Porting time [was Re: AVR port?]

On Fri, 31 May 2002, der Mouse wrote:
[...]
> >   + roughly, how many hours/days/months/years does an average port
> >     require?
>
> I'm not sure there is such a thing. :-)  I've never done the "second"
> step, above, so I can't speak to that.  If I were handed the task, and
> if some port already supports the CPU and MMU, and I had complete
> hardware doc, I would allow one full-time person-month for the port,
> plus another for dealing with unexpected gotchas along the way.
>
> But that assumes a lot of the work is already done (the gcc port, and
> the CPU/MMU support).  While I'm relatively familiar with the kernel,
> I've never done a full port, so I could well be way off, either way -
> but I've not seen anyone with more authoritative knowledge respond to
> this part....
>
[...]

Here's one data point: about 3 person-months to get NetBSD to the point
where it will boot from flash, run at least one user program in VM, and
allow someone else to port TCP/IP on ethernet.

These are the start conditions:
- Start out clueless about NetBSD, but know something about other kernels.
- Have a working gcc and tools.
- new (to *BSD) CPU and MMU.
- pretty good HW docs and sample code.

--Glenn S.