[PATCH 1/2] gdb: Workaround bad gdbserver qSupported:xmlRegisters=i386;UnknwnFeat+ handling

[Pedro Alves]

gdbserver's target_process_qsupported is called for each feature that
the gdbserver common code does not recognize.  The only current
implementation, for x86 Linux, does this:

  static void
  x86_linux_process_qsupported (const char *query)
  {
    /* Return if gdb doesn't support XML.  If gdb sends "xmlRegisters="
       with "i386" in qSupported query, it supports x86 XML target
       descriptions.  */
    use_xml = 0;
    if (query != NULL && startswith (query, "xmlRegisters="))
      {
	char *copy = xstrdup (query + 13);
	char *p;

	for (p = strtok (copy, ","); p != NULL; p = strtok (NULL, ","))
	  {
	    if (strcmp (p, "i386") == 0)
	      {
		use_xml = 1;
		break;
	      }
	  }

	free (copy);
      }

    x86_linux_update_xmltarget ();
  }

Notice that this clears use_xml and calls x86_linux_update_xmltarget
each time target_process_qsupported is called.  So if gdb sends in any
unknown feature after "xmlRegisters=i386", like e.g.,
"xmlRegisters=i386;UnknownFeature+" gdbserver ends up not reporting a
XML description...

Work around this by having GDB send the "xmlRegisters=" feature last.

gdb/ChangeLog:
2015-11-04  Pedro Alves  <palves@redhat.com>

	* remote.c (remote_query_supported): Send the "xmlRegisters="
	last.
---
 gdb/remote.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/gdb/remote.c b/gdb/remote.c
index fed397a..593bf63 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -4467,9 +4467,6 @@ remote_query_supported (void)
       if (packet_set_cmd_state (PACKET_hwbreak_feature) != AUTO_BOOLEAN_FALSE)
 	q = remote_query_supported_append (q, "hwbreak+");
 
-      if (remote_support_xml)
-	q = remote_query_supported_append (q, remote_support_xml);
-
       q = remote_query_supported_append (q, "qRelocInsn+");
 
       if (rs->extended)
@@ -4488,6 +4485,11 @@ remote_query_supported (void)
       if (packet_set_cmd_state (PACKET_vContSupported) != AUTO_BOOLEAN_FALSE)
 	q = remote_query_supported_append (q, "vContSupported+");
 
+      /* Keep this one last to work around a gdbserver <= 7.10 bug in
+	 the qSupported:xmlRegisters=i386 handling.  */
+      if (remote_support_xml != NULL)
+	q = remote_query_supported_append (q, remote_support_xml);
+
       q = reconcat (q, "qSupported:", q, (char *) NULL);
       putpkt (q);
 
-- 
1.9.3