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Volume 2, Part 1: System State and Programming Model
A sequence of reads of the RUC is guaranteed to return ever-increasing values (except
for the case of the counter wrapping back to 0) corresponding to the program order of
the reads. Applications can directly sample the RUC for active-running-time
calculations.
A 64-bit overflow condition can occur without notification. The RUC can be read at any
privilege level if PSR.si is zero. The timer can be secured from non-privileged access by
setting PSR.si to one. When secured, a read of the RUC by non-privileged code results
in a Privileged Register fault. Writes to the RUC can only be performed at privilege level
0; otherwise, a Privileged Register fault is raised.
Modification of the RUC is not necessarily serialized with respect to instruction
execution. Software can issue a data serialization operation to ensure the RUC updates
are observed by a given point in program execution. Software must accept a level of
sampling error when reading the resource utilization counter due to various machine
stall conditions, interruptions, bus contention effects, etc. Please see the
processor-specific documentation for further information on the level of sampling error
of the Itanium processor.
RUC should only be written by Virtual Machine Monitors; other Operating Systems
should not write to RUC, but should only read it.
The RUC register is not supported on all processor implementations. Software can
check CPUID register 4 to determine the availability of this feature. The RUC register is
reserved when this feature is not supported.
3.3.4.4
Interval Timer Offset (ITO – CR4)
The Interval Timer Offset (ITO) register allows virtual machine monitors to specify an
offset to the Interval Timer Counter (ITC) for the virtual processor. The layout of the
register is shown in
. For details of the usage of this register in virtual
Section 11.7.4.1.3, “Guest MOV-from-AR.ITC
The ITO register has no effects on instruction execution when PSR.vm is 0.
The ITO register does not affect the generation of interval timer interrupts, discussed in
Section 3.3.4.2, “Interval Time Counter and Match Register (ITC – AR44 and ITM –
CR1)”
.
The ITO register is not supported on all processor implementations. Software can call
either PAL_PROC_GET_FEATURES or PAL_VP_ENV_INFO to determine the availability of
this feature. The ITO register is reserved when this feature is not supported.
Figure 3-6.
Interval Timer Offset Register (ITO – CR4)
63
0
ITO
64
Summary of Contents for ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
Page 1: ......
Page 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 13: ...1 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
Page 57: ...1 46 Volume 1 Part 1 Execution Environment ...
Page 147: ...1 136 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Page 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
Page 230: ......
Page 248: ...236 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 250: ...2 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
Page 380: ...2 132 Volume 2 Part 1 Interruptions ...
Page 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Page 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Page 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Page 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Page 808: ...2 560 Volume 2 Part 2 Context Management ...
Page 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Page 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Page 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
Page 870: ...2 622 Volume 2 Part 2 Performance Monitoring Support ...
Page 891: ......
Page 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
Page 1295: ...3 396 Volume 3 Resource and Dependency Semantics ...
Page 1296: ......
Page 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Page 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Page 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Page 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Page 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...