From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
From: "Thomas Bushnell, BSG" <tb+usenet@becket.net>
Message-ID: <87lmiph421.fsf@becket.becket.net>
Content-Type: text/plain; charset=us-ascii
References: <20011001121653.3DC8F19A3D@mail.cse.psu.edu>
Subject: Re: [9fans] authorization schemes (was CORBA)
Date: Mon,  8 Oct 2001 09:36:28 +0000
Topicbox-Message-UUID: 01671db6-eaca-11e9-9e20-41e7f4b1d025

rob@plan9.bell-labs.com (rob pike) writes:

> Copy on write is easy on a uniprocessor. It gets nastier on
> a multiprocessor.  Our solution was to switch to copy on
> reference on the MP.

It can be a nice strategy to use copy-on-write to hold things like
libraries shared by many processes.  Then if one process happens to
get a breakpoint, the debugger can just write the library page in that
process's image, and the copy-on-write does the right thing.  Normal
processes all happily share.

Doesn't that break if you use copy on reference?  

Perhaps I'm misunderstanding you...