Revision as of 12:26, 1 May 2014 (view source) osdev>Griwes m (come on, guys, learn mediawiki at least a tiny bit before editing) ← Older edit		Revision as of 14:37, 5 June 2014 (view source) osdev>Sturmer m (Fix typos) Newer edit →
Line 1: ==Introduction== The SYSENTER/SYSEXIT instructions (and ~~equvialent~~equivalent SYSCALL/SYSRET on AMD) enable fast entry to the kernel, avoiding interrupt overhead. This is the method used by Windows NT (XP/Vista/7/8) for its API. SYSCALL/SYSRET are covered here as well, but operate slightly differently. ==INTEL: SYSENTER/SYSEXIT== Line 64: The operation in 64 bit mode is the same, execpt that RIP is loaded from LSTAR, or CSTAR of in IA32-e submode (A.K.A. compatibility mode). ==~~Compatability~~Compatibility across Intel and AMD== For a 32bit kernel, SYSENTER/SYSEXIT are the only compatible pair. For a 64bit kernel in Long mode only (not Long Compat mode), SYSCALL/SYSRET are the only compatible pair. For Intel 64bit, IA32_EFER.SCE must be set, or SYSCALL will result in a #UD exception. IA32_EFER is an MSR at 0xC0000080, and SCE (SYSCALL Enable) is its 0th bit.

SYSENTER: Difference between revisions

SYSENTER (view source)