[PATCH v2 1/3] gdb: add inferior_cloned observable

[PATCH v2 1/3] gdb: add inferior_cloned observable

[Simon Marchi]

The following patch makes the amdgpu port transfer a property from the
original inferior to the new inferior when using the clone-inferior
command.  Add the inferior_cloned observable to help with this.

Change-Id: Id845a799813ec49b1b7b2fcb97b07d0a1e5e2631
Approved-By: Tom Tromey <tom@tromey.com>
---
 gdb/inferior.c   | 2 ++
 gdb/observable.c | 1 +
 gdb/observable.h | 4 ++++
 3 files changed, 7 insertions(+)

diff --git a/gdb/inferior.c b/gdb/inferior.c
index ce4960a508aa..550bbd2827c0 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -1041,6 +1041,8 @@ clone_inferior_command (const char *args, int from_tty)
       for (const std::string &unset_var
 	   : orginf->environment.user_unset_env ())
 	inf->environment.unset (unset_var.c_str ());
+
+      gdb::observers::inferior_cloned.notify (orginf, inf);
     }
 }
 
diff --git a/gdb/observable.c b/gdb/observable.c
index a18b863fb471..33e51223cf41 100644
--- a/gdb/observable.c
+++ b/gdb/observable.c
@@ -58,6 +58,7 @@ DEFINE_OBSERVABLE (inferior_appeared);
 DEFINE_OBSERVABLE (inferior_pre_detach);
 DEFINE_OBSERVABLE (inferior_exit);
 DEFINE_OBSERVABLE (inferior_removed);
+DEFINE_OBSERVABLE (inferior_cloned);
 DEFINE_OBSERVABLE (memory_changed);
 DEFINE_OBSERVABLE (before_prompt);
 DEFINE_OBSERVABLE (gdb_datadir_changed);
diff --git a/gdb/observable.h b/gdb/observable.h
index c0bafc51f143..4ea203c6fc38 100644
--- a/gdb/observable.h
+++ b/gdb/observable.h
@@ -172,6 +172,10 @@ extern observable<struct inferior */* inf */> inferior_exit;
    This method is called immediately before freeing INF.  */
 extern observable<struct inferior */* inf */> inferior_removed;
 
+/* The inferior CLONE has been created by cloning INF.  */
+extern observable<struct inferior */* inf */, struct inferior */* clone */>
+    inferior_cloned;
+
 /* Bytes from DATA to DATA + LEN have been written to the inferior
    at ADDR.  */
 extern observable<struct inferior */* inferior */, CORE_ADDR /* addr */,

base-commit: d7680f13df105aa8fa0edbdf8efae31a5411f579
-- 
2.42.0

[PATCH v2 2/3] gdb/testsuite: add linux target check in allow_hipcc_tests

[Simon Marchi]

ROCm / HIP tests should only run on Linux for now, existing gdb.rocm
tests miss such a check.  Add an "istarget linux" check in
allow_hipcc_tests.

Change-Id: I71f69e510a754f2fdadc32de53b923ebb9835ab5
---
 gdb/testsuite/lib/rocm.exp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/gdb/testsuite/lib/rocm.exp b/gdb/testsuite/lib/rocm.exp
index 98a3b308228d..791f1b403bb7 100644
--- a/gdb/testsuite/lib/rocm.exp
+++ b/gdb/testsuite/lib/rocm.exp
@@ -67,6 +67,10 @@ gdb_caching_proc allow_hipcc_tests {} {
 	return {0 "remote debugging"}
     }
 
+    if {![istarget "*-linux*"]} {
+	return {0 "target platform is not Linux"}
+    }
+
     # Ensure that GDB is built with amd-dbgapi support.
     set output [remote_exec host $::GDB "$::INTERNAL_GDBFLAGS --configuration"]
     if { [string first "--with-amd-dbgapi" $output] == -1 } {
-- 
2.42.0

[PATCH v2 3/3] gdb/amdgpu: add precise-memory support

[Simon Marchi]

New in v2, address Lancelot's feedback:

 - factor out some code in try_set_process_memory_precision
 - Add missing _(...)
 - Fix parameter name in doc
 - Remove linux target check in test
 - Use new kernel launch syntax in tests
 - Don't introduce hcc_amdgpu_target, use existing hcc_amdgpu_targets
 - Minor formatting changes

The amd-dbgapi library exposes a setting called "memory precision" for
AMD GPUs [1].  Here's a copy of the description of the setting:

    The AMD GPU can overlap the execution of memory instructions with other
    instructions.  This can result in a wave stopping due to a memory violation
    or hardware data watchpoint hit with a program counter beyond the
    instruction that caused the wave to stop.

    Some architectures allow the hardware to be configured to always wait for
    memory operations to complete before continuing.  This will result in the
    wave stopping at the instruction immediately after the one that caused the
    stop event.  Enabling this mode can make execution of waves significantly
    slower.

Expose this option through a new "amdgpu precise-memory" setting.

The precise memory setting is per inferior.  The setting is transferred
from one inferior to another when using the clone-inferior command, or
when a new inferior is created following an exec or a fork.

It can be set before starting the inferior, in which case GDB will
attempt to apply what the user wants when attaching amd-dbgapi.  If the
user has requested to enable precise memory, but it can't be enabled
(not all hardware supports it), GDB prints a warning.

If precise memory is disabled, GDB prints a warning when hitting a
memory exception (translated into GDB_SIGNAL_SEGV or GDB_SIGNAL_BUS),
saying that the stop location may not be precise.

Note that the precise memory setting also affects memory watchpoint
reporting, but the watchpoint support for AMD GPUs hasn't been
upstreamed to GDB yet.  When we do upstream watchpoint support, GDB will
produce a similar warning message when stopping due to a watchpoint if
precise memory is disabled.

Add a handful of tests.  Add a util proc
"hip_devices_support_precise_memory", which indicates if all devices
used for testing support that feature.

[1] https://github.com/ROCm-Developer-Tools/ROCdbgapi/blob/687374258a27b5aab1309a7e8ded719e2f1ed3b1/include/amd-dbgapi.h.in#L6300-L6317

Change-Id: Ife1a99c0e960513da375ced8f8afaf8e47a61b3f
---
 gdb/amd-dbgapi-target.c                       | 173 +++++++++++++++++-
 gdb/doc/gdb.texinfo                           |  43 +++++
 gdb/testsuite/gdb.rocm/precise-memory-exec.c  |  44 +++++
 .../gdb.rocm/precise-memory-exec.exp          |  58 ++++++
 gdb/testsuite/gdb.rocm/precise-memory-fork.c  |  41 +++++
 .../gdb.rocm/precise-memory-fork.exp          |  50 +++++
 .../precise-memory-multi-inferiors.exp        |  87 +++++++++
 .../precise-memory-warning-sigsegv.cpp        |  33 ++++
 .../precise-memory-warning-sigsegv.exp        |  45 +++++
 gdb/testsuite/gdb.rocm/precise-memory.cpp     |  32 ++++
 gdb/testsuite/gdb.rocm/precise-memory.exp     |  57 ++++++
 gdb/testsuite/lib/rocm.exp                    |  19 ++
 12 files changed, 677 insertions(+), 5 deletions(-)
 create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-exec.c
 create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-exec.exp
 create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-fork.c
 create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-fork.exp
 create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-multi-inferiors.exp
 create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.cpp
 create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.exp
 create mode 100644 gdb/testsuite/gdb.rocm/precise-memory.cpp
 create mode 100644 gdb/testsuite/gdb.rocm/precise-memory.exp

diff --git a/gdb/amd-dbgapi-target.c b/gdb/amd-dbgapi-target.c
index 22c269b7992c..d38b790f53f7 100644
--- a/gdb/amd-dbgapi-target.c
+++ b/gdb/amd-dbgapi-target.c
@@ -23,6 +23,7 @@
 #include "amdgpu-tdep.h"
 #include "async-event.h"
 #include "cli/cli-cmds.h"
+#include "cli/cli-decode.h"
 #include "cli/cli-style.h"
 #include "inf-loop.h"
 #include "inferior.h"
@@ -139,6 +140,17 @@ struct amd_dbgapi_inferior_info
      Initialized to true, since that's the default in amd-dbgapi too.  */
   bool forward_progress_required = true;
 
+  struct
+  {
+    /* Whether precise memory reporting is requested.  */
+    bool requested = false;
+
+    /* Whether precise memory was requested and successfully enabled by
+       dbgapi (it may not be available for the current hardware, for
+       instance).  */
+    bool enabled = false;
+  } precise_memory;
+
   std::unordered_map<decltype (amd_dbgapi_breakpoint_id_t::handle),
 		     struct breakpoint *>
     breakpoint_map;
@@ -1326,6 +1338,29 @@ amd_dbgapi_target::stopped_by_hw_breakpoint ()
   return false;
 }
 
+/* Try to set the process's memory access reporting precision mode.
+
+   Warn if the requested mode is not supported on at least one agent in the
+   process.
+
+   Error out if setting the requested mode failed for some other reason.  */
+
+static void
+try_set_process_memory_precision (amd_dbgapi_inferior_info &info)
+{
+  auto mode = (info.precise_memory.requested
+	       ? AMD_DBGAPI_MEMORY_PRECISION_PRECISE
+	       : AMD_DBGAPI_MEMORY_PRECISION_NONE);
+  amd_dbgapi_status_t status
+    = amd_dbgapi_set_memory_precision (info.process_id, mode);
+
+  if (status == AMD_DBGAPI_STATUS_ERROR_NOT_SUPPORTED)
+    warning (_("AMDGPU precise memory access reporting could not be enabled."));
+  else if (status != AMD_DBGAPI_STATUS_SUCCESS)
+    error (_("amd_dbgapi_set_memory_precision failed (%s)"),
+	   get_status_string (status));
+}
+
 /* Make the amd-dbgapi library attach to the process behind INF.
 
    Note that this is unrelated to the "attach" GDB concept / command.
@@ -1399,6 +1434,8 @@ attach_amd_dbgapi (inferior *inf)
   amd_dbgapi_debug_printf ("process_id = %" PRIu64 ", notifier fd = %d",
 			   info->process_id.handle, info->notifier);
 
+  try_set_process_memory_precision (*info);
+
   /* If GDB is attaching to a process that has the runtime loaded, there will
      already be a "runtime loaded" event available.  Consume it and push the
      target.  */
@@ -1443,8 +1480,10 @@ detach_amd_dbgapi (inferior *inf)
   for (auto &&value : info->breakpoint_map)
     delete_breakpoint (value.second);
 
-  /* Reset the amd_dbgapi_inferior_info.  */
+  /* Reset the amd_dbgapi_inferior_info, except for precise_memory_mode.  */
+  bool precise_memory_requested = info->precise_memory.requested;
   *info = amd_dbgapi_inferior_info (inf);
+  info->precise_memory.requested = precise_memory_requested;
 
   maybe_reset_amd_dbgapi ();
 }
@@ -1668,6 +1707,22 @@ amd_dbgapi_target_inferior_created (inferior *inf)
   attach_amd_dbgapi (inf);
 }
 
+/* Callback called when an inferior is cloned.  */
+
+static void
+amd_dbgapi_target_inferior_cloned (inferior *original_inferior,
+				   inferior *new_inferior)
+{
+  auto *orig_info = get_amd_dbgapi_inferior_info (original_inferior);
+  auto *new_info = get_amd_dbgapi_inferior_info (new_inferior);
+
+  /* At this point, the process is not started.  Therefore it is sufficient to
+     copy the precise memory request, it will be applied when the process
+     starts.  */
+  gdb_assert (new_info->process_id == AMD_DBGAPI_PROCESS_NONE);
+  new_info->precise_memory.requested = orig_info->precise_memory.requested;
+}
+
 /* inferior_execd observer.  */
 
 static void
@@ -1677,6 +1732,13 @@ amd_dbgapi_inferior_execd (inferior *exec_inf, inferior *follow_inf)
      attached to the old process image, so we need to detach and re-attach to
      the new process image.  */
   detach_amd_dbgapi (exec_inf);
+
+  /* If using "follow-exec-mode new", carry over the precise-memory setting
+     to the new inferior (otherwise, FOLLOW_INF and ORIG_INF point to the same
+     inferior, so this is a no-op).  */
+  get_amd_dbgapi_inferior_info (follow_inf)->precise_memory.requested
+    = get_amd_dbgapi_inferior_info (exec_inf)->precise_memory.requested;
+
   attach_amd_dbgapi (follow_inf);
 }
 
@@ -1686,11 +1748,22 @@ static void
 amd_dbgapi_inferior_forked (inferior *parent_inf, inferior *child_inf,
 			    target_waitkind fork_kind)
 {
-  if (child_inf != nullptr  && fork_kind != TARGET_WAITKIND_VFORKED)
+  if (child_inf != nullptr)
     {
-      scoped_restore_current_thread restore_thread;
-      switch_to_thread (*child_inf->threads ().begin ());
-      attach_amd_dbgapi (child_inf);
+      /* Copy precise-memory requested value from parent to child.  */
+      amd_dbgapi_inferior_info *parent_info
+	= get_amd_dbgapi_inferior_info (parent_inf);
+      amd_dbgapi_inferior_info *child_info
+	= get_amd_dbgapi_inferior_info (child_inf);
+      child_info->precise_memory.requested
+	= parent_info->precise_memory.requested;
+
+      if (fork_kind != TARGET_WAITKIND_VFORKED)
+	{
+	  scoped_restore_current_thread restore_thread;
+	  switch_to_thread (*child_inf->threads ().begin ());
+	  attach_amd_dbgapi (child_inf);
+	}
     }
 }
 
@@ -1785,6 +1858,29 @@ amd_dbgapi_remove_breakpoint_callback
   return AMD_DBGAPI_STATUS_SUCCESS;
 }
 
+/* signal_received observer.  */
+
+static void
+amd_dbgapi_target_signal_received (gdb_signal sig)
+{
+  amd_dbgapi_inferior_info *info
+    = get_amd_dbgapi_inferior_info (current_inferior ());
+
+  if (info->process_id == AMD_DBGAPI_PROCESS_NONE)
+    return;
+
+  if (!ptid_is_gpu (inferior_thread ()->ptid))
+    return;
+
+  if (sig != GDB_SIGNAL_SEGV && sig != GDB_SIGNAL_BUS)
+    return;
+
+  if (!info->precise_memory.enabled)
+    gdb_printf (_("\
+Warning: precise memory violation signal reporting is not enabled, reported\n\
+location may not be accurate.  See \"show amdgpu precise-memory\".\n"));
+}
+
 /* Style for some kinds of messages.  */
 
 static cli_style_option fatal_error_style
@@ -1853,6 +1949,51 @@ amd_dbgapi_target::close ()
     delete_async_event_handler (&amd_dbgapi_async_event_handler);
 }
 
+/* Callback for "show amdgpu precise-memory".  */
+
+static void
+show_precise_memory_mode (struct ui_file *file, int from_tty,
+			  struct cmd_list_element *c, const char *value)
+{
+  amd_dbgapi_inferior_info *info
+    = get_amd_dbgapi_inferior_info (current_inferior ());
+
+  gdb_printf (file,
+	      _("AMDGPU precise memory access reporting is %s "
+		"(currently %s).\n"),
+	      info->precise_memory.requested ? "on" : "off",
+	      info->precise_memory.enabled ? "enabled" : "disabled");
+}
+
+/* Callback for "set amdgpu precise-memory".  */
+
+static void
+set_precise_memory_mode (bool value)
+{
+  amd_dbgapi_inferior_info *info
+    = get_amd_dbgapi_inferior_info (current_inferior ());
+
+  info->precise_memory.requested = value;
+
+  if (info->process_id != AMD_DBGAPI_PROCESS_NONE)
+    try_set_process_memory_precision (*info);
+}
+
+/* Return whether precise-memory is requested for the current inferior.  */
+
+static bool
+get_precise_memory_mode ()
+{
+  amd_dbgapi_inferior_info *info
+    = get_amd_dbgapi_inferior_info (current_inferior ());
+
+  return info->precise_memory.requested;
+}
+
+/* List of set/show amdgpu commands.  */
+struct cmd_list_element *set_amdgpu_list;
+struct cmd_list_element *show_amdgpu_list;
+
 /* List of set/show debug amd-dbgapi-lib commands.  */
 struct cmd_list_element *set_debug_amd_dbgapi_lib_list;
 struct cmd_list_element *show_debug_amd_dbgapi_lib_list;
@@ -1960,6 +2101,10 @@ _initialize_amd_dbgapi_target ()
   amd_dbgapi_set_log_level (get_debug_amd_dbgapi_lib_log_level ());
 
   /* Install observers.  */
+  gdb::observers::inferior_cloned.attach (amd_dbgapi_target_inferior_cloned,
+					  "amd-dbgapi");
+  gdb::observers::signal_received.attach (amd_dbgapi_target_signal_received,
+					  "amd-dbgapi");
   gdb::observers::inferior_created.attach
     (amd_dbgapi_target_inferior_created,
      amd_dbgapi_target_inferior_created_observer_token, "amd-dbgapi");
@@ -1968,6 +2113,24 @@ _initialize_amd_dbgapi_target ()
   gdb::observers::inferior_exit.attach (amd_dbgapi_inferior_exited, "amd-dbgapi");
   gdb::observers::inferior_pre_detach.attach (amd_dbgapi_inferior_pre_detach, "amd-dbgapi");
 
+  add_basic_prefix_cmd ("amdgpu", no_class,
+			_("Generic command for setting amdgpu flags."),
+			&set_amdgpu_list, 0, &setlist);
+
+  add_show_prefix_cmd ("amdgpu", no_class,
+		       _("Generic command for showing amdgpu flags."),
+		       &show_amdgpu_list, 0, &showlist);
+
+  add_setshow_boolean_cmd ("precise-memory", no_class,
+			   _("Set precise-memory mode."),
+			   _("Show precise-memory mode."), _("\
+If on, precise memory reporting is enabled if/when the inferior is running.\n\
+If off (default), precise memory reporting is disabled."),
+			   set_precise_memory_mode,
+			   get_precise_memory_mode,
+			   show_precise_memory_mode,
+			   &set_amdgpu_list, &show_amdgpu_list);
+
   add_basic_prefix_cmd ("amd-dbgapi-lib", no_class,
 			_("Generic command for setting amd-dbgapi library "
 			  "debugging flags."),
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 9b7e06f31566..aa3c67788871 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -26794,6 +26794,49 @@ either not mapped or accessed with incompatible permissions.
 If a single instruction raises more than one signal, they will be
 reported one at a time each time the wavefront is continued.
 
+@subsubsection @acronym{AMD GPU} Memory Violation Reporting
+
+A wavefront can report memory violation events.  However, the program
+location at which they are reported may be after the machine instruction
+that caused them.  This can result in the reported source statement
+being incorrect.  The following commands can be used to control this
+behavior:
+
+@table @code
+
+@kindex set amdgpu precise-memory
+@cindex AMD GPU precise memory event reporting
+@item set amdgpu precise-memory @var{mode}
+Controls how @acronym{AMD GPU} devices detect memory violations, where
+@var{mode} can be:
+
+@table @code
+
+@item off
+The program location may not be immediately after the instruction that
+caused the memory violation.  This is the default.
+
+@item on
+Requests that the program location will be immediately after the
+instruction that caused a memory violation.  Enabling this mode may make
+the @acronym{AMD GPU} device execution significantly slower as it has to
+wait for each memory operation to complete before executing the next
+instruction.
+
+@end table
+
+The @code{amdgpu precise-memory} parameter is per-inferior.  When an
+inferior forks or execs, or the user uses the @code{clone-inferior} command,
+and an inferior is created as a result, the newly created inferior inherits
+the parameter value of the original inferior.
+
+@kindex show amdgpu precise-memory
+@cindex AMD GPU precise memory event reporting
+@item show amdgpu precise-memory
+Displays the currently requested AMD GPU precise memory setting.
+
+@end table
+
 @subsubsection @acronym{AMD GPU} Logging
 
 The @samp{set debug amd-dbgapi} command can be used
diff --git a/gdb/testsuite/gdb.rocm/precise-memory-exec.c b/gdb/testsuite/gdb.rocm/precise-memory-exec.c
new file mode 100644
index 000000000000..a1f941dae030
--- /dev/null
+++ b/gdb/testsuite/gdb.rocm/precise-memory-exec.c
@@ -0,0 +1,44 @@
+/* Copyright 2021-2023 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+static void
+second (void)
+{
+}
+
+int
+main (int argc, char **argv)
+{
+  if (argc == 1)
+    {
+      /* First invocation.  */
+      int ret = execl (argv[0], argv[0], "Hello", NULL);
+      perror ("exec");
+      abort ();
+    }
+  else
+    {
+      /* Second invocation.  */
+      second ();
+    }
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.rocm/precise-memory-exec.exp b/gdb/testsuite/gdb.rocm/precise-memory-exec.exp
new file mode 100644
index 000000000000..601f30b3be8a
--- /dev/null
+++ b/gdb/testsuite/gdb.rocm/precise-memory-exec.exp
@@ -0,0 +1,58 @@
+# Copyright 2021-2023 Free Software Foundation, Inc.
+
+# This file is part of GDB.
+
+# 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/>.
+
+# Test that the "set amdgpu precise-memory" setting is inherited by an inferior
+# created following an exec.
+
+load_lib rocm.exp
+
+require allow_hipcc_tests
+
+standard_testfile .c
+
+if {[build_executable "failed to prepare $testfile" $testfile $srcfile {debug}]} {
+    return
+}
+
+proc do_test { follow-exec-mode } {
+    clean_restart $::binfile
+
+    with_rocm_gpu_lock {
+	if ![runto_main] {
+	    return
+	}
+
+	# Set precise-memory on the inferior before exec.
+	gdb_test "show amdgpu precise-memory" " is off.*" \
+	    "show amdgpu precise-memory before set"
+	gdb_test "set amdgpu precise-memory on"
+	gdb_test "show amdgpu precise-memory" " is on.*" \
+	    "show amdgpu precise-memory after set"
+
+	# Continue past exec.  The precise-memory setting should
+	# be on.
+	gdb_test_no_output "set follow-exec-mode ${follow-exec-mode}"
+	gdb_test "break second"
+	gdb_test "continue" "Breakpoint 1(\.$::decimal)?, main .*"
+	gdb_test "show amdgpu precise-memory" " is on.*" \
+	    "show amdgpu precise-memory after exec"
+    }
+}
+
+foreach_with_prefix follow-exec-mode {same new} {
+    do_test ${follow-exec-mode}
+}
diff --git a/gdb/testsuite/gdb.rocm/precise-memory-fork.c b/gdb/testsuite/gdb.rocm/precise-memory-fork.c
new file mode 100644
index 000000000000..67ce09f2c3dc
--- /dev/null
+++ b/gdb/testsuite/gdb.rocm/precise-memory-fork.c
@@ -0,0 +1,41 @@
+/* Copyright 2021-2023 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+#include <unistd.h>
+
+static void
+parent (void)
+{
+}
+
+static void
+child (void)
+{
+}
+
+int
+main (void)
+{
+  int pid = fork ();
+
+  if (pid != 0)
+    parent ();
+  else
+    child ();
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.rocm/precise-memory-fork.exp b/gdb/testsuite/gdb.rocm/precise-memory-fork.exp
new file mode 100644
index 000000000000..347b62ba88a6
--- /dev/null
+++ b/gdb/testsuite/gdb.rocm/precise-memory-fork.exp
@@ -0,0 +1,50 @@
+# Copyright 2021-2023 Free Software Foundation, Inc.
+
+# This file is part of GDB.
+
+# 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/>.
+
+# Test that the "set amdgpu precise-memory" setting is inherited by a fork
+# child.
+
+load_lib rocm.exp
+
+require allow_hipcc_tests
+
+standard_testfile .c
+
+if {[prepare_for_testing "failed to prepare $testfile" $testfile $srcfile {debug}]} {
+    return
+}
+
+with_rocm_gpu_lock {
+    if ![runto_main] {
+	return
+    }
+
+    # Set precise-memory on in the parent, before fork.
+    gdb_test "show amdgpu precise-memory" " is off.*" \
+	"show amdgpu precise-memory before set"
+    gdb_test "set amdgpu precise-memory on"
+    gdb_test "show amdgpu precise-memory" " is on.*" \
+	"show amdgpu precise-memory after set"
+
+    # Continue past fork, following the child.  The precise-memory setting should
+    # be on.
+    gdb_test "set follow-fork-mode child"
+    gdb_test "break child"
+    gdb_test "continue" "Thread 2.1 .* hit Breakpoint .*"
+    gdb_test "show amdgpu precise-memory" " is on.*" \
+	"show amdgpu precise-memory after fork"
+}
diff --git a/gdb/testsuite/gdb.rocm/precise-memory-multi-inferiors.exp b/gdb/testsuite/gdb.rocm/precise-memory-multi-inferiors.exp
new file mode 100644
index 000000000000..9968b422b0ee
--- /dev/null
+++ b/gdb/testsuite/gdb.rocm/precise-memory-multi-inferiors.exp
@@ -0,0 +1,87 @@
+# Copyright 2021-2023 Free Software Foundation, Inc.
+
+# This file is part of GDB.
+
+# 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/>.
+
+# Test that the "set amdgpu precise-memory" setting is per-inferior, and
+# inherited by an inferior created using the clone-inferior command.
+
+load_lib rocm.exp
+
+require allow_hipcc_tests
+
+clean_restart
+
+set test_python [allow_python_tests]
+
+proc test_per_inferior { } {
+    gdb_test "show amdgpu precise-memory" \
+	"AMDGPU precise memory access reporting is off \\(currently disabled\\)." \
+	"show initial value, inferior 1"
+    if $::test_python {
+	gdb_test "python print(gdb.parameter(\"amdgpu precise-memory\"))" \
+	    "False" \
+	    "show initial value using Python, inferior 1"
+    }
+    gdb_test_no_output "set amdgpu precise-memory" \
+	"set on inferior 1"
+    gdb_test "show amdgpu precise-memory" \
+	"AMDGPU precise memory access reporting is on \\(currently disabled\\)." \
+	"show new value, inferior 1"
+    if $::test_python {
+	gdb_test "python print(gdb.parameter(\"amdgpu precise-memory\"))" \
+	    "True" \
+	    "show new value using Python, inferior 1"
+    }
+
+    gdb_test "add-inferior" "Added inferior 2"
+    gdb_test "inferior 2" "Switching to inferior 2 .*"
+
+    gdb_test "show amdgpu precise-memory" \
+	"AMDGPU precise memory access reporting is off \\(currently disabled\\)." \
+	"show initial value, inferior 2"
+    if $::test_python {
+	gdb_test "python print(gdb.parameter(\"amdgpu precise-memory\"))" \
+	    "False" \
+	    "show initial value using Python, inferior 2"
+    }
+}
+
+proc test_copy_precise_memory_on_clone {precise_memory} {
+    set value $precise_memory
+    if {$precise_memory == "unspecified"} {
+	set value off
+    }
+
+    clean_restart
+    gdb_test "show amdgpu precise-memory" "is off.*" \
+	"show default amdgpu precise-memory"
+    if {$precise_memory != "unspecified"} {
+	gdb_test_no_output "set amdgpu precise-memory $value"
+	gdb_test "show amdgpu precise-memory" "is $value.*" \
+		 "show amdgpu precise-memory on original inferior"
+    }
+
+    gdb_test "clone-inferior" "Added inferior 2.*"
+    gdb_test "inferior 2"
+    gdb_test "show amdgpu precise-memory" "is $value.*" \
+	"show amdgpu precise-memory on cloned inferior"
+}
+
+test_per_inferior
+
+foreach_with_prefix precise_memory { unspecified on off } {
+    test_copy_precise_memory_on_clone $precise_memory
+}
diff --git a/gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.cpp b/gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.cpp
new file mode 100644
index 000000000000..bf1451ad8d5b
--- /dev/null
+++ b/gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.cpp
@@ -0,0 +1,33 @@
+/* Copyright 2021-2023 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+#include <hip/hip_runtime.h>
+
+__global__ void
+kernel ()
+{
+  int *p = nullptr;
+  *p = 1;
+}
+
+int
+main (int argc, char* argv[])
+{
+  kernel<<<1, 1>>> ();
+  hipDeviceSynchronize ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.exp b/gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.exp
new file mode 100644
index 000000000000..2813ca781f2a
--- /dev/null
+++ b/gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.exp
@@ -0,0 +1,45 @@
+# Copyright 2021-2023 Free Software Foundation, Inc.
+
+# This file is part of GDB.
+
+# 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/>.
+
+# Test that when "amdgpu precise-memory" is off, hitting a SIGSEGV shows a
+# warning about the stop location maybe being inaccurate.
+
+load_lib rocm.exp
+
+require allow_hipcc_tests
+
+standard_testfile .cpp
+
+if {[build_executable "failed to prepare" $testfile $srcfile {debug hip}]} {
+    return
+}
+
+proc do_test { } {
+    clean_restart $::binfile
+
+    with_rocm_gpu_lock {
+	if ![runto_main] {
+	    return
+	}
+
+	gdb_test_no_output "set amdgpu precise-memory off"
+	gdb_test "continue" \
+	    "SIGSEGV, Segmentation fault.*Warning: precise memory violation signal reporting is not enabled.*"
+    }
+}
+
+do_test
diff --git a/gdb/testsuite/gdb.rocm/precise-memory.cpp b/gdb/testsuite/gdb.rocm/precise-memory.cpp
new file mode 100644
index 000000000000..034f02382adc
--- /dev/null
+++ b/gdb/testsuite/gdb.rocm/precise-memory.cpp
@@ -0,0 +1,32 @@
+/* Copyright 2021-2023 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+#include <hip/hip_runtime.h>
+
+__global__ void
+kernel ()
+{
+  __builtin_amdgcn_s_sleep (1);
+}
+
+int
+main (int argc, char* argv[])
+{
+  kernel<<<1, 1>>> ();
+  hipDeviceSynchronize ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.rocm/precise-memory.exp b/gdb/testsuite/gdb.rocm/precise-memory.exp
new file mode 100644
index 000000000000..62b7515c251b
--- /dev/null
+++ b/gdb/testsuite/gdb.rocm/precise-memory.exp
@@ -0,0 +1,57 @@
+# Copyright 2022-2023 Free Software Foundation, Inc.
+
+# This file is part of GDB.
+
+# 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/>.
+
+# Test showing the "amdgpu precise-memory" setting.
+
+load_lib rocm.exp
+
+require allow_hipcc_tests
+
+standard_testfile .cpp
+
+if {[build_executable "failed to prepare" $testfile $srcfile {debug hip}]} {
+    return
+}
+
+proc do_test { } {
+    clean_restart $::binfile
+
+    with_rocm_gpu_lock {
+	if ![runto_main] {
+	    return
+	}
+
+	gdb_test "show amdgpu precise-memory" \
+	    "AMDGPU precise memory access reporting is off \\(currently disabled\\)." \
+	    "show precise-memory setting in CLI before"
+
+	if {[hip_devices_support_precise_memory]} {
+	    gdb_test_no_output "set amdgpu precise-memory on"
+	    set cli_effective_value "enabled"
+	} else {
+	    gdb_test "set amdgpu precise-memory on" \
+		"warning: AMDGPU precise memory access reporting could not be enabled."
+	    set cli_effective_value "disabled"
+	}
+
+	gdb_test "show amdgpu precise-memory" \
+	    "AMDGPU precise memory access reporting is on \\(currently ${cli_effective_value}\\)." \
+	    "show precise-memory setting in CLI after"
+    }
+}
+
+do_test
diff --git a/gdb/testsuite/lib/rocm.exp b/gdb/testsuite/lib/rocm.exp
index 791f1b403bb7..fcdf665aef96 100644
--- a/gdb/testsuite/lib/rocm.exp
+++ b/gdb/testsuite/lib/rocm.exp
@@ -190,3 +190,22 @@ proc hip_devices_support_debug_multi_process {} {
     }
     return 1
 }
+
+# Return true if all the devices on the host support precise memory.
+
+proc hip_devices_support_precise_memory {} {
+    set unsupported_targets \
+	{gfx900 gfx906 gfx908 gfx1010 gfx1011 gfx1012 gfx1030 gfx1031 gfx1032}
+
+    set targets [hcc_amdgpu_targets]
+    if { [llength $targets] == 0 } {
+	return 0
+    }
+
+    foreach target $targets {
+	if { [lsearch -exact $unsupported_targets $target] != -1 } {
+	    return 0
+	}
+    }
+    return 1
+}
-- 
2.42.0

Re: [PATCH v2 3/3] gdb/amdgpu: add precise-memory support

[Eli Zaretskii]

> Cc: Simon Marchi <simon.marchi@efficios.com>
> Date: Thu, 14 Sep 2023 12:14:19 -0400
> From: Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>
> 
>  gdb/amd-dbgapi-target.c                       | 173 +++++++++++++++++-
>  gdb/doc/gdb.texinfo                           |  43 +++++
>  gdb/testsuite/gdb.rocm/precise-memory-exec.c  |  44 +++++
>  .../gdb.rocm/precise-memory-exec.exp          |  58 ++++++
>  gdb/testsuite/gdb.rocm/precise-memory-fork.c  |  41 +++++
>  .../gdb.rocm/precise-memory-fork.exp          |  50 +++++
>  .../precise-memory-multi-inferiors.exp        |  87 +++++++++
>  .../precise-memory-warning-sigsegv.cpp        |  33 ++++
>  .../precise-memory-warning-sigsegv.exp        |  45 +++++
>  gdb/testsuite/gdb.rocm/precise-memory.cpp     |  32 ++++
>  gdb/testsuite/gdb.rocm/precise-memory.exp     |  57 ++++++
>  gdb/testsuite/lib/rocm.exp                    |  19 ++
>  12 files changed, 677 insertions(+), 5 deletions(-)
>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-exec.c
>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-exec.exp
>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-fork.c
>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-fork.exp
>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-multi-inferiors.exp
>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.cpp
>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.exp
>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory.cpp
>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory.exp

Thanks.

> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 9b7e06f31566..aa3c67788871 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo

This part is OK.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>

Re: [PATCH v2 3/3] gdb/amdgpu: add precise-memory support

[Simon Marchi]

On 9/14/23 12:39, Eli Zaretskii via Gdb-patches wrote:
>> Cc: Simon Marchi <simon.marchi@efficios.com>
>> Date: Thu, 14 Sep 2023 12:14:19 -0400
>> From: Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>
>>
>>  gdb/amd-dbgapi-target.c                       | 173 +++++++++++++++++-
>>  gdb/doc/gdb.texinfo                           |  43 +++++
>>  gdb/testsuite/gdb.rocm/precise-memory-exec.c  |  44 +++++
>>  .../gdb.rocm/precise-memory-exec.exp          |  58 ++++++
>>  gdb/testsuite/gdb.rocm/precise-memory-fork.c  |  41 +++++
>>  .../gdb.rocm/precise-memory-fork.exp          |  50 +++++
>>  .../precise-memory-multi-inferiors.exp        |  87 +++++++++
>>  .../precise-memory-warning-sigsegv.cpp        |  33 ++++
>>  .../precise-memory-warning-sigsegv.exp        |  45 +++++
>>  gdb/testsuite/gdb.rocm/precise-memory.cpp     |  32 ++++
>>  gdb/testsuite/gdb.rocm/precise-memory.exp     |  57 ++++++
>>  gdb/testsuite/lib/rocm.exp                    |  19 ++
>>  12 files changed, 677 insertions(+), 5 deletions(-)
>>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-exec.c
>>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-exec.exp
>>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-fork.c
>>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-fork.exp
>>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-multi-inferiors.exp
>>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.cpp
>>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory-warning-sigsegv.exp
>>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory.cpp
>>  create mode 100644 gdb/testsuite/gdb.rocm/precise-memory.exp
> 
> Thanks.
> 
>> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
>> index 9b7e06f31566..aa3c67788871 100644
>> --- a/gdb/doc/gdb.texinfo
>> +++ b/gdb/doc/gdb.texinfo
> 
> This part is OK.
> 
> Reviewed-By: Eli Zaretskii <eliz@gnu.org>

Thanks,

Simon

Re: [PATCH v2 3/3] gdb/amdgpu: add precise-memory support

[Lancelot SIX]

Hi Simon,

> diff --git a/gdb/amd-dbgapi-target.c b/gdb/amd-dbgapi-target.c
> index 22c269b7992c..d38b790f53f7 100644
> --- a/gdb/amd-dbgapi-target.c
> +++ b/gdb/amd-dbgapi-target.c
> @@ -1326,6 +1338,29 @@ amd_dbgapi_target::stopped_by_hw_breakpoint ()
>    return false;
>  }
>  
> +/* Try to set the process's memory access reporting precision mode.
> +
> +   Warn if the requested mode is not supported on at least one agent in the
> +   process.
> +
> +   Error out if setting the requested mode failed for some other reason.  */
> +
> +static void
> +try_set_process_memory_precision (amd_dbgapi_inferior_info &info)
> +{
> +  auto mode = (info.precise_memory.requested
> +	       ? AMD_DBGAPI_MEMORY_PRECISION_PRECISE
> +	       : AMD_DBGAPI_MEMORY_PRECISION_NONE);
> +  amd_dbgapi_status_t status
> +    = amd_dbgapi_set_memory_precision (info.process_id, mode);
> +
> +  if (status == AMD_DBGAPI_STATUS_ERROR_NOT_SUPPORTED)
> +    warning (_("AMDGPU precise memory access reporting could not be enabled."));
> +  else if (status != AMD_DBGAPI_STATUS_SUCCESS)
> +    error (_("amd_dbgapi_set_memory_precision failed (%s)"),
> +	   get_status_string (status));

I think you forgot something like

     else
       info.precise_memory.enabled = info.precise_memory.requested;

here.

> +}
> +
>  /* Make the amd-dbgapi library attach to the process behind INF.
>  
>     Note that this is unrelated to the "attach" GDB concept / command.
> @@ -1399,6 +1434,8 @@ attach_amd_dbgapi (inferior *inf)
>    amd_dbgapi_debug_printf ("process_id = %" PRIu64 ", notifier fd = %d",
>  			   info->process_id.handle, info->notifier);
>  
> +  try_set_process_memory_precision (*info);
> +
>    /* If GDB is attaching to a process that has the runtime loaded, there will
>       already be a "runtime loaded" event available.  Consume it and push the
>       target.  */
> @@ -1443,8 +1480,10 @@ detach_amd_dbgapi (inferior *inf)
>    for (auto &&value : info->breakpoint_map)
>      delete_breakpoint (value.second);
>  
> -  /* Reset the amd_dbgapi_inferior_info.  */
> +  /* Reset the amd_dbgapi_inferior_info, except for precise_memory_mode.  */
> +  bool precise_memory_requested = info->precise_memory.requested;
>    *info = amd_dbgapi_inferior_info (inf);

Not really significant, but I am wonedring if adding a
request_precise_memory bool parameter to the amd_dbgapi_inferior_info
ctor (maybe with default value to false) would make sense.

That being said, I'm happy either way.

> +  info->precise_memory.requested = precise_memory_requested;
>  
>    maybe_reset_amd_dbgapi ();
>  }

I have tested this patch (with the fix suggested above) on gfx900 (where
precise memory is not supported) and gfx90a (where precise memory is
supported).

With the correction, the patch looks good to me.

Best,
Lancelot.

Re: [PATCH v2 3/3] gdb/amdgpu: add precise-memory support

[Simon Marchi]

On 9/15/23 06:13, Lancelot SIX via Gdb-patches wrote:
> Hi Simon,
> 
>> diff --git a/gdb/amd-dbgapi-target.c b/gdb/amd-dbgapi-target.c
>> index 22c269b7992c..d38b790f53f7 100644
>> --- a/gdb/amd-dbgapi-target.c
>> +++ b/gdb/amd-dbgapi-target.c
>> @@ -1326,6 +1338,29 @@ amd_dbgapi_target::stopped_by_hw_breakpoint ()
>>    return false;
>>  }
>>  
>> +/* Try to set the process's memory access reporting precision mode.
>> +
>> +   Warn if the requested mode is not supported on at least one agent in the
>> +   process.
>> +
>> +   Error out if setting the requested mode failed for some other reason.  */
>> +
>> +static void
>> +try_set_process_memory_precision (amd_dbgapi_inferior_info &info)
>> +{
>> +  auto mode = (info.precise_memory.requested
>> +	       ? AMD_DBGAPI_MEMORY_PRECISION_PRECISE
>> +	       : AMD_DBGAPI_MEMORY_PRECISION_NONE);
>> +  amd_dbgapi_status_t status
>> +    = amd_dbgapi_set_memory_precision (info.process_id, mode);
>> +
>> +  if (status == AMD_DBGAPI_STATUS_ERROR_NOT_SUPPORTED)
>> +    warning (_("AMDGPU precise memory access reporting could not be enabled."));
>> +  else if (status != AMD_DBGAPI_STATUS_SUCCESS)
>> +    error (_("amd_dbgapi_set_memory_precision failed (%s)"),
>> +	   get_status_string (status));
> 
> I think you forgot something like
> 
>      else
>        info.precise_memory.enabled = info.precise_memory.requested;

Huh that's true, that got lost in my refactoring.  How come the test
didn't catch it?  Oh, oh my machine I have multiple AMD GPUs, not all of
which support this memory precision feature.  So it would just stay
disabled.  I spoke to Lancelot offline, there is apparently no way right
now to tell the whole stack to just consider a single card.

> 
> here.
> 
>> +}
>> +
>>  /* Make the amd-dbgapi library attach to the process behind INF.
>>  
>>     Note that this is unrelated to the "attach" GDB concept / command.
>> @@ -1399,6 +1434,8 @@ attach_amd_dbgapi (inferior *inf)
>>    amd_dbgapi_debug_printf ("process_id = %" PRIu64 ", notifier fd = %d",
>>  			   info->process_id.handle, info->notifier);
>>  
>> +  try_set_process_memory_precision (*info);
>> +
>>    /* If GDB is attaching to a process that has the runtime loaded, there will
>>       already be a "runtime loaded" event available.  Consume it and push the
>>       target.  */
>> @@ -1443,8 +1480,10 @@ detach_amd_dbgapi (inferior *inf)
>>    for (auto &&value : info->breakpoint_map)
>>      delete_breakpoint (value.second);
>>  
>> -  /* Reset the amd_dbgapi_inferior_info.  */
>> +  /* Reset the amd_dbgapi_inferior_info, except for precise_memory_mode.  */
>> +  bool precise_memory_requested = info->precise_memory.requested;
>>    *info = amd_dbgapi_inferior_info (inf);
> 
> Not really significant, but I am wonedring if adding a
> request_precise_memory bool parameter to the amd_dbgapi_inferior_info
> ctor (maybe with default value to false) would make sense.
> 
> That being said, I'm happy either way.

Yeah I can do that, it allows this to be a one-liner:

  *info = amd_dbgapi_inferior_info (inf, info->precise_memory.requested);

> 
>> +  info->precise_memory.requested = precise_memory_requested;
>>  
>>    maybe_reset_amd_dbgapi ();
>>  }
> 
> I have tested this patch (with the fix suggested above) on gfx900 (where
> precise memory is not supported) and gfx90a (where precise memory is
> supported).
> 
> With the correction, the patch looks good to me.

Thanks, I will post a v3 just to be sure.

Simon