DragonFly BSD
DragonFly kernel List (threaded) for 2003-09
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Re: Relocation (Re: Package system)

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Wed, 3 Sep 2003 11:12:24 -0700 (PDT)

:ibotty <me@xxxxxxxxxx> wrote:
:> btw: is someone interested in prelinking? on freebsd5, there is an effort to
:> prelink. but i do not know, how far this is.
:> if there is interest, i may dedicate some of my spare time to it (in one
:> month, more or less).
:prelinking is a really bad and ugly hack.
:	Sander

    It kinda reminds me of Amiga shared libraries... in the UNIX address
    space model, though, it's even easier.  I'm not sure what this 
    so-called 'prelinking' actually is, but I know how I would implement it
    in Dragonfly:

    The kernel manages a small section of reserved VM address space and
    generates pre-loaded library images within that space.  Library
    dependancies are also preloaded and linked.  When a user process 
    requests a library, if the user's VM space corresponding to 
    the kernel managed VM space is not in use, the kernel can simply map
    its pre-loaded version (+ dependancies) into the user's VM space.

    Not that I am going to actually do this any time soon.  I do not
    consider it to be all that important of an issue.  There are no
    significant performance gains, even for scripts, and memory is only
    saved in certain particular situations (lots of non-forking
    separately-exec'd instances).  But it seems to me that it *can*
    be done in a fashion that is totally transparent and fully compatible.

					Matthew Dillon 

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