Re: FreeBSD/s390 port (was: single user vs multiuser boot)

At 12:33 AM +0000 2/18/05, Alex Burke wrote:
>Hi,
>
>I was wondering what gives the kernel the ability to boot in
>multiuser mode, and whether it is some code in the kernel or
>whether it is the init process and associated tools?

http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/kern/init_main.c

is the part of the kernel which decides to execute the program
which is in /sbin/init.

http://www.freebsd.org/cgi/cvsweb.cgi/src/sbin/init/init.c

is the init program.  This is the program which notices you
requested 'boot -s', and it decides whether to go into
multi-user mode, or if it should ask you:

   "Enter full pathname of shell or RETURN for /bin/sh: "

So, if you're seeing that prompt when the system goes into
single-user mode, then you could check that source file to
see what it does for multi-usermode.

>As a follow-up question, if the kernel for a new architecture
>can already boot in single user mode, would it be just a matter
>of compiling init and those tools for that particular
>architecture to get the kernel to run in multiuser mode?

I'm afraid I have no idea how much additional work it would take
to get from single-user mode to multi-user mode.

>The reason I ask these questions is that I would like to continue
>work on the FreeBSD/390 port. I have a mini mainframe (P/390) which
>I could use to test the code on real hardware, and I'd much rather
>use FreeBSD/390 than Linux/390 on the little box!

About how much does it cost to buy a mini-Mainframe ?

>Since I cant write kernel code yet, I was going to try compiling
>init and the shared libraries as 390 code and try to get the
>system booting further (it would have to be a memory based
>filesystem mounted as root, I don't think a driver for mainframe
>CKD or FBA disk exists yet).

The last update I saw about the s390 port was:

    > Reaches mount root prompt in emulator.
    >
    > More info is on http://tzukanov.narod.ru/freebsd390/

Note:  Right now that web page says the project for a s390 port
is dead, but maybe someone else has picked up on it.  It does
include more info and pointers.  Also note that even though it
may get to single-user mode when running in an emulator, that
does not necessarily mean it will get to single-user mode on
real hardware.

>I was thinking eventually of porting linux 390 drivers to FreeBSD,
>but I am not sure if licensing issues come into that.

They do.

>Apologies if i have posted to the wrong mailing list, i am not
>sure what this comes under.

I am also have no idea if any work is being done on a s390 port.
It was never far enough along to have its own mailing list yet,
so this is probably a reasonable mailing list to ask about it.

-- 
Garance Alistair Drosehn            =   gad_at_gilead.netel.rpi.edu
Senior Systems Programmer           or  gad_at_freebsd.org
Rensselaer Polytechnic Institute    or  drosih_at_rpi.edu