[PATCH v4 06/44] gdb, gdbserver, gdbsupport: add 'device' tag to XML target description

[Markus Metzger <markus.t.metzger@intel.com>]

From: Nils-Christian Kempke <nils-christian.kempke@intel.com>

Add <device> tag to the XML target description.  The tag is a list of
device attributes.  The extension enables passing device information
within the target description XML sent from gdbserver to gdb.

Co-authored-by: Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
---
 gdb/NEWS                    |  8 ++++++
 gdb/doc/gdb.texinfo         | 17 ++++++++++++
 gdb/features/gdb-target.dtd | 11 +++++++-
 gdb/target-descriptions.c   | 19 +++++++++++++
 gdb/xml-tdesc.c             | 36 +++++++++++++++++++++++++
 gdbserver/tdesc.cc          | 16 +++++++++++
 gdbserver/tdesc.h           |  3 +++
 gdbsupport/tdesc.cc         | 24 +++++++++++++++++
 gdbsupport/tdesc.h          | 54 +++++++++++++++++++++++++++++++++++++
 9 files changed, 187 insertions(+), 1 deletion(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 10c182067f9..0b949ae7825 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,14 @@
 
 *** Changes since GDB 18
 
+* Changed remote packets
+
+qXfer:features:read:target.xml
+
+  The XML that is sent as a response can now include a "device" element
+  that can be used for passing information when the remote inferior
+  represents a device, e.g. a GPU.
+
 *** Changes in GDB 18
 
 * Support for the Common Trace Format (CTF) has been removed.  GDB now
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 0030698dcee..ce4bbc48385 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -49423,6 +49423,7 @@ are explained further below.
   @r{[}@var{architecture}@r{]}
   @r{[}@var{osabi}@r{]}
   @r{[}@var{compatible}@r{]}
+  @r{[}@var{device}@r{]}
   @r{[}@var{feature}@dots{}@r{]}
 </target>
 @end smallexample
@@ -49520,6 +49521,22 @@ capability with @samp{<compatible>} is as follows:
   <compatible>spu</compatible>
 @end smallexample
 
+@subsection Device Information
+@cindex <device>
+
+A @samp{<device>} element can be used for passing device information
+for when, e.g.@: the remote target represents a device, such as a GPU.
+@value{GDBN} can then use this information to display it to the user
+for informative purposes or to execute device-specific functions
+appropriately.  The element contains a number of attributes, best
+shown with the example below.  All attributes are optional.
+
+@smallexample
+  <device vendor-id="0x8086"
+          target-id="0x56a1"
+          name="Intel(R) Arc(TM) A750 Graphics" />
+@end smallexample
+
 @subsection Features
 @cindex <feature>
 
diff --git a/gdb/features/gdb-target.dtd b/gdb/features/gdb-target.dtd
index 2c405af8add..e22a07f9b48 100644
--- a/gdb/features/gdb-target.dtd
+++ b/gdb/features/gdb-target.dtd
@@ -9,7 +9,9 @@
 <!-- The osabi and compatible elements were added post GDB 6.8.  The version
      wasn't bumped, since older GDBs silently ignore unknown elements.  -->
 
-<!ELEMENT target	(architecture?, osabi?, compatible*, feature*)>
+<!ELEMENT target
+	(architecture?, osabi?, compatible*, device?, feature*)>
+
 <!ATTLIST target
 	version		CDATA	#FIXED "1.0">
 
@@ -19,6 +21,13 @@
 
 <!ELEMENT compatible	(#PCDATA)>
 
+<!ELEMENT device	EMPTY>
+<!ATTLIST device
+	vendor-id	CDATA	#IMPLIED
+	target-id	CDATA	#IMPLIED
+	name		CDATA	#IMPLIED
+	>
+
 <!ELEMENT feature
 	((vector | flags | struct | union )*, reg*)>
 <!ATTLIST feature
diff --git a/gdb/target-descriptions.c b/gdb/target-descriptions.c
index e1821fe7114..6e1bc2fa5e7 100644
--- a/gdb/target-descriptions.c
+++ b/gdb/target-descriptions.c
@@ -355,6 +355,9 @@ struct target_desc : tdesc_element
   /* The list of compatible architectures reported by the target.  */
   std::vector<tdesc_compatible_info_up> compatible;
 
+  /* The device reported by the target, if any.  */
+  tdesc_device_up device;
+
   /* Any architecture-specific properties specified by the target.  */
   std::vector<property> properties;
 
@@ -633,6 +636,22 @@ tdesc_osabi_name (const struct target_desc *target_desc)
   return nullptr;
 }
 
+/* See gdbsupport/tdesc.h.  */
+
+void
+set_tdesc_device_info (target_desc *target_desc, tdesc_device *device)
+{
+  target_desc->device.reset (device);
+}
+
+/* See gdbsupport/tdesc.h.  */
+
+const tdesc_device *
+tdesc_device_info (const target_desc *target_desc)
+{
+  return target_desc->device.get ();
+}
+
 /* Return 1 if this target description includes any registers.  */
 
 int
diff --git a/gdb/xml-tdesc.c b/gdb/xml-tdesc.c
index c0b1b635315..0481e16fab5 100644
--- a/gdb/xml-tdesc.c
+++ b/gdb/xml-tdesc.c
@@ -137,6 +137,33 @@ tdesc_end_compatible (struct gdb_xml_parser *parser,
   tdesc_add_compatible (data->tdesc, arch);
 }
 
+/* Handle the start of a <device> element and its value.  */
+
+static void
+tdesc_start_device (struct gdb_xml_parser *parser,
+		    const gdb_xml_element *element,
+		    void *user_data, std::vector<gdb_xml_value> &attributes)
+{
+  tdesc_parsing_data *data = (struct tdesc_parsing_data *) user_data;
+  tdesc_device *device = new tdesc_device ();
+
+  gdb_xml_value *attr;
+
+  attr = xml_find_attribute (attributes, "vendor-id");
+  if (attr != nullptr)
+    device->vendor_id = * (ULONGEST *) attr->value.get ();
+
+  attr = xml_find_attribute (attributes, "target-id");
+  if (attr != nullptr)
+    device->target_id = * (ULONGEST *) attr->value.get ();
+
+  attr = xml_find_attribute (attributes, "name");
+  if (attr != nullptr)
+    device->name = (char *) attr->value.get ();
+
+  set_tdesc_device_info (data->tdesc, device);
+}
+
 /* Handle the start of a <target> element.  */
 
 static void
@@ -587,6 +614,13 @@ static const struct gdb_xml_element feature_children[] = {
   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
 };
 
+static const struct gdb_xml_attribute device_attributes[] = {
+  { "vendor-id", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
+  { "target-id", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
+  { "name", GDB_XML_AF_OPTIONAL, NULL, NULL },
+  { NULL, GDB_XML_EF_NONE, NULL, NULL }
+};
+
 static const struct gdb_xml_attribute target_attributes[] = {
   { "version", GDB_XML_AF_NONE, NULL, NULL },
   { NULL, GDB_XML_AF_NONE, NULL, NULL }
@@ -599,6 +633,8 @@ static const struct gdb_xml_element target_children[] = {
     NULL, tdesc_end_osabi },
   { "compatible", NULL, NULL, GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
     NULL, tdesc_end_compatible },
+  { "device", device_attributes, NULL, GDB_XML_EF_OPTIONAL,
+    tdesc_start_device, NULL },
   { "feature", feature_attributes, feature_children,
     GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
     tdesc_start_feature, NULL },
diff --git a/gdbserver/tdesc.cc b/gdbserver/tdesc.cc
index 1d5f52b8948..cb8aad84f54 100644
--- a/gdbserver/tdesc.cc
+++ b/gdbserver/tdesc.cc
@@ -190,6 +190,22 @@ set_tdesc_osabi (struct target_desc *target_desc, enum gdb_osabi osabi)
 
 /* See gdbsupport/tdesc.h.  */
 
+void
+set_tdesc_device_info (target_desc *target_desc, tdesc_device *device)
+{
+  target_desc->device.reset (device);
+}
+
+/* See gdbsupport/tdesc.h.  */
+
+const tdesc_device *
+tdesc_device_info (const target_desc *target_desc)
+{
+  return target_desc->device.get ();
+}
+
+/* See gdbsupport/tdesc.h.  */
+
 const char *
 tdesc_get_features_xml (const target_desc *tdesc)
 {
diff --git a/gdbserver/tdesc.h b/gdbserver/tdesc.h
index 076451f4815..ffff346cf09 100644
--- a/gdbserver/tdesc.h
+++ b/gdbserver/tdesc.h
@@ -60,6 +60,9 @@ struct target_desc final : tdesc_element
   /* The value of <osabi> element in the XML, replying GDB.  */
   gdb::unique_xmalloc_ptr<char> osabi;
 
+  /* The value of the <device> element in the XML, replying GDB.  */
+  tdesc_device_up device;
+
 public:
   target_desc ()
     : registers_size (0)
diff --git a/gdbsupport/tdesc.cc b/gdbsupport/tdesc.cc
index 4b6aa815c81..c6ce443dac4 100644
--- a/gdbsupport/tdesc.cc
+++ b/gdbsupport/tdesc.cc
@@ -417,6 +417,8 @@ void print_xml_feature::visit_pre (const target_desc *e)
   for (const auto &c : compatible_list)
     add_line ("<compatible>%s</compatible>",
 	      tdesc_compatible_info_arch_name (c));
+
+  this->visit (tdesc_device_info (e));
 #endif
 }
 
@@ -426,6 +428,28 @@ void print_xml_feature::visit_post (const target_desc *e)
   add_line ("</target>");
 }
 
+void
+print_xml_feature::visit (const tdesc_device *device)
+{
+  if (device == nullptr)
+    return;
+
+  std::string tmp = "<device";
+  if (device->vendor_id.has_value ())
+    string_appendf (tmp, " vendor-id=\"0x%04" PRIx32 "\"",
+		    *device->vendor_id);
+
+  if (device->target_id.has_value ())
+    string_appendf (tmp, " target-id=\"0x%04" PRIx32 "\"",
+		    *device->target_id);
+
+  if (!device->name.empty ())
+    string_appendf (tmp, " name=\"%s\"", device->name.c_str ());
+
+  string_appendf (tmp, "/>");
+  add_line (tmp);
+}
+
 /* See gdbsupport/tdesc.h.  */
 
 void
diff --git a/gdbsupport/tdesc.h b/gdbsupport/tdesc.h
index a2ef21987bf..1051a1a98fb 100644
--- a/gdbsupport/tdesc.h
+++ b/gdbsupport/tdesc.h
@@ -26,6 +26,7 @@ struct tdesc_type_builtin;
 struct tdesc_type_vector;
 struct tdesc_type_with_fields;
 struct tdesc_reg;
+struct tdesc_device;
 struct target_desc;
 
 /* The interface to visit different elements of target description.  */
@@ -56,6 +57,9 @@ class tdesc_element_visitor
 
   virtual void visit (const tdesc_reg *e)
   {}
+
+  virtual void visit (const tdesc_device *e)
+  {}
 };
 
 class tdesc_element
@@ -315,6 +319,48 @@ struct tdesc_feature : tdesc_element
 
 using tdesc_feature_up = std::unique_ptr<tdesc_feature>;
 
+/* The device information in a target description.  */
+
+struct tdesc_device : tdesc_element
+{
+  tdesc_device ()
+  {
+    name = "";
+  }
+
+  virtual ~tdesc_device () = default;
+
+  DISABLE_COPY_AND_ASSIGN (tdesc_device);
+
+  /* The id of the device vendor.  */
+  std::optional<uint32_t> vendor_id;
+
+  /* The id of the device, given by its vendor.  */
+  std::optional<uint32_t> target_id;
+
+  /* The name of the device.  */
+  std::string name;
+
+  void accept (tdesc_element_visitor &v) const override
+  {
+    v.visit (this);
+  }
+
+  bool operator== (const tdesc_device &other) const
+  {
+    return (vendor_id == other.vendor_id
+	    && target_id == other.target_id
+	    && name == other.name);
+  }
+
+  bool operator!= (const tdesc_device &other) const
+  {
+    return !(*this == other);
+  }
+};
+
+typedef std::unique_ptr<tdesc_device> tdesc_device_up;
+
 /* A deleter adapter for a target_desc.  There are different
    implementations of this deleter class in gdb and gdbserver because even
    though the target_desc name is shared between the two projects, the
@@ -349,6 +395,13 @@ void set_tdesc_osabi (target_desc *target_desc, enum gdb_osabi osabi);
    or NULL if no osabi was specified.  */
 const char *tdesc_osabi_name (const struct target_desc *target_desc);
 
+/* Set TARGET_DESC's device information.  */
+void set_tdesc_device_info (target_desc *target_desc, tdesc_device *device);
+
+/* Return the device information associated with this target
+   description or NULL if device info does not exist.  */
+const tdesc_device *tdesc_device_info (const target_desc *target_desc);
+
 /* Return the type associated with ID in the context of FEATURE, or
    NULL if none.  */
 struct tdesc_type *tdesc_named_type (const struct tdesc_feature *feature,
@@ -441,6 +494,7 @@ class print_xml_feature : public tdesc_element_visitor
   void visit (const tdesc_type_vector *type) override;
   void visit (const tdesc_type_with_fields *type) override;
   void visit (const tdesc_reg *reg) override;
+  void visit (const tdesc_device *device) override;
 
 private:
 
-- 
2.43.0

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