From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ronald G Minnich <rminnich@lanl.gov>
To: <9fans@cse.psu.edu>
Subject: Re: [9fans] useful language extension, or no?
In-Reply-To: <20020717222200.7C97C19ACF@mail.cse.psu.edu>
Message-ID: <Pine.LNX.4.33.0207171625010.7533-100000@snaresland.acl.lanl.gov>
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Date: Wed, 17 Jul 2002 16:28:04 -0600
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On Thu, 18 Jul 2002 arisawa@ar.aichi-u.ac.jp wrote:

> Is it unavoidable machine codes in stack are executable?

your architecture has to support r,w,x on segments. then the OS has to
actually make that work. Most OSes I've seen always set x on all segments,
including stack. It's not even possible to do things otherwise on many of
them.

Does plan9 have x-only and r-only and rw-only segments in the VM system? I
was pretty sure it did not.

I got into fruitless argument with an architecture guy about the value of
x bits in the VM system. His argument was that it was a bad idea for
performance. I doubt even in the x86 that it is solid and well-tested, but
who knows.

ron