[messe]

32 bit x86 also has sysenter/sysexit.

[adrian_b]

Only Intel. AMD had its own "syscall" instead of Intel's "sysenter" since the K6 CPU, so x86-64 has inherited that.

AMD's "syscall" corrects some defects of Intel's "sysenter", but unfortunately it introduces some new defects.

Details can be found in the Linux documentation, in comments by Linus Torvalds about the use of these instructions in the kernel.