*BSD News Article 14225


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Newsgroups: comp.os.386bsd.development
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From: wollman@sadye.emba.uvm.edu (Garrett Wollman)
Subject: Re: File Truncation Philosophy
Message-ID: <1993Apr8.025858.22137@uvm.edu>
Sender: news@uvm.edu
Organization: University of Vermont, EMBA Computer Facility
References: <CGD.93Apr1204906@eden.CS.Berkeley.EDU> <1993Apr2.072443.790@cm.cf.ac.uk> <1993Apr8.002028.2376@fcom.cc.utah.edu>
Date: Thu, 8 Apr 1993 02:58:58 GMT
Lines: 26

In article <1993Apr8.002028.2376@fcom.cc.utah.edu> terry@cs.weber.edu (A Wizard of Earth C) writes:
>I can live with the canonical fix, but want the prettier fix, since
>the file would act like it *wasn't* a swap store... the same actions
>would be required on any inode write attempt, not just truncation.

I can't live with the prettier fix, unless you have a way to make
other memory-mapped files work correctly.  Remember that, as far as
the VM system is concerned, an executable is just another
memory-mapped file.  This is the reason why the ``obvious'' fix could
not be made in the vnodepager: it doesn't know that the file it's
paging is an executable---only execve() knows that.  I would argue
that that is as it should be.

I haven't tried out the execve implementation of the ``obvious'' fix
to see if it works yet.  (I'm so reluctant to reboot my machine when
my NTP is doing 
	xntpd[78]: offset 0.006774 freq -62.73834 comp 4
so well.)

-GAWollman

-- 
Garrett A. Wollman   | Shashish is simple, it's discreet, it's brief. ... 
wollman@emba.uvm.edu | Shashish is the bonding of hearts in spite of distance.
uvm-gen!wollman      | It is a bond more powerful than absence.  We like people
UVM disagrees.       | who like Shashish.  - Claude McKenzie + Florent Vollant