[prev in list] [next in list] [prev in thread] [next in thread] 

List:       eros-arch
Subject:    Resending
From:       Jonathan Shapiro shap () cobra ! cis ! upenn ! edu
Date:       1995-09-05 15:37:05
[Download RAW message or body]

Sorry - I had just added Colin McLean to the list, but like an idiot I
didn't save the new file out of emacs before shipping the note out.  Duh.


Subject: A quote from Organick

Seems as applicable now as ever (modulo KeyKOS, of course):

    The failure to solve the general protection problem by prior
    architectures (descriptor based or not) has had serious
    consequences.  It has meant, for example, that system software
    modules must be set apart and explicitly protected from
    application programs; the former cannot be permitted to *trust*
    the integrity of in-bount pointer arguments such as descriptors.
    Thie dispartiy has, in turn, made it imptactical and unsage to
    permit users the freedom to substitute their own versions of
    selected modules.  A frequent consequence has been that much
    software within a system tends to be relegated to a small number
    of very large (monolithic) *protection domains*.  This
    consequence, in turn, leads to high software maintenance costs.

						Elliott I. Organick
			A Programmer's View of the Intel 432 System

I'ld note as an aside that the 432 had not equivalent to factories,
and therefore suggest that it didn't really solve the problem either.


Jonathan

[prev in list] [next in list] [prev in thread] [next in thread]