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From: thomson@uthub.UUCP (Brian Thomson)
Newsgroups: net.micro.68k,net.micro.16k
Subject: Re: Pre-fetch
Message-ID: <221@uthub.UUCP>
Date: Thu, 18-Jul-85 13:42:41 EDT
Article-I.D.: uthub.221
Posted: Thu Jul 18 13:42:41 1985
Date-Received: Thu, 18-Jul-85 14:35:01 EDT
References: <891@bunker.UUCP>, <644@terak.UUCP>
Organization: CSRG, University of Toronto
Lines: 10
Xref: utai net.micro.68k:719 net.micro.16k:241

Yes, the 32016 does properly handle (i.e. ignore) page fault and
protection traps on prefetches, but it still isn't quite perfect.
We have seen a 32016 continue to prefetch after partially executing
an SVC instruction, such that it uses the old user-mode PC for
the prefetch address but does the accesses in system mode.
This can be a problem if the system-space address is, eg., a device
register or if the page is valid but mapped to nonexistent memory.
-- 
		    Brian Thomson,	    CSRI Univ. of Toronto
		    {linus,ihnp4,uw-beaver,floyd,utzoo}!utcsrgv!uthub!thomson