bsd-kvm target, always a thread

[Pedro Alves <pedro at codesourcery dot com>]

Hi,

This patches makes the bsd-kvm target register a main thread.

I've "tested" this on a x86 OpenBSD-4.3 VM, but I'm not qualified
to do much more openbsd kernel debugging other than:

 (gdb) tar kvm
 #0  0x00000006 in ?? ()
 (gdb) info threads
 * 1 <kvm>  0x00000006 in ?? ()

B.T.W, with GDB 6.3, which came with the distro I always get:

 (gdb) tar kvm
 #0  0xd034ee05 in ?? ()

With HEAD I always get 0x00000006.

Is this difference expected?  Related to the recent change to
build on 4.3?

OK?

-- 
Pedro Alves

2008-08-08  Pedro Alves  <pedro@codesourcery.com>

	* bsd-kvm.c: Include "gdbthread.h".
	(bsd_kvm_ptid): New.
	(bsd_kvm_open): Add a main thread.
	(bsd_kvm_close): Delete it.
	(bsd_kvm_thread_alive): New.
	(bsd_kvm_pid_to_str): New.
	(bsd_kvm_add_target): Register bsd_kvm_thread_alive and
	bsd_kvm_pid_to_str.

---
 gdb/bsd-kvm.c |   33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

Index: src/gdb/bsd-kvm.c
===================================================================
--- src.orig/gdb/bsd-kvm.c	2008-08-08 04:04:34.000000000 +0100
+++ src/gdb/bsd-kvm.c	2008-08-08 04:10:58.000000000 +0100
@@ -25,6 +25,7 @@
 #include "target.h"
 #include "value.h"
 #include "gdbcore.h"		/* for get_exec_file */
+#include "gdbthread.h"
 
 #include "gdb_assert.h"
 #include <fcntl.h>
@@ -56,6 +57,12 @@ static int (*bsd_kvm_supply_pcb)(struct 
 /* Target ops for libkvm interface.  */
 static struct target_ops bsd_kvm_ops;
 
+/* This is the ptid we use while we're connected to kvm.  Its value is
+   arbitrary, as the kvm target don't have a notion or processes or
+   thread ids, but we need something non-null to place in
+   inferior_ptid.  */
+static ptid_t bsd_kvm_ptid;
+
 static void
 bsd_kvm_open (char *filename, int from_tty)
 {
@@ -89,6 +96,9 @@ bsd_kvm_open (char *filename, int from_t
   core_kd = temp_kd;
   push_target (&bsd_kvm_ops);
 
+  add_thread_silent (bsd_kvm_ptid);
+  inferior_ptid = bsd_kvm_ptid;
+
   target_fetch_registers (get_current_regcache (), -1);
 
   reinit_frame_cache ();
@@ -104,6 +114,9 @@ bsd_kvm_close (int quitting)
 	warning (("%s"), kvm_geterr(core_kd));
       core_kd = NULL;
     }
+
+  inferior_ptid = null_ptid;
+  delete_thread_silent (bsd_kvm_ptid);
 }
 
 static LONGEST
@@ -297,6 +310,20 @@ bsd_kvm_pcb_cmd (char *arg, int fromtty)
   print_stack_frame (get_selected_frame (NULL), -1, 1);
 }
 
+static int
+bsd_kvm_thread_alive (ptid_t ptid)
+{
+  return 1;
+}
+
+static char *
+bsd_kvm_pid_to_str (ptid_t ptid)
+{
+  static char buf[64];
+  xsnprintf (buf, sizeof buf, "<kvm>");
+  return buf;
+}
+
 /* Add the libkvm interface to the list of all possible targets and
    register CUPPLY_PCB as the architecture-specific process control
    block interpreter.  */
@@ -316,6 +343,8 @@ Optionally specify the filename of a cor
   bsd_kvm_ops.to_fetch_registers = bsd_kvm_fetch_registers;
   bsd_kvm_ops.to_xfer_partial = bsd_kvm_xfer_partial;
   bsd_kvm_ops.to_files_info = bsd_kvm_files_info;
+  bsd_kvm_ops.to_thread_alive = bsd_kvm_thread_alive;
+  bsd_kvm_ops.to_pid_to_str = bsd_kvm_pid_to_str;
   bsd_kvm_ops.to_stratum = process_stratum;
   bsd_kvm_ops.to_has_memory = 1;
   bsd_kvm_ops.to_has_stack = 1;
@@ -335,4 +364,8 @@ Generic command for manipulating the ker
   add_cmd ("pcb", class_obscure, bsd_kvm_pcb_cmd,
 	   /* i18n: PCB == "Process Control Block" */
 	   _("Set current context from pcb address"), &bsd_kvm_cmdlist);
+
+  /* Yes, 42000 is arbitrary.  The only sense out of it, is that it
+     isn't 0.  */
+  bsd_kvm_ptid = ptid_build (42000, 0, 42000);
 }