Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!rpi!crdgw1!crdos1!davidsen
From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: comp.arch
Subject: Re: Workstation Data Integrity
Message-ID: <2476@crdos1.crd.ge.COM>
Date: 30 Aug 90 14:18:46 GMT
References: <1990Aug3.204358.330@portia.Stanford.EDU> <40694@mips.mips.COM> <2399@crdos1.crd.ge.COM> <1990Aug29.150017@sparc2.hri.com>
Reply-To: davidsen@crdos1.crd.ge.com (bill davidsen)
Organization: GE Corp R&D Center, Schenectady NY
Lines: 20

In article <1990Aug29.150017@sparc2.hri.com> limey@hri.com writes:
| In the interest of keeping the machine up, even with a potentially fatal
| problem, how about having the hardware notify the OS (through some kind
| of exception) that there is a problem with a certain area of memory? The
| O/S could then dynamically remove that portion of physical
| memory from it's virtual map after copying the data to a new page, 
| log the error, and continue processing. 

  This is how it usually works in a good O/S. If the page is
instructions, it can be reloaded from disk, as can an unmodified data
page. If the data page is dirty the process must be terminated.

  On a PC running XX-DOS, it makes more sense to take the whole system
down, since there is no way to tell if the page is dirty or clean, and
no memory mapping to do anything about it if you could. And no penalty,
since the current task is the only task (unless extenders are running).

-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
    VMS is a text-only adventure game. If you win you can use unix.