[Unix-jun72] UNIX V1 bootstrap

[Unix-jun72] UNIX V1 bootstrap

[James A. Markevitch]

I've ported the bootstrap stuff over the whole UNIX V1 build process.
(Note: it would be nice to have a V1 as, so that all of these hacks
we've been doing can go away).

I'll send out the .tar.gz under a separate e-mail, but it's small enough (10K)
and I don't know who's in which timezone, so somebody should be able
to commit it.

There are two versions included: one that copies the bootstrap into
the rf0.dsk image before running the simulator, and one that runs
native under V1.  Given that, if someone builds the kernel using
as under V1, they can use the usr/boot/msys command to install it
without leaving the simulation.

The good news is that you can use that to copy your test kernel into
the cold boot area and if it fails, can re-start the simulator from
the warm boot area and not lose any of your filesystem (assuming your
bad kernel didn't trash it, of course).

I also have a boot command, but haven't tested it yet.  It could be
used to reboot without leaving the simulation.  That's fine if your
kernel works, of course.

James Markevitch

[Unix-jun72] UNIX V1 bootstrap

[Tim Newsham]

> I've ported the bootstrap stuff over the whole UNIX V1 build process.
> (Note: it would be nice to have a V1 as, so that all of these hacks
> we've been doing can go away).

Did you write bos.s and msys.s from scratch?   I noticed your
wunix contains no header, just the binary bits.  Was this standard
procedure in other versions of unix or is it possible that
the msys program took in an 0405 or 0407 and stripped the header
off before writing it?  Is there an easy way to strip the header
from within the unix system with standard commands?

> James Markevitch

Tim Newsham
http://www.thenewsh.com/~newsham/

[Unix-jun72] UNIX V1 bootstrap

[James A. Markevitch]

> > I've ported the bootstrap stuff over the whole UNIX V1 build process.
> > (Note: it would be nice to have a V1 as, so that all of these hacks
> > we've been doing can go away).
> 
> Did you write bos.s and msys.s from scratch?   I noticed your
> wunix contains no header, just the binary bits.  Was this standard
> procedure in other versions of unix or is it possible that
> the msys program took in an 0405 or 0407 and stripped the header
> off before writing it?  Is there an easy way to strip the header
> from within the unix system with standard commands?

I wrote bos.s and msys.s from scratch.  I am not aware of any binaries
or source for these.

bos is written in an entirely position-independent manner so that it can be
compiled with a v1 assembler, v2 assembler, etc. and still run when loaded
at location 54000 in core.  Other than the option to load a paper tape, I
believe this to be as true to V1 as possible.

msys was implemented to be as true to V1 as I believed possible.  It copies
images directly from disk without modifying them, as I believe the original
V1 msys did.  There is no header kludging, since a V1 a.out UNIX kernel
should be bootable without modification.

For wunix (warm unix), I took the build/loadfile, stripped off the
first 6 bytes, then copied the next 16K bytes, just as the boot/installboot
script does.

For building under UNIX itself, there are a variety of strategies.  Here
is my list, in order of preference:

1. Use the V1 assembler.  This will produce a 12-byte header that is
exactly compatible with the kernel source as it appears in the listing.  As
many people on this are aware, the first 12 bytes get manually patched
by the UNIX code when it starts up.  But, I don't think the V1 assembler
exists anywhere, or at least not that has been found.  That kind of makes
this option moot.

2. Modify the V2 assembler to produce V1 binaries.  If the V2 assembler
can be built from sources, then it should be straighforward to edit it
to produce V1 binaries (i.e. 405 instead of 407).  This would allow a
kernel in the true spirit of V1 to be created, then copied into the
boot area by msys.  It would also allow other programs to all be created
as V1 binaries, which has a lot of attraction to me.

3. Modify msys.s to be msys2.s to strip the 407 header and also truncate
the copy to not overrun the size of the area being copied into (1K, 6K,
6K, 3K).  I just tested a modified version of this and attached it below,
since that should help to get things going; but I really think that
option #2 would be nice to have eventually.

Note to use msys2, you need to copy build/a.out to fs/usr/boot/unix.out,
and to put msys2.s into fs/usr/boot/msys2.s.  Then after you boot, do:
	chdir /usr/boot
	as msys2.s
	mv a.out msys2
	msys2 u unix.out
I'll clean up the source and send a complete fs/usr/boot out later
tonight.

James Markevitch

--------------------------- fs/usr/boot/msys2.s -------------------------
/ msys2 -- copy file to RF read only slot
/
/ re-creation, based on description in UNIX_ProgammersManual_Nov71.pdf,
/ page 7-06, BOOT PROCEDURES (VII)
/ 5/9/08 jam at magic.com
/ 5/17/08 jam at magic.com -- hacked to copy 407-format a.out files

/ b bos		1700
/ u warm unix	1704
/ 1 cold unix	1734
/ 2 unassigned	1764

	mov	sp,r5
	mov	(r5)+,r3	/ argc
	cmp	$3,r3		/ must be 3
	bne	badcmd		/ else error
	tst	(r5)+
	mov	(r5)+,r4	/ get first arg

	cmpb	(r4),$'b
	bne	1f
	mov	$1700,r3
	mov	$4,r4
	br	2f
1:
	cmpb	(r4),$'u
	bne	1f
	mov	$1704,r3
	mov	$30,r4
	br	2f
1:
	cmpb	(r4),$'1
	bne	1f
	mov	$1734,r3
	mov	$30,r4
	br	2f
1:
	cmpb	(r4),$'2
	bne	badcmd
	mov	$1764,r3
	mov	$14,r4
2:

	/ open file
	mov	(r5),r5
	mov	r5,0f
	sys	open; 0:..; 0
	bes	error
	mov	r0,r1
	sys	seek; 20; 0
	bes	error

	/ open rf0 and seek to correct block
	sys	open; disk; 1
	bes	error
	mov	r0,r2
	mov	r3,0f
	sys	seek; 0:..; 0
	bes	error

	/ copy file from file to disk one block at a time
1:
	mov	r1,r0
	sys	read; buf; 512.
	mov	r0,r5
	mov	r2,r0
	sys	write; buf; 512.
	bes	error
	dec	r4
	beq	3f
	tst	r5
	bne	1b

3:
	sys	exit

error:
	mov	$1,r0
	sys	write; 1f; 2
	4
	sys	exit
1:
	<?\n>

badcmd:
	mov	$1,r0
	sys	write; 1f; 2
	4
	sys	exit
1:
	<?\n>

disk:
	</dev/rf0\0>
	.even

buf:	.=.+512.

[Unix-jun72] UNIX V1 bootstrap

[Warren Toomey]

On Sat, May 17, 2008 at 06:04:48PM -0700, James A. Markevitch wrote:
> For building under UNIX itself, there are a variety of strategies.  Here
> is my list, in order of preference:
> 
> 2. Modify the V2 assembler to produce V1 binaries.

I'm going to take a "devil's advocate" stance here, and argue to keep the
existing "as" binary untouched.

We have a bunch of userland executables which come from a point in time
after V1, including "as" and the C compiler. While we have kernel source
which is V1 on paper, we already have had to modify it to suit the userland
tools and the simulator. We will never get to a "pure V1" setup, so I would
prefer to see us aim for a "just after V1" system.

I'm fairly confident that, as V1 morphed into V2, they kept support for
0405 and 0407 in the kernel, but migrated the tools and boot chain towards
0407. Given we can't get back to pure V1, it would not hurt for us to have a
boot chain which can deal with 0407 headers.

Cheers,
	Warren

[Unix-jun72] UNIX V1 bootstrap

[Doug Merritt]

Warren wrote:
> I'm going to take a "devil's advocate" stance here, and argue to keep the
> existing "as" binary untouched.

As first priority, certainly. We want to preserve original
data for posterity.

As second priority, there may be several possibilities.

A best-guess reconstruction of an approximation of V1
is one such additional possibility. Interpolation based
on noisy data sources is a time honored practice -- as
long as one carefully differentiates the results from
pristinely clean data.

I don't see one kind of reconstruction as inherently better
or worse than another kind; it depends on what the goal is.

I think Apout, for instance, is a *really* nice variation
on the usual approach of a closed-world simulation.

And certainly there are sharp limits on what we have available
right *now*, but I would be quite cautious about saying "never".
Additional data sources may become available; who knows.
	Doug
--
Professional Wild-eyed Visionary        Member, Crusaders for a Better Tomorrow

[Unix-jun72] UNIX V1 bootstrap

[James A. Markevitch]

> > For building under UNIX itself, there are a variety of strategies.  Here
> > is my list, in order of preference:
> > 
> > 2. Modify the V2 assembler to produce V1 binaries.
> 
> I'm going to take a "devil's advocate" stance here, and argue to keep the
> existing "as" binary untouched.

In any event, the msys2.s will work to install a V2-assembled kernel
into the boot area.

I've sent a new copy of the boot directory and fs/usr/boot to Warren and
Tim to install.  msys2.s is now the program to use to install the bootstrap
and the fs/usr/boot/unix.out file is a copy of build/a.out.

This means that if the kernel is assembled using the V2 assembler under
UNIX V1 itself, then the a.out from that assembly can be used directly
by msys2 to install into the boot area.

James Markevitch

[Unix-jun72] UNIX V1 bootstrap

[Warren Toomey]

On Sat, May 17, 2008 at 11:18:56PM -0700, James A. Markevitch wrote:
> I've sent a new copy of the boot directory and fs/usr/boot to Warren and
> Tim to install.  msys2.s is now the program to use to install the bootstrap
> and the fs/usr/boot/unix.out file is a copy of build/a.out.

Thanks James, I'll check it out tonight/tomorrow.
	Warren