Vmware was Re: Announcing shell machine availability for dragonfly developers

Kip Macy kmacy at fsmware.com
Fri Aug 29 08:06:33 PDT 2003

This is extremely interesting, particularly the apart about
dynamic translation, a la VirtualPC. There are so many cool
projects out there and I have so little spare time :-).
I just wanted to ask what additional debugging benefit it provides
to an OS like FreeBSD that has a gdb stub by default. VMWare allows
one to map a serial port on the virtual machine to either a serial
port on one's physical machine or to a fifo. One can attach to it
with gdb just as one could on real hardware. From a quick look at
QEMU's docs it appears that QEMU's main additional benefit comes
from it providing its own gdb stub. That seems like it would be
primarily useful for an OS that (unpatched) _doesn't_ have one, e.g.

Also take a look at QEMU, which uses dynamic translation to
virtualise the system.  QEMU achieves around 25% of native
speed, despite being fully emulated...
It also makes it way easier to debug a kernel then using eg.
vmware, because you can more easily look inside the qemu
virtual machine.  The disadvantage is that QEMU doesn't yet
do full MMU emulation, which means you need to build a
special kernel to use with QEMU (different address space
layout, but that's basically it).


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