*BSD News Article 74498


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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.os.linux.hardware,comp.os.ms-windows.win95.misc,comp.os.os2.setup.misc,comp.unix.bsd.freebsd.misc
Subject: Re: HELP: Can I mix memory speeds
Date: 22 Jul 1996 22:20:22 GMT
Organization: Private BSD site, Dresden
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Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
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stephenk@netcom.com (Stephen Knilans) wrote:

> >Btw., panic does even try to flush the disk buffers, so its effect is
> >not as desastrous as you describe unless the disk subsystem itself is
> >hosed.  But in this case, you lose anyway.
> 
> Are you saying that Linux intercepts that interrupt, and flushes?

I haven't looked into Linux' code for it, but i would expect it to do
so.  The interrupt is not ``intercepted'', it's actually being
delivered as a hardware trap just like all other traps caused by
hardware events.  It has to be handled by the operating system itself
in any case.

The usual handling is to panic(), and this usually involves flushing
the disk buffers.  Of course, this is _always_ a tradeoff between the
risk of flushing wrong data, and the intention to save as much data as
you can.  But i think the general consensus is that the latter is much
more likely useful than the former is to be afraid of.  (If your data
are not yet there, you are not thinking of what you might have done if
they were there but were faulty. ;-)

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)