From owner-freebsd-hackers  Sat Mar 15  6:48:14 2003
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Date: Sat, 15 Mar 2003 08:48:04 -0600 (CST)
From: Mark Tinguely <tinguely@casselton.net>
Message-Id: <200303151448.h2FEm4Mt089695@casselton.net>
To: andykinney@advantagecom.net
Subject: Re: increasing KVA_PAGES and broken pthreads
Cc: freebsd-hackers@FreeBSD.ORG
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Intel x86 hardware allows windows of 4GB of virtual memory even if
you have the PSE-36 and the PAE extensions with more the 4GB of
physical memory. Sound a little like Intel's 64KB windows, but
if I remember correctly, the 4GB does not have to be contiguous.

It would require a true MMU such as those in the 64 bit architectures
(AMD opteron, Intel ia64, sparc64) to simulataneously be able to use
more than 4GB of RAM.

So far the thought it is better to go with a true 64 MMU than take
and get a flat address space than take the performance hit (, plus
the memory loss for the much larger page table without much benefit)
than try to shuffle in the 4GB windows. Check the thread on this topic
in the archives.

--Mark Tinguely.

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