System Instructions

25 x86 instructions in this extension - click any row for encoding, pseudocode, and full documentation.

Mnemonic ⇅	Syntax	Format ⇅	Summary
clts	CLTS	System	Clears the TS flag in CR0 (Privileged).
invd	INVD	System	Flushes internal caches without writing back data (Privileged).
invlpg	INVLPG m	System	Invalidates a specific TLB entry (Privileged).
lar	LAR r, r/m16	System	Reads access rights from segment descriptor.
lgdt	LGDT m16&32	System	Loads the GDT register (Privileged).
lidt	LIDT m16&32	System	Loads the IDT register (Privileged).
lldt	LLDT r/m16	System	Loads LDT segment selector (Privileged).
lmsw	LMSW r/m16	System	Loads Machine Status Word (Legacy CR0 modification).
lsl	LSL r, r/m16	System	Reads segment limit from descriptor.
ltr	LTR r/m16	System	Loads Task Register (Privileged).
mov cr	MOV CRn, r	System	Moves data to/from Control Registers (CR0, CR3, etc.) (Privileged).
mov dr	MOV DRn, r	System	Moves data to/from Debug Registers (DR0-DR7) (Privileged).
rdmsr	RDMSR	System	Reads MSR specified by ECX into EDX:EAX (Privileged).
rdpmc	RDPMC	System	Reads performance counter specified by ECX into EDX:EAX.
sgdt	SGDT m	System	Stores GDT limit and base address to memory.
sidt	SIDT m	System	Stores IDT limit and base address to memory.
sldt	SLDT r/m16	System	Stores LDT segment selector.
smsw	SMSW r/m16	System	Stores Machine Status Word.
str	STR r/m16	System	Stores Task Register.
sysenter	SYSENTER	System	Fast call to level 0 system procedures.
sysexit	SYSEXIT	System	Fast return to level 3 user code.
verr	VERR r/m16	System	Checks if segment can be read; sets ZF.
verw	VERW r/m16	System	Checks if segment can be written; sets ZF.
wbinvd	WBINVD	System	Writes back modified data and invalidates caches (Privileged).
wrmsr	WRMSR	System	Writes EDX:EAX to MSR specified by ECX (Privileged).