Re: G packet format ...

[Daniel Jacobowitz <drow at mvista dot com>]

On Mon, Nov 12, 2001 at 12:24:04AM -0500, Andrew Cagney wrote:
> Hello,
> 
> For those that don't know, GDB's remote protocol G packet currently 
> determins the layout of GDB's internal register cache.  Doh!

Indeed.

> NB: Why do this?
> 
> The objective is to decouple the remote protocol's G packet from the 
> rest of GDB.  That way, GDB has greater flexability in how it implements 
> its regcache.  For instance, with the MIPS, it will be possible to have 
> a single internal register layout while still being able to connect to 
> all the remote MIPS targets.

I guess I posted my gdbserver register cache patch before I converted
it to generate them from a shell script.  Here's what I've been using. 
I didn't consider the issue of only-transferable-in-P-packet registers
(and I still don't see a good reason... well, maybe I can come up with
one, actually.  Things that react when read.).

Here's an example and a shell script; ideally these would be built into
an archive and then linked to both gdb and gdbserver.  Possibly
autogenerate a manual chapter from them?  Should not be hard.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer

/* *INDENT-OFF* */ /* THIS FILE IS GENERATED */

/* A register protocol for GDB, the GNU debugger.
   Copyright 2001 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/* This file was created with the aid of ``regdat.sh'' and ``dat/reg-i386.dat''.  */

struct reg regs_i386[] = {
  { "eax", 0, 4 },
  { "ecx", 4, 4 },
  { "edx", 8, 4 },
  { "ebx", 12, 4 },
  { "esp", 16, 4 },
  { "ebp", 20, 4 },
  { "esi", 24, 4 },
  { "edi", 28, 4 },
  { "eip", 32, 4 },
  { "eflags", 36, 4 },
  { "cs", 40, 4 },
  { "ss", 44, 4 },
  { "ds", 48, 4 },
  { "es", 52, 4 },
  { "fs", 56, 4 },
  { "gs", 60, 4 },
  { "st0", 64, 10 },
  { "st1", 74, 10 },
  { "st2", 84, 10 },
  { "st3", 94, 10 },
  { "st4", 104, 10 },
  { "st5", 114, 10 },
  { "st6", 124, 10 },
  { "st7", 134, 10 },
  { "fctrl", 144, 4 },
  { "fstat", 148, 4 },
  { "ftag", 152, 4 },
  { "fiseg", 156, 4 },
  { "fioff", 160, 4 },
  { "foseg", 164, 4 },
  { "fooff", 168, 4 },
  { "fop", 172, 4 },
  { "xmm0", 176, 16 },
  { "xmm1", 192, 16 },
  { "xmm2", 208, 16 },
  { "xmm3", 224, 16 },
  { "xmm4", 240, 16 },
  { "xmm5", 256, 16 },
  { "xmm6", 272, 16 },
  { "xmm7", 288, 16 },
  { "mxcsr", 304, 4 },
};

const char *resume_regs_i386 = { "ebp", "esp", "eip", 0 };

<snip here>


#!/bin/sh -u

# Register protocol definitions for GDB, the GNU debugger.
# Copyright 2001 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

move_if_change ()
{
    file=$1
    if test -r ${file} && cmp -s "${file}" new-"${file}"
    then
	echo "${file} unchanged." 1>&2
    else
	mv new-"${file}" "${file}"
	echo "${file} updated." 1>&2
    fi
}

# Format of the input files
read="type entry"

do_read ()
{
    type=""
    entry=""
    while read line
    do
	if test "${line}" = ""
	then
	    continue
	elif test "${line}" = "#" -a "${comment}" = ""
	then
	    continue
	elif expr "${line}" : "#" > /dev/null
	then
	    comment="${comment}
${line}"
	else

	    # The semantics of IFS varies between different SH's.  Some
	    # treat ``::' as three fields while some treat it as just too.
	    # Work around this by eliminating ``::'' ....
	    line="`echo "${line}" | sed -e 's/::/: :/g' -e 's/::/: :/g'`"

	    OFS="${IFS}" ; IFS="[:]"
	    eval read ${read} <<EOF
${line}
EOF
	    IFS="${OFS}"

	    # .... and then going back through each field and strip out those
	    # that ended up with just that space character.
	    for r in ${read}
	    do
		if eval test \"\${${r}}\" = \"\ \"
		then
		    eval ${r}=""
		fi
	    done

	    break
	fi
    done
    if [ -n "${type}" ]
    then
	true
    else
	false
    fi
}

if test ! -r $1; then
  echo "$0: Could not open $1." 1>&2
  exit 1
fi

copyright ()
{
cat <<EOF
/* *INDENT-OFF* */ /* THIS FILE IS GENERATED */

/* A register protocol for GDB, the GNU debugger.
   Copyright 2001 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/* This file was created with the aid of \`\`regdat.sh'' and \`\`$1''.  */

EOF
}


exec > new-$2
copyright
offset=0
i=0
name=x
resume=x
exec < $1
while do_read
do
  if test "${type}" = "name"; then
    name="${entry}"
    echo "struct reg regs_${name}[] = {"
    continue
  elif test "${type}" = "resume"; then
    resume="${entry}"
    continue
  elif test "${name}" = x; then
    echo "$0: $1 does not specify \`\`name''." 1>&2
    exit 1
  else
    echo "  { \"${entry}\", ${offset}, ${type} },"
    offset=`expr ${offset} + ${type}`
    i=`expr $i + 1`
  fi
done

echo "};"
echo
echo "const char *resume_regs_${name} = { \"`echo ${resume} | sed 's/,/", "/g'`\", 0 };"

# close things off
exec 1>&2
move_if_change $2