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Vol. 3 13-19
SYSTEM PROGRAMMING FOR INSTRUCTION SET EXTENSIONS AND
If all three requirements are met, applications can use the target new instruction set
extensions. If any of the above requirements are not met, an attempt to execute an
instruction operating on a processor extended state corresponding to bit offset
higher than 1 in the XFEATURE_ENABLED_MASK register (XCR0) will cause a #UD
exception.
Newer instruction extensions operating on SSE state, but not on any processor
extended states corresponding bits in XCR0 with an offset higher than 1, follow the
programming model described by
Section 13.1 through Section 13.5. XCR0 is not
required to enable OS support for SSE state management, but CR4.OSFXSR is
required.
Figure 13-4. Application Detection of New Instruction Extensions and Processor
Extended State
Implied HW support for
Check enabled state in
XCR0 via XGETBV
Check feature flag
for Instruction set
Check feature flag
CPUID.1H:ECX.OXSAVE = 1?
OS provides processor
extended state management
State
ok to use
XSAVE, XRSTOR, XGETBV, XCR0
enabled
Instructions
Yes