running at privilege level 0.</p>
<p>When executed in IA-32e mode, the SYSENTER instruction transitions the logical processor to 64-bit mode; other-wise, the logical processor remains in protected mode.</p>
<p>Prior to executing the SYSENTER instruction, software must specify the privilege level 0 code segment and code entry point, and the privilege level 0 stack segment and stack pointer by writing values to the following MSRs:</p>
<p>These MSRs can be read from and written to using RDMSR/WRMSR. The WRMSR 