The software workaround for the FDIV bug required the actual userspace software to be modified and recompiled. There was a decade of pre-existing software out t

The software workaround for the FDIV bug required the actual userspace software to be modified and recompiled. There was a decade of pre-existing software out there that would be hard to fix, especially in the days before most people had the internet. There was nothing the OS could do to work around the bug, short of disabling the entire FPU and falling back to expensive software emulation of all floating point math. The workarounds for all these speculation bugs can be mostly applied at the operating system and/or microcode level, and is comparably cheap.