Bochs

Introduction

Bochs [1] is a processor emulator. It can be used as a virtual PC to test your OS.

Run bochs

You can configure bochs to run from a floppy image. Some required settings:

floppya: image=bootdisk.img, status=inserted
boot: floppy

Next run bochs:

$ bochs -q

You will see bochs boot and the emulated x86 PC is displayed:

The debug screen

Enable the GUI debugger by using the following in the configuration file bochsrc.txt (note that this feature is not always compiled in):

display_library: x, options="gui_debug"

Now a debug window show up:

Breakpoints

Insert into bochsrc.txt:

magic_break: enabled=1

Now bochs will brake when the instruction:

xchg bx, bx

which does nothing, but bochs detects this and stops and enters the debugger.

References

[1] Bochs