The 386 lacked support for some basic atomic primitives like CMPXCHG. It was possible to work around this, but it took a significant amount of extra code for a

The 386 lacked support for some basic atomic primitives like CMPXCHG. It was possible to work around this, but it took a significant amount of extra code for a configuration that was essentially extinct in the wild. The presence of these workarounds was an obstacle to maintenance of other x86 code. Meanwhile, the presence of a driver for an old Macintosh system is hardly an obstacle to anyone.