LEGACY-RAO-INT exception class

Exception conditions

When an instruction of the class raises each exception, and in which processor modes. Protected mode includes compatibility mode. How to read the table.

Exception	Real	Virtual-8086	Protected	64-bit	Condition
`#UD`	yes	yes	yes	yes	A LOCK prefix is used.
`#UD`	yes	yes	yes	yes	CPUID reports no RAO-INT (CPUID.(EAX=07H,ECX=1):EAX bit 3).
`#SS`	yes	no	no	no	The memory address is not valid in the SS segment.
`#SS(0)`	no	yes	yes	no	The memory address is not valid in the SS segment.
`#SS(0)`	no	no	no	yes	The memory address uses the SS segment and is not canonical.
`#GP`	yes	no	no	no	The operand reaches past offset FFFFH of its segment.
`#GP(0)`	no	yes	yes	no	The memory address is not valid in the CS, DS, ES, FS or GS segment it uses.
`#GP(0)`	no	no	no	yes	The memory address is not canonical.
`#GP`	yes	no	no	no	The destination is not 4-byte aligned.
`#GP`	yes	no	no	no	The destination’s memory type is not write-back (WB).
`#GP(0)`	no	yes	yes	no	The destination is not 4-byte aligned.
`#GP(0)`	no	no	no	yes	The destination is not naturally aligned: to 4 bytes, or to 8 for the 64-bit form.
`#GP(0)`	no	yes	yes	yes	The destination’s memory type is not write-back (WB).
`#PF(fault-code)`	no	yes	yes	yes	The memory access causes a page fault.

Notes

No Intel document defines this class. The rows come from the exception sections of AADD, AAND, AOR and AXOR in the ISE, which are the same for all four. The instructions work in every mode; only their 64-bit forms, with REX.W, need 64-bit mode.

Remote atomic operations may be carried out close to memory, in a shared cache or the memory controller. They require natural alignment so that one update never straddles two cache lines, and a misaligned destination, like one whose memory type is not write-back, raises #GP rather than #AC. They are atomic without a LOCK prefix, which raises #UD.

Instructions

Intel XED puts forms of 4 mnemonics in this class, listed here by extension. Where a mnemonic also has forms of other classes, its link leads to its first form of this one.

Exception conditions

Notes

Related classes

Instructions

RAO-INT

Sources