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Re: [PATCH, v2] Add command to erase all flash memory regions

On 01/10/2017 12:22 PM, Pedro Alves wrote:
On 01/09/2017 07:04 PM, Luis Machado wrote:
Changes in v2:

- Added NEWS entry.
- Fixed long lines.
- Address printing with paddress.

Years ago we contributed flash programming patches upstream.  The following
patch is a leftover one that complements that functionality by adding a new
command to erase all reported flash memory blocks.

The command is most useful when we're dealing with flash-enabled targets
(mostly bare-metal) and we need to reset the board for some reason.

The wiping out of flash memory regions should help the target come up with a
known clean state from which the user can load a new image and resume
debugging. It is convenient enough to do this from the debugger, and there is
also an MI command to expose this functionality to the IDE's.

Regression tested on Ubuntu 16.04 x86-64. No regressions.



2017-01-09  Mike Wrighton  <>
	    Luis Machado  <>

	* gdb.texinfo (-target-flash-erase): New MI command description.
	(flash-erase): New CLI command description.


2017-01-09  Mike Wrighton  <>
	    Luis Machado  <>

	* NEWS (New commands): Mention flash-erase.
	(New MI commands): Mention target-flash-erase.
	* mi/mi-cmds.c (mi_cmd_target_flash_erase): Added target-flash-erase MI
	* mi/mi-cmds.h (mi_cmd_target_flash_erase): New declaration.
	* mi/mi-main.c (mi_cmd_target_flash_erase): New function.
	* target-memory.c: Include "memattr.h" and "ui-out.h".
	* target.c (flash_erase_all_command): New function.
	(initialize_targets): Add new flash-erase command.
	* target.h (flash_erase_all_command): New declaration.
 gdb/NEWS            | 11 +++++++++++
 gdb/doc/gdb.texinfo | 32 ++++++++++++++++++++++++++++++++
 gdb/mi/mi-cmds.c    |  1 +
 gdb/mi/mi-cmds.h    |  1 +
 gdb/mi/mi-main.c    |  5 +++++
 gdb/target.c        | 45 +++++++++++++++++++++++++++++++++++++++++++++
 gdb/target.h        |  3 +++
 7 files changed, 98 insertions(+)

diff --git a/gdb/NEWS b/gdb/NEWS
index b976815..4d9effa 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -57,6 +57,17 @@ FreeBSD/mips			mips*-*-freebsd
 Synopsys ARC			arc*-*-elf32
 FreeBSD/mips			mips*-*-freebsd

+* New commands
+  Erases all the flash memory regions reported by the target.
+* New MI commands
+  Erases all the flash memory regions reported by the target.  This is
+  equivalent to the CLI command flash-erase.
 *** Changes in GDB 7.12

 * GDB and GDBserver now build with a C++ compiler by default.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 14628fa..24d6cf7 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -19626,6 +19626,16 @@ load programs into flash memory.
 @code{load} does not repeat if you press @key{RET} again after using it.
 @end table

+@table @code
+@kindex flash-erase
+@item flash-erase
+Erases all known flash memory regions on the target.
+@end table
 @node Byte Order
 @section Choosing Target Byte Order

@@ -31863,6 +31873,28 @@ No equivalent.
 @subsubheading Example

+@subheading The @code{-target-flash-erase} Command
+@findex -target-flash-erase
+@subsubheading Synopsis
+ -target-flash-erase
+@end smallexample
+Erases all known flash memory regions on the target.
+The corresponding @value{GDBN} command is @samp{flash-erase}.
+The output is a list of flash regions that have been erased, sorted by

Are they really sorted by size?

+@end smallexample

 @subheading The @code{-target-select} Command
 @findex -target-select
diff --git a/gdb/mi/mi-cmds.c b/gdb/mi/mi-cmds.c
index cdea008..abb70bd 100644
--- a/gdb/mi/mi-cmds.c
+++ b/gdb/mi/mi-cmds.c
@@ -147,6 +147,7 @@ static struct mi_cmd mi_cmds[] =
   DEF_MI_CMD_MI ("target-file-delete", mi_cmd_target_file_delete),
   DEF_MI_CMD_MI ("target-file-get", mi_cmd_target_file_get),
   DEF_MI_CMD_MI ("target-file-put", mi_cmd_target_file_put),
+  DEF_MI_CMD_MI ("target-flash-erase", mi_cmd_target_flash_erase),
   DEF_MI_CMD_CLI ("target-select", "target", 1),
   DEF_MI_CMD_MI ("thread-info", mi_cmd_thread_info),
   DEF_MI_CMD_MI ("thread-list-ids", mi_cmd_thread_list_ids),
diff --git a/gdb/mi/mi-cmds.h b/gdb/mi/mi-cmds.h
index 8bd947b..d0906e6 100644
--- a/gdb/mi/mi-cmds.h
+++ b/gdb/mi/mi-cmds.h
@@ -93,6 +93,7 @@ extern mi_cmd_argv_ftype mi_cmd_target_detach;
 extern mi_cmd_argv_ftype mi_cmd_target_file_get;
 extern mi_cmd_argv_ftype mi_cmd_target_file_put;
 extern mi_cmd_argv_ftype mi_cmd_target_file_delete;
+extern mi_cmd_argv_ftype mi_cmd_target_flash_erase;
 extern mi_cmd_argv_ftype mi_cmd_thread_info;
 extern mi_cmd_argv_ftype mi_cmd_thread_list_ids;
 extern mi_cmd_argv_ftype mi_cmd_thread_select;
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index 22803cb..e432a01 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -552,6 +552,11 @@ mi_cmd_target_detach (char *command, char **argv, int argc)
   detach_command (NULL, 0);

+void mi_cmd_target_flash_erase (char *command, char **argv, int argc)

Like break after void.

+  flash_erase_all_command (NULL, 0);
 mi_cmd_thread_select (char *command, char **argv, int argc)
diff --git a/gdb/target.c b/gdb/target.c
index be7367c..02e80d2 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -3943,6 +3943,48 @@ do_monitor_command (char *cmd,
   target_rcmd (cmd, gdb_stdtarg);

+flash_erase_all_command (char *cmd, int from_tty)


+  int i;
+  int found_flash_region = 0;

Use bool.  Add comment explaining why we need it?

+  struct mem_region *m;
+  struct mem_attrib *attrib;
+  struct cleanup *cleanup_tuple;
+  struct gdbarch *gdbarch = target_gdbarch ();

And move all these to the scope that needs them.  Maybe
even declare them on first use.

+  VEC(mem_region_s) * mem_regions = target_memory_map ();
+  /* Iterate over all memory regions.  */
+  for (i = 0; VEC_iterate (mem_region_s, mem_regions, i, m); i++)
+    {
+      attrib = &m->attrib;
+      /* Is this a flash memory region?  */
+      if (attrib->mode == MEM_FLASH)
+        {
+          found_flash_region = 1;
+          target_flash_erase (m->lo, m->hi - m->lo);
+          cleanup_tuple =

= goes on next line.

+	      make_cleanup_ui_out_tuple_begin_end (current_uiout,
+						   "erasing-regions");
+          current_uiout->message ("Erasing flash memory region at address ");
+          current_uiout->field_fmt ("address", "%s", paddress (gdbarch,
+								 m->lo));
+          current_uiout->message (", size = ");
+          current_uiout->field_fmt ("size", "%lu",
+				    (unsigned long) (m->hi - m->lo));

Pedantically, long is the wrong type to use, since it'll be 32-bit
on 64-bit Windows.  Use pulongest?

I've used phex now. I agree it is more appropriate. I've updated the documentation as well.

Addressed the other comments locally as well.

+          current_uiout->message ("\n");
+          do_cleanups (cleanup_tuple);
+        }
+    }
+  if (found_flash_region)
+    target_flash_done ();

I was wondering how this is supposed to work if the command
is interrupted w/ ctrl-c midway.  If the command is interrupted before
sending the vFlashDone RSP command, then it seems to me that the stub
is doing to get confused, since it seems there's no RSP command to
mean "I'm starting a batch of flash operations from scratch, forget
any stale list of pending vFlashWrite/vFlashErase ops you may have.
Am I missing something that prevents that from happening?

Yeah, that scenario can indeed happen if one interrupts the flash programming midway. It is a bit of an oversight in the design of this functionality i think.

The target stub, as it is today, will not be too confused about this. The memory regions will be appended to a list and the stub will wait for the vFlashDone packet to commit the changes.

The way the commit process is implemented will attempt to combine writes/deletions in a single operation. So, in the worst case, the stub will only execute these operations next time it sees vFlashDone.

Not ideal, but it is how it works nowadays.

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