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Re: [PATCH v2 2/3] gdb: New maintenance command to disable bfd sharing.
- From: Pedro Alves <palves at redhat dot com>
- To: Andrew Burgess <andrew dot burgess at embecosm dot com>, gdb-patches at sourceware dot org
- Date: Mon, 17 Aug 2015 18:34:28 +0100
- Subject: Re: [PATCH v2 2/3] gdb: New maintenance command to disable bfd sharing.
- Authentication-results: sourceware.org; auth=none
- References: <cover dot 1439454669 dot git dot andrew dot burgess at embecosm dot com> <77dce5f054bd1f7be0f87fe36c5d7e4acdef7c9b dot 1439454670 dot git dot andrew dot burgess at embecosm dot com>
On 08/13/2015 01:44 PM, Andrew Burgess wrote:
> In some rare maintainer cases it is desirable to be able to disable bfd
> sharing. This patch adds new commands maintenance set/show commands for
> bfd-sharing, allowing gdb's bfd cache to be turned off.
> * Support for process record-replay and reverse debugging on aarch64*-linux*
> diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
> index 846ac24..9d553db 100644
> --- a/gdb/doc/ChangeLog
> +++ b/gdb/doc/ChangeLog
> @@ -1,3 +1,10 @@
> +2015-08-11 Andrew Burgess <andrew.burgess@embecosm.com>
> +
> + * gdb.texinfo (Maintenance Commands): Move documentation of "main
> + info bfds" to...
> + (File Caching): A New section. Outline bfd caching, and add new
> + description for "main set/show bfd-sharing".
> +
> 2015-08-07 Pedro Alves <palves@redhat.com>
>
> * gdb.texinfo (Maintenance Commands): Document "maint set/show
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 900970b..3cfb1a7 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -18190,6 +18190,36 @@ Set whether a source file may have multiple base names.
> Show whether a source file may have multiple base names.
> @end table
>
> +@node File Caching
> +@section File Caching
> +@cindex caching of opened files
> +@cindex caching of bfd objects
> +
> +To speed up file loading, and reduce memory usage, @value{GDBN} will
> +reuse the @code{bfd} objects used to track open files. @xref{Top, ,
> +BFD, bfd, The Binary File Descriptor Library}. The following commands
> +allow visibility and control of the caching beaviour.
typo "beaviour". (While at it, I think the manual is meant to
standardize on USA spelling, thus "behavior".)
> +
> +@table @code
> +@kindex maint info bfds
> +@item maint info bfds
> +This prints information about each @code{bfd} object that is known to
> +@value{GDBN}.
> +
> +@kindex maint set bfd-sharing
> +@kindex maint show bfd-sharing
> +@kindex bfd caching
> +@item maint set bfd-sharing
> +@item maint show bfd-sharing
> +Control whether @code{bfd} objects can be shared. When sharing is
> +enabled @value{GDBN} will reuse already open @code{bfd} objects rather
I believe present tense is preferred in the manual, like:
s/will reuse/reuses/
> +than reopening the same file. Turning sharing off does not cause
> +already shared @code{bfd} objects to be unshared, but all future files
> +that are opened will create a new @code{bfd} object. Similarly,
> +re-enabling sharing will not cause multiple existing @code{bfd}
...re-enabling sharing does not cause...
> +objects to be collapsed into a single shared @code{bfd} object.
> +@end table
> +
> @node Separate Debug Files
> @section Debugging Information in Separate Files
> @cindex separate debugging information files
> @@ -33987,11 +34017,6 @@ Shared library events.
> @@ -111,6 +111,11 @@ DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR)
>
> static htab_t gdb_bfd_cache;
>
> +/* When true gdb will reuse an existing bfd object if the filename,
> + modification time, and file size all match. */
> +
> +static int bfd_sharing;
Initialize it here? Like:
static int bfd_sharing = 1;
> gdb_bfd_ref (abfd);
> return abfd;
> @@ -942,4 +950,17 @@ _initialize_gdb_bfd (void)
> add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\
> List the BFDs that are currently open."),
> &maintenanceinfolist);
> +
> + add_setshow_boolean_cmd ("bfd-sharing", no_class,
> + &bfd_sharing, _("\
> +Set whether gdb will share bfds that appear to be the same file."), _("\
> +Show whether gdb will share bfds that appear to be the same file."), _("\
> +When enabled gdb will reuse existing bfds rather than reopening the\n\
> +same file. To decide if two files are the same then gdb compares the\n\
> +filename, file size, file modification time, and file inode."),
> + NULL,
> + NULL,
Please add a show hook, for i18n.
> + &maintenance_set_cmdlist,
> + &maintenance_show_cmdlist);
> + bfd_sharing = 1;
See above.
> }
>
Otherwise LGTM.
Thanks,
Pedro Alves