[PATCH v3 0/5] Enable the user to dump all memory regions

[PATCH v3 0/5] Enable the user to dump all memory regions

[Sergio Lopez]

GDB versions prior to df8411da087dc05481926f4c4a82deabc5bc3859
unconditionally included all memory regions in the core dump.

After that change, while is still possible to ask GDB to ignore
/proc/PID/coredump_filter using the 'set use-coredump-filter' command,
there's no way to request it to dump regions marked with the VM_DONTDUMP
flag ("dd" in /proc/PID/smaps").

This patch series implement the new 'set dump-excluded-mappings' command
for GDB, and the "-a" argument for gcore, allowing the user to mimic the
behavior of previous GDB versions.

---

Changes since v2:
  - 1/5: Removed an empty line between command and definition of variable.
  - 5/5: Added a test case for 'set dump-excluded-mappings'.

Sergio Lopez (5):
  Implement 'set dump-excluded-mappings' command
  Document new {set,show} dump-excluded-mappings commands.
  Implement "-a" command line option for gcore
  Document the new "-a" command line option for gcore
  Extend gdb.core/coredump-filter.exp to test dump-excluded-mappings.

 gdb/NEWS                                   | 10 +++++++
 gdb/doc/gdb.texinfo                        | 21 +++++++++++--
 gdb/gcore.in                               | 47 +++++++++++++++++++-----------
 gdb/linux-tdep.c                           | 30 ++++++++++++++++++-
 gdb/testsuite/gdb.base/coredump-filter.exp | 46 +++++++++++++++++++++--------
 5 files changed, 122 insertions(+), 32 deletions(-)

-- 
2.14.3

[PATCH v3 3/5] Implement "-a" command line option for gcore

[Sergio Lopez]

With the new "-a" command line option, the user may request gcore to
actually dump all present memory mappings. The actual effect of this
argument is OS dependent.

On GNU/Linux, it will disable use-coredump-filter and enable
dump-excluded-mappings.

gdb/ChangeLog:
2017-11-29  Sergio Lopez  <slp@redhat.com>

	* gcore.in: Add "-a" command line option for instructing gdb to
	dump all memory mappings (OS dependent).
---
 gdb/gcore.in | 47 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 30 insertions(+), 17 deletions(-)

diff --git a/gdb/gcore.in b/gdb/gcore.in
index 632f21bdfa..44b2e98b27 100644
--- a/gdb/gcore.in
+++ b/gdb/gcore.in
@@ -20,27 +20,39 @@
 # It starts up gdb, attaches to the given PID and invokes the gcore command.
 #
 
-if [ "$#" -eq "0" ]
-then
-    echo "usage:  @GCORE_TRANSFORM_NAME@ [-o filename] pid"
-    exit 2
-fi
-
 # Need to check for -o option, but set default basename to "core".
 name=core
 
-if [ "$1" = "-o" ]
+# When the -a option is present, this may hold additional commands
+# to ensure gdb dumps all mappings (OS dependent).
+dump_all_cmds=()
+
+while getopts :ao: opt; do
+    case $opt in
+        a)
+            case $OSTYPE in
+                linux*)
+                    dump_all_cmds=("-ex" "set use-coredump-filter off")
+                    dump_all_cmds+=("-ex" "set dump-excluded-mappings on")
+                    ;;
+            esac
+            ;;
+        o)
+            name=$OPTARG
+            ;;
+        *)
+            echo "usage:  @GCORE_TRANSFORM_NAME@ [-a] [-o filename] pid"
+            exit 2
+            ;;
+    esac
+done
+
+shift $((OPTIND-1))
+
+if [ "$#" -eq "0" ]
 then
-    if [ "$#" -lt "3" ]
-    then
-	# Not enough arguments.
-	echo "usage:  @GCORE_TRANSFORM_NAME@ [-o filename] pid"
-	exit 2
-    fi
-    name=$2
-
-    # Shift over to start of pid list
-    shift; shift
+    echo "usage:  @GCORE_TRANSFORM_NAME@ [-a] [-o filename] pid"
+    exit 2
 fi
 
 # Attempt to fetch the absolute path to the gcore script that was
@@ -87,6 +99,7 @@ do
 	# available but not accessible as GDB would get stopped on SIGTTIN.
 	$binary_path/@GDB_TRANSFORM_NAME@ </dev/null --nx --batch \
 	    -ex "set pagination off" -ex "set height 0" -ex "set width 0" \
+	    "${dump_all_cmds[@]}" \
 	    -ex "attach $pid" -ex "gcore $name.$pid" -ex detach -ex quit
 
 	if [ -r $name.$pid ] ; then 
-- 
2.14.3

[PATCH v3 1/5] Implement 'set dump-excluded-mappings' command

[Sergio Lopez]

Commit df8411da087dc05481926f4c4a82deabc5bc3859 implemented support for
checking /proc/PID/coredump_filter, and also changed gcore behavior to
unconditionally honor the VM_DONTDUMP flag, preventing sections marked
as such for being dumped into the core file.

This patch implements the 'set dump-excluded-mappings' command for
instructing gdb to ignore the VM_DONTDUMP flag. Combined with 'set
use-coredump-filter', this allows the user to restore the old behavior,
dumping all sections (except the ones marked as IO) unconditionally.

gdb/Changelog:
2017-11-29  Sergio Lopez  <slp@redhat.com>

	* linux-tdep.c (dump_excluded_mappings): New variable.
	(dump_mapping_p): Use dump_excluded_mappings variable.
	(_initialize_linux_tdep): New command 'set dump_excluded_mappings'.
---
 gdb/linux-tdep.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index 24237b8d39..c8a8216c54 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -93,6 +93,11 @@ struct smaps_vmflags
 
 static int use_coredump_filter = 1;
 
+/* Whether the value of smaps_vmflags->exclude_coredump should be
+   ignored, including mappings marked with the VM_DONTDUMP flag in
+   the dump.  */
+static int dump_excluded_mappings = 0;
+
 /* This enum represents the signals' numbers on a generic architecture
    running the Linux kernel.  The definition of "generic" comes from
    the file <include/uapi/asm-generic/signal.h>, from the Linux kernel
@@ -655,7 +660,7 @@ dump_mapping_p (filter_flags filterflags, const struct smaps_vmflags *v,
 	return 0;
 
       /* Check if we should exclude this mapping.  */
-      if (v->exclude_coredump)
+      if (!dump_excluded_mappings && v->exclude_coredump)
 	return 0;
 
       /* Update our notion of whether this mapping is shared or
@@ -2469,6 +2474,17 @@ show_use_coredump_filter (struct ui_file *file, int from_tty,
 			    " corefiles is %s.\n"), value);
 }
 
+/* Display whether the gcore command is dumping mappings marked with
+   the VM_DONTDUMP flag.  */
+
+static void
+show_dump_excluded_mappings (struct ui_file *file, int from_tty,
+			     struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("Dumping of mappings marked with the VM_DONTDUMP"
+			    " flag is %s.\n"), value);
+}
+
 /* To be called from the various GDB_OSABI_LINUX handlers for the
    various GNU/Linux architectures and machine types.  */
 
@@ -2517,4 +2533,16 @@ of /proc/PID/coredump_filter when generating the corefile.  For more information
 about this file, refer to the manpage of core(5)."),
 			   NULL, show_use_coredump_filter,
 			   &setlist, &showlist);
+
+  add_setshow_boolean_cmd ("dump-excluded-mappings", class_files,
+			   &dump_excluded_mappings, _("\
+Set whether gcore should dump mappings marked with the VM_DONTDUMP flag."),
+			   _("\
+Show whether gcore should dump mappings marked with the VM_DONTDUMP flag."),
+			   _("\
+Use this command to set whether gcore should dump mappings marked with the\n\
+VM_DONTDUMP flag (\"dd\" in /proc/PID/smaps) when generating the corefile.  For\n\
+more information about this file, refer to the manpage of proc(5) and core(5)."),
+			   NULL, show_dump_excluded_mappings,
+			   &setlist, &showlist);
 }
-- 
2.14.3

[PATCH v3 2/5] Document new {set,show} dump-excluded-mappings commands.

[Sergio Lopez]

gdb/ChangeLog:
2017-11-29  Sergio Lopez  <slp@redhat.com>

	* NEWS (Changes since GDB 8.0): Announce {set,show}
	dump_excluded_mappings commands.

gdb/doc/ChangeLog:
2017-11-29  Sergio Lopez  <slp@redhat.com>

	* gdb.texinfo (gcore): Mention new {set,show}
	dump-excluded-mappings commands.
	(set dump-excluded-mappings): Document new command.
---
 gdb/NEWS            |  5 +++++
 gdb/doc/gdb.texinfo | 14 +++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 754ce103bd..1372552a37 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -134,6 +134,11 @@ set debug separate-debug-file
 show debug separate-debug-file
   Control the display of debug output about separate debug file search.
 
+set dump-excluded-mappings
+show dump-excluded-mappings
+  Control whether mappings marked with the VM_DONTDUMP flag should be
+  dumped when generating a core file.
+
 maint info selftests
   List the registered selftests.
 
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 675f6e7bc8..7b25912e49 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -11543,7 +11543,9 @@ this writing, @sc{gnu}/Linux, FreeBSD, Solaris, and S390).
 
 On @sc{gnu}/Linux, this command can take into account the value of the
 file @file{/proc/@var{pid}/coredump_filter} when generating the core
-dump (@pxref{set use-coredump-filter}).
+dump (@pxref{set use-coredump-filter}), and by default honors the
+@code{VM_DONTDUMP} flag for mappings where it is present in the file
+@file{/proc/@var{pid}/smaps} (@pxref{set dump-excluded-mappings}).
 
 @kindex set use-coredump-filter
 @anchor{set use-coredump-filter}
@@ -11573,6 +11575,16 @@ value is currently @code{0x33}, which means that bits @code{0}
 (anonymous private mappings), @code{1} (anonymous shared mappings),
 @code{4} (ELF headers) and @code{5} (private huge pages) are active.
 This will cause these memory mappings to be dumped automatically.
+
+@kindex set dump-excluded-mappings
+@anchor{set dump-excluded-mappings}
+@item set dump-excluded-mappings on
+@itemx set dump-excluded-mappings off
+If @code{on} is specified, @value{GDBN} will dump memory mappings
+marked with the @code{VM_DONTDUMP} flag.  This flag is represented in
+the file @file{/proc/@var{pid}/smaps} with the acronym @code{dd}.
+
+The default value is @code{off}.
 @end table
 
 @node Character Sets
-- 
2.14.3

[PATCH v3 4/5] Document the new "-a" command line option for gcore

[Sergio Lopez]

gdb/ChangeLog:
2017-11-29  Sergio Lopez  <slp@redhat.com>

	* NEWS (Changes since GDB 8.0): Announce new "-a"
	command line option for gcore.

gdb/doc/ChangeLog:
2017-11-29  Sergio Lopez  <slp@redhat.com>

	* gdb.texinfo (gcore man): Document new "-a" command line option.
---
 gdb/NEWS            | 5 +++++
 gdb/doc/gdb.texinfo | 7 ++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 1372552a37..ce84fe7924 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -52,6 +52,11 @@
 
   ** The "complete" command now mimics TAB completion accurately.
 
+* New command line options (gcore)
+
+-a
+  Dump all memory mappings.
+
 * Python Scripting
 
   ** New events gdb.new_inferior, gdb.inferior_deleted, and
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 7b25912e49..88d6820998 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -42948,7 +42948,7 @@ Richard M. Stallman and Roland H. Pesch, July 1991.
 
 @format
 @c man begin SYNOPSIS gcore
-gcore [-o @var{filename}] @var{pid}
+gcore [-a] [-o @var{filename}] @var{pid}
 @c man end
 @end format
 
@@ -42962,6 +42962,11 @@ running without any change.
 
 @c man begin OPTIONS gcore
 @table @env
+@item -a
+Dump all memory mappings.  The actual effect of this option depends on the
+Operating System.  On @sc{gnu}/Linux, it will disable
+@code{use-coredump-filter} and enable @code{dump-excluded-mappings}.
+
 @item -o @var{filename}
 The optional argument
 @var{filename} specifies the file name where to put the core dump.
-- 
2.14.3

[PATCH v3 5/5] Extend gdb.core/coredump-filter.exp to test dump-excluded-mappings.

[Sergio Lopez]

gdb/testsuite/ChangeLog:
2017-11-30  Sergio Lopez  <slp@redhat.com>

	* gdb.core/coredump-filter.exp: Extend test to verify
	the functionality of the dump-excluded-mappings command.
---
 gdb/testsuite/gdb.base/coredump-filter.exp | 46 ++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/gdb/testsuite/gdb.base/coredump-filter.exp b/gdb/testsuite/gdb.base/coredump-filter.exp
index f54164f75f..de2f22983f 100644
--- a/gdb/testsuite/gdb.base/coredump-filter.exp
+++ b/gdb/testsuite/gdb.base/coredump-filter.exp
@@ -33,16 +33,26 @@ if { ![runto_main] } {
 gdb_breakpoint [gdb_get_line_number "break-here"]
 gdb_continue_to_breakpoint "break-here" ".* break-here .*"
 
-proc do_save_core { filter_flag core } {
+proc do_save_core { filter_flag core dump_excluded } {
     verbose -log "writing $filter_flag to /proc/<inferior pid>/coredump_filter"
 
     gdb_test "p set_coredump_filter ($filter_flag)" " = 0"
 
+    # Enable dumping of excluded mappings (i.e. VM_DONTDUMP).
+    if { $dump_excluded == 1 } {
+        gdb_test_no_output "set dump-excluded-mappings on"
+    }
+
     # Generate a corefile.
     gdb_gcore_cmd "$core" "save corefile"
+
+    # Restore original status.
+    if { $dump_excluded == 1 } {
+        gdb_test_no_output "set dump-excluded-mappings off"
+    }
 }
 
-proc do_load_and_test_core { core var working_var working_value } {
+proc do_load_and_test_core { core var working_var working_value dump_excluded } {
     global hex decimal coredump_var_addr
 
     set core_loaded [gdb_core_cmd "$core" "load core"]
@@ -52,10 +62,16 @@ proc do_load_and_test_core { core var working_var working_value } {
     }
 
     # Access the memory the addresses point to.
-    gdb_test "print/x *(char *) $coredump_var_addr($var)" "\(\\\$$decimal = <error: \)?Cannot access memory at address $hex\(>\)?" \
-	"printing $var when core is loaded (should not work)"
-    gdb_test "print/x *(char *) $coredump_var_addr($working_var)" " = $working_value.*" \
-	"print/x *$working_var ( = $working_value)"
+    if { $dump_excluded == 0 } {
+        gdb_test "print/x *(char *) $coredump_var_addr($var)" "\(\\\$$decimal = <error: \)?Cannot access memory at address $hex\(>\)?" \
+	    "printing $var when core is loaded (should not work)"
+        gdb_test "print/x *(char *) $coredump_var_addr($working_var)" " = $working_value.*" \
+	    "print/x *$working_var ( = $working_value)"
+    } else {
+        # Check if VM_DONTDUMP mappings are present in the core file.
+        gdb_test "print/x *(char *) $coredump_var_addr($var)" " = $working_value.*" \
+	    "print/x *$var ( = $working_value)"
+    }
 }
 
 # We do not do file-backed mappings in the test program, but it is
@@ -107,6 +123,7 @@ set non_shared_anon_core [standard_output_file non-shared-anon.gcore]
 # A corefile without {private,shared} {anonymous,file-backed} pages
 set non_private_shared_anon_file_core [standard_output_file non-private-shared-anon-file.gcore]
 set dont_dump_core [standard_output_file dont-dump.gcore]
+set dump_excluded_core [standard_output_file dump-excluded.gcore]
 
 # We will generate a few corefiles.
 #
@@ -122,6 +139,8 @@ set dont_dump_core [standard_output_file dont-dump.gcore]
 # - name of a variable in the C source code that points to a memory
 #   mapping that WILL be present in the corefile
 # - corresponding value expected for the above variable
+# - whether to include mappings marked as VM_DONTDUMP in the
+#   corefile (1) or not (0).
 #
 # This list refers to the corefiles generated by MAP_ANONYMOUS in the
 # test program.
@@ -129,13 +148,16 @@ set dont_dump_core [standard_output_file dont-dump.gcore]
 set all_anon_corefiles { { "non-Private-Anonymous" "0x7e" \
 			       $non_private_anon_core \
 			       "private_anon" \
-			       "shared_anon" "0x22" }
+			       "shared_anon" "0x22" "0" }
     { "non-Shared-Anonymous" "0x7d" \
 	  $non_shared_anon_core "shared_anon" \
-	  "private_anon" "0x11" }
+	  "private_anon" "0x11" "0" }
     { "DoNotDump" "0x33" \
 	  $dont_dump_core "dont_dump" \
-	  "shared_anon" "0x22" } }
+	  "shared_anon" "0x22" "0" }
+    { "DoNotDump-DumpExcluded" "0x33" \
+	  $dump_excluded_core "dont_dump" \
+	  "shared_anon" "0x55" "1" } }
 
 # If corefile loading is not supported, we do not even try to run the
 # tests.
@@ -181,12 +203,12 @@ foreach item $all_anon_corefiles {
 # Generate corefiles for the "anon" case.
 foreach item $all_anon_corefiles {
     with_test_prefix "saving corefile for [lindex $item 0]" {
-	do_save_core [lindex $item 1] [subst [lindex $item 2]]
+	do_save_core [lindex $item 1] [subst [lindex $item 2]] [lindex $item 6]
     }
 }
 
 with_test_prefix "saving corefile for non-Private-Shared-Anon-File" {
-    do_save_core "0x60" $non_private_shared_anon_file_core
+    do_save_core "0x60" $non_private_shared_anon_file_core "0"
 }
 
 clean_restart $testfile
@@ -194,7 +216,7 @@ clean_restart $testfile
 foreach item $all_anon_corefiles {
     with_test_prefix "loading and testing corefile for [lindex $item 0]" {
 	do_load_and_test_core [subst [lindex $item 2]] [lindex $item 3] \
-	    [lindex $item 4] [lindex $item 5]
+	    [lindex $item 4] [lindex $item 5] [lindex $item 6]
     }
 
     with_test_prefix "disassembling function main for [lindex $item 0]" {
-- 
2.14.3

Re: [PATCH v3 0/5] Enable the user to dump all memory regions

[Pedro Alves]

On 12/04/2017 08:17 AM, Sergio Lopez wrote:
> GDB versions prior to df8411da087dc05481926f4c4a82deabc5bc3859
> unconditionally included all memory regions in the core dump.
> 
> After that change, while is still possible to ask GDB to ignore
> /proc/PID/coredump_filter using the 'set use-coredump-filter' command,
> there's no way to request it to dump regions marked with the VM_DONTDUMP
> flag ("dd" in /proc/PID/smaps").
> 
> This patch series implement the new 'set dump-excluded-mappings' command
> for GDB, and the "-a" argument for gcore, allowing the user to mimic the
> behavior of previous GDB versions.
> 
> ---
> 
> Changes since v2:
>   - 1/5: Removed an empty line between command and definition of variable.
>   - 5/5: Added a test case for 'set dump-excluded-mappings'.

Thanks!

This is OK.

Pedro Alves

Re: [PATCH v3 2/5] Document new {set,show} dump-excluded-mappings commands.

[Eli Zaretskii]

> From: Sergio Lopez <slp@redhat.com>
> Cc: Sergio Lopez <slp@redhat.com>
> Date: Mon,  4 Dec 2017 09:17:13 +0100
> 
> gdb/ChangeLog:
> 2017-11-29  Sergio Lopez  <slp@redhat.com>
> 
> 	* NEWS (Changes since GDB 8.0): Announce {set,show}
> 	dump_excluded_mappings commands.
> 
> gdb/doc/ChangeLog:
> 2017-11-29  Sergio Lopez  <slp@redhat.com>
> 
> 	* gdb.texinfo (gcore): Mention new {set,show}
> 	dump-excluded-mappings commands.
> 	(set dump-excluded-mappings): Document new command.

OK.

Re: [PATCH v3 4/5] Document the new "-a" command line option for gcore

[Eli Zaretskii]

> From: Sergio Lopez <slp@redhat.com>
> Cc: Sergio Lopez <slp@redhat.com>
> Date: Mon,  4 Dec 2017 09:17:15 +0100
> 
> gdb/ChangeLog:
> 2017-11-29  Sergio Lopez  <slp@redhat.com>
> 
> 	* NEWS (Changes since GDB 8.0): Announce new "-a"
> 	command line option for gcore.
> 
> gdb/doc/ChangeLog:
> 2017-11-29  Sergio Lopez  <slp@redhat.com>
> 
> 	* gdb.texinfo (gcore man): Document new "-a" command line option.

OK, but...

>  @c man begin OPTIONS gcore
>  @table @env
> +@item -a
> +Dump all memory mappings.  The actual effect of this option depends on the
> +Operating System.  On @sc{gnu}/Linux, it will disable
> +@code{use-coredump-filter} and enable @code{dump-excluded-mappings}.

...should we have a cross-reference here to where the above commands
are described?

Re: [PATCH v3 0/5] Enable the user to dump all memory regions

[Sergio Durigan Junior]

On Monday, December 04 2017, Pedro Alves wrote:

> On 12/04/2017 08:17 AM, Sergio Lopez wrote:
>> GDB versions prior to df8411da087dc05481926f4c4a82deabc5bc3859
>> unconditionally included all memory regions in the core dump.
>> 
>> After that change, while is still possible to ask GDB to ignore
>> /proc/PID/coredump_filter using the 'set use-coredump-filter' command,
>> there's no way to request it to dump regions marked with the VM_DONTDUMP
>> flag ("dd" in /proc/PID/smaps").
>> 
>> This patch series implement the new 'set dump-excluded-mappings' command
>> for GDB, and the "-a" argument for gcore, allowing the user to mimic the
>> behavior of previous GDB versions.
>> 
>> ---
>> 
>> Changes since v2:
>>   - 1/5: Removed an empty line between command and definition of variable.
>>   - 5/5: Added a test case for 'set dump-excluded-mappings'.
>
> Thanks!
>
> This is OK.

I pushed the patches for him (courtesy from Sergio to Sergio).

3e1a70a018 Extend gdb.core/coredump-filter.exp to test dump-excluded-mappings.
c179febe79 Document the new "-a" command line option for gcore
cd93789b89 Implement "-a" command line option for gcore
1e52e8495a Document new {set,show} dump-excluded-mappings commands.
afa840dcc0 Implement 'set dump-excluded-mappings' command

Thanks,

-- 
Sergio
GPG key ID: 237A 54B1 0287 28BF 00EF  31F4 D0EB 7628 65FC 5E36
Please send encrypted e-mail if possible
http://sergiodj.net/

Re: [PATCH v3 4/5] Document the new "-a" command line option for gcore

[Sergio Durigan Junior]

On Monday, December 04 2017, Eli Zaretskii wrote:

>> From: Sergio Lopez <slp@redhat.com>
>> Cc: Sergio Lopez <slp@redhat.com>
>> Date: Mon,  4 Dec 2017 09:17:15 +0100
>> 
>> gdb/ChangeLog:
>> 2017-11-29  Sergio Lopez  <slp@redhat.com>
>> 
>> 	* NEWS (Changes since GDB 8.0): Announce new "-a"
>> 	command line option for gcore.
>> 
>> gdb/doc/ChangeLog:
>> 2017-11-29  Sergio Lopez  <slp@redhat.com>
>> 
>> 	* gdb.texinfo (gcore man): Document new "-a" command line option.
>
> OK, but...
>
>>  @c man begin OPTIONS gcore
>>  @table @env
>> +@item -a
>> +Dump all memory mappings.  The actual effect of this option depends on the
>> +Operating System.  On @sc{gnu}/Linux, it will disable
>> +@code{use-coredump-filter} and enable @code{dump-excluded-mappings}.
>
> ...should we have a cross-reference here to where the above commands
> are described?

Pedro approved the patches and I pushed them for Sergio.  I also took
the liberty to address Eli's comment before applying the patches.
here's the diff against Sergio's original patch.

Thanks,

-- 
Sergio
GPG key ID: 237A 54B1 0287 28BF 00EF  31F4 D0EB 7628 65FC 5E36
Please send encrypted e-mail if possible
http://sergiodj.net/

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 1c383b4d47..3b251c60c1 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -43063,9 +43063,11 @@ running without any change.
 @c man begin OPTIONS gcore
 @table @env
 @item -a
-Dump all memory mappings.  The actual effect of this option depends on the
-Operating System.  On @sc{gnu}/Linux, it will disable
-@code{use-coredump-filter} and enable @code{dump-excluded-mappings}.
+Dump all memory mappings.  The actual effect of this option depends on
+the Operating System.  On @sc{gnu}/Linux, it will disable
+@code{use-coredump-filter} (@pxref{set use-coredump-filter}) and
+enable @code{dump-excluded-mappings} (@pxref{set
+dump-excluded-mappings}).
 
 @item -o @var{filename}
 The optional argument