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From: barry@adelie.Adelie.COM (Barry A. Burke)
Newsgroups: comp.os.research,mod.os
Subject: Re: Shared Libraries
Message-ID: <3046@sdcsvax.UCSD.EDU>
Date: Sun, 26-Apr-87 22:53:13 EDT
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Posted: Sun Apr 26 22:53:13 1987
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Ooops. In my previous article, I said the list of shared routines' names
where kept at the start of each programs DATA area. Wrong- the indirect
"address" pointer were kept there. The list of names are actually kept in a
list that begins at a fixed memory locations (but it links through several
different "libraries", each within it's own segment(s)). The routines
themselves are generally free-floating, but pre-loaded (at startup time) into
fixed memory areas. This works well in a truly dynamic paging environment- the
pages are on the paging device until needed, then they are dynamically located
in memory when paged in. The Prime's have neat hardware to do this sort of
memory management (wish that DEC did!), so there is very little overhead in
this scheme. I'm not sure sure that the 68000 MMU can handle such complex
tasks (I recall discussions at Prime that indicated that such was out of the
realm of most any `generic' MMU).

Sorry for any confusion...

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