rfc909.txt
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TXT
2,217 行
RFC-909 July 1984
Command Class | Command Type | Symbol
----------------+---------------+----------
PROTOCOL | 1 | HELLO
| 2 | HELLO_REPLY
| 3 | SYNCH
| 4 | SYNCH_REPLY
| 5 | ERROR
| 6 | ERRACK
| 7 | ABORT
| 8 | ABORT_DONE
| 9 - 63 | <reserved>
| |
DATA_TRANSFER | 1 | WRITE
| 2 | READ
| 3 | READ_DONE
| 4 | READ_DATA
| 5 | MOVE
| 6 | MOVE_DONE
| 7 | MOVE_DATA
| 8 | REPEAT_DATA
| 9 | BREAKPOINT_DATA
| 10 | WRITE_MASK
| 11 - 63 | <reserved>
| |
CONTROL | 1 | START
| 2 | STOP
| 3 | CONTINUE
| 4 | STEP
| 5 | REPORT
| 6 | STATUS
| 7 | EXCEPTION
| 8 - 63 | <reserved>
| |
MANAGEMENT | 1 | CREATE
| 2 | CREATE_DONE
| 3 | DELETE
| 4 | DELETE_DONE
| 5 | LIST_ADDRESSES
| 6 | ADDRESS_LIST
| 7 | GET_PHYS_ADDRESS
| 8 | GOT_PHYS_ADDRESS
| 9 | GET_OBJECT
| 10 | GOT_OBJECT
| 11 | LIST_BREAKPOINTS
| 12 | BREAKPOINT_LIST
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LDP Specification Commands and Formats
| 13 | LIST_NAMES
| 14 | NAME_LIST
| 15 | LIST_PROCESSES
| 16 | PROCESS_LIST
| 17 - 63 | <reserved>
| |
BREAKPOINT | 1 | INCREMENT
| 2 | INC_COUNT
| 3 | OR
| 4 | SET_PTR
| 5 | SET_STATE
| 6 - 63 | <reserved>
| |
CONDITION | 1 | CHANGED
| 2 | COMPARE
| 3 | COUNT_EQ
| 4 | COUNT_GT
| 5 | COUNT_LT
| 6 | TEST
| 7 - 63 | <reserved>
Command Types
Figure 8
4.3 Addressing
Addresses are used in LDP commands to refer to memory
locations, processes, buffers, breakpoints and other entities.
Many of these entities are machine-dependent; some machines have
named objects, some machines have multiple address spaces, the
size of address spaces varies, etc. The format for specifying
addresses needs to be general enough to handle all of these
cases. This speaks for a large, hierarchically structured
address format. However, the disadvantage of a large format is
that it imposes extra overhead on communication with targets that
have simpler address schemes.
LDP resolves this conflict by employing two address formats:
a short three-word format for addressing simpler targets, and a
long five-word format for others. Each target LDP is required to
implement at least one of these formats. At the start of an LDP
session, the target specifies the address format(s) it uses in
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RFC-909 July 1984
the Flag field of the HELLO_REPLY message. In each address, the
first bit of the mode octet is a format flag: 0 indicates LONG
address format, and 1 indicates SHORT format.
4.3.1 Long Address Format
The long address format is five words long and consists of a
three-word address descriptor and a two-word offset (see Figure
9). The descriptor specifies an address space to which the offset
is applied. The descriptor is subdivided into several fields, as
described below. The structuring of the descriptor is designed
to support complex addressing modes. For example, on targets
with multiple processes, descriptors may reference virtual
addresses, registers, and other entities within a particular
process.
The addressing modes defined below are intended as a base to
which target-specific modes may be added. Modes up to 63. are
reserved by the protocol. The range 64. to 127. may be used for
target-specific address modes.
Long Format - Format bit is LONG=0
0 0 0 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-------------------------------+ +-+
|0| Mode | Mode Arg | |
+-------------------------------+ |
| (31-16) | | Descriptor
+---- ID ---+ |
| (15-0) | |
+-------------------------------+ +-+
| (31-16) | |
+---- Offset ---+ | Offset
| (15-0) | |
+-------------------------------+ +-+
Long Address Format
Figure 9
LONG ADDRESS FIELDS:
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LDP Specification Commands and Formats
Mode
The address mode identifies the type of address space being
referenced. The mode is qualified by the mode argument and
the ID field. Implementation of modes other than physical
and host is machine-dependent. Currently defined modes and
the address space they reference are shown in Figure 10.
Mode | Symbol | Address space
-----+----------------------+---------------------------
0 HOST Host
1 PHYS_MACRO Macromemory
2 PHYS_MICRO Micromemory
3 PHYS_I/O I/O space
4 PHYS_MACRO_PTR Macro contains a pointer
5 PHYS_REG Register
6 PHYS_REG_OFFSET Register plus offset
7 PHYS_REG_INDIRECT Register contains address
of a pointer
8 PROCESS_CODE Process code space
9 PROCESS_DATA Process data space
10 PROCESS_DATA_PTR Process data contains a ptr
11 PROCESS_REG Process virtual register
12 PROCESS_REG_OFFSET Process register plus offset
13 PROCESS_REG_INDIRECT Process register contains
address of a pointer
14 OBJECT_OFFSET Memory object (queue, pool)
15 OBJECT_HEADER System header for an object
16 BREAKPOINT Breakpoint
17 WATCHPOINT Watchpoint
18 BPT_PTR_OFFSET Breakpoint ptr plus offset
19 BPT_PTR_INDIRECT Breakpoint ptr plus offset
gives address of a pointer
20 - <reserved>
63
Long Address Modes
Figure 10
Mode Argument
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RFC-909 July 1984
Provides a numeric argument to the mode field. Specifies
the register in physical and process REG and REG_OFFSET
modes.
ID Field
Identifies a particular process, buffer or object.
Offset
The offset into the linear address space defined by the
mode. The size of the machine word determines the number of
significant bits in the offset. Likewise, the addressing
units of the target are the units of the offset.
The interpretation of the mode argument, ID field and offset for
each address mode is given below:
HOST
The ID and offset fields are numbers assigned arbitrarily by
the host side of the debugger. These numbers are used in
MOVE and MOVE_DATA messages. MOVE_DATA responses containing
this mode as the destination are sent by the target to the
host. This may occur in debugging when data is sent to the
host from the target breakpoint.
PHYS_MACRO
The offset contains the 32-bit physical address of a
location in macromemory. The mode argument and ID field are
not used. For example, mode=PHYS_MACRO and offset=1000
specifies location 1000 in physical memory.
PHYS_MICRO
Like PHYS_MACRO, but the location is in micromemory.
PHYS_I/O
Like PHYS_MACRO, but the location is in I/O space.
PHYS_MACRO_PTR
The offset contains the address of a pointer in macromemory.
The location pointed to (the effective address) is also in
macromemory. The mode argument and ID field are unused.
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LDP Specification Commands and Formats
PHYS_REG
The mode argument gives the physical register. If the
register is used by the LDP target process, then the saved
copy from the previous context is used. This comment
applies to PHYS_REG_OFFSET mode as well. The ID field is
not used.
PHYS_REG_OFFSET
The offset is added to the contents of a register given as
the mode argument. The result is used as a physical address
in macromemory. ID is unused.
PHYS_REG_INDIRECT
The register specified in the mode arg contains the address
of a pointer in macromemory. The effective address is the
macromemory location specified in the pointer, plus the
offset. The ID field is unused.
PROCESS_CODE
The ID is a process ID, the offset is into the code space
for this process. Mode argument is not used.
PROCESS_DATA
The ID is a process ID, the offset is into the data space
for this process. Mode argument is not used. On systems
that do not distinguish between code and data space, these
two modes are equivalent, and reference the virtual address
space of the process.
PROCESS_DATA_PTR
The offset contains the address of a pointer in the data
space of the process specified by the ID. The location
pointed to (the effective address) is also in the data
space. The mode argument is not used.
PROCESS_REG
Accesses the registers (and other system data) of the
process given by the ID field. Mode argument 0 starts the
registers. After the registers, the mode argument is an
offset into the system area for the process.
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RFC-909 July 1984
PROCESS_REG_OFFSET
The offset plus the contents of the register given in the
mode argument specifies a location in the data space of the
process specified by the ID.
PROCESS_REG_INDIRECT
The register specified in the mode arg contains the address
of a pointer in the data space of the process given by the
ID. The effective address is the location in process data
space specified in the pointer, plus the offset.
OBJECT_OFFSET (optional)
The offset is into the memory space defined by the object ID
in ID. Recommended for remote control of parameter
segments.
OBJECT_HEADER (optional)
The offset is into the system header for the object
specified by the ID. Intended for use with the Butterfly.
BREAKPOINT
The descriptor specifies a breakpoint. The offset is never
used, this type is only used in descriptors referring to
breakpoints. (See Breakpoints and Watchpoints, below, for
an explanation of breakpoint descriptors.)
WATCHPOINT
The descriptor specifies a watchpoint. The offset is never
used, this type is only used in descriptors referring to
watchpoints. (See Breakpoints and Watchpoints, below, for
an explanation of watchpoint descriptors).
BPT_PTR_OFFSET
For this mode and BPT_PTR_INDIRECT, the mode argument
specifies one of two breakpoint pointer variables local to
the breakpoint in which this address occurs. These pointers
and the SET_PTR command which manipulates them provide for
an arbitrary amount of address indirection. They are
intended for use in traversing data structures: for example,
chasing queues. In BPT_PTR_OFFSET, the offset is added to
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LDP Specification Commands and Formats
the pointer variable to give the effective address. In
targets which support multiple processes, the location is in
the data space of the process given by the ID. Otherwise,
the location is a physical address in macro-memory.
BPT_PTR.* modes are valid only in breakpoints and
watchpoints.
BPT_PTR_INDIRECT
Like BPT_PTR_OFFSET, except that it uses one more level of
indirection. The pointer variable given by the mode
argument plus the offset specify an address which points to
the effective address. See the description of
BPT_PTR_OFFSET for a discussion of usage, limitations and
address space.
4.3.2 Short Address Format
The short address format is intended for use in
implementations where protocol overhead must be minimized. This
format is a subset of the long address format: it contains the
same fields except for the ID field. Therefore, the short
addressing format supports only HOST and PHYS_* address modes.
Only the LOADER_DUMPER implementation level commands may be used
with the short addressing format. The short address format is
three words long, consisting of a 16-bit word describing the
address space, and a 32-bit offset.
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