From owner-freebsd-questions  Sat Aug 11 10:47:36 2001
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Date: Sat, 11 Aug 2001 12:47:31 -0500 (CDT)
From: mark tinguely <tinguely@web.cs.ndsu.nodak.edu>
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To: freebsd-questions@FreeBSD.ORG, root@hostonfly.com
Subject: Re: Kernel address space
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>  Can someone tell me please - do I need to increase kernel address
>  space if I have box with 2 GB RAM and how to increase it?
>  System on this box is unstable. I tried to increase like
>  http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/advanced.html#CHANGE-KERNEL-ADDRESS-SPACE
>  but got unloadable kernel...

the kernel address space is the VIRTUAL kernel memory. The 4.x default is
1GB for kernel virtual and 3GB for user virtual space. This does not
guarrentee that all of that space will be physically backed with real
memory.

You can ask for 2GB of kernel virtual space, but with only 2GB physical
memory, you may still only get, say 512MB, of RAM backing up that kernel
virtual space and the rest is used in the user virtual space or stay
un-used at a given time, depending on all that is going on in the system.

You do not have to change the formula unless yo want to increase
space for the kernel (and you have enough physical memory to honor the
pages).

What exactly did you try and what was the error message. 

--mark tinguely

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