Hi Folks,

  Please allow me to submit my first patch set. The main purpose is to allow a 
32bit dom0 to support debug of a 64bit guest via gdbserver-xen. This also 
fixes gdbserver-xen not attaching to a 32 PAE guest.

Description:
  At present libxc and gdbserver-xen are compiled on the same architecture 
that dom0 is, ie, 32bit or 64bit. As a result, when 32bit binary is run on 
dom0 to attach to a 64bit guest, the data structures are incorrect, and the 
process fails. This patch addresses that by :

    - introducing a new compiler directive, _GDB_CROSS_COMP that will create a 
32bit binary on an x86_64 system (by using -m32).

    - including x86_64 data structures if the above is defined.

    - changing long's to long long's in relevant cases if the above is defined.

    - linking libxc statically to the gdbserver-xen binary if above is defined.

The process is explained in the debugger/gdb/README file. The patch set is 
divided in three parts:
    - part 0 : description + libxc/xen related changes
    - part 1 : files changed in gdbserver xen-sparse tree.
    - part 2 : new files in gdbserver xen-sparse tree.

Please note, to achieve the above, an ifdef had to be added to user.h. This 
forced it to be copied locally. As a result, files that included this header, 
had also to be created/copied in the xen-sparse tree from the gdbserver tree 
to include local user.h.

Finally, mkbuildtree fixes "find" warning in the new version, and is not 
related to the patch objectives.


In summary, files changed are:
  config/x86_64.mk
  tools/libxc/xc_ptrace.c
  tools/libxc/xenctrl.h
  tools/libxc/xc_ptrace.h
  tools/libxc/xg_private.h
  xen/include/public/arch-x86/xen.h
  xen/include/public/arch-x86/xen-x86_32.h
  xen/include/public/foreign/mkheader.py
  xen/include/public/domctl.h

  tools/debugger/gdb/gdb-6.2.1-xen-sparse/gdb/gdbserver/linux-xen-low.c
  tools/debugger/gdb/gdb-6.2.1-xen-sparse/gdb/gdbserver/Makefile.in
  tools/debugger/gdb/gdb-6.2.1-xen-sparse/mkbuildtree
  tools/debugger/gdb/gdbbuild
  tools/debugger/gdb/README

  tools/debugger/gdb/gdb-6.2.1-xen-sparse/gdb/gdbserver/linux-x86-64-low.c
  tools/debugger/gdb/gdb-6.2.1-xen-sparse/gdb/gdb_proc_service.h
  tools/debugger/gdb/gdb-6.2.1-xen-sparse/gdb/amd64-linux-nat.c
  tools/debugger/gdb/gdb-6.2.1-xen-sparse/gdb/linux-proc.c
  tools/debugger/gdb/gdb-6.2.1-xen-sparse/bfd/elf.c
  tools/debugger/gdb/gdb-6.2.1-xen-sparse/include/user.h


Testing:
    After the above patch, I was able to build three binaries and attach to 
32bit, 32bit PAE, and 64bit guests on a 32bit dom0, and was able to set 
breakpoints, see stacks, step, walk the task list, and set correct 32bit/64bit 
values for global long variables.

Thanks a lot,
Mukesh Rathor