How much of microkernel?

Matthew Dillon dillon at
Tue Aug 22 10:00:07 PDT 2006

:Hi Matt,
:I've always been a fan of microkernel design and I would like to know 
:how much towards microkernel design do you have plans to go with 
:DragonFly? I know you will be incorporating VFS into userland which is 
:normally a feature of a microkernel, but where do you wanna go after 
:that, in regards to microkernelizing DragonFly? Drivers? TCP/IP? other 
:Cheers and good luck programming! :)

    Well, DragonFly is definitely not a microkernel.  We forked off of
    FreeBSD, after all, and that is a fairly monolithic kernel.  I like
    the microkernel concept but putting core elements of an operating
    system into their own protection boxes result in fairly significant
    performance issues.

    That said, in order to reach our clustering goals we will have to
    be able to operate most major kernel operations, such as devices and
    filesystems, over a communications protocol as well as natively.  This
    infrastructure will make it possible to implement devices and filesystems
    as user processes and thus become more microkernel-like.

    Personally I think that non-performance-oriented devices really should
    be run from their own sandboxes.  There is no real need to have
    msdosfs built into the kernel, for example.  But devices for which
    performance is important probably ought to stay in the kernel.

					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>

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