Re: Reporting the OSABI in target descriptions.

[Pedro Alves <pedro at codesourcery dot com>]

Hi Eli,

On Monday 06 July 2009 21:29:31, Eli Zaretskii wrote:
> > From: Pedro Alves <pedro@codesourcery.com>
> > Date: Mon, 6 Jul 2009 16:17:58 +0100
> > Cc: Eli Zaretskii <eliz@gnu.org>
> > 
> > > So that gdbserver supports this, I've tweaked the regformats/regdat.sh
> > > script to grok a new "osabi" field in the .dat files, and done
> > > a couple of examples: x86/x86_64-linux, which covers the specifying
> > > the osabi in the .dat files directly, and mips-linux, that covers doing
> > > it in from an embedded xml file.  I didn't touch other archs as their
> > > xml and dat files didn't have "linux" in the filename, but
> > > it probably just means that we'd have to go add such linux files,
> > > or check which ones aren't named foolinux.xml or foolinux.dat,
> > > but are only really used by gdbserver-linux.
> 
> Sorry, I don't follow: why just Linux?

Hmmm.  The feature is not Linux specific.  In this patch,
I only implemented support for gdbserver on linux and only for
a couple of archs, where it was very simple to do it --- because
there were already linux specific files to tweak.  I just wanted
to show that the feature works as expected.  For other gdbserver
targets, we'll need to add new copies of existing files, and do
some mechanical changes on them to add osabi elements.  In sum I've only
added support to gdbserver targets where the change was very small so to
not mix mostly mechanical boring changes with the required
gdb/docs/protocol changes.

> 
> > >  We can of course
> > > easilly add .xml and .dat files for Windows or other hosts
> > > gdbserver runs on.
> 
> Perhaps we should indeed add that for the popular platforms.

Yep.

> 
> > Eli, are is the docs (mostly doing the same as the description of
> > the "architecture" element does) and NEWS patch hunks below okay?
> 
> Yes, with a couple of comments:
> 
> > +* Target descriptions can now describe the target OS ABI.  See the
> > +section on target descriptions in the user manual for more
> > +information.
> 
> In fact <osabi> is described in "Target Description Format", not in
> "Target Descriptions".  So maybe use the exact section name here.

Done.

> 
> > +@cindex <osabi>
> 
> "<osabi>" is a kind of symbol, so it's better to have it in @code.

Done.

> 
> > +An @samp{<osabi>} element has this form:
> > +
> > +@smallexample
> > +  <osabi>@var{osabi}</osabi>
> > +@end smallexample
> > +
> > +@var{osabi} is an OS ABI name from the same selection accepted by
> 
> Using "osabi" both for the tag and the OS ABI name could confuse the
> reader.  Suggest to use "abi" or "abi-name" for the latter.

Good point.  Changed.  

> 
> Thanks.

Thank you!  I think I addressed your concerns.  Does this version
still look okay (doc hunks at end of patch) to you?  No other changes
were made apart from those needed to address your concerns.

-- 
Pedro Alves

2009-07-20  Pedro Alves  <pedro@codesourcery.com>

	* features/gdb-target.dtd (target): Accept an optional 'osabi'
	element.
	(osabi): Define element.
	* features/mips-linux.xml (target): Add an osabi subelement set to
	GNU/Linux.
	* regformats/regdat.sh (xmlarch, xmlosabi): New variables.  Don't
	write the architecture into $xmltarget.  Store it in $xmlarch.
	Handle the 'osabi' type.  Handle outputting the osabi element of
	the target description.
	* regformats/reg-x86-64-linux.dat (osabi): Set to GNU/Linux.
	* regformats/reg-i386-linux.dat (osabi): Set to GNU/Linux.

	* target-descriptions.h (tdesc_osabi, set_tdesc_osabi): Declare.
	* target-descriptions.c (struct target_desc) <osabi>: New field.
	(tdesc_osabi): New function.
	(set_tdesc_osabi): New function.
	* xml-tdesc.c: Include osabi.h.
	(tdesc_end_osabi): New.
	(target_children): Parse "osabi" elements.
	* arch-utils.c (gdbarch_info_fill): Try to get the osabi from the
	target description if the user didn't override it or it is not
	extractable from the bfd.  If that still fails, fallback to the
	configured in default.
	* osabi.h (osabi_from_tdesc_string): Declare.
	* osabi.c (osabi_from_tdesc_string): New.
	(gdbarch_lookup_osabi): Return GDB_OSABI_UNKNOWN instead of
	GDB_OSABI_DEFAULT.

	* NEWS: Mention that target descriptions can now describe the
	target OS ABI.

2009-07-20  Pedro Alves  <pedro@codesourcery.com>

	* gdb.texinfo (Target Description Format): Mention the new <osabi>
	optional element.
	(subsection OS ABI): New subsection.

---
 gdb/NEWS                            |    4 +++
 gdb/arch-utils.c                    |    7 ++++++
 gdb/doc/gdb.texinfo                 |   19 +++++++++++++++++-
 gdb/features/gdb-target.dtd         |    7 +++++-
 gdb/features/mips-linux.xml         |    1 
 gdb/osabi.c                         |   38 +++++++++++++++++++++++++++---------
 gdb/osabi.h                         |    4 +++
 gdb/regformats/reg-i386-linux.dat   |    1 
 gdb/regformats/reg-x86-64-linux.dat |    1 
 gdb/regformats/regdat.sh            |   20 +++++++++++++++++-
 gdb/target-descriptions.c           |   20 ++++++++++++++++++
 gdb/target-descriptions.h           |    6 +++++
 gdb/xml-tdesc.c                     |   21 +++++++++++++++++++
 13 files changed, 136 insertions(+), 13 deletions(-)

Index: src/gdb/features/gdb-target.dtd
===================================================================
--- src.orig/gdb/features/gdb-target.dtd	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/features/gdb-target.dtd	2009-07-20 18:12:38.000000000 +0100
@@ -6,12 +6,17 @@
 
 <!-- The root element of a GDB target description is <target>.  -->
 
-<!ELEMENT target	(architecture?, feature*)>
+<!-- The osabi element was added post GDB 6.8.  The version wasn't
+     bumped, since older GDBs silently ignore unknown elements.  -->
+
+<!ELEMENT target	(architecture?, osabi?, feature*)>
 <!ATTLIST target
 	version		CDATA	#FIXED "1.0">
 
 <!ELEMENT architecture	(#PCDATA)>
 
+<!ELEMENT osabi	(#PCDATA)>
+
 <!ELEMENT feature	((vector | union)*, reg*)>
 <!ATTLIST feature
 	name		ID	#REQUIRED>
Index: src/gdb/features/mips-linux.xml
===================================================================
--- src.orig/gdb/features/mips-linux.xml	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/features/mips-linux.xml	2009-07-20 18:12:38.000000000 +0100
@@ -8,6 +8,7 @@
 <!DOCTYPE target SYSTEM "gdb-target.dtd">
 <target>
   <architecture>mips</architecture>
+  <osabi>GNU/Linux</osabi>
   <xi:include href="mips-cpu.xml"/>
   <xi:include href="mips-cp0.xml"/>
   <xi:include href="mips-fpu.xml"/>
Index: src/gdb/regformats/regdat.sh
===================================================================
--- src.orig/gdb/regformats/regdat.sh	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/regformats/regdat.sh	2009-07-20 18:12:38.000000000 +0100
@@ -128,6 +128,8 @@ offset=0
 i=0
 name=x
 xmltarget=x
+xmlarch=x
+xmlosabi=x
 expedite=x
 exec < $1
 while do_read
@@ -140,7 +142,10 @@ do
     xmltarget="${entry}"
     continue
   elif test "${type}" = "xmlarch"; then
-    xmltarget="@<target><architecture>${entry}</architecture></target>"
+    xmlarch="${entry}"
+    continue
+  elif test "${type}" = "osabi"; then
+    xmlosabi="${entry}"
     continue
   elif test "${type}" = "expedite"; then
     expedite="${entry}"
@@ -159,7 +164,18 @@ echo "};"
 echo
 echo "const char *expedite_regs_${name}[] = { \"`echo ${expedite} | sed 's/,/", "/g'`\", 0 };"
 if test "${xmltarget}" = x; then
-  echo "const char *xmltarget_${name} = 0;"
+  if test "${xmlarch}" = x && test "${xmlosabi}" = x; then
+    echo "const char *xmltarget_${name} = 0;"
+  else
+    echo "const char *xmltarget_${name} = \"@<target>\\"
+    if test "${xmlarch}" != x; then
+      echo "<architecture>${xmlarch}</architecture>\\"
+    fi
+    if test "${xmlosabi}" != x; then
+      echo "<osabi>${xmlosabi}</osabi>\\"
+    fi
+    echo "</target>\";"
+  fi
 else
   echo "const char *xmltarget_${name} = \"${xmltarget}\";"
 fi
Index: src/gdb/regformats/reg-x86-64-linux.dat
===================================================================
--- src.orig/gdb/regformats/reg-x86-64-linux.dat	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/regformats/reg-x86-64-linux.dat	2009-07-20 18:12:38.000000000 +0100
@@ -1,5 +1,6 @@
 name:x86_64_linux
 xmlarch:i386:x86-64
+osabi:GNU/Linux
 expedite:rbp,rsp,rip
 64:rax
 64:rbx
Index: src/gdb/regformats/reg-i386-linux.dat
===================================================================
--- src.orig/gdb/regformats/reg-i386-linux.dat	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/regformats/reg-i386-linux.dat	2009-07-20 18:12:38.000000000 +0100
@@ -1,5 +1,6 @@
 name:i386_linux
 xmlarch:i386
+osabi:GNU/Linux
 expedite:ebp,esp,eip
 32:eax
 32:ecx
Index: src/gdb/target-descriptions.h
===================================================================
--- src.orig/gdb/target-descriptions.h	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/target-descriptions.h	2009-07-20 18:12:38.000000000 +0100
@@ -123,6 +123,11 @@ int tdesc_numbered_register_choices (con
 const struct bfd_arch_info *tdesc_architecture
   (const struct target_desc *);
 
+/* Return the OSABI associated with this target description, or
+   GDB_OSABI_UNKNOWN if no osabi was specified.  */
+
+enum gdb_osabi tdesc_osabi (const struct target_desc *);
+
 /* Return the string value of a property named KEY, or NULL if the
    property was not specified.  */
 
@@ -167,6 +172,7 @@ struct target_desc *allocate_target_desc
 struct cleanup *make_cleanup_free_target_description (struct target_desc *);
 void set_tdesc_architecture (struct target_desc *,
 			     const struct bfd_arch_info *);
+void set_tdesc_osabi (struct target_desc *, enum gdb_osabi osabi);
 void set_tdesc_property (struct target_desc *,
 			 const char *key, const char *value);
 
Index: src/gdb/target-descriptions.c
===================================================================
--- src.orig/gdb/target-descriptions.c	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/target-descriptions.c	2009-07-20 18:12:38.000000000 +0100
@@ -165,6 +165,10 @@ struct target_desc
   /* The architecture reported by the target, if any.  */
   const struct bfd_arch_info *arch;
 
+  /* The osabi reported by the target, if any; GDB_OSABI_UNKNOWN
+     otherwise.  */
+  enum gdb_osabi osabi;
+
   /* Any architecture-specific properties specified by the target.  */
   VEC(property_s) *properties;
 
@@ -351,6 +355,16 @@ tdesc_architecture (const struct target_
 {
   return target_desc->arch;
 }
+
+/* Return the OSABI associated with this target description, or
+   GDB_OSABI_UNKNOWN if no osabi was specified.  */
+
+enum gdb_osabi
+tdesc_osabi (const struct target_desc *target_desc)
+{
+  return target_desc->osabi;
+}
+
 
 
 /* Return 1 if this target description includes any registers.  */
@@ -1161,6 +1175,12 @@ set_tdesc_architecture (struct target_de
 {
   target_desc->arch = arch;
 }
+
+void
+set_tdesc_osabi (struct target_desc *target_desc, enum gdb_osabi osabi)
+{
+  target_desc->osabi = osabi;
+}
 
 
 static struct cmd_list_element *tdesc_set_cmdlist, *tdesc_show_cmdlist;
Index: src/gdb/xml-tdesc.c
===================================================================
--- src.orig/gdb/xml-tdesc.c	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/xml-tdesc.c	2009-07-20 18:12:38.000000000 +0100
@@ -24,6 +24,7 @@
 #include "target-descriptions.h"
 #include "xml-support.h"
 #include "xml-tdesc.h"
+#include "osabi.h"
 
 #include "filenames.h"
 
@@ -105,6 +106,24 @@ tdesc_end_arch (struct gdb_xml_parser *p
   set_tdesc_architecture (data->tdesc, arch);
 }
 
+/* Handle the end of an <osabi> element and its value.  */
+
+static void
+tdesc_end_osabi (struct gdb_xml_parser *parser,
+		 const struct gdb_xml_element *element,
+		 void *user_data, const char *body_text)
+{
+  struct tdesc_parsing_data *data = user_data;
+  enum gdb_osabi osabi;
+
+  osabi = osabi_from_tdesc_string (body_text);
+  if (osabi == GDB_OSABI_UNKNOWN)
+    warning (_("Target description specified unknown osabi \"%s\""),
+	     body_text);
+  else
+    set_tdesc_osabi (data->tdesc, osabi);
+}
+
 /* Handle the start of a <target> element.  */
 
 static void
@@ -313,6 +332,8 @@ static const struct gdb_xml_attribute ta
 static const struct gdb_xml_element target_children[] = {
   { "architecture", NULL, NULL, GDB_XML_EF_OPTIONAL,
     NULL, tdesc_end_arch },
+  { "osabi", NULL, NULL, GDB_XML_EF_OPTIONAL,
+    NULL, tdesc_end_osabi },
   { "feature", feature_attributes, feature_children,
     GDB_XML_EF_OPTIONAL | GDB_XML_EF_REPEATABLE,
     tdesc_start_feature, NULL },
Index: src/gdb/arch-utils.c
===================================================================
--- src.orig/gdb/arch-utils.c	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/arch-utils.c	2009-07-20 18:12:38.000000000 +0100
@@ -710,8 +710,15 @@ gdbarch_info_fill (struct gdbarch_info *
   info->byte_order_for_code = info->byte_order;
 
   /* "(gdb) set osabi ...".  Handled by gdbarch_lookup_osabi.  */
+  /* From the manual override, or from file.  */
   if (info->osabi == GDB_OSABI_UNINITIALIZED)
     info->osabi = gdbarch_lookup_osabi (info->abfd);
+  /* From the target.  */
+  if (info->osabi == GDB_OSABI_UNKNOWN && info->target_desc != NULL)
+    info->osabi = tdesc_osabi (info->target_desc);
+  /* From the configured default.  */
+  if (info->osabi == GDB_OSABI_UNKNOWN)
+    info->osabi = GDB_OSABI_DEFAULT;
 
   /* Must have at least filled in the architecture.  */
   gdb_assert (info->bfd_arch_info != NULL);
Index: src/gdb/osabi.h
===================================================================
--- src.orig/gdb/osabi.h	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/osabi.h	2009-07-20 18:12:38.000000000 +0100
@@ -40,6 +40,10 @@ void gdbarch_register_osabi (enum bfd_ar
 /* Lookup the OS ABI corresponding to the specified BFD.  */
 enum gdb_osabi gdbarch_lookup_osabi (bfd *);
 
+/* Lookup the OS ABI corresponding to the specified target description
+   string.  */
+enum gdb_osabi osabi_from_tdesc_string (const char *text);
+
 /* Initialize the gdbarch for the specified OS ABI variant.  */
 void gdbarch_init_osabi (struct gdbarch_info, struct gdbarch *);
 
Index: src/gdb/osabi.c
===================================================================
--- src.orig/gdb/osabi.c	2009-07-20 18:10:56.000000000 +0100
+++ src/gdb/osabi.c	2009-07-20 18:12:38.000000000 +0100
@@ -87,6 +87,30 @@ gdbarch_osabi_name (enum gdb_osabi osabi
   return gdb_osabi_names[GDB_OSABI_INVALID];
 }
 
+/* Lookup the OS ABI corresponding to the specified target description
+   string.  */
+
+enum gdb_osabi
+osabi_from_tdesc_string (const char *name)
+{
+  int i;
+
+  for (i = 0; i < ARRAY_SIZE (gdb_osabi_names); i++)
+    if (strcmp (name, gdb_osabi_names[i]) == 0)
+      {
+	/* See note above: the name table matches the indices assigned
+	   to enum gdb_osabi.  */
+	enum gdb_osabi osabi = (enum gdb_osabi) i;
+
+	if (osabi == GDB_OSABI_INVALID)
+	  return GDB_OSABI_UNKNOWN;
+	else
+	  return osabi;
+      }
+
+  return GDB_OSABI_UNKNOWN;
+}
+
 /* Handler for a given architecture/OS ABI pair.  There should be only
    one handler for a given OS ABI each architecture family.  */
 struct gdb_osabi_handler  
@@ -205,10 +229,11 @@ gdbarch_lookup_osabi (bfd *abfd)
   if (user_osabi_state == osabi_user)
     return user_selected_osabi;
 
-  /* If we don't have a binary, return the default OS ABI (if set) or
-     unknown (otherwise).  */
+  /* If we don't have a binary, just return unknown.  The caller may
+     have other sources the OSABI can be extracted from, e.g., the
+     target description.  */
   if (abfd == NULL) 
-    return GDB_OSABI_DEFAULT;
+    return GDB_OSABI_UNKNOWN;
 
   match = GDB_OSABI_UNKNOWN;
   match_specific = 0;
@@ -269,12 +294,7 @@ gdbarch_lookup_osabi (bfd *abfd)
 	}
     }
 
-  /* If we didn't find a match, but a default was specified at configure
-     time, return the default.  */
-  if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN && match == GDB_OSABI_UNKNOWN)
-    return GDB_OSABI_DEFAULT;
-  else
-    return match;
+  return match;
 }
 
 
Index: src/gdb/NEWS
===================================================================
--- src.orig/gdb/NEWS	2009-07-20 18:11:23.000000000 +0100
+++ src/gdb/NEWS	2009-07-20 18:12:38.000000000 +0100
@@ -194,6 +194,10 @@ add new commands to existing prefixes, e
   visible changes; see "New commands" and also "Removed commands"
   below.
 
+* Target descriptions can now describe the target OS ABI.  See the
+"Target Description Format" section in the user manual for more
+information.
+
 * New commands (for set/show, see "New options" below)
 
 find [/size-char] [/max-count] start-address, end-address|+search-space-size,
Index: src/gdb/doc/gdb.texinfo
===================================================================
--- src.orig/gdb/doc/gdb.texinfo	2009-07-20 18:11:28.000000000 +0100
+++ src/gdb/doc/gdb.texinfo	2009-07-20 18:12:38.000000000 +0100
@@ -30781,7 +30781,8 @@ their targets, we also describe the gram
 
 Target descriptions can identify the architecture of the remote target
 and (for some architectures) provide information about custom register
-sets.  @value{GDBN} can use this information to autoconfigure for your
+sets.  They can also identify the OS ABI of the remote target.
+@value{GDBN} can use this information to autoconfigure for your
 target, or to warn you if you connect to an unsupported target.
 
 Here is a simple target description:
@@ -30805,6 +30806,7 @@ are explained further below.
 <!DOCTYPE target SYSTEM "gdb-target.dtd">
 <target version="1.0">
   @r{[}@var{architecture}@r{]}
+  @r{[}@var{osabi}@r{]}
   @r{[}@var{feature}@dots{}@r{]}
 </target>
 @end smallexample
@@ -30860,6 +30862,21 @@ An @samp{<architecture>} element has thi
 accepted by @code{set architecture} (@pxref{Targets, ,Specifying a
 Debugging Target}).
 
+@subsection OS ABI
+@cindex @code{<osabi>}
+
+This optional field was introduced in @value{GDBN} version 7.0.
+Previous versions of @value{GDBN} ignore it.
+
+An @samp{<osabi>} element has this form:
+
+@smallexample
+  <osabi>@var{abi-name}</osabi>
+@end smallexample
+
+@var{abi-name} is an OS ABI name from the same selection accepted by
+@w{@code{set osabi}} (@pxref{ABI, ,Configuring the Current ABI}).
+
 @subsection Features
 @cindex <feature>