On 14-Mar-98 Chuck Cranor wrote:

>> I subscribed to this list thinking there would be discussion of uvm.
>> Instead, I've received absolutely no mail from it, on any topic whatsoever.
>> Is anyone there?  Is the mailing list functional?
>
> what aspect of UVM would you like to discuss?
>
> chuck

Well, hrmph....actually, I was looking to follow whatever might be going on and
then see if I had additional questions.

Unfortunately, I wasn't able to get a kernel with it running.  I have a 1.2/i386
installation.  A 1.3 kernel built (by hand for my hardware) with uvm refused to
boot -- froze trying to run init, I think.  My 1.2 kernel with uvm as a drop-in
replacement never built successfully.

One thing I do know is that with the Mach vm system, shared libraries don't
share code pages properly.  I've tested things pretty thoroughly, and that
conclusion sifts out consistently.  Code pages from core process files are
properly shared; those from shared library files are not.  You are literally
better off to run a completely statically linked system, than to use any shared
libraries (especially with X).  I've been meaning to plant some code in the
kernel to get internal record keeping dumps in search of a cause, because after
searching every conceivable code path from one end to the other, I haven't found
any smoking guns.

Of course, the CSRG code never had shared libraries in mind.  The support was
hacked in on top using the GNU development tools.  In my view, the shared
library support has been unsuccessful and is counter-productive.

There may be one or two other problems, but that one I'm convinced of.

Aside from the traditional page cleaner stability problems, I guess that's the
main reason the uvm announcement attracted my interest:  hoping a fresh effort
would somehow cure that problem as a by-product, and obviate further digging.


--Jim Howard  <jiho@mail.c-zone.net>


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E-Mail: jiho@mail.c-zone.net
Date: 14-Mar-98
Time: 15:21:03

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