Information about Steps to install GDB in Mac: If you want to install a GDB in Mac then firstly you have to download a GDB from MinGW and install it at the same location (c:/MinGW by default). After that you have to install a eclipse and MinGW. This page explains how to build and install gdb on OS X using #Homebrew or #Fink. Since OS X Mavericks 10.9, Xcode 5 no longer installs gdb by default and not globally.
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4.10 Debugging Programs with Multiple Threads
In some operating systems, such as GNU/Linux and Solaris, a single programmay have more than one thread of execution. The precise semanticsof threads differ from one operating system to another, but in generalthe threads of a single program are akin to multiple processes—exceptthat they share one address space (that is, they can all examine andmodify the same variables). On the other hand, each thread has its ownregisters and execution stack, and perhaps private memory.
GDB provides these facilities for debugging multi-threadprograms:
- automatic notification of new threads
- ‘thread thread-id’, a command to switch among threads
- ‘info threads’, a command to inquire about existing threads
- ‘thread apply [thread-id-list | all] args’,a command to apply a command to a list of threads
- thread-specific breakpoints
- ‘set print thread-events’, which controls printing of messages on thread start and exit.
- ‘set libthread-db-search-path path’, which letsthe user specify which
libthread_db
to use if the default choiceisn’t compatible with the program.
The GDB thread debugging facility allows you to observe allthreads while your program runs—but whenever GDB takescontrol, one thread in particular is always the focus of debugging.This thread is called the current thread. Debugging commands showprogram information from the perspective of the current thread.
Whenever GDB detects a new thread in your program, it displaysthe target system’s identification for the thread with a message in theform ‘[New systag]’, where systag is a thread identifierwhose form varies depending on the particular system. For example, onGNU/Linux, you might see
when GDB notices a new thread. In contrast, on other systems,the systag is simply something like ‘process 368’, with nofurther qualifier.
For debugging purposes, GDB associates its own thread number—always a single integer—with each thread of an inferior. Thisnumber is unique between all threads of an inferior, but not uniquebetween threads of different inferiors.
You can refer to a given thread in an inferior using the qualifiedinferior-num.thread-num syntax, also known asqualified thread ID, with inferior-num being the inferiornumber and thread-num being the thread number of the giveninferior. For example, thread
2.3
refers to thread number 3 ofinferior 2. If you omit inferior-num (e.g., thread 3
),then GDB infers you’re referring to a thread of the currentinferior.Until you create a second inferior, GDB does not show theinferior-num part of thread IDs, even though you can always usethe full inferior-num.thread-num form to refer to threadsof inferior 1, the initial inferior.
Some commands accept a space-separated thread ID list Spss 17 free download for android. asargument. A list element can be:
- A thread ID as shown in the first field of the ‘info threads’display, with or without an inferior qualifier. E.g., ‘2.1’ or‘1’.
- A range of thread numbers, again with or without an inferiorqualifier, as in inf.thr1-thr2 orthr1-thr2. E.g., ‘1.2-4’ or ‘2-4’.
- All threads of an inferior, specified with a star wildcard, with orwithout an inferior qualifier, as in inf.
*
(e.g.,‘1.*’) or*
. The former refers to all threads of thegiven inferior, and the latter form without an inferior qualifierrefers to all threads of the current inferior.
For example, if the current inferior is 1, and inferior 7 has onethread with ID 7.1, the thread list ‘1 2-3 4.5 6.7-9 7.*’includes threads 1 to 3 of inferior 1, thread 5 of inferior 4, threads7 to 9 of inferior 6 and all threads of inferior 7. That is, inexpanded qualified form, the same as ‘1.1 1.2 1.3 4.5 6.7 6.8 6.97.1’.
In addition to a per-inferior number, each thread is alsoassigned a unique global number, also known as globalthread ID, a single integer. Unlike the thread number component ofthe thread ID, no two threads have the same global ID, even whenyou’re debugging multiple inferiors.
From GDB’s perspective, a process always has at least onethread. In other words, GDB assigns a thread number to theprogram’s “main thread” even if the program is not multi-threaded.
The debugger convenience variables ‘$_thread’ and‘$_gthread’ contain, respectively, the per-inferior thread numberand the global thread number of the current thread. You may find thisuseful in writing breakpoint conditional expressions, command scripts,and so forth. See Convenience Variables, forgeneral information on convenience variables.
Free samsung s5 unlock code instructions. If GDB detects the program is multi-threaded, it augments theusual message about stopping at a breakpoint with the ID and name ofthe thread that hit the breakpoint.
Gdb Macro Value
Likewise when the program receives a signal:
info threads [thread-id-list]
Download Gdb For Mac
Display information about one or more threads. With no argumentsdisplays information about all threads. You can specify the list ofthreads that you want to display using the thread ID list syntax(see thread ID lists).
GDB displays for each thread (in this order):
- the per-inferior thread number assigned by GDB
- the global thread number assigned by GDB, if the ‘-gid’option was specified
- the target system’s thread identifier (systag)
- the thread’s name, if one is known. A thread can either be named bythe user (see
thread name
, below), or, in some cases, by theprogram itself. - the current stack frame summary for that thread
An asterisk ‘*’ to the left of the GDB thread numberindicates the current thread.
For example,
If you’re debugging multiple inferiors, GDB displays threadIDs using the qualified inferior-num.thread-num format.Otherwise, only thread-num is shown.
If you specify the ‘-gid’ option, GDB displays a columnindicating each thread’s global thread ID:
On Solaris, you can display more information about user threads with aSolaris-specific command:
maint info sol-threads
Display info on Solaris user threads.
thread thread-id
Make thread ID thread-id the current thread. The commandargument thread-id is the GDB thread ID, as shown inthe first field of the ‘info threads’ display, with or without aninferior qualifier (e.g., ‘2.1’ or ‘1’).
GDB responds by displaying the system identifier of thethread you selected, and its current stack frame summary:
As with the ‘[New …]’ message, the form of the text after‘Switching to’ depends on your system’s conventions for identifyingthreads.
thread apply [thread-id-list | all [-ascending]] [flag]… command
The
thread apply
command allows you to apply the namedcommand to one or more threads. Specify the threads that youwant affected using the thread ID list syntax (see thread ID lists), or specify all
to apply to all threads. To apply acommand to all threads in descending order, type thread apply allcommand. To apply a command to all threads in ascending order,type thread apply all -ascending command.The flag arguments control what output to produce and how to handleerrors raised when applying command to a thread. flagmust start with a
-
directly followed by one letter inqcs
. If several flags are provided, they must be givenindividually, such as -c -q
.https://renewcolorado517.weebly.com/minecraft-20-download-mac.html. By default, GDB displays some thread information before theoutput produced by command, and an error raised during theexecution of a command will abort
thread apply
. Thefollowing flags can be used to fine-tune this behavior:-c
The flag
-c
, which stands for ‘continue’, causes anyerrors in command to be displayed, and the execution ofthread apply
then continues.-s
The flag
-s
, which stands for ‘silent’, causes any errorsor empty output produced by a command to be silently ignored.That is, the execution continues, but the thread information and errorsare not printed.-q
The flag
-q
(‘quiet’) disables printing the threadinformation.Flags
-c
and -s
cannot be used together.taas command
Shortcut for
thread apply all -s command
.Applies command on all threads, ignoring errors and empty output.tfaas command
Shortcut for
thread apply all -s frame apply all -s command
.Applies command on all frames of all threads, ignoring errorsand empty output. Note that the flag -s
is specified twice:The first -s
ensures that thread apply
only shows the threadinformation of the threads for which frame apply
producessome output. The second -s
is needed to ensure that frameapply
shows the frame information of a frame only if thecommand successfully produced some output.It can for example be used to print a local variable or a functionargument without knowing the thread or frame where this variable or argumentis, using:
thread name [name]
This command assigns a name to the current thread. If no argument isgiven, any existing user-specified name is removed. The thread nameappears in the ‘info threads’ display.
On some systems, such as GNU/Linux, GDB is able todetermine the name of the thread as given by the OS. On thesesystems, a name specified with ‘thread name’ will override thesystem-give name, and removing the user-specified name will causeGDB to once again display the system-specified name.
thread find [regexp]
Search for and display thread ids whose name or systagmatches the supplied regular expression.
As well as being the complement to the ‘thread name’ command, this command also allows you to identify a thread by its target systag. For instance, on GNU/Linux, the target systag Cutepdf for mac. is the LWP id.
set print thread-events
Gdb Machine Interface
set print thread-events on
set print thread-events off
The
set print thread-events
command allows you to enable ordisable printing of messages when GDB Nook for mac. notices that new threads havestarted or that threads have exited. By default, these messages willbe printed if detection of these events is supported by the target.Note that these messages cannot be disabled on all targets.show print thread-events
Show whether messages will be printed when GDB Ps2 emulator for mac. detects that threadshave started and exited.
See Stopping and Starting Multi-thread Programs, formore information about how GDB behaves when you stop and startprograms with multiple threads.
See Setting Watchpoints, for information aboutwatchpoints in programs with multiple threads.
set libthread-db-search-path [path]
If this variable is set, path is a colon-separated list ofdirectories GDB will use to search for
libthread_db
.If you omit path, ‘libthread-db-search-path’ will be reset toits default value ($sdir:$pdir
on GNU/Linux and Solaris systems).Internally, the default value comes from the LIBTHREAD_DB_SEARCH_PATH
macro.On GNU/Linux and Solaris systems, GDB uses a “helper”
libthread_db
library to obtain information about threads in theinferior process. GDB will use ‘libthread-db-search-path’to find libthread_db
. GDB also consults first if inferiorspecific thread debugging library loading is enabledby ‘set auto-load libthread-db’ (see libthread_db.so.1 file).![Gdb Gdb](/uploads/1/3/3/8/133890531/923116993.png)
A special entry ‘$sdir’ for ‘libthread-db-search-path’refers to the default system directories that arenormally searched for loading shared libraries. The ‘$sdir’ entryis the only kind not needing to be enabled by ‘set auto-load libthread-db’(see libthread_db.so.1 file).
A special entry ‘$pdir’ for ‘libthread-db-search-path’refers to the directory from which
libpthread
was loaded in the inferior process.For any
libthread_db
library GDB finds in above directories,GDB attempts to initialize it with the current inferior process.If this initialization fails (which could happen because of a versionmismatch between libthread_db
and libpthread
), GDBwill unload libthread_db
, and continue with the next directory.If none of libthread_db
libraries initialize successfully,GDB will issue a warning and thread debugging will be disabled.Setting
libthread-db-search-path
is currently implementedonly on some platforms.show libthread-db-search-path
Display current libthread_db search path.
set debug libthread-db
show debug libthread-db
Turns on or off display of
libthread_db
-related events.Use 1
to enable, 0
to disable.Next: Forks, Previous: Inferiors and Programs, Up: Running [Contents][Index]