Make native gdbserver boards no longer be "remote" (in DejaGnu terms)

This commit finally clears the "isremote" flag in the native-gdbserver
and native-stdio-gdbserver boards.  The goal is to make all "native"
boards be considered not remote in DejaGnu terms, like the
native-extended-gdbserver board is too.

DejaGnu automatically considers boards remote if their names don't
match the local hostname.  That means that native-gdbserver and
native-extended-gdbserver are considered remote by default by DejaGnu,
even though they run locally.  native-extended-gdbserver, however,
overrides its isremote flag to force it to be not remote.  So we are
in that weird state where native-gdbserver is considered remote, and
native-extended-gdbserver is considered not remote.

A recent set of commits fixed all the problems (and some more) exposed
by testing with --target_board=native-gdbserver and
--target_board=native-stdio-gdbserver with isremote forced off on
x86-64 GNU/Linux.  I believe we're good to go now.

The native-stdio-gdbserver.exp/remote-stdio-gdbserver.exp boards
required deep non-obvious modifications unfortunately...  The problem
is that if a board is not remote, then DejaGnu doesn't call
${board}_spawn / ${board}_exec at all, and the
native-stdio-gdbserver.exp board relies on those procedures being
called.  To fix that, this commit redesigns how the stdio boards hook
into the testing framework to spawn gdbserver.  IMO, this is a good
change anyway, because the way its done currently is a bit of a hack,
and the result turns out to be simpler, even.  With this commit, they
now no longer load the "gdbserver" generic config, and hook at the
mi_gdb_target_load/gdb_reload level instead, making them more like
traditional board files.

To share code between native-stdio-gdbserver.exp and
remote-stdio-gdbserver.exp, a new shared stdio-gdbserver-base.exp file
is created.

Instead of having each native board clear isremote manually, boards
source the new "local-board.exp" file.

This also adds a new section to testsuite/README file discussing
local/remote/native, so that we can easily refer to it.

gdb/testsuite/ChangeLog:
2017-10-16  Pedro Alves  <palves@redhat.com>
	    Simon Marchi  <simon.marchi@polymtl.ca>

	* README (Local vs Remote vs Native): New section.
	* boards/local-board.exp: New file, with bits factored out from
	...
	* boards/native-extended-gdbserver.exp: ... here.  Load
	"local-board".
	* boards/native-gdbserver.exp: Load "local-board".
	(${board}_spawn, ${board}_exec): Delete.
	* boards/native-stdio-gdbserver.exp: Most contents factored out to
	...
	* boards/stdio-gdbserver-base.exp: ... this new file.
	* boards/native-stdio-gdbserver.exp: Reimplement, by loading
	"stdio-gdbserver-base" and defining a get_target_remote_pipe_cmd
	procedure.
	* boards/remote-stdio-gdbserver.exp: Load stdio-gdbserver-base
	instead of native-stdio-gdbserver.  Don't set gdb_server_prog nor
	stdio_gdbserver_command.
	(${board}_get_remote_address, ${board}_get_comm_port)
	(${board}_download, ${board}_upload): Delete.
	(get_target_remote_pipe_cmd): New.

6 files changed, 89 insertions, 124 deletions

diff --git a/gdb/testsuite/boards/local-board.exp b/gdb/testsuite/boards/local-board.exp
new file mode 100644
index 0000000000..0af454b70c
--- /dev/null
+++ b/gdb/testsuite/boards/local-board.exp
@@ -0,0 +1,24 @@
+# Copyright 2011-2017 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# By default, DejaGnu makes the board remote unless the board name
+# matches localhost.  Sourcing this script from a board file forces
+# the board to be NOT remote.
+
+global board
+global board_info
+# Remove any target variant specifications from the name.
+set baseboard [lindex [split $board "/"] 0]
+set board_info($baseboard,isremote) 0
diff --git a/gdb/testsuite/boards/native-extended-gdbserver.exp b/gdb/testsuite/boards/native-extended-gdbserver.exp
index 564ffd2229..cf0ea47aca 100644
--- a/gdb/testsuite/boards/native-extended-gdbserver.exp
+++ b/gdb/testsuite/boards/native-extended-gdbserver.exp
@@ -22,14 +22,7 @@
 
 load_generic_config "extended-gdbserver"
 load_board_description "gdbserver-base"
-
-# By default, dejagnu makes the board remote unless the board name
-# matches localhost.  Force it to be NOT remote.
-global board
-global board_info
-# Remove any target variant specifications from the name.
-set baseboard [lindex [split $board "/"] 0]
-set board_info($baseboard,isremote) 0
+load_board_description "local-board"
 
 set_board_info sockethost "localhost:"
 
diff --git a/gdb/testsuite/boards/native-gdbserver.exp b/gdb/testsuite/boards/native-gdbserver.exp
index e7c3d15e44..093289d068 100644
--- a/gdb/testsuite/boards/native-gdbserver.exp
+++ b/gdb/testsuite/boards/native-gdbserver.exp
@@ -22,6 +22,7 @@
 
 load_generic_config "gdbserver"
 load_board_description "gdbserver-base"
+load_board_description "local-board"
 
 # This gdbserver can only run a process once per session.
 set_board_info gdb,do_reload_on_run 1
@@ -35,27 +36,3 @@ set_board_info exit_is_reliable 1
 
 # We will be using the standard GDB remote protocol.
 set_board_info gdb_protocol "remote"
-
-proc ${board}_spawn { board cmd } {
-    global board_info
-
-    set baseboard [lindex [split $board "/"] 0]
-
-    set board_info($baseboard,isremote) 0
-    set result [remote_spawn $board $cmd]
-    set board_info($baseboard,isremote) 1
-
-    return $result
-}
-
-proc ${board}_exec { hostname program args } {
-    global board_info
-
-    set baseboard [lindex [split $hostname "/"] 0]
-
-    set board_info($baseboard,isremote) 0
-    set result [remote_exec $hostname $program $args]
-    set board_info($baseboard,isremote) 1
-
-    return $result
-}
diff --git a/gdb/testsuite/boards/native-stdio-gdbserver.exp b/gdb/testsuite/boards/native-stdio-gdbserver.exp
index 4ab5b28954..f8e7468bc0 100644
--- a/gdb/testsuite/boards/native-stdio-gdbserver.exp
+++ b/gdb/testsuite/boards/native-stdio-gdbserver.exp
@@ -20,70 +20,10 @@
 # bash$ cd ${build_dir}/gdb
 # bash$ make check RUNTESTFLAGS="--target_board=native-stdio-gdbserver"
 
-load_generic_config "gdbserver"
-load_board_description "gdbserver-base"
+load_board_description "stdio-gdbserver-base"
 
-# This gdbserver can only run a process once per session.
-set_board_info gdb,do_reload_on_run 1
-
-# There's no support for argument-passing (yet).
-set_board_info noargs 1
-
-# Hack the host,port to pass our peculiar remote connection string.
-set_board_info sockethost ""
-set_board_info gdb,socketport "stdio"
-set_board_info gdb,get_remote_address ${board}_get_remote_address
-set_board_info gdbserver,get_comm_port ${board}_get_comm_port
-
-set_board_info use_gdb_stub 1
-set_board_info exit_is_reliable 1
-
-# We will be using the standard GDB remote protocol.
-set_board_info gdb_protocol "remote"
-
-# Used to pass a value between ${board}_spawn and ${board}_get_remote_address.
-set stdio_gdbserver_command "--unset--"
-
-proc ${board}_get_remote_address { host port } {
-    global stdio_gdbserver_command
-    return "| $stdio_gdbserver_command"
-}
-
-proc ${board}_get_comm_port { port } {
-    return $port
-}
-
-proc ${board}_spawn { board cmd } {
-    global board_info
-
-    verbose -log "${board}_spawn: $board $cmd"
-
-    # Save the command to start gdbserver for later retrieval by
-    # ${board}_get_remote_address.
-    global stdio_gdbserver_command
-    set stdio_gdbserver_command $cmd
-
-    set baseboard [lindex [split $board "/"] 0]
-
-    # We don't spawn gdbserver here, that is done by the subsequent
-    # "target remote | ..." command.
-    set board_info($baseboard,isremote) 0
-    # Pretend as if we've started gdbserver, provide the test harness
-    # with what it's waiting for.
-    set result [remote_spawn $board "echo Listening on stdio"]
-    set board_info($baseboard,isremote) 1
-
-    return $result
-}
-
-proc ${board}_exec { hostname program args } {
-    global board_info
-
-    set baseboard [lindex [split $hostname "/"] 0]
-
-    set board_info($baseboard,isremote) 0
-    set result [remote_exec $hostname $program $args]
-    set board_info($baseboard,isremote) 1
-
-    return $result
+proc get_target_remote_pipe_cmd {} {
+    global last_loaded_file
+    set gdbserver [find_gdbserver]
+    return "$gdbserver --once stdio $last_loaded_file"
 }
diff --git a/gdb/testsuite/boards/remote-stdio-gdbserver.exp b/gdb/testsuite/boards/remote-stdio-gdbserver.exp
index 3d76829916..7570dfe0f4 100644
--- a/gdb/testsuite/boards/remote-stdio-gdbserver.exp
+++ b/gdb/testsuite/boards/remote-stdio-gdbserver.exp
@@ -24,7 +24,7 @@
 #    REMOTE_USERNAME=... REMOTE_HOSTNAME=... REMOTE_PORTNUM=... \
 #    [REMOTE_TMPDIR=${remote_dir}] [GDBSERVER=${remote_gdbserver}]"
 
-load_board_description "native-stdio-gdbserver"
+load_board_description "stdio-gdbserver-base"
 
 # Test machine info. The generic_config gdbserver reads some of these
 # values from board_info, so this file must set them there.
@@ -56,12 +56,6 @@ if [info exists REMOTE_TMPDIR] {
     set_board_info remotedir $REMOTE_TMPDIR
 }
 
-unset_board_info gdb_server_prog
-set_board_info gdb_server_prog "/usr/bin/gdbserver"
-
-# Used to pass a value between ${board}_spawn and ${board}_get_remote_address.
-set stdio_gdbserver_command "--unset--"
-
 proc get_remote_login { } {
     set result ""
     if {[board_info [target_info name] exists username]} {
@@ -73,27 +67,10 @@ proc get_remote_login { } {
     return $result
 }
 
-proc ${board}_get_remote_address { host port } {
-    global stdio_gdbserver_command
+proc get_target_remote_pipe_cmd { } {
+    set target_exec [gdbserver_download_current_prog]
     set rsh_cmd "[board_info [target_info name] rsh_prog] [get_remote_login]"
-    return "| $rsh_cmd $stdio_gdbserver_command"
-}
-
-proc ${board}_get_comm_port { port } {
-    return $port
-}
-
-proc ${board}_download { board host dest } {
-    if { [board_info [target_info name] exists remotedir] } {
-	set remotedir "[board_info [target_info name] remotedir]/"
-    } else {
-	set remotedir ""
-    }
-    return [standard_download $board $host "$remotedir$dest"]
-}
-
-proc ${board}_upload {dest srcfile args} {
-    return [standard_upload $dest $srcfile $args]
+    return "$rsh_cmd /usr/bin/gdbserver --once stdio $target_exec"
 }
 
 proc ${board}_file { dest op args } {
diff --git a/gdb/testsuite/boards/stdio-gdbserver-base.exp b/gdb/testsuite/boards/stdio-gdbserver-base.exp
new file mode 100644
index 0000000000..f3bf25c8eb
--- /dev/null
+++ b/gdb/testsuite/boards/stdio-gdbserver-base.exp
@@ -0,0 +1,54 @@
+# Copyright 2011-2017 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file has common bits shared between other dejagnu "board files"
+# that are used to run the testsuite with gdbserver connected via
+# stdio.  Boards that source this must reimplement the
+# get_target_remote_pipe_address procedure.
+
+load_board_description "gdbserver-base"
+
+# Note this is loaded for gdb_target_cmd, not for making this board
+# use the generic "gdbserver" config.
+load_lib gdbserver-support.exp
+
+# This gdbserver can only run a process once per session.
+set_board_info gdb,do_reload_on_run 1
+
+# There's no support for argument-passing (yet).
+set_board_info noargs 1
+
+set_board_info use_gdb_stub 1
+set_board_info exit_is_reliable 1
+
+# We will be using the standard GDB remote protocol.
+set_board_info gdb_protocol "remote"
+
+# Return the CMD string in "target remote | CMD".
+proc get_target_remote_pipe_cmd {} {
+    error "must reimplement this procedure"
+}
+
+proc make_gdbserver_stdio_port {} {
+    return "| [get_target_remote_pipe_cmd]"
+}
+
+proc gdb_reload { } {
+    return [gdb_target_cmd "remote" [make_gdbserver_stdio_port]]
+}
+
+proc mi_gdb_target_load { } {
+    return [mi_gdb_target_cmd "remote" [make_gdbserver_stdio_port]]
+}