Intel 253666-024US - Manual (Page 580)

3-534 Vol. 2A LDS/LES/LFS/LGS/LSS—Load Far Pointer
INSTRUCTION SET REFERENCE, A-M
#NP(selector) If FS, or GS register is being loaded with a non-NULL segment
selector and the segment is marked not present.
#PF(fault-code) If a page fault occurs.
#AC(0) If alignment checking is enabled and an unaligned memory
reference is made while the current privilege level is 3.
#UD If source operand is not a memory location.
If the LOCK prefix is used.