What is fun is that x86-64 ended up having CPU vendor dependent things like SYSENTER vs SYSCALL (and even SYSCALL ended up having a bunch of vendor dependent th

What is fun is that x86-64 ended up having CPU vendor dependent things like SYSENTER vs SYSCALL (and even SYSCALL ended up having a bunch of vendor dependent things about it too). Win10 had to add INT 2E to the 64-bit kernel for 32-bit system calls.