Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1365

CLTS—Clear Task-Switched Flag in CR0
Opcode
0F 06
Description
Clears the task-switched (TS) flag in the CR0 register. This instruction is intended for
use in operating-system procedures. It is a privileged instruction that can only be
executed at a CPL of 0. It is allowed to be executed in real-address mode to allow
initialization for protected mode.
The processor sets the TS flag every time a task switch occurs. The flag is used to
synchronize the saving of FPU context in multitasking applications. See the description
of the TS flag in the Intel Architecture Software Developer's Manual, Volume 3 for more
information about this flag.
Operation
IF Itanium System Environment THEN IA-32_Intercept(INST,CLTS);
CR0(TS)  0;
Flags Affected
The TS flag in CR0 register is cleared.
Additional Itanium System Environment Exceptions
IA-32_Intercept
Protected Mode Exceptions
#GP(0)
Real Address Mode Exceptions
None.
Virtual 8086 Mode Exceptions
#GP(0)
Volume 4: Base IA-32 Instruction Reference
Instruction
CLTS
Mandatory Instruction Intercept fault.
If the CPL is greater than 0.
If the CPL is greater than 0.
Description
Clears TS flag in CR0
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