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Volume 2, Part 2: I/O Architecture
2:617
As a result of the spreading-out of the I/O ports into individual 4KB pages, Itanium
architecture-based operating system code can control IA-32 IN, OUT instruction and
IA-32 or Itanium load/store accessibility to blocks of 4 virtual I/O ports using the TLBs.
This allows Itanium architecture-based operating systems to securely map devices that
inhabit the I/O port space to different Itanium architecture-based device drivers or to
user-space Itanium architecture-based applications.
Itanium architecture-based operating systems must ensure that the I/O port space is
always mapped as uncacheable memory, and that Itanium architecture-based software
only issues aligned 1, 2 or 4 byte references to I/O port space, otherwise device
behavior is undefined.
When porting an IA-32 device driver to the Itanium architecture it can be useful to
emulate the behavior of IA-32 IN and OUT instructions. The following code examples
should be used for this purpose, since they enforce the strict memory ordering and
platform acceptance requirements that IA-32 IN and OUT instructions are subject to.
The following Itanium architecture-based assembly code outb (out byte) and inb (in
byte) examples assume that the io_port_base is the virtual address mapping pointer
set up by the IA_64 operating system. An
mf.a
instruction is used to verify acceptance
by the platform before returning to the calling routine. Interrupts would expected to be
disabled if these routines are called from user mode. This is for possible issues with
process migration after servicing an interrupt.
//
// void outb(unsigned char *io_port,unsigned char byte)
//
//Output a byte to an I/O port.
//
ENTRY(outb)
base_addr = r16
port_addr = r17
port_offset = r18
mask = r19
alloc r13 = ar.pfs, 2, 0, 0, 0 // 2 in, 0 local, 0 out, 0 rot
movl base_addr = io_port_base
extr.u port_offset = in0, 2, 14
mov mask = 0xfff
;;
ld8 port_addr = [base_addr]
shl port_offset = port_offset, 12
and in0 = mask, in0
;;
add port_offset = port_offset, in0
;;
mf
add port_addr = port_addr, port_offset
;;
st1.rel [port_addr] = in1
mf.a
mf
br.ret.spnt.few rp
END(outb)
//
// unsigned char inb(unsigned char *io_port)
//
// Input a byte from an I/O port.
//
ENTRY(inb)
base_addr = r16
port_addr = r17
port_offset = r18
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 ...