Debugging with GDB: GDB/MI Async Records

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27.5.3 GDB/MI Async Records

Async records are used to notify the GDB/MI client of additional changes that have occurred. Those changes can either be a consequence of GDB/MI commands (e.g., a breakpoint modified) or a result of target activity (e.g., target stopped).

The following is the list of possible async records:

*running,thread-id="thread"

The target is now running. The thread field can be the global thread ID of the the thread that is now running, and it can be ‘all’ if all threads are running. The frontend should assume that no interaction with a running thread is possible after this notification is produced. The frontend should not assume that this notification is output only once for any command. GDB may emit this notification several times, either for different threads, because it cannot resume all threads together, or even for a single thread, if the thread must be stepped though some code before letting it run freely.

*stopped,reason="reason",thread-id="id",stopped-threads="stopped",core="core"

The target has stopped. The reason field can have one of the following values:

breakpoint-hit

A breakpoint was reached.

watchpoint-trigger

A watchpoint was triggered.

read-watchpoint-trigger

A read watchpoint was triggered.

access-watchpoint-trigger

An access watchpoint was triggered.

function-finished

An -exec-finish or similar CLI command was accomplished.

location-reached

An -exec-until or similar CLI command was accomplished.

watchpoint-scope

A watchpoint has gone out of scope.

end-stepping-range

An -exec-next, -exec-next-instruction, -exec-step, -exec-step-instruction or similar CLI command was accomplished.

exited-signalled

The inferior exited because of a signal.

exited

The inferior exited.

exited-normally

The inferior exited normally.

signal-received

A signal was received by the inferior.

solib-event

The inferior has stopped due to a library being loaded or unloaded. This can happen when stop-on-solib-events (see Files) is set or when a catch load or catch unload catchpoint is in use (see Set Catchpoints).

fork

The inferior has forked. This is reported when catch fork (see Set Catchpoints) has been used.

vfork

The inferior has vforked. This is reported in when catch vfork (see Set Catchpoints) has been used.

syscall-entry

The inferior entered a system call. This is reported when catch syscall (see Set Catchpoints) has been used.

syscall-return

The inferior returned from a system call. This is reported when catch syscall (see Set Catchpoints) has been used.

exec

The inferior called exec. This is reported when catch exec (see Set Catchpoints) has been used.

The id field identifies the global thread ID of the thread that directly caused the stop – for example by hitting a breakpoint. Depending on whether all-stop mode is in effect (see All-Stop Mode), GDB may either stop all threads, or only the thread that directly triggered the stop. If all threads are stopped, the stopped field will have the value of "all". Otherwise, the value of the stopped field will be a list of thread identifiers. Presently, this list will always include a single thread, but frontend should be prepared to see several threads in the list. The core field reports the processor core on which the stop event has happened. This field may be absent if such information is not available.

=thread-group-added,id="id"

=thread-group-removed,id="id"

A thread group was either added or removed. The id field contains the GDB identifier of the thread group. When a thread group is added, it generally might not be associated with a running process. When a thread group is removed, its id becomes invalid and cannot be used in any way.

=thread-group-started,id="id",pid="pid"

A thread group became associated with a running program, either because the program was just started or the thread group was attached to a program. The id field contains the GDB identifier of the thread group. The pid field contains process identifier, specific to the operating system.

=thread-group-exited,id="id"[,exit-code="code"]

A thread group is no longer associated with a running program, either because the program has exited, or because it was detached from. The id field contains the GDB identifier of the thread group. The code field is the exit code of the inferior; it exists only when the inferior exited with some code.

=thread-created,id="id",group-id="gid"

=thread-exited,id="id",group-id="gid"

A thread either was created, or has exited. The id field contains the global GDB identifier of the thread. The gid field identifies the thread group this thread belongs to.

=thread-selected,id="id"[,frame="frame"]

Informs that the selected thread or frame were changed. This notification is not emitted as result of the -thread-select or -stack-select-frame commands, but is emitted whenever an MI command that is not documented to change the selected thread and frame actually changes them. In particular, invoking, directly or indirectly (via user-defined command), the CLI thread or frame commands, will generate this notification. Changing the thread or frame from another user interface (see Interpreters) will also generate this notification.

The frame field is only present if the newly selected thread is stopped. See GDB/MI Frame Information for the format of its value.

We suggest that in response to this notification, front ends highlight the selected thread and cause subsequent commands to apply to that thread.

=library-loaded,...

Reports that a new library file was loaded by the program. This notification has 5 fields—id, target-name, host-name, symbols-loaded and ranges. The id field is an opaque identifier of the library. For remote debugging case, target-name and host-name fields give the name of the library file on the target, and on the host respectively. For native debugging, both those fields have the same value. The symbols-loaded field is emitted only for backward compatibility and should not be relied on to convey any useful information. The thread-group field, if present, specifies the id of the thread group in whose context the library was loaded. If the field is absent, it means the library was loaded in the context of all present thread groups. The ranges field specifies the ranges of addresses belonging to this library.

=library-unloaded,...

Reports that a library was unloaded by the program. This notification has 3 fields—id, target-name and host-name with the same meaning as for the =library-loaded notification. The thread-group field, if present, specifies the id of the thread group in whose context the library was unloaded. If the field is absent, it means the library was unloaded in the context of all present thread groups.

=traceframe-changed,num=tfnum,tracepoint=tpnum

=traceframe-changed,end

Reports that the trace frame was changed and its new number is tfnum. The number of the tracepoint associated with this trace frame is tpnum.

=tsv-created,name=name,initial=initial

Reports that the new trace state variable name is created with initial value initial.

=tsv-deleted,name=name

=tsv-deleted

Reports that the trace state variable name is deleted or all trace state variables are deleted.

=tsv-modified,name=name,initial=initial[,current=current]

Reports that the trace state variable name is modified with the initial value initial. The current value current of trace state variable is optional and is reported if the current value of trace state variable is known.

=breakpoint-created,bkpt={...}

=breakpoint-modified,bkpt={...}

=breakpoint-deleted,id=number

Reports that a breakpoint was created, modified, or deleted, respectively. Only user-visible breakpoints are reported to the MI user.

The bkpt argument is of the same form as returned by the various breakpoint commands; See GDB/MI Breakpoint Commands. The number is the ordinal number of the breakpoint.

Note that if a breakpoint is emitted in the result record of a command, then it will not also be emitted in an async record.

=record-started,thread-group="id",method="method"[,format="format"]

=record-stopped,thread-group="id"

Execution log recording was either started or stopped on an inferior. The id is the GDB identifier of the thread group corresponding to the affected inferior.

The method field indicates the method used to record execution. If the method in use supports multiple recording formats, format will be present and contain the currently used format. See Process Record and Replay, for existing method and format values.

=cmd-param-changed,param=param,value=value

Reports that a parameter of the command set param is changed to value. In the multi-word set command, the param is the whole parameter list to set command. For example, In command set check type on, param is check type and value is on.

=memory-changed,thread-group=id,addr=addr,len=len[,type="code"]

Reports that bytes from addr to data + len were written in an inferior. The id is the identifier of the thread group corresponding to the affected inferior. The optional type="code" part is reported if the memory written to holds executable code.

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