OPUS..BJORNDAHL@engvax.UUCP.UUCP (05/16/86)
does anyone know if it is possible to put ultrix and uVMS on the same (and only) disk? and boot either one?
george@GVAX.CS.CORNELL.EDU (George R. Boyce) (05/21/86)
In article <8605161846.AA11333@csvax.caltech.edu> OPUS..BJORNDAHL@ENGVAX.UUCP (Portia) writes: >does anyone know if it is possible to put ultrix and uVMS on the same >(and only) disk? and boot either one? I understand that DEC will not currently sell you a license that would allow you to have both vms and ultrix on the same machine (even if you had several seperate disks). They want to sell you two machines. I think DEC marketing is considering a change in this policy...
bzs@CSNET-RELAY.ARPA.UUCP (05/25/86)
>From: OPUS..BJORNDAHL@ENGVAX.UUCP (Portia) >does anyone know if it is possible to put ultrix and uVMS on the same >(and only) disk? and boot either one? A long time ago, maybe 3 years, there was an article I believe in Walter Zintz' column about this (was that the DEC Professional?) Anyhow, he didn't give any particularly useful details other than that it was someone in England he had run into who had done this with SOME version of VMS and SOME version of UNIX and SOME Vax and SOME disk. At any rate, I think the strategy was you make a large contiguous file under VMS. You then generate a UNIX which has been modified such that the boot program and the disk partitions point to this area instead of the normal 'zero'. You would build an image, roll it off from tape to the contiguous partiton and boot (I suppose the console media would have to be modified to allow the boot to start.) Although finding the exact places to change might take a little while I think it would only be a few integers and should turn out to be fairly simple (unless I am missing something here.) And of course, there would be numerous opportunities while running VMS to wreak havoc (like deleting the contiguous file and having later to figure out a way to put it into the exact same place, perhaps somehow the boot could be convinced to prompt for the block offsets, like the way SUN added another arg as in ':vmunix(major,minor,block-offset)' on an interactive boot?) Anyhow, sounds like a project, I'd buy another disk if I could... Also, no guarantee that something hasn't changed in Ultrix to make this less straightforward although I doubt it (disk partitioning? hmm, maybe that makes it easier? Only need to change the boot program?) You would of course need some sources tho not many. I propose it would be an interesting/amusing/braggadaccio kind of thing for the Ultrix group to do, if it's like I described, I mean, what the heck, it gets lonely out there in the suburbs. -Barry Shein, Boston University
z@rocksvax.UUCP (Jim Ziobro) (05/28/86)
Another way to allow VMS and Unix to coexist on a single disk is by
modifying the VMS device driver to think that the drive is shorter than
it really is. All VMS utilities are supposed to query the disk driver
as to its geometry.
We did this on a RP07 once. For the most part it worked except it
seemed that VMS was writing on the Unix partition randomly anyways. If
you make the VMS partition 600 cylinders you can boot unix without
modifying the Unix boot floppy by booting the 'g' partition. Perhaps
some utilties in VMS ignore the values in the device driver. BTW, this
was back with VMS2. and 4.1BSD.
//Z\\
James M. Ziobro
Ziobro.Henr@Xerox.COM
{rochester,amd,sunybcs,ihnp4}!rocksvax!z
Ziobro:henr801g:xerox