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2:242
Volume 2, Part 1: Itanium
®
Architecture-based Operating System Interaction Model with IA-32 Applications
System segment selectors and descriptors for GDT and LDT are maintained in Itanium
general registers to support segment register loads used extensively by segmented
16-bit code. On the transition into the IA-32 instruction set, GDT/LDT descriptor table
must be initialized if IA-32 code will perform protected mode segment register loads or
far control transfers.
Within the IA-32 System Environment, GDT and LDT are considered privileged
operating system segmentation resources. However, in the Itanium System
Environment, applications can transition between the IA-32 and Itanium instruction set
and bypass IA-32 segmentation. Itanium user level instructions can also directly modify
all selectors and descriptors including GDT and LDT. An operating system should either
protect memory with virtual memory management mechanisms defined by the Itanium
architecture or disabled application level instruction set transitions. Within the Itanium
System Environment, GDT/LDT memory spaces must be mapped into user space, since
supervisor overrides for accesses to GDT/LDT are disabled.
The TSSD descriptor points to the I/O Permission Bitmap. If CFLG.io is 1, IN, INS, OUT,
and OUTS consult the TSSD I/O permission bitmap as defined in the
Intel
®
64 and
IA-32 Architectures Software Developer’s Manual
. If CFLG.io is 0, the TSSD I/O
permission bitmap is not checked. See
Section 10.7, “I/O Port Space Model”
on I/O port permission and for TLB-based access control. The TSSD register is not used
within the Itanium System Environment to support task switches, or interlevel control
transfers. If the TSSD is used for I/O Permissions, Itanium architecture-based
operating system software must ensure that a valid 286 or 386 Task State Descriptor is
loaded, otherwise IN/OUT operations to the TSSD I/O permission bitmap will result in
undefined behavior.
The IDT descriptor is not supported or defined within the Itanium System Environment.
Table 10-2.
IA-32 System Segment Register Fields (LDT, GDT, TSS)
Field
Bits
Description
base
31:0
Segment Base value. This value when zero extended to 64-bits, points to the start of the
segment in the 64-bit virtual address space for IA-32 instruction set memory references.
This value is ignored for Intel Itanium instruction set memory references.
lim
51:32 Segment Limit. Contains the maximum effective address value within the segment. See the
Intel
®
64 and IA-32 Architectures Software Developer’s Manual
for details and segment
limit fault conditions.
stype
55:52 Segment Type identifier. See the
Intel
®
64 and IA-32 Architectures Software Developer’s
Manual
for encodings and definition.
s
56
Non System Segment. If 1, a data segment, if 0 a system segment.
dpl
58:57 Descriptor Privilege Level. The DPL is checked for memory access permission for IA-32
instruction set memory references.
p
59
Segment Present bit. If 0, and an IA-32 memory reference uses this segment an
IA_Exception(GPFault) is generated.
ig
62:60 Ignored – For the LDT/GDT/TSS descriptors reads of this field return the last value written
by Itanium architecture-based code. Reads of this field return zero if written by IA-32
descriptor loads.This field is ignored by the processor during IA-32 instruction set execution.
This field may have a future use and should be set to zero by software.
g
63
Segment Limit Granularity. If 1, scales the segment limit by lim=(lim<<12) | 0xFFF for IA-32
instruction set memory references.
Содержание ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
Страница 1: ......
Страница 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 12: ...1 1 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part I Application Architecture Guide ...
Страница 13: ...1 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
Страница 57: ...1 46 Volume 1 Part 1 Execution Environment ...
Страница 147: ...1 136 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Страница 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
Страница 230: ......
Страница 248: ...236 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 249: ...2 1 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part I System Architecture Guide ...
Страница 250: ...2 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
Страница 380: ...2 132 Volume 2 Part 1 Interruptions ...
Страница 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Страница 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Страница 749: ...2 501 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part II System Programmer s Guide ...
Страница 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Страница 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Страница 808: ...2 560 Volume 2 Part 2 Context Management ...
Страница 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Страница 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Страница 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
Страница 870: ...2 622 Volume 2 Part 2 Performance Monitoring Support ...
Страница 891: ......
Страница 941: ...3 42 Volume 3 Instruction Reference cmp illegal_operation_fault PR p1 0 PR p2 0 Interruptions Illegal Operation fault ...
Страница 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
Страница 1191: ...3 292 Volume 3 Pseudo Code Functions Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1295: ...3 396 Volume 3 Resource and Dependency Semantics ...
Страница 1296: ......
Страница 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Страница 1564: ...4 262 Volume 4 Base IA 32 Instruction Reference LES Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1565: ...Volume 4 Base IA 32 Instruction Reference 4 263 LFS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1568: ...4 266 Volume 4 Base IA 32 Instruction Reference LGS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1583: ...Volume 4 Base IA 32 Instruction Reference 4 281 LSS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Страница 1663: ...Volume 4 Base IA 32 Instruction Reference 4 361 SHL SHR Shift Instructions See entry for SAL SAR SHL SHR ...
Страница 1668: ...4 366 Volume 4 Base IA 32 Instruction Reference SIDT Store Interrupt Descriptor Table Register See entry for SGDT SIDT ...
Страница 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Страница 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Страница 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...