Re: installboot is broken

[Johnny Billquist <bqt%softjar.se@localhost>]

On 2013-03-24 22:20, Anders Magnusson wrote:
> On 03/24/2013 10:07 PM, Mark Pizzolato - Info Comm wrote:
> > On Sunday, March 24, 2013 at 1:51 PM, Anders Magnusson wrote:
> > > On 03/24/2013 08:08 PM, Mark Pizzolato - Info Comm wrote:
> > > > This issue CAN and SHOULD be fixed.  However, there is a fundamental
> > > > chicken and egg problem here in that every available NetBSD vax ISO
> > > > image
> > > > going back to the earliest available (NetBSD 1.6.2) are all missing
> > > > this boot
> > > > block on that media.  Clearly no one has attempted to install any
> > > > version of
> > > > NetBSD on a legacy VAX (one which boots without the aid of a ROM based
> > > > VMB).
> > > I have done that on all of them; since I actually wrote the code :-)
> > Something has broken since then or you really never installed from a
> > CD.  These systems generally didn't have CD drives...
> True.  I do not ever think I have installed from CD.

I actually have done this, but with a slight twist. dd the CD onto any 
RA disk, and then you're set to go. (I also have the VMS 7.3 CD on an RA 
disk, from which I then did my VMS installation on the 8650 from.)

> > > > This issue came to light due to efforts to use NetBSD with the
> > > > latest simh's
> > > > new VAX simulators (VAX 11/730, VAX 11/750 and VAX 8600/8650).  All of
> > > > these systems use VMB to initiate the bootstrap process and since
> > > > the disk
> > > > being booted doesn't contain a Digitial ODS2 disk structure, they
> > > > boot using
> > > > they achieve a boot using the bootstrap code provide in sector 0 of the
> > > > device being booted.  The systems with ROM based VMB have built in code
> > > > in the ROM VMB to use the pointers describing the bootstrap location in
> > > > sector 0 to directly load the rest of the bootstrap (usually from
> > > > sectors 1 thru
> > > > 13) and dispatch to that.
> > > You are not supposed to use VMB on those big machines.  You should load
> > > boot directly from the console media.
> > > This is how all BSDs always have worked.
> > I guess that might be possible (even on a VAX 11/750, you could always
> > boot thru the console TU58).  Given hard booting a dedicated loader
> > program the details of the boot block won't matter.  However, you'd
> > still have to make the TU58 media bootable.  The 750 Boot procedure
> > (for any device) loads sector 0 and starts execution at offset 2 of
> > the 512 bytes loaded.   There current isn't any code in sector 0.
> This seems to be the installboot bug, yes.  But in some way it must get
> the boot code installed sometimes; I installed NetBSD 6 on a fresh
> 4000/600 just a few months ago.  It had VMS on its disks before.  (Or
> maybe I did some creative to get it work but do not remember it :-)

Ha! Yes! That is the point.
The MicroVAX, as well as probably all "new" VAXen use the boot block in 
a different way. They just read the boot block in to get a couple of 
magic values, and then start execution from data read in from block 1. 
The ROM-based VMB have been working right all the time.
It is just the console based VMB.EXE which this does not work on.

> > Many systems I came into contact with from the early 80's onward
> > (mostly 750's then) booted BSD OSes directly from disk, No console
> > media in the picture.    Likewise, as Johnny mentioned, Ultrix has
> > always booted directly from the target media using a 'Boot Block' boot.
> Hm, this is old time, but IIRC the problem was not the booting itself,
> it was that my 750 did not have ROM for the RA drives.

That would be another, but maybe even more interesting problem. :-)

> Also, there were some trickiness with the microcode patching which
> needed to be done, it was not trivial to get it right.

We still have the microcode patch distributed with NetBSD. As far as I 
know, it originated in Ultrix.

        Johnny

--
Johnny Billquist                  || "I'm on a bus
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