Intel 64 and IA-32 Architectures Software Developers Manual Volume 2B, Instruction Set Reference, N-Z

4-364 Vol. 2B
INSTRUCTION SET REFERENCE, N-Z
SYSENTER/SYSEXIT_Supported; FI;
FI;
When the CPUID instruction is executed on the Pentium Pro processor (model 1), the
processor returns a the SEP flag as set, but does not support the SYSENTER/SYSEXIT
instructions.
Operation
IF CR0.PE = 0 THEN #GP(0); FI;
IF SYSENTER_CS_MSR[15:2]
= 0 THEN #GP(0); FI;
EFLAGS.VM ← 0; (* Insures protected mode execution *)
EFLAGS.IF ← 0; (* Mask interrupts *)
EFLAGS.RF ← 0;
CS.SEL ← SYSENTER_CS_MSR (* Operating system provides CS *)
(* Set rest of CS to a fixed value *)
CS.BASE ← 0; (* Flat segment *)
CS.LIMIT ← FFFFFH; (* 4-GByte limit *)
CS.ARbyte.G ← 1; (* 4-KByte granularity *)
CS.ARbyte.S ← 1;
CS.ARbyte.TYPE ← 1011B; (* Execute + Read, Accessed *)
CS.ARbyte.D ← 1; (* 32-bit code segment*)
CS.ARbyte.DPL ← 0;
CS.SEL.RPL ← 0;
CS.ARbyte.P ← 1;
CPL ← 0;
SS.SEL ← CS.SEL + 8;
(* Set rest of SS to a fixed value *)
SS.BASE ← 0; (* Flat segment *)
SS.LIMIT ← FFFFFH; (* 4-GByte limit *)
SS.ARbyte.G ← 1; (* 4-KByte granularity *)
SS.ARbyte.S ←;
SS.ARbyte.TYPE ← 0011B; (* Read/Write, Accessed *)
SS.ARbyte.D ← 1; (* 32-bit stack segment*)
SS.ARbyte.DPL ← 0;
SS.SEL.RPL ← 0;
SS.ARbyte.P ← 1;
ESP ← SYSENTER_ESP_MSR;
EIP ← SYSENTER_EIP_MSR;