vkernel & GSoC, some questions

Matthew Dillon dillon at apollo.backplane.com
Tue Mar 18 18:06:41 UTC 2008

:We use VMWare Server at work. It does not have the same nice image management interface and/or video capture as commercial counterparts. However, it is is free and testing on it helps us out big time. We never concluded whether it maked sense to pay for VMWare licenses, instead of using free shell scripts legally available for free.
:I have used UML for development in the past. I even used bochs once to debug a boot loader. All nice tools. Beats real hardware for me.
:Xen and KVM are significantly slower than commercial products due to hardware switching. There is a GPLed product that works about as fast as VMWare's BT - VirtualBox by innotek. Sun recently scooped them up.

    You've tried them all pretty much.  VirtualBox is the only one that's
    actually open-source (well, bochs is too but bochs is a full simulator
    and unusably slow).  VB is very nicely documented too, though I get a 
    headache trying to read all that C++.   I know several people using
    VB on linux host systems.

    The reason I ask is simply because I am trying to point out *the* major
    issue for open-source systems when it comes to hardware virtualization,
    that being the availability of an open-source solution.  I have never
    trusted VMWare to maintain compatibility with any longevity.  VB has
    a better chance and even though it is hard to gauge what Sun will do
    with it, I'd rather it be Sun then MS.

:Don't you use something like VMWare for development and debugging?

    We use vkernel's for development and debugging.  Pretty much everything
    except hardware device driver development can be done using a vkernel
    and being able to gdb the kernel binary (gdb, not kgdb) on a whim is
    rather nice.  Kinda hard to beat a 5-second reboot, it makes the
    engineering test cycle almost as short as hitting ^C and re-running a
    program.  I don't even bother to do a clean halt of the vkernel most of
    time, I just pop it into it's DDB with ctl-\ and then kill it with ^C,
    then restart.

    One interesting side-effect of having a vkernel so easily accessible
    is that it opens up kernel development to normal programmers.  More
    DragonFly developers have been dipping their fingers into the kernel
    code in the last 6 months then in all the time before then.  That alone
    justifies the time spent doing it.  Except for hardware device driver
    development, the agonizing engineering cycle for kernel development
    is completely gone now.


:In production, we don't use any of these products - too slow and too much RAM would be required.
:Igor Shmukler, http://www.elusiva.com

More information about the freebsd-hackers mailing list