Fixes for the magic number used in PDP11 AOUT binaries.

	PR ld/25677
include	* aout/aout64.h (N_DATADDR): Add IMAGIC case.

bfd	* pdp11.c: Add implementation of --imagic option.
	(adjust_o_magic): Fix objcopy --extract-symbol test.
	* libaout.h (enum aout_magic): Add i_magic.

ld	* emulparams/pdp11.sh (SCRIPT_NAME): Change to pdp11.
	(EXTRA_EM_FILE): New, add emulation file pdp11.
	* scripttempl/pdp11.sc: New, derived from aout.sc without
	irrelevant input sections.
	* emultempl/pdp11.em (_add_options, _handle_option)
	(_list_options): New. Add options -z, --imagic for pdp11-aout.
	(_before_parse): Make --omagic be default instead of --nmagic.
	(_get_script): Modify special-case linker script for --imagic.
	* lexsup.c (parse_args): Explictly set config.text_read_only for -n.
	* ld.texi (Options): Add documentation of PDP11-specific options.
	(Options): Fix unrelated typo to --no-compact-branches.
	* gen-doc.texi: @set PDP11.
	* testsuite/ld-pdp11/pdp11.exp: New, start pdp11 testing.
	* testsuite/ld-pdp11/sections.s: New, source for options tests.
	* testsuite/ld-pdp11/imagic.d: New, test --imagic format.
	* testsuite/ld-pdp11/imagicz.d: New, test -z (imagic) format.
	* testsuite/ld-pdp11/nmagic.d: New, test --nmagic format.
	* testsuite/ld-pdp11/omagic.d: New, test --omagic format.

6 files changed, 93 insertions, 0 deletions

diff --git a/ld/testsuite/ld-pdp11/imagic.d b/ld/testsuite/ld-pdp11/imagic.d
new file mode 100644
index 00000000000..2e1566c2466
--- /dev/null
+++ b/ld/testsuite/ld-pdp11/imagic.d
@@ -0,0 +1,12 @@
+#name: pdp11-aout imagic format
+# nm sort alphabetically since both _start and _data are 0
+#source: sections.s
+#ld: --imagic
+#DUMPPROG: nm
+#...
+0+2 B _bss
+#...
+0+0 D _data
+#...
+0+0 T _start
+#pass
diff --git a/ld/testsuite/ld-pdp11/imagicz.d b/ld/testsuite/ld-pdp11/imagicz.d
new file mode 100644
index 00000000000..38a11b46171
--- /dev/null
+++ b/ld/testsuite/ld-pdp11/imagicz.d
@@ -0,0 +1,12 @@
+#name: pdp11-aout imagic format -z
+# nm sort alphabetically since both _start and _data are 0
+#source: sections.s
+#ld: -z
+#DUMPPROG: nm
+#...
+0+2 B _bss
+#...
+0+0 D _data
+#...
+0+0 T _start
+#pass
diff --git a/ld/testsuite/ld-pdp11/nmagic.d b/ld/testsuite/ld-pdp11/nmagic.d
new file mode 100644
index 00000000000..acdae245340
--- /dev/null
+++ b/ld/testsuite/ld-pdp11/nmagic.d
@@ -0,0 +1,11 @@
+#name: pdp11-aout nmagic format
+#source: sections.s
+#ld: --nmagic
+#nm: -n
+#...
+0+0 T _start
+#...
+0*2000 D _data
+#...
+0*2002 B _bss
+#pass
diff --git a/ld/testsuite/ld-pdp11/omagic.d b/ld/testsuite/ld-pdp11/omagic.d
new file mode 100644
index 00000000000..ed3a4233d2a
--- /dev/null
+++ b/ld/testsuite/ld-pdp11/omagic.d
@@ -0,0 +1,12 @@
+#name: pdp11-aout omagic format
+# also testing that --omagic is the default
+#source: sections.s
+#ld:
+#nm: -n
+#...
+0+0 T _start
+#...
+0+6 D _data
+#...
+0+8 B _bss
+#pass
diff --git a/ld/testsuite/ld-pdp11/pdp11.exp b/ld/testsuite/ld-pdp11/pdp11.exp
new file mode 100644
index 00000000000..90c82df19a8
--- /dev/null
+++ b/ld/testsuite/ld-pdp11/pdp11.exp
@@ -0,0 +1,33 @@
+# Expect script for ld-pdp11 tests
+#   Copyright (C) 2016-2020 Free Software Foundation, Inc.
+#
+# This file is part of the GNU Binutils.
+#
+# 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, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+# MA 02110-1301, USA.
+#
+
+# Test pdp11 linking; at this point just the options for the three
+# a.out format variants.
+
+if ![istarget "pdp11-*-*"] then {
+    return
+}
+
+set pdp11_test_list [lsort [glob -nocomplain $srcdir/$subdir/*.d]]
+foreach pdp11_test $pdp11_test_list {
+    verbose [file rootname $pdp11_test]
+    run_dump_test [file rootname $pdp11_test]
+}
diff --git a/ld/testsuite/ld-pdp11/sections.s b/ld/testsuite/ld-pdp11/sections.s
new file mode 100644
index 00000000000..c6e40a07c60
--- /dev/null
+++ b/ld/testsuite/ld-pdp11/sections.s
@@ -0,0 +1,13 @@
+	.globl	_start
+	.text
+_start:
+	mov	_data,_bss
+	.globl	_data
+	.data
+_data:
+	.word	1
+	.globl	_bss
+	.bss
+_bss:
+	.=.+2
+	.end