Path: utzoo!utgpu!water!watmath!clyde!rutgers!mit-eddie!bbn!rochester!PT.CS.CMU.EDU!IUS3.IUS.CS.CMU.EDU!ralphw
From: ralphw@IUS3.IUS.CS.CMU.EDU (Ralph Hyre)
Newsgroups: comp.os.minix
Subject: Re: Question + Threat = Answer
Message-ID: <1280@PT.CS.CMU.EDU>
Date: 1 Apr 88 21:36:39 GMT
References: <207600002@trsvax> <207600004@trsvax> <294@sp7040.UUCP>
Sender: netnews@PT.CS.CMU.EDU
Organization: Carnegie-Mellon University, CS/RI
Lines: 34

In article <294@sp7040.UUCP> jsp@sp7040.UUCP (John Peters) writes:
>In article <207600004@trsvax>, johnm@trsvax.UUCP writes:
>>. this is the kind of response we can expect
>> then I would hope that the ST owners don't lose any sleep over not having 
>> their programs run on the IBM Minix.
>
>	This is indeed going to be a real problem.  However I can no answer
>to the problem.  It really lies with the klude of 64k segments (yell at intel).
Well, yell at more people than Intel, most processors I know of have some
sort of segmentation warts on them.
In the 68000 world, for example, parts of the Mac 'OS' limit code segments to
32K, presumably to provide for easy-to-relocate code. (I suppose you can use
relative branches that way.)  If I were to try to port Minix to a machine with
16 bit addresses (and bank-switched memory), it would also effectively have 
64k segments.

I think the Minix ST port (and other ports) should make the developer do
something explicit to override the 64k segment limitation (like a special
compiler switch), because it will be a win when you add swapping & paging 
anyway, since you will be able to shove code anywhere in the address space
(modulo 64k).

The problem of trying to port code between the Unix variants will also happen
with Minix, unless someone (Andy?) takes a stand.  It would be a shame.
--
					- Ralph W. Hyre, Jr.

Internet: ralphw@ius2.cs.cmu.edu    Phone:(412)268-{2847,3275} CMU-{BUGS,DARK}
Amateur Packet Radio: N3FGW@W2XO, or c/o W3VC, CMU Radio Club, Pittsburgh, PA
-- 
					- Ralph W. Hyre, Jr.

Internet: ralphw@ius2.cs.cmu.edu    Phone:(412)268-{2847,3275} CMU-{BUGS,DARK}
Amateur Packet Radio: N3FGW@W2XO, or c/o W3VC, CMU Radio Club, Pittsburgh, PA