Subject: Re: Porting NetBSD to Sega Dreamcast / 200MHz SH4
To: None <>
From: None <>
List: port-sh3
Date: 06/30/2000 11:08:16
Hey Sonikku, 

I just joined the list yesterday, and what's the first
message that I see but yours asking "How possible is it that NetBSD *could*
be compiled for the Dreamcast?"

Well, I'm (slowly) working on it.  So far I have the start of a cross-
development environment done. I have gcc and the gnu binutils compiled
to produce SH binaries.  There were a couple of minor problems which I
had to solve before I got them to work under OpenBSD 2.6.  My next step
is to grab the crt0.a from the NetBSD/sh3 port and try using it.

It's not a matter of "could", because there is no doubt that it _can_ 
be done. It's a matter of deciding exactly _how_ to do it. 
Thank you very much for the URL's in your post.  They contain invaluable
information, and confirm many suspicions that I had, such as the DC's
ability to boot from a normal ISO-9660 session, rather than only from a
GDROM.  I surmised this last year, but had no way of testing it.

> it *should* be possible and perhaps not even VERY dificult, as I believe
> the SH4 is backwards compatible with the SH3 to a certain degree.

Yes, the SH-4 is a superset of the SH-3, so code should run unmodifed on
the SH-4 unless it uses SH-3 features that are necessarily changed on the
SH-4, such as MMU control registers.  gcc and gas support both sh3 and sh4
as targets. 

Now that we have (1) a means to boot the Dreamcast to our own code, from 
CD-R, and (2) a means to load code from the PC via the serial port for
testing, and (3) a cross-development system, work should proceed more 
quickly towards getting BSD/DC going.   While I'm initally concentrating
on OpenBSD as a target, NetBSD should be a simple matter of using the 
NetBSD source tree instead of the OpenBSD source.

> 56k Hardware Modem (US model LAN/DSL/etc adaptors available soon)

Yes, I'm looking forward to the 10BaseT adaptor for the DC. 
It will turn the DC into a diskless workstation.  And when 
the DC ZIP Disk unit comes out, the system will be complete.

> 4 Controller Inputs (of use to this port, a Keyboard is available and a
> mouse will be shortly)

The controller inputs are each a dual serial bus.  Each bus runs at
1.0 megabit per second, and uses a packetized protocol with Manchester
encoding.  They are versatile, much like a USB port.  Besides keyboards,
game controllers, and smart memory cards (VMU), there are microphones and 
cameras for them. 
> Certainly seem's it could handle it, from a hardware point of view. Any
> thoughts?

A sun 3/60 can run SunOS 4.1 or NetBSD with X11 just fine, in 16 MB of
memory and diskless, so the DC won't have any problem handling it either.

 - William -  (spuug)