Last week, AMD updated “AMD64 Architecture Programmer’s Manual Volume 2: System Programming”. The changelog does not give a lot of information, you have to visit all the Tables/Sections to see what was changed:
Modified CR4 Register, Section 3.1.3.
Removed UD2 in Table 6-1.
Added new bullet in Section 7.1.1.
Modified Note in Table 7-1.
Added new Section 7.4.1.
Clarified Self Modifying Code in Section 7.6.1.
Added UD0 and UD1 instructions in Section 8.2.7.
Added Instructions Retired Performance counter in Section 13.1.1.
Modified Table in Section 15.34.9.
http://developer.amd.com/resources/developer-guides-manuals/