A.5.289 SGDT, SIDT, SLDT: Store Descriptor Table Pointers
SGDT mem ; 0F 01 /0 [286,PRIV]
SIDT mem ; 0F 01 /1 [286,PRIV]
SLDT r/m16 ; 0F 00 /0 [286,PRIV]
SGDT and SIDT both take a 6-byte memory area as an operand: they store
the contents of the GDTR (global descriptor table register) or IDTR
(interrupt descriptor table register) into that area as a 32-bit linear
address and a 16-bit size limit from that area (in that order). These
are the only instructions which directly use _linear_ addresses, rather
than segment/offset pairs.
SLDT stores the segment selector corresponding to the LDT (local
descriptor table) into the given operand.
See also LGDT, LIDT and LLDT (section A.5.138).