the breakpoints are conditional, this is even useful
(@pxref{Conditions, ,Break Conditions}).
+@cindex multiple locations, breakpoints
+@cindex breakpoints, multiple locations
It is possible that a breakpoint corresponds to several locations
in your program. Examples of this situation are:
@itemize @bullet
-
@item
For a C@t{++} constructor, the @value{NGCC} compiler generates several
instances of the function body, used in different cases.
@item
For an inlined function, a given source line can correspond to
several places where that function is inlined.
-
@end itemize
In all those cases, @value{GDBN} will insert a breakpoint at all
-the relevant locations.
+the relevant locations@footnote{
+As of this writing, multiple-location breakpoints work only if there's
+line number information for all the locations. This means that they
+will generally not work in system libraries, unless you have debug
+info with line numbers for them.}.
A breakpoint with multiple locations is displayed in the breakpoint
table using several rows---one header row, followed by one row for
trying to set software breakpoint at a read-only address.
@end table
+@value{GDBN} normally implements breakpoints by replacing the program code
+at the breakpoint address with a special instruction, which, when
+executed, given control to the debugger. By default, the program
+code is so modified only when the program is resumed. As soon as
+the program stops, @value{GDBN} restores the original instructions. This
+behaviour guards against leaving breakpoints inserted in the
+target should gdb abrubptly disconnect. However, with slow remote
+targets, inserting and removing breakpoint can reduce the performance.
+This behavior can be controlled with the following commands::
+
+@kindex set breakpoint always-inserted
+@kindex show breakpoint always-inserted
+@table @code
+@item set breakpoint always-inserted off
+This is the default behaviour. All breakpoints, including newly added
+by the user, are inserted in the target only when the target is
+resumed. All breakpoints are removed from the target when it stops.
+
+@item set breakpoint always-inserted on
+Causes all breakpoints to be inserted in the target at all times. If
+the user adds a new breakpoint, or changes an existing breakpoint, the
+breakpoints in the target are updated immediately. A breakpoint is
+removed from the target only when breakpoint itself is removed.
+@end table
@cindex negative breakpoint numbers
@cindex internal @value{GDBN} breakpoints
source line debug information.
@kindex finish
+@kindex fin @r{(@code{finish})}
@item finish
Continue running until just after function in the selected stack frame
-returns. Print the returned value (if any).
+returns. Print the returned value (if any). This command can be
+abbreviated as @code{fin}.
Contrast this with the @code{return} command (@pxref{Returning,
,Returning from a Function}).
@cindex machine instructions
@cindex listing machine instructions
@item disassemble
+@itemx disassemble /m
This specialized command dumps a range of memory as machine
-instructions. The default memory range is the function surrounding the
+instructions. It can also print mixed source+disassembly by specifying
+the @code{/m} modifier.
+The default memory range is the function surrounding the
program counter of the selected frame. A single argument to this
command is a program counter value; @value{GDBN} dumps the function
surrounding this value. Two arguments specify a range of addresses
End of assembler dump.
@end smallexample
+Here is an example showing mixed source+assembly for Intel x86:
+
+@smallexample
+(@value{GDBP}) disas /m main
+Dump of assembler code for function main:
+5 @{
+0x08048330 <main+0>: push %ebp
+0x08048331 <main+1>: mov %esp,%ebp
+0x08048333 <main+3>: sub $0x8,%esp
+0x08048336 <main+6>: and $0xfffffff0,%esp
+0x08048339 <main+9>: sub $0x10,%esp
+
+6 printf ("Hello.\n");
+0x0804833c <main+12>: movl $0x8048440,(%esp)
+0x08048343 <main+19>: call 0x8048284 <puts@@plt>
+
+7 return 0;
+8 @}
+0x08048348 <main+24>: mov $0x0,%eax
+0x0804834d <main+29>: leave
+0x0804834e <main+30>: ret
+
+End of assembler dump.
+@end smallexample
+
Some architectures have more than one commonly-used set of instruction
mnemonics or other syntax.
* Character Sets:: Debugging programs that use a different
character set than GDB does
* Caching Remote Data:: Data caching for remote targets
+* Searching Memory:: Searching memory for a sequence of bytes
@end menu
@node Expressions
the data cache operation.
@end table
+@node Searching Memory
+@section Search Memory
+@cindex searching memory
+
+Memory can be searched for a particular sequence of bytes with the
+@code{find} command.
+
+@table @code
+@kindex find
+@item find @r{[}/@var{sn}@r{]} @var{start_addr}, +@var{len}, @var{val1} @r{[}, @var{val2}, @dots{}@r{]}
+@itemx find @r{[}/@var{sn}@r{]} @var{start_addr}, @var{end_addr}, @var{val1} @r{[}, @var{val2}, @dots{}@r{]}
+Search memory for the sequence of bytes specified by @var{val1}, @var{val2},
+etc. The search begins at address @var{start_addr} and continues for either
+@var{len} bytes or through to @var{end_addr} inclusive.
+@end table
+
+@var{s} and @var{n} are optional parameters.
+They may be specified in either order, apart or together.
+
+@table @r
+@item @var{s}, search query size
+The size of each search query value.
+
+@table @code
+@item b
+bytes
+@item h
+halfwords (two bytes)
+@item w
+words (four bytes)
+@item g
+giant words (eight bytes)
+@end table
+
+All values are interpreted in the current language.
+This means, for example, that if the current source language is C/C@t{++}
+then searching for the string ``hello'' includes the trailing '\0'.
+
+If the value size is not specified, it is taken from the
+value's type in the current language.
+This is useful when one wants to specify the search
+pattern as a mixture of types.
+Note that this means, for example, that in the case of C-like languages
+a search for an untyped 0x42 will search for @samp{(int) 0x42}
+which is typically four bytes.
+
+@item @var{n}, maximum number of finds
+The maximum number of matches to print. The default is to print all finds.
+@end table
+
+You can use strings as search values. Quote them with double-quotes
+ (@code{"}).
+The string value is copied into the search pattern byte by byte,
+regardless of the endianness of the target and the size specification.
+
+The address of each match found is printed as well as a count of the
+number of matches found.
+
+The address of the last value found is stored in convenience variable
+@samp{$_}.
+A count of the number of matches is stored in @samp{$numfound}.
+
+For example, if stopped at the @code{printf} in this function:
+
+@smallexample
+void
+hello ()
+@{
+ static char hello[] = "hello-hello";
+ static struct @{ char c; short s; int i; @}
+ __attribute__ ((packed)) mixed
+ = @{ 'c', 0x1234, 0x87654321 @};
+ printf ("%s\n", hello);
+@}
+@end smallexample
+
+@noindent
+you get during debugging:
+
+@smallexample
+(gdb) find &hello[0], +sizeof(hello), "hello"
+0x804956d <hello.1620+6>
+1 pattern found
+(gdb) find &hello[0], +sizeof(hello), 'h', 'e', 'l', 'l', 'o'
+0x8049567 <hello.1620>
+0x804956d <hello.1620+6>
+2 patterns found
+(gdb) find /b1 &hello[0], +sizeof(hello), 'h', 0x65, 'l'
+0x8049567 <hello.1620>
+1 pattern found
+(gdb) find &mixed, +sizeof(mixed), (char) 'c', (short) 0x1234, (int) 0x87654321
+0x8049560 <mixed.1625>
+1 pattern found
+(gdb) print $numfound
+$1 = 1
+(gdb) print $_
+$2 = (void *) 0x8049560
+@end smallexample
@node Macros
@chapter C Preprocessor Macros
@item :
The range operator. Normally used in the form of array(low:high) to
represent a section of array.
+
+@item %
+The access component operator. Normally used to access elements in derived
+types. Also suitable for unions. As unions aren't part of regular Fortran,
+this can only happen when accessing a register that uses a gdbarch-defined
+union type.
@end table
@node Fortran Defaults
@tab @code{qGetTLSAddr}
@tab Displaying @code{__thread} variables
+@item @code{search-memory}
+@tab @code{qSearch:memory}
+@tab @code{find}
+
@item @code{supported-packets}
@tab @code{qSupported}
@tab Remote communications parameters
@item show arm abi
Show the currently used ABI.
+@item set arm fallback-mode (arm|thumb|auto)
+@value{GDBN} uses the symbol table, when available, to determine
+whether instructions are ARM or Thumb. This command controls
+@value{GDBN}'s default behavior when the symbol table is not
+available. The default is @samp{auto}, which causes @value{GDBN} to
+use the current execution mode (from the @code{T} bit in the @code{CPSR}
+register).
+
+@item show arm fallback-mode
+Show the current fallback instruction mode.
+
+@item set arm force-mode (arm|thumb|auto)
+This command overrides use of the symbol table to determine whether
+instructions are ARM or Thumb. The default is @samp{auto}, which
+causes @value{GDBN} to use the symbol table and then the setting
+of @samp{set arm fallback-mode}.
+
+@item show arm force-mode
+Show the current forced instruction mode.
+
@item set debug arm
Toggle whether to display ARM-specific debugging messages from the ARM
target support subsystem.
@item regs
@kindex regs@r{, Super-H}
Show the values of all Super-H registers.
+
+@item set sh calling-convention @var{convention}
+@kindex set sh calling-convention
+Set the calling-convention used when calling functions from @value{GDBN}.
+Allowed values are @samp{gcc}, which is the default setting, and @samp{renesas}.
+With the @samp{gcc} setting, functions are called using the @value{NGCC} calling
+convention. If the DWARF-2 information of the called function specifies
+that the function follows the Renesas calling convention, the function
+is called using the Renesas calling convention. If the calling convention
+is set to @samp{renesas}, the Renesas calling convention is always used,
+regardless of the DWARF-2 information. This can be used to override the
+default of @samp{gcc} if debug information is missing, or the compiler
+does not emit the DWARF-2 calling convention entry for a function.
+
+@item show sh calling-convention
+@kindex show sh calling-convention
+Show the current calling convention setting.
+
@end table
module.
@item show debug aix-thread
Show the current state of AIX thread debugging info display.
+@item set debug displaced
+@cindex displaced stepping debugging info
+Turns on or off display of @value{GDBN} debugging info for the
+displaced stepping support. The default is off.
+@item show debug displaced
+Displays the current state of displaying @value{GDBN} debugging info
+related to displaced stepping.
@item set debug event
@cindex event debugging info
Turns on or off display of @value{GDBN} event debugging info. The
All output sequences end in a single line containing a period.
@item
-The @code{@var{token}} is from the corresponding request. If an execution
-command is interrupted by the @samp{-exec-interrupt} command, the
-@var{token} associated with the @samp{*stopped} message is the one of the
-original execution command, not the one of the interrupt command.
+The @code{@var{token}} is from the corresponding request. Note that
+for all async output, while the token is allowed by the grammar and
+may be output by future versions of @value{GDBN} for select async
+output messages, it is generally omitted. Frontends should treat
+all async output as reporting general changes in the state of the
+target and there should be no need to associate async output to any
+prior command.
@item
@cindex status output in @sc{gdb/mi}
The best way to avoid unexpected changes in MI that might break your front
end is to make your project known to @value{GDBN} developers and
follow development on @email{gdb@@sourceware.org} and
-@email{gdb-patches@@sourceware.org}. There is also the mailing list
-@email{dmi-discuss@@lists.freestandards.org}, hosted by the Free Standards
-Group, which has the aim of creating a more general MI protocol
-called Debugger Machine Interface (DMI) that will become a standard
-for all debuggers, not just @value{GDBN}.
+@email{gdb-patches@@sourceware.org}.
@cindex mailing lists
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@menu
* GDB/MI Result Records::
* GDB/MI Stream Records::
-* GDB/MI Out-of-band Records::
+* GDB/MI Async Records::
@end menu
@node GDB/MI Result Records
internals.
@end table
-@node GDB/MI Out-of-band Records
-@subsection @sc{gdb/mi} Out-of-band Records
+@node GDB/MI Async Records
+@subsection @sc{gdb/mi} Async Records
-@cindex out-of-band records in @sc{gdb/mi}
-@cindex @sc{gdb/mi}, out-of-band records
-@dfn{Out-of-band} records are used to notify the @sc{gdb/mi} client of
+@cindex async records in @sc{gdb/mi}
+@cindex @sc{gdb/mi}, async records
+@dfn{Async} records are used to notify the @sc{gdb/mi} client of
additional changes that have occurred. Those changes can either be a
-consequence of @sc{gdb/mi} (e.g., a breakpoint modified) or a result of
+consequence of @sc{gdb/mi} commands (e.g., a breakpoint modified) or a result of
target activity (e.g., target stopped).
-The following is a preliminary list of possible out-of-band records.
-In particular, the @var{exec-async-output} records.
+The following is the list of possible async records:
@table @code
-@item *stopped,reason="@var{reason}"
-@end table
-@var{reason} can be one of the following:
+@item *stopped,reason="@var{reason}"
+The target has stopped. The @var{reason} field can have one of the
+following values:
@table @code
@item breakpoint-hit
A signal was received by the inferior.
@end table
+@item =thread-created,id="@var{id}"
+@itemx =thread-exited,id="@var{id}"
+A thread either was created, or has exited. The @var{id} field
+contains the @value{GDBN} identifier of the thread.
+@end table
+
+
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@node GDB/MI Simple Examples
-> -exec-run
<- ^running
<- (gdb)
-<- *stopped,reason="breakpoint-hit",bkptno="1",thread-id="0",
+<- *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
frame=@{addr="0x08048564",func="main",
args=[@{name="argc",value="1"@},@{name="argv",value="0xbfc4d4d4"@}],
file="myprog.c",fullname="/home/nickrob/myprog.c",line="68"@}
@smallexample
(gdb)
-break-insert main
-^done,bkpt=@{number="1",addr="0x000100d0",file="hello.c",
+^done,bkpt=@{number="1",type="breakpoint",disp="keep",
+enabled="y",addr="0x000100d0",func="main",file="hello.c",
fullname="/home/foo/hello.c",line="5",times="0"@}
(gdb)
-break-after 1 3
^running
(gdb)
@@Hello world
-*stopped,reason="breakpoint-hit",bkptno="2",frame=@{func="foo",args=[],
-file="hello.c",fullname="/home/foo/bar/hello.c",line="13"@}
+*stopped,reason="breakpoint-hit",disp="keep",bkptno="2",frame=@{
+func="foo",args=[],file="hello.c",fullname="/home/foo/bar/hello.c",
+line="13"@}
(gdb)
@end smallexample
000-exec-run
000^running
(gdb)
-000*stopped,reason="breakpoint-hit",bkptno="1",
+000*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
frame=@{func="callee4",args=[],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"@}
-exec-run
^running
(gdb)
-*stopped,reason="breakpoint-hit",bkptno="1",
+*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
frame=@{func="main",args=[],file="recursive2.c",
fullname="/home/foo/bar/recursive2.c",line="4"@}
(gdb)
Sets the output format for the value of the object @var{name} to be
@var{format-spec}.
+@anchor{-var-set-format}
The syntax for the @var{format-spec} is as follows:
@smallexample
@subsubheading Synopsis
@smallexample
- -var-evaluate-expression @var{name}
+ -var-evaluate-expression [-f @var{format-spec}] @var{name}
@end smallexample
Evaluates the expression that is represented by the specified variable
-object and returns its value as a string. The format of the
-string can be changed using the @code{-var-set-format} command.
+object and returns its value as a string. The format of the string
+can be specified with the @samp{-f} option. The possible values of
+this option are the same as for @code{-var-set-format}
+(@pxref{-var-set-format}). If the @samp{-f} option is not specified,
+the current display format will be used. The current display format
+can be changed using the @code{-var-set-format} command.
@smallexample
value=@var{value}
object names, all existing variable objects are updated, except
for frozen ones (@pxref{-var-set-frozen}). The option
@var{print-values} determines whether both names and values, or just
-names are printed. The possible values of this options are the same
+names are printed. The possible values of this option are the same
as for @code{-var-list-children} (@pxref{-var-list-children}). It is
recommended to use the @samp{--all-values} option, to reduce the
number of MI commands needed on each program stop.
^running
(gdb)
-*stopped,reason="breakpoint-hit",bkptno="1",frame=@{func="main",
-args=[],file="try.c",fullname="/home/foo/bar/try.c",line="5"@}
+*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame=@{
+func="main",args=[],file="try.c",fullname="/home/foo/bar/try.c",
+line="5"@}
(gdb)
-data-list-changed-registers
^done,changed-registers=["0","1","2","4","5","6","7","8","9",
@end smallexample
-@subheading The @code{-target-file-put} Command
+@subheading The @code{-target-file-get} Command
@findex -target-file-get
@subsubheading Synopsis
-exec-run
^running
(gdb)
-*stopped,reason="breakpoint-hit",bkptno="1",thread-id="0",
+*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
frame=@{addr="0x080484ed",func="main",args=[@{name="argc",value="1"@},
@{name="argv",value="0xbfb60364"@}],file="myprog.c",
fullname="/home/nickrob/myprog.c",line="73"@}
MS-Windows shared libraries (@pxref{Shared Libraries})
@end itemize
+@item zlib
+@cindex compressed debug sections
+@value{GDBN} will use the @samp{zlib} library, if available, to read
+compressed debug sections. Some linkers, such as GNU gold, are capable
+of producing binaries with compressed debug sections. If @value{GDBN}
+is compiled with @samp{zlib}, it will be able to read the debug
+information in such binaries.
+
+The @samp{zlib} library is likely included with your operating system
+distribution; if it is not, you can get the latest version from
+@url{http://zlib.net}.
+
@end table
@node Running Configure
@end table
+@kindex maint set can-use-displaced-stepping
+@kindex maint show can-use-displaced-stepping
+@cindex displaced stepping support
+@cindex out-of-line single-stepping
+@item maint set can-use-displaced-stepping
+@itemx maint show can-use-displaced-stepping
+Control whether or not @value{GDBN} will do @dfn{displaced stepping}
+if the target supports it. The default is on. Displaced stepping is
+a way to single-step over breakpoints without removing them from the
+inferior, by executing an out-of-line copy of the instruction that was
+originally at the breakpoint location. It is also known as
+out-of-line single-stepping.
+
@kindex maint check-symtabs
@item maint check-symtabs
Check the consistency of psymtabs and symtabs.
Control whether to display the execution time for each command. If
set to a nonzero value, @value{GDBN} will display how much time it
took to execute each command, following the command's own output.
+The time is not printed for the commands that run the target, since
+there's no mechanism currently to compute how much time was spend
+by @value{GDBN} and how much time was spend by the program been debugged.
+it's not possibly currently
This can also be requested by invoking @value{GDBN} with the
@option{--statistics} command-line switch (@pxref{Mode Options}).
@item vAttach;@var{pid}
@cindex @samp{vAttach} packet
Attach to a new process with the specified process ID. @var{pid} is a
-hexadecimal integer identifying the process. If the stub is currently
-controlling a process, it is killed. The attached process is stopped.
+hexadecimal integer identifying the process. The attached process is
+stopped.
This packet is only available in extended mode (@pxref{extended mode}).
command line. The file and arguments are hex-encoded strings. If
@var{filename} is an empty string, the stub may use a default program
(e.g.@: the last program run). The program is created in the stopped
-state. If the stub is currently controlling a process, it is killed.
+state.
This packet is only available in extended mode (@pxref{extended mode}).
conventions above. Please don't use this packet as a model for new
packets.)
+@item qSearch:memory:@var{address};@var{length};@var{search-pattern}
+@cindex searching memory, in remote debugging
+@cindex @samp{qSearch:memory} packet
+@anchor{qSearch memory}
+Search @var{length} bytes at @var{address} for @var{search-pattern}.
+@var{address} and @var{length} are encoded in hex.
+@var{search-pattern} is a sequence of bytes, hex encoded.
+
+Reply:
+@table @samp
+@item 0
+The pattern was not found.
+@item 1,address
+The pattern was found at @var{address}.
+@item E @var{NN}
+A badly formed request or an error was encountered while searching memory.
+@item
+An empty reply indicates that @samp{qSearch:memory} is not recognized.
+@end table
+
@item qSupported @r{[}:@var{gdbfeature} @r{[};@var{gdbfeature}@r{]}@dots{} @r{]}
@cindex supported packets, remote query
@cindex features of the remote protocol
projects / binutils-gdb.git / blobdiff