Xref: utzoo comp.sys.amiga:67659 comp.os.minix:12643 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!strath-cs!cs.glasgow.ac.uk!bru-cc!eesrajm From: eesrajm@cc.brunel.ac.uk (Andrew J Michael) Newsgroups: comp.sys.amiga,comp.os.minix Subject: Re: MINIX on the Amiga... Summary: Not as bad as all that Message-ID: <1838@Terra.cc.brunel.ac.uk> Date: 2 Oct 90 17:59:40 GMT References: <1990Sep24.114627.14857@watserv1.waterloo.edu> <1990Oct1.000617.3676@zorch.SF-Bay.ORG> Organization: Brunel University, Uxbridge, UK Lines: 70 In article <1990Oct1.000617.3676@zorch.SF-Bay.ORG>, xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) writes: > sreiz@cs.vu.nl (Reiz Steven) writes: > >guineau@wjg.enet.dec.com (W. John Guineau) writes: > > > >>I've been talking with Andy Tanenbaum about Minix. > >>He says he doubts that it will run on a 68030 based machine > >>(ie A3000, A2500/30). Minix does not set up the MMU. > [...] [stuff deleted] > Whew! We already got bitten by this one with AmigaBASIC. I hope > someone guts this with a huge set of "#ifdef SANE_DESIGN"s pretty > fast and leaves the full 32-bit memory addressing accessible. This > is pretty gross for code written for the 1990's. > > >- Minix can't access memory outside the 16 MB range. This is caused by > > the way addresses are encoded in the memory manager. I don't know if > > any 68020/68030 boards really have memory outside the 16 MB range, but this > > doesn't seem a very serious problem to me anyhow. > > It does to me! I'm running a vanilla Amiga 2000 with 9.5 meg of > RAM, and I could easily put ten times as much to use on a regular > basis. [stuff deleted] > There is little if any excuse for > turning address longwords into records to save a byte here or > there in a memory management scheme's overhead when memory is dirt > cheap and widely available. > > Kent, the man from xanth. > > -- > Fanning the flames a bit, my hands were cold. Andy Tanenbaum is probably correct in saying that out-of-the box MINIX won't run on a 68030. It won't run on a 68020 either. The problem is in the way dummy stack frames are set up in stmpx.s; they are correct for a 68000, but omit the format word for 68020s and above. You only need to change two lines, if my memory serves me correctly. Note that you don't need to set up the 68030 MMU unless you are actually using it for anything. By default the MMU is switched off on a reset, so there isn't any problem there. As regards your other comments, they are, IMHO a bit over the top. Remember that the code from which the Amiga MINIX is derived was originally written to run on an ST, which has a hardware design limitation of 4Mb of memory. I think that the encoding of the vector number into the upper nybble of the PC is actually pretty neat; admittedly not very portable, but then we all have 20-20 hindsight, don't we ? The difficulties of running MINIX on 68020s and the like have been addressed previously in this newsgroup; I have been running a 68020 MINIX engine since April 1989, and I'm not the only one. And remember that memory is not necessarily as cheap elsewhere in the world as it is in the USA ... Andy Michael -- Andy Michael (eesrajm@cc.brunel.ac.uk) " Emulation is the sincerest 85 Hawthorne Crescent form of pottery." West Drayton Middlesex - William Frend De Morgan UB7 9PA