1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
@c OBSOLETE
@c OBSOLETE @node Convex,,, Top
@c OBSOLETE @appendix Convex-specific info
@c OBSOLETE @cindex Convex notes
@c OBSOLETE
@c OBSOLETE Scalar registers are 64 bits long, which is a pain since
@c OBSOLETE left half of an S register frequently contains noise.
@c OBSOLETE Therefore there are two ways to obtain the value of an S register.
@c OBSOLETE
@c OBSOLETE @table @kbd
@c OBSOLETE @item $s0
@c OBSOLETE returns the low half of the register as an int
@c OBSOLETE
@c OBSOLETE @item $S0
@c OBSOLETE returns the whole register as a long long
@c OBSOLETE @end table
@c OBSOLETE
@c OBSOLETE You can print the value in floating point by using @samp{p/f $s0} or @samp{p/f $S0}
@c OBSOLETE to print a single or double precision value.
@c OBSOLETE
@c OBSOLETE @cindex vector registers
@c OBSOLETE Vector registers are handled similarly, with @samp{$V0} denoting the whole
@c OBSOLETE 64-bit register and @kbd{$v0} denoting the 32-bit low half; @samp{p/f $v0}
@c OBSOLETE or @samp{p/f $V0} can be used to examine the register in floating point.
@c OBSOLETE The length of the vector registers is taken from @samp{$vl}.
@c OBSOLETE
@c OBSOLETE Individual elements of a vector register are denoted in the obvious way;
@c OBSOLETE @samp{print $v3[9]} prints the tenth element of register @kbd{v3}, and
@c OBSOLETE @samp{set $v3[9] = 1234} alters it.
@c OBSOLETE
@c OBSOLETE @kbd{$vl} and @kbd{$vs} are int, and @kbd{$vm} is an int vector.
@c OBSOLETE Elements of @kbd{$vm} can't be assigned to.
@c OBSOLETE
@c OBSOLETE @cindex communication registers
@c OBSOLETE @kindex info comm-registers
@c OBSOLETE Communication registers have names @kbd{$C0 .. $C63}, with @kbd{$c0 .. $c63}
@c OBSOLETE denoting the low-order halves. @samp{info comm-registers} will print them
@c OBSOLETE all out, and tell which are locked. (A communication register is
@c OBSOLETE locked when a value is sent to it, and unlocked when the value is
@c OBSOLETE received.) Communication registers are, of course, global to all
@c OBSOLETE threads, so it does not matter what the currently selected thread is.
@c OBSOLETE @samp{info comm-reg @var{name}} prints just that one communication
@c OBSOLETE register; @samp{name} may also be a communication register number
@c OBSOLETE @samp{nn} or @samp{0xnn}.
@c OBSOLETE @samp{info comm-reg @var{address}} prints the contents of the resource
@c OBSOLETE structure at that address.
@c OBSOLETE
@c OBSOLETE @kindex info psw
@c OBSOLETE The command @samp{info psw} prints the processor status word @kbd{$ps}
@c OBSOLETE bit by bit.
@c OBSOLETE
@c OBSOLETE @kindex set base
@c OBSOLETE GDB normally prints all integers in base 10, but the leading
@c OBSOLETE @kbd{0x80000000} of pointers is intolerable in decimal, so the default
@c OBSOLETE output radix has been changed to try to print addresses appropriately.
@c OBSOLETE The @samp{set base} command can be used to change this.
@c OBSOLETE
@c OBSOLETE @table @code
@c OBSOLETE @item set base 10
@c OBSOLETE Integer values always print in decimal.
@c OBSOLETE
@c OBSOLETE @item set base 16
@c OBSOLETE Integer values always print in hex.
@c OBSOLETE
@c OBSOLETE @item set base
@c OBSOLETE Go back to the initial state, which prints integer values in hex if they
@c OBSOLETE look like pointers (specifically, if they start with 0x8 or 0xf in the
@c OBSOLETE stack), otherwise in decimal.
@c OBSOLETE @end table
@c OBSOLETE
@c OBSOLETE @kindex set pipeline
@c OBSOLETE When an exception such as a bus error or overflow happens, usually the PC
@c OBSOLETE is several instructions ahead by the time the exception is detected.
@c OBSOLETE The @samp{set pipe} command will disable this.
@c OBSOLETE
@c OBSOLETE @table @code
@c OBSOLETE @item set pipeline off
@c OBSOLETE Forces serial execution of instructions; no vector chaining and no
@c OBSOLETE scalar instruction overlap. With this, exceptions are detected with
@c OBSOLETE the PC pointing to the instruction after the one in error.
@c OBSOLETE
@c OBSOLETE @item set pipeline on
@c OBSOLETE Returns to normal, fast, execution. This is the default.
@c OBSOLETE @end table
@c OBSOLETE
@c OBSOLETE @cindex parallel
@c OBSOLETE In a parallel program, multiple threads may be executing, each
@c OBSOLETE with its own registers, stack, and local memory. When one of them
@c OBSOLETE hits a breakpoint, that thread is selected. Other threads do
@c OBSOLETE not run while the thread is in the breakpoint.
@c OBSOLETE
@c OBSOLETE @kindex 1cont
@c OBSOLETE The selected thread can be single-stepped, given signals, and so
@c OBSOLETE on. Any other threads remain stopped. When a @samp{cont} command is given,
@c OBSOLETE all threads are resumed. To resume just the selected thread, use
@c OBSOLETE the command @samp{1cont}.
@c OBSOLETE
@c OBSOLETE @kindex thread
@c OBSOLETE The @samp{thread} command will show the active threads and the
@c OBSOLETE instruction they are about to execute. The selected thread is marked
@c OBSOLETE with an asterisk. The command @samp{thread @var{n}} will select thread @var{n},
@c OBSOLETE shifting the debugger's attention to it for single-stepping,
@c OBSOLETE registers, local memory, and so on.
@c OBSOLETE
@c OBSOLETE @kindex info threads
@c OBSOLETE The @samp{info threads} command will show what threads, if any, have
@c OBSOLETE invisibly hit breakpoints or signals and are waiting to be noticed.
@c OBSOLETE
@c OBSOLETE @kindex set parallel
@c OBSOLETE The @samp{set parallel} command controls how many threads can be active.
@c OBSOLETE
@c OBSOLETE @table @code
@c OBSOLETE @item set parallel off
@c OBSOLETE One thread. Requests by the program that other threads join in
@c OBSOLETE (spawn and pfork instructions) do not cause other threads to start up.
@c OBSOLETE This does the same thing as the @samp{limit concurrency 1} command.
@c OBSOLETE
@c OBSOLETE @item set parallel fixed
@c OBSOLETE All CPUs are assigned to your program whenever it runs. When it
@c OBSOLETE executes a pfork or spawn instruction, it begins parallel execution
@c OBSOLETE immediately. This does the same thing as the @samp{mpa -f} command.
@c OBSOLETE
@c OBSOLETE @item set parallel on
@c OBSOLETE One or more threads. Spawn and pfork cause CPUs to join in when and if
@c OBSOLETE they are free. This is the default. It is very good for system
@c OBSOLETE throughput, but not very good for finding bugs in parallel code. If you
@c OBSOLETE suspect a bug in parallel code, you probably want @samp{set parallel fixed.}
@c OBSOLETE @end table
@c OBSOLETE
@c OBSOLETE @subsection Limitations
@c OBSOLETE
@c OBSOLETE WARNING: Convex GDB evaluates expressions in long long, because S
@c OBSOLETE registers are 64 bits long. However, GDB expression semantics are not
@c OBSOLETE exactly C semantics. This is a bug, strictly speaking, but it's not one I
@c OBSOLETE know how to fix. If @samp{x} is a program variable of type int, then it
@c OBSOLETE is also type int to GDB, but @samp{x + 1} is long long, as is @samp{x + y}
@c OBSOLETE or any other expression requiring computation. So is the expression
@c OBSOLETE @samp{1}, or any other constant. You only really have to watch out for
@c OBSOLETE calls. The innocuous expression @samp{list_node (0x80001234)} has an
@c OBSOLETE argument of type long long. You must explicitly cast it to int.
@c OBSOLETE
@c OBSOLETE It is not possible to continue after an uncaught fatal signal by using
@c OBSOLETE @samp{signal 0}, @samp{return}, @samp{jump}, or anything else. The difficulty is with
@c OBSOLETE Unix, not GDB.
@c OBSOLETE
@c OBSOLETE I have made no big effort to make such things as single-stepping a
@c OBSOLETE @kbd{join} instruction do something reasonable. If the program seems to
@c OBSOLETE hang when doing this, type @kbd{ctrl-c} and @samp{cont}, or use
@c OBSOLETE @samp{thread} to shift to a live thread. Single-stepping a @kbd{spawn}
@c OBSOLETE instruction apparently causes new threads to be born with their T bit set;
@c OBSOLETE this is not handled gracefully. When a thread has hit a breakpoint, other
@c OBSOLETE threads may have invisibly hit the breakpoint in the background; if you
@c OBSOLETE clear the breakpoint gdb will be surprised when threads seem to continue
@c OBSOLETE to stop at it. All of these situations produce spurious signal 5 traps;
@c OBSOLETE if this happens, just type @samp{cont}. If it becomes a nuisance, use
@c OBSOLETE @samp{handle 5 nostop}. (It will ask if you are sure. You are.)
@c OBSOLETE
@c OBSOLETE There is no way in GDB to store a float in a register, as with
@c OBSOLETE @kbd{set $s0 = 3.1416}. The identifier @kbd{$s0} denotes an integer,
@c OBSOLETE and like any C expression which assigns to an integer variable, the
@c OBSOLETE right-hand side is casted to type int. If you should need to do
@c OBSOLETE something like this, you can assign the value to @kbd{@{float@} ($sp-4)}
@c OBSOLETE and then do @kbd{set $s0 = $sp[-4]}. Same deal with @kbd{set $v0[69] = 6.9}.
|
