of driver updates

 - updated net scheduling code (CONFIG_NET_SCHED)

Most of the fixes aren't all that noticeable, but some of them can be
showstoppers depending on whether you've ever seen them.