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From: John Baldwin <jhb@freebsd.org>
To: "Jin Guojun [VFFS]" <j_guojun@lbl.gov>
Date: Wed, 9 Aug 2006 17:12:47 -0400
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Cc: Julian Stacey <jhs@berklix.org>, freebsd-hardware@freebsd.org
Subject: Re: Real and available memory?
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On Wednesday 09 August 2006 16:34, Jin Guojun [VFFS] wrote:

Please don't use HTML-only e-mail.

>> Well, that's where the missing 40 meg is. :)  The kernel text (including
>> any modules and preloaded mfsroot's) aren't include in the 'avail memory'
>> count.
> 
> This is not where the memory goes.
> The MFS root is probably not allocated yet at this point.

Huh?  Of course it is!  You load it from /boot/loader into RAM at the same
point when you load the kernel.  All of the kernel text plus any loaded
modules are not considered available memory when 'avail memory' is output.
(Along with a few other pages needed for things like crashdumps, some VM
bootstrapping data structures, etc.)  You can't load a MFS root after the
kernel is booted because if it's the root filesystem, there's no place for
it to be loaded from once the kernel boots.

-- 
John Baldwin