New file for remote protocol to embedded HPPA targets.

1 files changed, 1479 insertions, 0 deletions

diff --git a/gdb/remote-pa.c b/gdb/remote-pa.c
new file mode 100644
index 0000000..6628dff
--- /dev/null
+++ b/gdb/remote-pa.c
@@ -0,0 +1,1479 @@
+/* Remote target communications for serial-line targets in custom GDB protocol
+   Copyright 1988, 1991, 1992, 1993, 1994 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 2 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, write to the Free Software
+Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* Remote communication protocol.
+
+   A debug packet whose contents are <data>
+   is encapsulated for transmission in the form:
+
+	$ <data> # CSUM1 CSUM2
+
+	<data> must be ASCII alphanumeric and cannot include characters
+	'$' or '#'.  If <data> starts with two characters followed by
+	':', then the existing stubs interpret this as a sequence number.
+
+	CSUM1 and CSUM2 are ascii hex representation of an 8-bit 
+	checksum of <data>, the most significant nibble is sent first.
+	the hex digits 0-9,a-f are used.
+
+   Receiver responds with:
+
+	+	- if CSUM is correct and ready for next packet
+	-	- if CSUM is incorrect
+
+   <data> is as follows:
+   All values are encoded in ascii hex digits.
+
+	Request		Packet
+
+	read registers  g
+	reply		XX....X		Each byte of register data
+					is described by two hex digits.
+					Registers are in the internal order
+					for GDB, and the bytes in a register
+					are in the same order the machine uses.
+			or ENN		for an error.
+
+	write regs	GXX..XX		Each byte of register data
+					is described by two hex digits.
+	reply		OK		for success
+			ENN		for an error
+
+        write reg	Pn...=r...	Write register n... with value r...,
+					which contains two hex digits for each
+					byte in the register (target byte
+					order).
+	reply		OK		for success
+			ENN		for an error
+	(not supported by all stubs).
+
+	read mem	mAA..AA,LLLL	AA..AA is address, LLLL is length.
+	reply		XX..XX		XX..XX is mem contents
+					Can be fewer bytes than requested
+					if able to read only part of the data.
+			or ENN		NN is errno
+
+	write mem	MAA..AA,LLLL:XX..XX
+					AA..AA is address,
+					LLLL is number of bytes,
+					XX..XX is data
+	reply		OK		for success
+			ENN		for an error (this includes the case
+					where only part of the data was
+					written).
+
+	cont		cAA..AA		AA..AA is address to resume
+					If AA..AA is omitted,
+					resume at same address.
+
+	step		sAA..AA		AA..AA is address to resume
+					If AA..AA is omitted,
+					resume at same address.
+
+	last signal     ?               Reply the current reason for stopping.
+                                        This is the same reply as is generated
+					for step or cont : SAA where AA is the
+					signal number.
+
+	There is no immediate reply to step or cont.
+	The reply comes when the machine stops.
+	It is		SAA		AA is the "signal number"
+
+	or...		TAAn...:r...;n:r...;n...:r...;
+					AA = signal number
+					n... = register number
+					r... = register contents
+	or...		WAA		The process exited, and AA is
+					the exit status.  This is only
+					applicable for certains sorts of
+					targets.
+	kill request	k
+
+	toggle debug	d		toggle debug flag (see 386 & 68k stubs)
+	reset		r		reset -- see sparc stub.
+	reserved	<other>		On other requests, the stub should
+					ignore the request and send an empty
+					response ($#<checksum>).  This way
+					we can extend the protocol and GDB
+					can tell whether the stub it is
+					talking to uses the old or the new.
+	search		tAA:PP,MM	Search backwards starting at address
+					AA for a match with pattern PP and
+					mask MM.  PP and MM are 4 bytes.
+					Not supported by all stubs.
+
+	general query	qXXXX		Request info about XXXX.
+	general set	QXXXX=yyyy	Set value of XXXX to yyyy.
+	query sect offs	qOffsets	Get section offsets.  Reply is
+					Text=xxx;Data=yyy;Bss=zzz
+	console output	Otext		Send text to stdout.  Only comes from
+					remote target.
+
+	Responses can be run-length encoded to save space.  A '*' means that
+	the next character is an ASCII encoding giving a repeat count which
+	stands for that many repititions of the character preceding the '*'.
+	The encoding is n+29, yielding a printable character where n >=3 
+	(which is where rle starts to win).  Don't use an n > 126.
+
+	So 
+	"0* " means the same as "0000".  */
+
+#include "defs.h"
+#include <string.h>
+#include <fcntl.h>
+#include "frame.h"
+#include "inferior.h"
+#include "bfd.h"
+#include "symfile.h"
+#include "target.h"
+#include "wait.h"
+#include "terminal.h"
+#include "gdbcmd.h"
+#include "objfiles.h"
+#include "gdb-stabs.h"
+
+#include "dcache.h"
+
+#ifdef USG
+#include <sys/types.h>
+#endif
+
+#include <signal.h>
+#include "serial.h"
+
+/* Prototypes for local functions */
+
+static int
+remote_write_bytes PARAMS ((CORE_ADDR memaddr, unsigned char *myaddr, int len));
+
+static int
+remote_read_bytes PARAMS ((CORE_ADDR memaddr, unsigned char *myaddr, int len));
+
+static void
+remote_files_info PARAMS ((struct target_ops *ignore));
+
+static int
+remote_xfer_memory PARAMS ((CORE_ADDR memaddr, char *myaddr, int len,
+			    int should_write, struct target_ops *target));
+
+static void 
+remote_prepare_to_store PARAMS ((void));
+
+static void
+remote_fetch_registers PARAMS ((int regno));
+
+static void
+remote_resume PARAMS ((int pid, int step, enum target_signal siggnal));
+
+static int
+remote_start_remote PARAMS ((char *dummy));
+
+static void
+remote_open PARAMS ((char *name, int from_tty));
+
+static void
+remote_close PARAMS ((int quitting));
+
+static void
+remote_store_registers PARAMS ((int regno));
+
+static void
+getpkt PARAMS ((char *buf, int forever));
+
+static void
+putpkt PARAMS ((char *buf));
+
+static void
+remote_send PARAMS ((char *buf));
+
+static int
+readchar PARAMS ((int timeout));
+
+static int remote_wait PARAMS ((int pid, struct target_waitstatus *status));
+
+static int
+tohex PARAMS ((int nib));
+
+static int
+fromhex PARAMS ((int a));
+
+static void
+remote_detach PARAMS ((char *args, int from_tty));
+
+static void
+remote_interrupt PARAMS ((int signo));
+
+static void
+remote_interrupt_twice PARAMS ((int signo));
+
+static void
+interrupt_query PARAMS ((void));
+
+extern struct target_ops remote_ops;	/* Forward decl */
+
+/* This was 5 seconds, which is a long time to sit and wait.
+   Unless this is going though some terminal server or multiplexer or
+   other form of hairy serial connection, I would think 2 seconds would
+   be plenty.  */
+static int remote_timeout = 2;
+
+#if 0
+int icache;
+#endif
+
+/* Descriptor for I/O to remote machine.  Initialize it to NULL so that
+   remote_open knows that we don't have a file open when the program
+   starts.  */
+serial_t remote_desc = NULL;
+
+/* Having this larger than 400 causes us to be incompatible with m68k-stub.c
+   and i386-stub.c.  Normally, no one would notice because it only matters
+   for writing large chunks of memory (e.g. in downloads).  Also, this needs
+   to be more than 400 if required to hold the registers (see below, where
+   we round it up based on REGISTER_BYTES).  */
+#define	PBUFSIZ	400
+
+/* Maximum number of bytes to read/write at once.  The value here
+   is chosen to fill up a packet (the headers account for the 32).  */
+#define MAXBUFBYTES ((PBUFSIZ-32)/2)
+
+/* Round up PBUFSIZ to hold all the registers, at least.  */
+/* The blank line after the #if seems to be required to work around a
+   bug in HP's PA compiler.  */
+#if REGISTER_BYTES > MAXBUFBYTES
+
+#undef PBUFSIZ
+#define	PBUFSIZ	(REGISTER_BYTES * 2 + 32)
+#endif
+
+/* Should we try the 'P' request?  If this is set to one when the stub
+   doesn't support 'P', the only consequence is some unnecessary traffic.  */
+static int stub_supports_P = 1;
+
+
+/* Clean up connection to a remote debugger.  */
+
+/* ARGSUSED */
+static void
+remote_close (quitting)
+     int quitting;
+{
+  if (remote_desc)
+    SERIAL_CLOSE (remote_desc);
+  remote_desc = NULL;
+}
+
+/* Query the remote side for the text, data and bss offsets. */
+
+static void
+get_offsets ()
+{
+  unsigned char buf[PBUFSIZ];
+  int nvals;
+  CORE_ADDR text_addr, data_addr, bss_addr;
+  struct section_offsets *offs;
+
+  putpkt ("qOffsets");
+
+  getpkt (buf, 0);
+
+  if (buf[0] == '\000')
+    return;			/* Return silently.  Stub doesn't support this
+				   command. */
+  if (buf[0] == 'E')
+    {
+      warning ("Remote failure reply: %s", buf);
+      return;
+    }
+
+  nvals = sscanf (buf, "Text=%lx;Data=%lx;Bss=%lx", &text_addr, &data_addr,
+		  &bss_addr);
+  if (nvals != 3)
+    error ("Malformed response to offset query, %s", buf);
+
+  if (symfile_objfile == NULL)
+    return;
+
+  offs = (struct section_offsets *) alloca (sizeof (struct section_offsets)
+					    + symfile_objfile->num_sections
+					    * sizeof (offs->offsets));
+  memcpy (offs, symfile_objfile->section_offsets,
+	  sizeof (struct section_offsets)
+	  + symfile_objfile->num_sections
+	  * sizeof (offs->offsets));
+
+  /* FIXME: This code assumes gdb-stabs.h is being used; it's broken
+     for xcoff, dwarf, sdb-coff, etc.  But there is no simple
+     canonical representation for this stuff.  (Just what does "text"
+     as seen by the stub mean, anyway?  I think it means all sections
+     with SEC_CODE set, but we currently have no way to deal with that).  */
+
+  ANOFFSET (offs, SECT_OFF_TEXT) = text_addr;
+
+  /* This is a temporary kludge to force data and bss to use the same offsets
+     because that's what nlmconv does now.  The real solution requires changes
+     to the stub and remote.c that I don't have time to do right now.  */
+
+  ANOFFSET (offs, SECT_OFF_DATA) = data_addr;
+  ANOFFSET (offs, SECT_OFF_BSS) = data_addr;
+
+  objfile_relocate (symfile_objfile, offs);
+}
+
+/* Stub for catch_errors.  */
+
+static int
+remote_start_remote (dummy)
+     char *dummy;
+{
+  immediate_quit = 1;		/* Allow user to interrupt it */
+
+  /* Ack any packet which the remote side has already sent.  */
+
+  SERIAL_WRITE (remote_desc, "+", 1);
+
+  get_offsets ();		/* Get text, data & bss offsets */
+
+  putpkt ("?");			/* initiate a query from remote machine */
+  immediate_quit = 0;
+
+  start_remote ();		/* Initialize gdb process mechanisms */
+
+  return 1;
+}
+
+/* Open a connection to a remote debugger.
+   NAME is the filename used for communication.  */
+
+static DCACHE *remote_dcache;
+
+static void
+remote_open (name, from_tty)
+     char *name;
+     int from_tty;
+{
+  if (name == 0)
+    error (
+"To open a remote debug connection, you need to specify what serial\n\
+device is attached to the remote system (e.g. /dev/ttya).");
+
+  target_preopen (from_tty);
+
+  unpush_target (&remote_ops);
+
+  remote_dcache = dcache_init (remote_read_bytes, remote_write_bytes);
+
+  remote_desc = SERIAL_OPEN (name);
+  if (!remote_desc)
+    perror_with_name (name);
+
+  if (baud_rate != -1)
+    {
+      if (SERIAL_SETBAUDRATE (remote_desc, baud_rate))
+	{
+	  SERIAL_CLOSE (remote_desc);
+	  perror_with_name (name);
+	}
+    }
+
+  SERIAL_RAW (remote_desc);
+
+  /* If there is something sitting in the buffer we might take it as a
+     response to a command, which would be bad.  */
+  SERIAL_FLUSH_INPUT (remote_desc);
+
+  if (from_tty)
+    {
+      puts_filtered ("Remote debugging using ");
+      puts_filtered (name);
+      puts_filtered ("\n");
+    }
+  push_target (&remote_ops);	/* Switch to using remote target now */
+
+  /* Start out by trying the 'P' request to set registers.  We set this each
+     time that we open a new target so that if the user switches from one
+     stub to another, we can (if the target is closed and reopened) cope.  */
+  stub_supports_P = 1;
+
+  /* Without this, some commands which require an active target (such as kill)
+     won't work.  This variable serves (at least) double duty as both the pid
+     of the target process (if it has such), and as a flag indicating that a
+     target is active.  These functions should be split out into seperate
+     variables, especially since GDB will someday have a notion of debugging
+     several processes.  */
+
+  inferior_pid = 42000;
+
+  /* Start the remote connection; if error (0), discard this target.
+     In particular, if the user quits, be sure to discard it
+     (we'd be in an inconsistent state otherwise).  */
+  if (!catch_errors (remote_start_remote, (char *)0, 
+	"Couldn't establish connection to remote target\n", RETURN_MASK_ALL))
+    pop_target();
+}
+
+/* remote_detach()
+   takes a program previously attached to and detaches it.
+   We better not have left any breakpoints
+   in the program or it'll die when it hits one.
+   Close the open connection to the remote debugger.
+   Use this when you want to detach and do something else
+   with your gdb.  */
+
+static void
+remote_detach (args, from_tty)
+     char *args;
+     int from_tty;
+{
+  if (args)
+    error ("Argument given to \"detach\" when remotely debugging.");
+  
+  pop_target ();
+  if (from_tty)
+    puts_filtered ("Ending remote debugging.\n");
+}
+
+/* Convert hex digit A to a number.  */
+
+static int
+fromhex (a)
+     int a;
+{
+  if (a >= '0' && a <= '9')
+    return a - '0';
+  else if (a >= 'a' && a <= 'f')
+    return a - 'a' + 10;
+  else
+    error ("Reply contains invalid hex digit");
+}
+
+/* Convert number NIB to a hex digit.  */
+
+static int
+tohex (nib)
+     int nib;
+{
+  if (nib < 10)
+    return '0'+nib;
+  else
+    return 'a'+nib-10;
+}
+
+/* Tell the remote machine to resume.  */
+
+static void
+remote_resume (pid, step, siggnal)
+     int pid, step;
+     enum target_signal siggnal;
+{
+  char buf[PBUFSIZ];
+
+  if (siggnal)
+    {
+      target_terminal_ours_for_output ();
+      printf_filtered
+	("Can't send signals to a remote system.  %s not sent.\n",
+	 target_signal_to_name (siggnal));
+      target_terminal_inferior ();
+    }
+
+  dcache_flush (remote_dcache);
+
+  strcpy (buf, step ? "s": "c");
+
+  putpkt (buf);
+}
+
+/* Send ^C to target to halt it.  Target will respond, and send us a
+   packet.  */
+
+static void
+remote_interrupt (signo)
+     int signo;
+{
+  /* If this doesn't work, try more severe steps.  */
+  signal (signo, remote_interrupt_twice);
+  
+  if (remote_debug)
+    printf_unfiltered ("remote_interrupt called\n");
+
+  SERIAL_WRITE (remote_desc, "\003", 1); /* Send a ^C */
+}
+
+static void (*ofunc)();
+
+/* The user typed ^C twice.  */
+static void
+remote_interrupt_twice (signo)
+     int signo;
+{
+  signal (signo, ofunc);
+  
+  interrupt_query ();
+
+  signal (signo, remote_interrupt);
+}
+
+/* Ask the user what to do when an interrupt is received.  */
+
+static void
+interrupt_query ()
+{
+  target_terminal_ours ();
+
+  if (query ("Interrupted while waiting for the program.\n\
+Give up (and stop debugging it)? "))
+    {
+      target_mourn_inferior ();
+      return_to_top_level (RETURN_QUIT);
+    }
+
+  target_terminal_inferior ();
+}
+
+/* Wait until the remote machine stops, then return,
+   storing status in STATUS just as `wait' would.
+   Returns "pid" (though it's not clear what, if anything, that
+   means in the case of this target).  */
+
+static int
+remote_wait (pid, status)
+     int pid;
+     struct target_waitstatus *status;
+{
+  unsigned char buf[PBUFSIZ];
+
+  status->kind = TARGET_WAITKIND_EXITED;
+  status->value.integer = 0;
+
+  while (1)
+    {
+      unsigned char *p;
+
+      ofunc = (void (*)()) signal (SIGINT, remote_interrupt);
+      getpkt ((char *) buf, 1);
+      signal (SIGINT, ofunc);
+
+      switch (buf[0])
+	{
+	case 'E':		/* Error of some sort */
+	  warning ("Remote failure reply: %s", buf);
+	  continue;
+	case 'T':		/* Status with PC, SP, FP, ... */
+	  {
+	    int i;
+	    long regno;
+	    char regs[MAX_REGISTER_RAW_SIZE];
+
+	    /* Expedited reply, containing Signal, {regno, reg} repeat */
+	    /*  format is:  'Tssn...:r...;n...:r...;n...:r...;#cc', where
+		ss = signal number
+		n... = register number
+		r... = register contents
+		*/
+
+	    p = &buf[3];	/* after Txx */
+
+	    while (*p)
+	      {
+		unsigned char *p1;
+
+		regno = strtol (p, &p1, 16); /* Read the register number */
+
+		if (p1 == p)
+		  warning ("Remote sent badly formed register number: %s\nPacket: '%s'\n",
+			   p1, buf);
+
+		p = p1;
+
+		if (*p++ != ':')
+		  warning ("Malformed packet (missing colon): %s\nPacket: '%s'\n",
+			   p, buf);
+
+		if (regno >= NUM_REGS)
+		  warning ("Remote sent bad register number %d: %s\nPacket: '%s'\n",
+			   regno, p, buf);
+
+		for (i = 0; i < REGISTER_RAW_SIZE (regno); i++)
+		  {
+		    if (p[0] == 0 || p[1] == 0)
+		      warning ("Remote reply is too short: %s", buf);
+		    regs[i] = fromhex (p[0]) * 16 + fromhex (p[1]);
+		    p += 2;
+		  }
+
+		if (*p++ != ';')
+		  warning ("Remote register badly formatted: %s", buf);
+
+		supply_register (regno, regs);
+	      }
+	  }
+	  /* fall through */
+	case 'S':		/* Old style status, just signal only */
+	  status->kind = TARGET_WAITKIND_STOPPED;
+	  status->value.sig = (enum target_signal)
+	    (((fromhex (buf[1])) << 4) + (fromhex (buf[2])));
+
+	  return inferior_pid;
+	case 'W':		/* Target exited */
+	  {
+	    /* The remote process exited.  */
+	    status->kind = TARGET_WAITKIND_EXITED;
+	    status->value.integer = (fromhex (buf[1]) << 4) + fromhex (buf[2]);
+	    return inferior_pid;
+	  }
+	case 'O':		/* Console output */
+	  fputs_filtered (buf + 1, gdb_stdout);
+	  continue;
+	default:
+	  warning ("Invalid remote reply: %s", buf);
+	  continue;
+	}
+    }
+  return inferior_pid;
+}
+
+/* Number of bytes of registers this stub implements.  */
+static int register_bytes_found;
+
+/* Read the remote registers into the block REGS.  */
+/* Currently we just read all the registers, so we don't use regno.  */
+/* ARGSUSED */
+static void
+remote_fetch_registers (regno)
+     int regno;
+{
+  char buf[PBUFSIZ];
+  int i;
+  char *p;
+  char regs[REGISTER_BYTES];
+
+  sprintf (buf, "g");
+  remote_send (buf);
+
+  /* Unimplemented registers read as all bits zero.  */
+  memset (regs, 0, REGISTER_BYTES);
+
+  /* We can get out of synch in various cases.  If the first character
+     in the buffer is not a hex character, assume that has happened
+     and try to fetch another packet to read.  */
+  while ((buf[0] < '0' || buf[0] > '9')
+	 && (buf[0] < 'a' || buf[0] > 'f'))
+    {
+      if (remote_debug)
+	printf_unfiltered ("Bad register packet; fetching a new packet\n");
+      getpkt (buf, 0);
+    }
+
+  /* Reply describes registers byte by byte, each byte encoded as two
+     hex characters.  Suck them all up, then supply them to the
+     register cacheing/storage mechanism.  */
+
+  p = buf;
+  for (i = 0; i < REGISTER_BYTES; i++)
+    {
+      if (p[0] == 0)
+	break;
+      if (p[1] == 0)
+	{
+	  warning ("Remote reply is of odd length: %s", buf);
+	  /* Don't change register_bytes_found in this case, and don't
+	     print a second warning.  */
+	  goto supply_them;
+	}
+      regs[i] = fromhex (p[0]) * 16 + fromhex (p[1]);
+      p += 2;
+    }
+
+  if (i != register_bytes_found)
+    {
+      register_bytes_found = i;
+#ifdef REGISTER_BYTES_OK
+      if (!REGISTER_BYTES_OK (i))
+	warning ("Remote reply is too short: %s", buf);
+#endif
+    }
+
+ supply_them:
+  for (i = 0; i < NUM_REGS; i++)
+    supply_register (i, &regs[REGISTER_BYTE(i)]);
+}
+
+/* Prepare to store registers.  Since we may send them all (using a
+   'G' request), we have to read out the ones we don't want to change
+   first.  */
+
+static void 
+remote_prepare_to_store ()
+{
+  /* Make sure the entire registers array is valid.  */
+  read_register_bytes (0, (char *)NULL, REGISTER_BYTES);
+}
+
+/* Store register REGNO, or all registers if REGNO == -1, from the contents
+   of REGISTERS.  FIXME: ignores errors.  */
+
+static void
+remote_store_registers (regno)
+     int regno;
+{
+  char buf[PBUFSIZ];
+  int i;
+  char *p;
+
+  if (regno >= 0 && stub_supports_P)
+    {
+      /* Try storing a single register.  */
+      char *regp;
+
+      sprintf (buf, "P%x=", regno);
+      p = buf + strlen (buf);
+      regp = &registers[REGISTER_BYTE (regno)];
+      for (i = 0; i < REGISTER_RAW_SIZE (regno); ++i)
+	{
+	  *p++ = tohex ((regp[i] >> 4) & 0xf);
+	  *p++ = tohex (regp[i] & 0xf);
+	}
+      *p = '\0';
+      remote_send (buf);
+      if (buf[0] != '\0')
+	{
+	  /* The stub understands the 'P' request.  We are done.  */
+	  return;
+	}
+
+      /* The stub does not support the 'P' request.  Use 'G' instead,
+	 and don't try using 'P' in the future (it will just waste our
+	 time).  */
+      stub_supports_P = 0;
+    }
+
+  buf[0] = 'G';
+
+  /* Command describes registers byte by byte,
+     each byte encoded as two hex characters.  */
+
+  p = buf + 1;
+  /* remote_prepare_to_store insures that register_bytes_found gets set.  */
+  for (i = 0; i < register_bytes_found; i++)
+    {
+      *p++ = tohex ((registers[i] >> 4) & 0xf);
+      *p++ = tohex (registers[i] & 0xf);
+    }
+  *p = '\0';
+
+  remote_send (buf);
+}
+
+#if 0
+
+/* Use of the data cache is disabled because it loses for looking at
+   and changing hardware I/O ports and the like.  Accepting `volatile'
+   would perhaps be one way to fix it, but a better way which would
+   win for more cases would be to use the executable file for the text
+   segment, like the `icache' code below but done cleanly (in some
+   target-independent place, perhaps in target_xfer_memory, perhaps
+   based on assigning each target a speed or perhaps by some simpler
+   mechanism).  */
+
+/* Read a word from remote address ADDR and return it.
+   This goes through the data cache.  */
+
+static int
+remote_fetch_word (addr)
+     CORE_ADDR addr;
+{
+#if 0
+  if (icache)
+    {
+      extern CORE_ADDR text_start, text_end;
+
+      if (addr >= text_start && addr < text_end)
+	{
+	  int buffer;
+	  xfer_core_file (addr, &buffer, sizeof (int));
+	  return buffer;
+	}
+    }
+#endif
+  return dcache_fetch (remote_dcache, addr);
+}
+
+/* Write a word WORD into remote address ADDR.
+   This goes through the data cache.  */
+
+static void
+remote_store_word (addr, word)
+     CORE_ADDR addr;
+     int word;
+{
+  dcache_poke (remote_dcache, addr, word);
+}
+#endif /* 0 */
+
+/* Write memory data directly to the remote machine.
+   This does not inform the data cache; the data cache uses this.
+   MEMADDR is the address in the remote memory space.
+   MYADDR is the address of the buffer in our space.
+   LEN is the number of bytes.
+
+   Returns number of bytes transferred, or 0 for error.  */
+
+static int
+remote_write_bytes (memaddr, myaddr, len)
+     CORE_ADDR memaddr;
+     unsigned char *myaddr;
+     int len;
+{
+  char buf[PBUFSIZ];
+  int i;
+  char *p;
+
+  /* FIXME-32x64: Need a version of print_address_numeric which puts the
+     result in a buffer like sprintf.  */
+  sprintf (buf, "M%lx,%x:", (unsigned long) memaddr, len);
+
+  /* We send target system values byte by byte, in increasing byte addresses,
+     each byte encoded as two hex characters.  */
+
+  p = buf + strlen (buf);
+  for (i = 0; i < len; i++)
+    {
+      *p++ = tohex ((myaddr[i] >> 4) & 0xf);
+      *p++ = tohex (myaddr[i] & 0xf);
+    }
+  *p = '\0';
+
+  putpkt (buf);
+  getpkt (buf, 0);
+
+  if (buf[0] == 'E')
+    {
+      /* There is no correspondance between what the remote protocol uses
+	 for errors and errno codes.  We would like a cleaner way of
+	 representing errors (big enough to include errno codes, bfd_error
+	 codes, and others).  But for now just return EIO.  */
+      errno = EIO;
+      return 0;
+    }
+  return len;
+}
+
+/* Read memory data directly from the remote machine.
+   This does not use the data cache; the data cache uses this.
+   MEMADDR is the address in the remote memory space.
+   MYADDR is the address of the buffer in our space.
+   LEN is the number of bytes.
+
+   Returns number of bytes transferred, or 0 for error.  */
+
+static int
+remote_read_bytes (memaddr, myaddr, len)
+     CORE_ADDR memaddr;
+     unsigned char *myaddr;
+     int len;
+{
+  char buf[PBUFSIZ];
+  int i;
+  char *p;
+
+  if (len > PBUFSIZ / 2 - 1)
+    abort ();
+
+  /* FIXME-32x64: Need a version of print_address_numeric which puts the
+     result in a buffer like sprintf.  */
+  sprintf (buf, "m%lx,%x", (unsigned long) memaddr, len);
+  putpkt (buf);
+  getpkt (buf, 0);
+
+  if (buf[0] == 'E')
+    {
+      /* There is no correspondance between what the remote protocol uses
+	 for errors and errno codes.  We would like a cleaner way of
+	 representing errors (big enough to include errno codes, bfd_error
+	 codes, and others).  But for now just return EIO.  */
+      errno = EIO;
+      return 0;
+    }
+
+  /* Reply describes memory byte by byte,
+     each byte encoded as two hex characters.  */
+
+  p = buf;
+  for (i = 0; i < len; i++)
+    {
+      if (p[0] == 0 || p[1] == 0)
+	/* Reply is short.  This means that we were able to read only part
+	   of what we wanted to.  */
+	break;
+      myaddr[i] = fromhex (p[0]) * 16 + fromhex (p[1]);
+      p += 2;
+    }
+  return i;
+}
+
+/* Read or write LEN bytes from inferior memory at MEMADDR, transferring
+   to or from debugger address MYADDR.  Write to inferior if SHOULD_WRITE is
+   nonzero.  Returns length of data written or read; 0 for error.  */
+
+/* ARGSUSED */
+static int
+remote_xfer_memory(memaddr, myaddr, len, should_write, target)
+     CORE_ADDR memaddr;
+     char *myaddr;
+     int len;
+     int should_write;
+     struct target_ops *target;			/* ignored */
+{
+  int xfersize;
+  int bytes_xferred;
+  int total_xferred = 0;
+
+  while (len > 0)
+    {
+      if (len > MAXBUFBYTES)
+	xfersize = MAXBUFBYTES;
+      else
+	xfersize = len;
+
+      if (should_write)
+        bytes_xferred = remote_write_bytes (memaddr,
+					    (unsigned char *)myaddr, xfersize);
+      else
+	bytes_xferred = remote_read_bytes (memaddr,
+					   (unsigned char *)myaddr, xfersize);
+
+      /* If we get an error, we are done xferring.  */
+      if (bytes_xferred == 0)
+	break;
+
+      memaddr += bytes_xferred;
+      myaddr  += bytes_xferred;
+      len     -= bytes_xferred;
+      total_xferred += bytes_xferred;
+    }
+  return total_xferred;
+}
+
+#if 0
+/* Enable after 4.12.  */
+
+void
+remote_search (len, data, mask, startaddr, increment, lorange, hirange
+	       addr_found, data_found)
+     int len;
+     char *data;
+     char *mask;
+     CORE_ADDR startaddr;
+     int increment;
+     CORE_ADDR lorange;
+     CORE_ADDR hirange;
+     CORE_ADDR *addr_found;
+     char *data_found;
+{
+  if (increment == -4 && len == 4)
+    {
+      long mask_long, data_long;
+      long data_found_long;
+      CORE_ADDR addr_we_found;
+      char buf[PBUFSIZ];
+      long returned_long[2];
+      char *p;
+
+      mask_long = extract_unsigned_integer (mask, len);
+      data_long = extract_unsigned_integer (data, len);
+      sprintf (buf, "t%x:%x,%x", startaddr, data_long, mask_long);
+      putpkt (buf);
+      getpkt (buf, 0);
+      if (buf[0] == '\0')
+	{
+	  /* The stub doesn't support the 't' request.  We might want to
+	     remember this fact, but on the other hand the stub could be
+	     switched on us.  Maybe we should remember it only until
+	     the next "target remote".  */
+	  generic_search (len, data, mask, startaddr, increment, lorange,
+			  hirange, addr_found, data_found);
+	  return;
+	}
+
+      if (buf[0] == 'E')
+	/* There is no correspondance between what the remote protocol uses
+	   for errors and errno codes.  We would like a cleaner way of
+	   representing errors (big enough to include errno codes, bfd_error
+	   codes, and others).  But for now just use EIO.  */
+	memory_error (EIO, startaddr);
+      p = buf;
+      addr_we_found = 0;
+      while (*p != '\0' && *p != ',')
+	addr_we_found = (addr_we_found << 4) + fromhex (*p++);
+      if (*p == '\0')
+	error ("Protocol error: short return for search");
+
+      data_found_long = 0;
+      while (*p != '\0' && *p != ',')
+	data_found_long = (data_found_long << 4) + fromhex (*p++);
+      /* Ignore anything after this comma, for future extensions.  */
+
+      if (addr_we_found < lorange || addr_we_found >= hirange)
+	{
+	  *addr_found = 0;
+	  return;
+	}
+
+      *addr_found = addr_we_found;
+      *data_found = store_unsigned_integer (data_we_found, len);
+      return;
+    }
+  generic_search (len, data, mask, startaddr, increment, lorange,
+		  hirange, addr_found, data_found);
+}
+#endif /* 0 */
+
+static void
+remote_files_info (ignore)
+     struct target_ops *ignore;
+{
+  puts_filtered ("Debugging a target over a serial line.\n");
+}
+
+/* Stuff for dealing with the packets which are part of this protocol.
+   See comment at top of file for details.  */
+
+/* Read a single character from the remote end, masking it down to 7 bits. */
+
+static int
+readchar (timeout)
+     int timeout;
+{
+  int ch;
+
+  ch = SERIAL_READCHAR (remote_desc, timeout);
+
+  switch (ch)
+    {
+    case SERIAL_EOF:
+      error ("Remote connection closed");
+    case SERIAL_ERROR:
+      perror_with_name ("Remote communication error");
+    case SERIAL_TIMEOUT:
+      return ch;
+    default:
+      return ch & 0x7f;
+    }
+}
+
+/* Send the command in BUF to the remote machine,
+   and read the reply into BUF.
+   Report an error if we get an error reply.  */
+
+static void
+remote_send (buf)
+     char *buf;
+{
+
+  putpkt (buf);
+  getpkt (buf, 0);
+
+  if (buf[0] == 'E')
+    error ("Remote failure reply: %s", buf);
+}
+
+/* Send a packet to the remote machine, with error checking.
+   The data of the packet is in BUF.  */
+
+static void
+putpkt (buf)
+     char *buf;
+{
+  int i;
+  unsigned char csum = 0;
+  char buf2[PBUFSIZ];
+  int cnt = strlen (buf);
+  int ch;
+  char *p;
+
+  /* Copy the packet into buffer BUF2, encapsulating it
+     and giving it a checksum.  */
+
+  if (cnt > sizeof(buf2) - 5)		/* Prosanity check */
+    abort();
+
+  p = buf2;
+  *p++ = '$';
+
+  for (i = 0; i < cnt; i++)
+    {
+      csum += buf[i];
+      *p++ = buf[i];
+    }
+  *p++ = '#';
+  *p++ = tohex ((csum >> 4) & 0xf);
+  *p++ = tohex (csum & 0xf);
+
+  /* Send it over and over until we get a positive ack.  */
+
+  while (1)
+    {
+      int started_error_output = 0;
+
+      if (remote_debug)
+	{
+	  *p = '\0';
+	  printf_unfiltered ("Sending packet: %s...", buf2);
+	  gdb_flush(gdb_stdout);
+	}
+      if (SERIAL_WRITE (remote_desc, buf2, p - buf2))
+	perror_with_name ("putpkt: write failed");
+
+      /* read until either a timeout occurs (-2) or '+' is read */
+      while (1)
+	{
+	  ch = readchar (remote_timeout);
+
+	  if (remote_debug)
+	    {
+	      switch (ch)
+		{
+		case '+':
+		case SERIAL_TIMEOUT:
+		case '$':
+		  if (started_error_output)
+		    {
+		      putc_unfiltered ('\n');
+		      started_error_output = 0;
+		    }
+		}
+	    }
+
+	  switch (ch)
+	    {
+	    case '+':
+	      if (remote_debug)
+		printf_unfiltered("Ack\n");
+	      return;
+	    case SERIAL_TIMEOUT:
+	      break;		/* Retransmit buffer */
+	    case '$':
+	      {
+		unsigned char junkbuf[PBUFSIZ];
+
+	      /* It's probably an old response, and we're out of sync.  Just
+		 gobble up the packet and ignore it.  */
+		getpkt (junkbuf, 0);
+		continue;		/* Now, go look for + */
+	      }
+	    default:
+	      if (remote_debug)
+		{
+		  if (!started_error_output)
+		    {
+		      started_error_output = 1;
+		      printf_unfiltered ("putpkt: Junk: ");
+		    }
+		  putc_unfiltered (ch & 0177);
+		}
+	      continue;
+	    }
+	  break;		/* Here to retransmit */
+	}
+
+#if 0
+      /* This is wrong.  If doing a long backtrace, the user should be
+	 able to get out next time we call QUIT, without anything as violent
+	 as interrupt_query.  If we want to provide a way out of here
+	 without getting to the next QUIT, it should be based on hitting
+	 ^C twice as in remote_wait.  */
+      if (quit_flag)
+	{
+	  quit_flag = 0;
+	  interrupt_query ();
+	}
+#endif
+    }
+}
+
+/* Come here after finding the start of the frame.  Collect the rest into BUF,
+   verifying the checksum, length, and handling run-length compression.
+   Returns 0 on any error, 1 on success.  */
+
+static int
+read_frame (buf)
+     char *buf;
+{
+  unsigned char csum;
+  char *bp;
+  int c;
+
+  csum = 0;
+  bp = buf;
+
+  while (1)
+    {
+      c = readchar (remote_timeout);
+
+      switch (c)
+	{
+	case SERIAL_TIMEOUT:
+	  if (remote_debug)
+	    puts_filtered ("Timeout in mid-packet, retrying\n");
+	  return 0;
+	case '$':
+	  if (remote_debug)
+	    puts_filtered ("Saw new packet start in middle of old one\n");
+	  return 0;		/* Start a new packet, count retries */
+	case '#':
+	  {
+	    unsigned char pktcsum;
+
+	    *bp = '\000';
+
+	    pktcsum = fromhex (readchar (remote_timeout)) << 4;
+	    pktcsum |= fromhex (readchar (remote_timeout));
+
+	    if (csum == pktcsum)
+	      return 1;
+
+	    printf_filtered ("Bad checksum, sentsum=0x%x, csum=0x%x, buf=",
+			     pktcsum, csum);
+	    puts_filtered (buf);
+	    puts_filtered ("\n");
+
+	    return 0;
+	  }
+	case '*':		/* Run length encoding */
+	  csum += c;
+	  c = readchar (remote_timeout);
+	  csum += c;
+	  c = c - ' ' + 3;	/* Compute repeat count */
+
+	  if (bp + c - 1 < buf + PBUFSIZ - 1)
+	    {
+	      memset (bp, *(bp - 1), c);
+	      bp += c;
+	      continue;
+	    }
+
+	  *bp = '\0';
+	  printf_filtered ("Repeat count %d too large for buffer: ", c);
+	  puts_filtered (buf);
+	  puts_filtered ("\n");
+	  return 0;
+
+	default:
+	  if (bp < buf + PBUFSIZ - 1)
+	    {
+	      *bp++ = c;
+	      csum += c;
+	      continue;
+	    }
+
+	  *bp = '\0';
+	  puts_filtered ("Remote packet too long: ");
+	  puts_filtered (buf);
+	  puts_filtered ("\n");
+
+	  return 0;
+	}
+    }
+}
+
+/* Read a packet from the remote machine, with error checking,
+   and store it in BUF.  BUF is expected to be of size PBUFSIZ.
+   If FOREVER, wait forever rather than timing out; this is used
+   while the target is executing user code.  */
+
+static void
+getpkt (buf, forever)
+     char *buf;
+     int forever;
+{
+  char *bp;
+  int c;
+  int tries;
+  int timeout;
+  int val;
+
+  if (forever)
+    timeout = -1;
+  else
+    timeout = remote_timeout;
+
+#define MAX_TRIES 10
+
+  for (tries = 1; tries <= MAX_TRIES; tries++)
+    {
+      /* This can loop forever if the remote side sends us characters
+	 continuously, but if it pauses, we'll get a zero from readchar
+	 because of timeout.  Then we'll count that as a retry.  */
+
+      /* Note that we will only wait forever prior to the start of a packet.
+	 After that, we expect characters to arrive at a brisk pace.  They
+	 should show up within remote_timeout intervals.  */
+
+      do
+	{
+	  c = readchar (timeout);
+
+	  if (c == SERIAL_TIMEOUT)
+	    {
+	      if (remote_debug)
+		puts_filtered ("Timed out.\n");
+	      goto retry;
+	    }
+	}
+      while (c != '$');
+
+      /* We've found the start of a packet, now collect the data.  */
+
+      val = read_frame (buf);
+
+      if (val == 1)
+	{
+	  if (remote_debug)
+	    fprintf_unfiltered (gdb_stderr, "Packet received: %s\n", buf);
+	  SERIAL_WRITE (remote_desc, "+", 1);
+	  return;
+	}
+
+      /* Try the whole thing again.  */
+retry:
+      SERIAL_WRITE (remote_desc, "-", 1);
+    }
+
+  /* We have tried hard enough, and just can't receive the packet.  Give up. */
+
+  printf_unfiltered ("Ignoring packet error, continuing...\n");
+  SERIAL_WRITE (remote_desc, "+", 1);
+}
+
+static void
+remote_kill ()
+{
+  putpkt ("k");
+  /* Don't wait for it to die.  I'm not really sure it matters whether
+     we do or not.  For the existing stubs, kill is a noop.  */
+  target_mourn_inferior ();
+}
+
+static void
+remote_mourn ()
+{
+  unpush_target (&remote_ops);
+  generic_mourn_inferior ();
+}
+
+#ifdef REMOTE_BREAKPOINT
+
+/* On some machines, e.g. 68k, we may use a different breakpoint instruction
+   than other targets.  */
+static unsigned char break_insn[] = REMOTE_BREAKPOINT;
+
+/* Check that it fits in BREAKPOINT_MAX bytes.  */
+static unsigned char check_break_insn_size[BREAKPOINT_MAX] = REMOTE_BREAKPOINT;
+
+#else /* No REMOTE_BREAKPOINT.  */
+
+/* Same old breakpoint instruction.  This code does nothing different
+   than mem-break.c.  */
+static unsigned char break_insn[] = BREAKPOINT;
+
+#endif /* No REMOTE_BREAKPOINT.  */
+
+/* Insert a breakpoint on targets that don't have any better breakpoint
+   support.  We read the contents of the target location and stash it,
+   then overwrite it with a breakpoint instruction.  ADDR is the target
+   location in the target machine.  CONTENTS_CACHE is a pointer to 
+   memory allocated for saving the target contents.  It is guaranteed
+   by the caller to be long enough to save sizeof BREAKPOINT bytes (this
+   is accomplished via BREAKPOINT_MAX).  */
+
+static int
+remote_insert_breakpoint (addr, contents_cache)
+     CORE_ADDR addr;
+     char *contents_cache;
+{
+  int val;
+
+  val = target_read_memory (addr, contents_cache, sizeof break_insn);
+
+  if (val == 0)
+    val = target_write_memory (addr, (char *)break_insn, sizeof break_insn);
+
+  return val;
+}
+
+static int
+remote_remove_breakpoint (addr, contents_cache)
+     CORE_ADDR addr;
+     char *contents_cache;
+{
+  return target_write_memory (addr, contents_cache, sizeof break_insn);
+}
+
+/* Define the target subroutine names */
+
+struct target_ops remote_ops = {
+  "remote",			/* to_shortname */
+  "Remote serial target in gdb-specific protocol",	/* to_longname */
+  "Use a remote computer via a serial line, using a gdb-specific protocol.\n\
+Specify the serial device it is connected to (e.g. /dev/ttya). or telnet port",  /* to_doc */
+  remote_open,			/* to_open */
+  remote_close,			/* to_close */
+  NULL,				/* to_attach */
+  remote_detach,		/* to_detach */
+  remote_resume,		/* to_resume */
+  remote_wait,			/* to_wait */
+  remote_fetch_registers,	/* to_fetch_registers */
+  remote_store_registers,	/* to_store_registers */
+  remote_prepare_to_store,	/* to_prepare_to_store */
+  remote_xfer_memory,		/* to_xfer_memory */
+  remote_files_info,		/* to_files_info */
+
+  remote_insert_breakpoint,	/* to_insert_breakpoint */
+  remote_remove_breakpoint,	/* to_remove_breakpoint */
+
+  NULL,				/* to_terminal_init */
+  NULL,				/* to_terminal_inferior */
+  NULL,				/* to_terminal_ours_for_output */
+  NULL,				/* to_terminal_ours */
+  NULL,				/* to_terminal_info */
+  remote_kill,			/* to_kill */
+  generic_load,			/* to_load */
+  NULL,				/* to_lookup_symbol */
+  NULL,				/* to_create_inferior */
+  remote_mourn,			/* to_mourn_inferior */
+  0,				/* to_can_run */
+  0,				/* to_notice_signals */
+  process_stratum,		/* to_stratum */
+  NULL,				/* to_next */
+  1,				/* to_has_all_memory */
+  1,				/* to_has_memory */
+  1,				/* to_has_stack */
+  1,				/* to_has_registers */
+  1,				/* to_has_execution */
+  NULL,				/* sections */
+  NULL,				/* sections_end */
+  OPS_MAGIC			/* to_magic */
+};
+
+void
+_initialize_remote ()
+{
+  add_target (&remote_ops);
+}