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zynamics Bochs Python Instrumentation Patch has moved to Google Code

This repository has moved to Google Code:

This patch for Bochs provides a Python interpreter instead of Bochs' own
debugger, yet still providing the debugger functionality.  It also
allows to interact with the instrumentation interface on-demand, by
dynamically associating Python methods to handle instrumentation events.


The patch has been testes mostly tested under a Linux environment but
there should not be any limitations preventing it from working wherever
Bochs compiles.

We will attempt to release a working patch for every single public
release of Bochs.  Usually the patches tend to work for a while on the
CVS version without modification.


-Grab the Bochs source code version corresponding to the patch

-Apply the patch.  Go into the directory containing Bochs' source code
and run:

  patch -p1 < ../bochs_python-XXXXX.diff

Adjust it accordingly to match the location/name of the patch

-Run: autoconf

-Run: "./configure --enable-debugger
  --enable-instrumentation=python_hooks" Other recommended options are:
    --enable-x86-debugger --enable-all-optimizations
    --enable-show-ips --enable-fast-function-calls
    --enable-host-specific-asms --enable-fpu --enable-pci
    --enable-cpu-level=6 --enable-vbe

Depending on your environment you might want to disable some of the
graphic front-ends:

  --without-sdl --without-x11 --without-x --without-wx

or enable others such as: --with-nogui

-Run: make


If the patching and compiling ran correctly a bochs binary should have
been produced.  This version will sport a interactive Python command
line instead of the standard Bochs debugger, exhibiting the Bochs
debugger functionality as well as additional one through different
modules in the Python interpreter namespace.

The methods available under module "bx" will provide most of the
original debugger's functionality.

For instance, the "cont" command, to resume execution, will be exposed
as bx.cont().  Similarly, "stepN <cpu> <number>" is available as
bx.stepN(cpu, number).

Running dir(bx) on the Python interpreter command line will show the
methods and attributes available through the "bx" module.

The "cpu" module will provide means of writing and reading to/from the
CPU registers.  The module consists of the get() and set() methods plus
all the register constants to pass to those methods.

  cpu.get(cpu.EAX) # returns the value of EAX
  cpu.set(cpu.EAX, value) # assigns to EAX a given value.  Any register
                          # should be available, even EIP

(Same applies for 64-bit registers)

The "dbg" module encapsulates extra functionality allowing to set
callbacks for Bochs' powerful instrumentation interface.  As an example,
in order to read 1KiB of virtual memory starting from the address
contained in EIP:

  mem_at_eip = dbg.read_memory_block_linear(cpu.get(cpu.EIP), 1024)

To hook the "new instruction" instrumentation call and memory access

  dbg.set_callback(dbg.INSTR_NEW_INSTRUCTION, method1)
  dbg.set_callback(dbg.INSTR_MEM_DATA, method2)

Where method1 y method2 are Python methods.  The methods will take the
same parameters as specified in the instrumentation interface in Bochs.

To capture interrupts:

  dbg.set_callback(dbg.INSTR_INTERRUPT, do_int)

The method should take two arguments: "def do_int(cpu_number,

For "dbg.set_callback(dbg.INSTR_NEW_INSTRUCTION, method1)" method1 would

  def method1(cpu_num): 
    print cpu_num, hex(cpu.get(cpu.EIP))

For "dbg.set_callback(dbg.INSTR_MEM_DATA_ACCESS, method2)" method2 would
look like:

  def method2(cpu_number, segment, offset, length, mode_rw):
    print cpu_number, segment, hex(offset), length, mode_rw

The methods installed through "set_callback" will be called every time
the corresponding event takes place.  To reset a callback suffices to
pass None as the method.


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