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RE: installboot is broken
On Sunday, March 24, 2013 at 2:20 PM, Anders Magnusson wrote:
> >>> 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 :-)
You didn't have to do anything special. The 4000/600 has a ROM base VMB
version which doesn't need any code in sector 0.
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