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authorPedro Alves <palves@redhat.com>2014-09-22 09:56:55 +0100
committerPedro Alves <palves@redhat.com>2014-09-22 10:07:04 +0100
commita25a5a45ef9340eb9a435f9b70599a90bb142658 (patch)
tree759b01c841bba84e5e788e7940609b81b67079f3 /gdb/NEWS
parent04086b458aebb38994486b09f4492645f03e971f (diff)
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Fix "breakpoint always-inserted off"; remove "breakpoint always-inserted auto"
By default, GDB removes all breakpoints from the target when the target stops and the prompt is given back to the user. This is useful in case GDB crashes while the user is interacting, as otherwise, there's a higher chance breakpoints would be left planted on the target. But, as long as any thread is running free, we need to make sure to keep breakpoints inserted, lest a thread misses a breakpoint. With that in mind, in preparation for non-stop mode, we added a "breakpoint always-inserted on" mode. This traded off the extra crash protection for never having threads miss breakpoints, and in addition is more efficient if there's a ton of breakpoints to remove/insert at each user command (e.g., at each "step"). When we added non-stop mode, and for a period, we required users to manually set "always-inserted on" when they enabled non-stop mode, as otherwise GDB removes all breakpoints from the target as soon as any thread stops, which means the other threads still running will miss breakpoints. The test added by this patch exercises this. That soon revealed a nuisance, and so later we added an extra "breakpoint always-inserted auto" mode, that made GDB behave like "always-inserted on" when non-stop was enabled, and "always-inserted off" when non-stop was disabled. "auto" was made the default at the same time. In hindsight, this "auto" setting was unnecessary, and not the ideal solution. Non-stop mode does depends on breakpoints always-inserted mode, but only as long as any thread is running. If no thread is running, no breakpoint can be missed. The same is true for all-stop too. E.g., if, in all-stop mode, and the user does: (gdb) c& (gdb) b foo That breakpoint at "foo" should be inserted immediately, but it currently isn't -- currently it'll end up inserted only if the target happens to trip on some event, and is re-resumed, e.g., an internal breakpoint triggers that doesn't cause a user-visible stop, and so we end up in keep_going calling insert_breakpoints. The test added by this patch also covers this. IOW, no matter whether in non-stop or all-stop, if the target fully stops, we can remove breakpoints. And no matter whether in all-stop or non-stop, if any thread is running in the target, then we need breakpoints to be immediately inserted. And then, if the target has global breakpoints, we need to keep breakpoints even when the target is stopped. So with that in mind, and aiming at reducing all-stop vs non-stop differences for all-stop-on-stop-of-non-stop, this patch fixes "breakpoint always-inserted off" to not remove breakpoints from the target until it fully stops, and then removes the "auto" setting as unnecessary. I propose removing it straight away rather than keeping it as an alias, unless someone complains they have scripts that need it and that can't adjust. Tested on x86_64 Fedora 20. gdb/ 2014-09-22 Pedro Alves <palves@redhat.com> * NEWS: Mention merge of "breakpoint always-inserted" modes "off" and "auto" merged. * breakpoint.c (enum ugll_insert_mode): New enum. (always_inserted_mode): Now a plain boolean. (show_always_inserted_mode): No longer handle AUTO_BOOLEAN_AUTO. (breakpoints_always_inserted_mode): Delete. (breakpoints_should_be_inserted_now): New function. (insert_breakpoints): Pass UGLL_INSERT to update_global_location_list instead of calling insert_breakpoint_locations manually. (create_solib_event_breakpoint_1): New, factored out from ... (create_solib_event_breakpoint): ... this. (create_and_insert_solib_event_breakpoint): Use create_solib_event_breakpoint_1 instead of calling insert_breakpoint_locations manually. (update_global_location_list): Change parameter type from boolean to enum ugll_insert_mode. All callers adjusted. Adjust to use breakpoints_should_be_inserted_now and handle UGLL_INSERT. (update_global_location_list_nothrow): Change parameter type from boolean to enum ugll_insert_mode. (_initialize_breakpoint): "breakpoint always-inserted" option is now a boolean command. Update help text. * breakpoint.h (breakpoints_always_inserted_mode): Delete declaration. (breakpoints_should_be_inserted_now): New declaration. * infrun.c (handle_inferior_event) <TARGET_WAITKIND_LOADED>: Remove breakpoints_always_inserted_mode check. (normal_stop): Adjust to use breakpoints_should_be_inserted_now. * remote.c (remote_start_remote): Likewise. gdb/doc/ 2014-09-22 Pedro Alves <palves@redhat.com> * gdb.texinfo (Set Breaks): Document that "set breakpoint always-inserted off" is the default mode now. Delete documentation of "set breakpoint always-inserted auto". gdb/testsuite/ 2014-09-22 Pedro Alves <palves@redhat.com> * gdb.threads/break-while-running.exp: New file. * gdb.threads/break-while-running.c: New file.
Diffstat (limited to 'gdb/NEWS')
-rw-r--r--gdb/NEWS7
1 files changed, 7 insertions, 0 deletions
diff --git a/gdb/NEWS b/gdb/NEWS
index 82ee57b..11326f1 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -33,6 +33,13 @@ queue-signal signal-name-or-number
confirmation if the program had stopped for a signal and the user
switched threads meanwhile.
+* "breakpoint always-inserted" modes "off" and "auto" merged.
+
+ Now, when 'breakpoint always-inserted mode' is set to "off", GDB
+ won't remove breakpoints from the target until all threads stop,
+ even in non-stop mode. The "auto" mode has been removed, and "off"
+ is now the default mode.
+
*** Changes in GDB 7.8
* New command line options